Python/compile.c

/* Compile an expression node to intermediate code */

/* XXX TO DO:
   XXX add __doc__ attribute == co_doc to code object attributes?
   XXX   (it's currently the first item of the co_const tuple)
   XXX Generate simple jump for break/return outside 'try...finally'
   XXX Allow 'continue' inside finally clause of try-finally
   XXX New opcode for loading the initial index for a for loop
   XXX other JAR tricks?
*/

#include "Python.h"

#include "node.h"
#include "token.h"
#include "graminit.h"
#include "compile.h"
#include "symtable.h"
#include "opcode.h"
#include "structmember.h"

#include <ctype.h>

/* Three symbols from graminit.h are also defined in Python.h, with
   Py_ prefixes to their names.  Python.h can't include graminit.h
   (which defines too many confusing symbols), but we can check here
   that they haven't changed (which is very unlikely, but possible). */
#if Py_single_input != single_input
  #error "single_input has changed -- update Py_single_input in Python.h"
#endif
#if Py_file_input != file_input
  #error "file_input has changed -- update Py_file_input in Python.h"
#endif
#if Py_eval_input != eval_input
  #error "eval_input has changed -- update Py_eval_input in Python.h"
#endif

int Py_OptimizeFlag = 0;

#define OP_DELETE 0
#define OP_ASSIGN 1
#define OP_APPLY 2

#define VAR_LOAD 0
#define VAR_STORE 1
#define VAR_DELETE 2

#define DEL_CLOSURE_ERROR \
"can not delete variable '%.400s' referenced in nested scope"

#define DUPLICATE_ARGUMENT \
"duplicate argument '%s' in function definition"

#define ILLEGAL_DYNAMIC_SCOPE \
"%.100s: exec or 'import *' makes names ambiguous in nested scope"

#define GLOBAL_AFTER_ASSIGN \
"name '%.400s' is assigned to before global declaration"

#define GLOBAL_AFTER_USE \
"name '%.400s' is used prior to global declaration"

#define LOCAL_GLOBAL \
"name '%.400s' is a function parameter and declared global"

#define LATE_FUTURE \
"from __future__ imports must occur at the beginning of the file"

#define ASSIGN_DEBUG \
"can not assign to __debug__"

#define MANGLE_LEN 256

#define OFF(x) offsetof(PyCodeObject, x)

static PyMemberDef code_memberlist[] = {
	{"co_argcount",	T_INT,		OFF(co_argcount),	READONLY},
	{"co_nlocals",	T_INT,		OFF(co_nlocals),	READONLY},
	{"co_stacksize",T_INT,		OFF(co_stacksize),	READONLY},
	{"co_flags",	T_INT,		OFF(co_flags),		READONLY},
	{"co_code",	T_OBJECT,	OFF(co_code),		READONLY},
	{"co_consts",	T_OBJECT,	OFF(co_consts),		READONLY},
	{"co_names",	T_OBJECT,	OFF(co_names),		READONLY},
	{"co_varnames",	T_OBJECT,	OFF(co_varnames),	READONLY},
	{"co_freevars",	T_OBJECT,	OFF(co_freevars),	READONLY},
	{"co_cellvars",	T_OBJECT,	OFF(co_cellvars),	READONLY},
	{"co_filename",	T_OBJECT,	OFF(co_filename),	READONLY},
	{"co_name",	T_OBJECT,	OFF(co_name),		READONLY},
	{"co_firstlineno", T_INT,	OFF(co_firstlineno),	READONLY},
	{"co_lnotab",	T_OBJECT,	OFF(co_lnotab),		READONLY},
	{NULL}	/* Sentinel */
};

static void
code_dealloc(PyCodeObject *co)
{
	Py_XDECREF(co->co_code);
	Py_XDECREF(co->co_consts);
	Py_XDECREF(co->co_names);
	Py_XDECREF(co->co_varnames);
	Py_XDECREF(co->co_freevars);
	Py_XDECREF(co->co_cellvars);
	Py_XDECREF(co->co_filename);
	Py_XDECREF(co->co_name);
	Py_XDECREF(co->co_lnotab);
	PyObject_DEL(co);
}

static PyObject *
code_repr(PyCodeObject *co)
{
	char buf[500];
	int lineno = -1;
	char *filename = "???";
	char *name = "???";

	if (co->co_firstlineno != 0)
		lineno = co->co_firstlineno;
	if (co->co_filename && PyString_Check(co->co_filename))
		filename = PyString_AS_STRING(co->co_filename);
	if (co->co_name && PyString_Check(co->co_name))
		name = PyString_AS_STRING(co->co_name);
	PyOS_snprintf(buf, sizeof(buf),
		      "<code object %.100s at %p, file \"%.300s\", line %d>",
		      name, co, filename, lineno);
	return PyString_FromString(buf);
}

static int
code_compare(PyCodeObject *co, PyCodeObject *cp)
{
	int cmp;
	cmp = PyObject_Compare(co->co_name, cp->co_name);
	if (cmp) return cmp;
	cmp = co->co_argcount - cp->co_argcount;
	if (cmp) return cmp;
	cmp = co->co_nlocals - cp->co_nlocals;
	if (cmp) return cmp;
	cmp = co->co_flags - cp->co_flags;
	if (cmp) return cmp;
	cmp = PyObject_Compare(co->co_code, cp->co_code);
	if (cmp) return cmp;
	cmp = PyObject_Compare(co->co_consts, cp->co_consts);
	if (cmp) return cmp;
	cmp = PyObject_Compare(co->co_names, cp->co_names);
	if (cmp) return cmp;
	cmp = PyObject_Compare(co->co_varnames, cp->co_varnames);
	if (cmp) return cmp;
	cmp = PyObject_Compare(co->co_freevars, cp->co_freevars);
	if (cmp) return cmp;
	cmp = PyObject_Compare(co->co_cellvars, cp->co_cellvars);
	return cmp;
}

static long
code_hash(PyCodeObject *co)
{
	long h, h0, h1, h2, h3, h4, h5, h6;
	h0 = PyObject_Hash(co->co_name);
	if (h0 == -1) return -1;
	h1 = PyObject_Hash(co->co_code);
	if (h1 == -1) return -1;
	h2 = PyObject_Hash(co->co_consts);
	if (h2 == -1) return -1;
	h3 = PyObject_Hash(co->co_names);
	if (h3 == -1) return -1;
	h4 = PyObject_Hash(co->co_varnames);
	if (h4 == -1) return -1;
	h5 = PyObject_Hash(co->co_freevars);
	if (h5 == -1) return -1;
	h6 = PyObject_Hash(co->co_cellvars);
	if (h6 == -1) return -1;
	h = h0 ^ h1 ^ h2 ^ h3 ^ h4 ^ h5 ^ h6 ^
		co->co_argcount ^ co->co_nlocals ^ co->co_flags;
	if (h == -1) h = -2;
	return h;
}

/* XXX code objects need to participate in GC? */

PyTypeObject PyCode_Type = {
	PyObject_HEAD_INIT(&PyType_Type)
	0,
	"code",
	sizeof(PyCodeObject),
	0,
	(destructor)code_dealloc, 	/* tp_dealloc */
	0,				/* tp_print */
	0, 				/* tp_getattr */
	0,				/* tp_setattr */
	(cmpfunc)code_compare, 		/* tp_compare */
	(reprfunc)code_repr,		/* tp_repr */
	0,				/* tp_as_number */
	0,				/* tp_as_sequence */
	0,				/* tp_as_mapping */
	(hashfunc)code_hash, 		/* tp_hash */
	0,				/* tp_call */
	0,				/* tp_str */
	PyObject_GenericGetAttr,	/* tp_getattro */
	0,				/* tp_setattro */
	0,				/* tp_as_buffer */
	Py_TPFLAGS_DEFAULT,		/* tp_flags */
	0,				/* tp_doc */
	0,				/* tp_traverse */
	0,				/* tp_clear */
	0,				/* tp_richcompare */
	0,				/* tp_weaklistoffset */
	0,				/* tp_iter */
	0,				/* tp_iternext */
	0,				/* tp_methods */
	code_memberlist,		/* tp_members */
	0,				/* tp_getset */
	0,				/* tp_base */
	0,				/* tp_dict */
	0,				/* tp_descr_get */
	0,				/* tp_descr_set */
	0,				/* tp_dictoffset */
	0,				/* tp_init */
	0,				/* tp_alloc */
	0,				/* tp_new */
};

#define NAME_CHARS \
	"0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ_abcdefghijklmnopqrstuvwxyz"

/* all_name_chars(s): true iff all chars in s are valid NAME_CHARS */

static int
all_name_chars(unsigned char *s)
{
	static char ok_name_char[256];
	static unsigned char *name_chars = (unsigned char *)NAME_CHARS;

	if (ok_name_char[*name_chars] == 0) {
		unsigned char *p;
		for (p = name_chars; *p; p++)
			ok_name_char[*p] = 1;
	}
	while (*s) {
		if (ok_name_char[*s++] == 0)
			return 0;
	}
	return 1;
}

static int
intern_strings(PyObject *tuple)
{
	int i;

	for (i = PyTuple_GET_SIZE(tuple); --i >= 0; ) {
		PyObject *v = PyTuple_GET_ITEM(tuple, i);
		if (v == NULL || !PyString_Check(v)) {
			Py_FatalError("non-string found in code slot");
			PyErr_BadInternalCall();
			return -1;
		}
		PyString_InternInPlace(&PyTuple_GET_ITEM(tuple, i));
	}
	return 0;
}

PyCodeObject *
PyCode_New(int argcount, int nlocals, int stacksize, int flags,
	   PyObject *code, PyObject *consts, PyObject *names,
	   PyObject *varnames, PyObject *freevars, PyObject *cellvars,
	   PyObject *filename, PyObject *name, int firstlineno,
	   PyObject *lnotab) 
{
	PyCodeObject *co;
	int i;
	/* Check argument types */
	if (argcount < 0 || nlocals < 0 ||
	    code == NULL ||
	    consts == NULL || !PyTuple_Check(consts) ||
	    names == NULL || !PyTuple_Check(names) ||
	    varnames == NULL || !PyTuple_Check(varnames) ||
	    freevars == NULL || !PyTuple_Check(freevars) ||
	    cellvars == NULL || !PyTuple_Check(cellvars) ||
	    name == NULL || !PyString_Check(name) ||
	    filename == NULL || !PyString_Check(filename) ||
	    lnotab == NULL || !PyString_Check(lnotab) ||
	    !PyObject_CheckReadBuffer(code)) {
		PyErr_BadInternalCall();
		return NULL;
	}
	intern_strings(names);
	intern_strings(varnames);
	intern_strings(freevars);
	intern_strings(cellvars);
	/* Intern selected string constants */
	for (i = PyTuple_Size(consts); --i >= 0; ) {
		PyObject *v = PyTuple_GetItem(consts, i);
		if (!PyString_Check(v))
			continue;
		if (!all_name_chars((unsigned char *)PyString_AS_STRING(v)))
			continue;
		PyString_InternInPlace(&PyTuple_GET_ITEM(consts, i));
	}
	co = PyObject_NEW(PyCodeObject, &PyCode_Type);
	if (co != NULL) {
		co->co_argcount = argcount;
		co->co_nlocals = nlocals;
		co->co_stacksize = stacksize;
		co->co_flags = flags;
		Py_INCREF(code);
		co->co_code = code;
		Py_INCREF(consts);
		co->co_consts = consts;
		Py_INCREF(names);
		co->co_names = names;
		Py_INCREF(varnames);
		co->co_varnames = varnames;
		Py_INCREF(freevars);
		co->co_freevars = freevars;
		Py_INCREF(cellvars);
		co->co_cellvars = cellvars;
		Py_INCREF(filename);
		co->co_filename = filename;
		Py_INCREF(name);
		co->co_name = name;
		co->co_firstlineno = firstlineno;
		Py_INCREF(lnotab);
		co->co_lnotab = lnotab;
	}
	return co;
}


/* Data structure used internally */

/* The compiler uses two passes to generate bytecodes.  The first pass
   builds the symbol table.  The second pass generates the bytecode.

   The first pass uses a single symtable struct.  The second pass uses
   a compiling struct for each code block.  The compiling structs
   share a reference to the symtable.

   The two passes communicate via symtable_load_symbols() and via
   is_local() and is_global().  The former initializes several slots
   in the compiling struct: c_varnames, c_locals, c_nlocals,
   c_argcount, c_globals, and c_flags.
*/

/* All about c_lnotab.

c_lnotab is an array of unsigned bytes disguised as a Python string.  In -O
mode, SET_LINENO opcodes aren't generated, and bytecode offsets are mapped
to source code line #s (when needed for tracebacks) via c_lnotab instead.
The array is conceptually a list of
    (bytecode offset increment, line number increment)
pairs.  The details are important and delicate, best illustrated by example:

    byte code offset    source code line number
        0		    1
        6		    2
       50		    7
      350                 307
      361                 308

The first trick is that these numbers aren't stored, only the increments
from one row to the next (this doesn't really work, but it's a start):

    0, 1,  6, 1,  44, 5,  300, 300,  11, 1

The second trick is that an unsigned byte can't hold negative values, or
values larger than 255, so (a) there's a deep assumption that byte code
offsets and their corresponding line #s both increase monotonically, and (b)
if at least one column jumps by more than 255 from one row to the next, more
than one pair is written to the table. In case #b, there's no way to know
from looking at the table later how many were written.  That's the delicate
part.  A user of c_lnotab desiring to find the source line number
corresponding to a bytecode address A should do something like this

    lineno = addr = 0
    for addr_incr, line_incr in c_lnotab:
        addr += addr_incr
        if addr > A:
            return lineno
        lineno += line_incr

In order for this to work, when the addr field increments by more than 255,
the line # increment in each pair generated must be 0 until the remaining addr
increment is < 256.  So, in the example above, com_set_lineno should not (as
was actually done until 2.2) expand 300, 300 to 255, 255,  45, 45, but to
255, 0,  45, 255,  0, 45.
*/

struct compiling {
	PyObject *c_code;	/* string */
	PyObject *c_consts;	/* list of objects */
	PyObject *c_const_dict; /* inverse of c_consts */
	PyObject *c_names;	/* list of strings (names) */
	PyObject *c_name_dict;  /* inverse of c_names */
	PyObject *c_globals;	/* dictionary (value=None) */
	PyObject *c_locals;	/* dictionary (value=localID) */
	PyObject *c_varnames;	/* list (inverse of c_locals) */
	PyObject *c_freevars;	/* dictionary (value=None) */
	PyObject *c_cellvars;	/* list */
	int c_nlocals;		/* index of next local */
	int c_argcount;		/* number of top-level arguments */
	int c_flags;		/* same as co_flags */
	int c_nexti;		/* index into c_code */
	int c_errors;		/* counts errors occurred */
	int c_infunction;	/* set when compiling a function */
	int c_interactive;	/* generating code for interactive command */
	int c_loops;		/* counts nested loops */
	int c_begin;		/* begin of current loop, for 'continue' */
	int c_block[CO_MAXBLOCKS]; /* stack of block types */
	int c_nblocks;		/* current block stack level */
	char *c_filename;	/* filename of current node */
	char *c_name;		/* name of object (e.g. function) */
	int c_lineno;		/* Current line number */
	int c_stacklevel;	/* Current stack level */
	int c_maxstacklevel;	/* Maximum stack level */
	int c_firstlineno;
	PyObject *c_lnotab;	/* Table mapping address to line number */
	int c_last_addr, c_last_line, c_lnotab_next;
	char *c_private;	/* for private name mangling */
	int c_tmpname;		/* temporary local name counter */
	int c_nested;		/* Is block nested funcdef or lamdef? */
	int c_closure;		/* Is nested w/freevars? */
	struct symtable *c_symtable; /* pointer to module symbol table */
        PyFutureFeatures *c_future; /* pointer to module's __future__ */
};

static int
is_free(int v)
{
	if ((v & (USE | DEF_FREE))
	    && !(v & (DEF_LOCAL | DEF_PARAM | DEF_GLOBAL)))
		return 1;
	if (v & DEF_FREE_CLASS)
		return 1;
	return 0;
}

static void
com_error(struct compiling *c, PyObject *exc, char *msg)
{
	PyObject *t = NULL, *v = NULL, *w = NULL, *line = NULL;

	if (c == NULL) {
		/* Error occurred via symtable call to
		   is_constant_false */
		PyErr_SetString(exc, msg);
		return;
	}
	c->c_errors++;
	if (c->c_lineno < 1 || c->c_interactive) { 
		/* Unknown line number or interactive input */
		PyErr_SetString(exc, msg);
		return;
	}
	v = PyString_FromString(msg);
	if (v == NULL)
		return; /* MemoryError, too bad */

	line = PyErr_ProgramText(c->c_filename, c->c_lineno);
	if (line == NULL) {
		Py_INCREF(Py_None);
		line = Py_None;
	}
	if (exc == PyExc_SyntaxError) {
		t = Py_BuildValue("(ziOO)", c->c_filename, c->c_lineno,
				  Py_None, line);
		if (t == NULL)
			goto exit;
		w = Py_BuildValue("(OO)", v, t);
		if (w == NULL)
			goto exit;
		PyErr_SetObject(exc, w);
	} else {
		/* Make sure additional exceptions are printed with
		   file and line, also. */
		PyErr_SetObject(exc, v);
		PyErr_SyntaxLocation(c->c_filename, c->c_lineno);
	}
 exit:
	Py_XDECREF(t);
	Py_XDECREF(v);
	Py_XDECREF(w);
	Py_XDECREF(line);
}

/* Interface to the block stack */

static void
block_push(struct compiling *c, int type)
{
	if (c->c_nblocks >= CO_MAXBLOCKS) {
		com_error(c, PyExc_SystemError,
			  "too many statically nested blocks");
	}
	else {
		c->c_block[c->c_nblocks++] = type;
	}
}

static void
block_pop(struct compiling *c, int type)
{
	if (c->c_nblocks > 0)
		c->c_nblocks--;
	if (c->c_block[c->c_nblocks] != type && c->c_errors == 0) {
		com_error(c, PyExc_SystemError, "bad block pop");
	}
}

/* Prototype forward declarations */

static int com_init(struct compiling *, char *);
static void com_free(struct compiling *);
static void com_push(struct compiling *, int);
static void com_pop(struct compiling *, int);
static void com_done(struct compiling *);
static void com_node(struct compiling *, node *);
static void com_factor(struct compiling *, node *);
static void com_addbyte(struct compiling *, int);
static void com_addint(struct compiling *, int);
static void com_addoparg(struct compiling *, int, int);
static void com_addfwref(struct compiling *, int, int *);
static void com_backpatch(struct compiling *, int);
static int com_add(struct compiling *, PyObject *, PyObject *, PyObject *);
static int com_addconst(struct compiling *, PyObject *);
static int com_addname(struct compiling *, PyObject *);
static void com_addopname(struct compiling *, int, node *);
static void com_list(struct compiling *, node *, int);
static void com_list_iter(struct compiling *, node *, node *, char *);
static int com_argdefs(struct compiling *, node *);
static void com_assign(struct compiling *, node *, int, node *);
static void com_assign_name(struct compiling *, node *, int);
static PyCodeObject *icompile(node *, struct compiling *);
static PyCodeObject *jcompile(node *, char *, struct compiling *,
			      PyCompilerFlags *);
static PyObject *parsestrplus(struct compiling*, node *);
static PyObject *parsestr(struct compiling *, char *);
static node *get_rawdocstring(node *);

static int get_ref_type(struct compiling *, char *);

/* symtable operations */
static int symtable_build(struct compiling *, node *);
static int symtable_load_symbols(struct compiling *);
static struct symtable *symtable_init(void);
static void symtable_enter_scope(struct symtable *, char *, int, int);
static int symtable_exit_scope(struct symtable *);
static int symtable_add_def(struct symtable *, char *, int);
static int symtable_add_def_o(struct symtable *, PyObject *, PyObject *, int);

static void symtable_node(struct symtable *, node *);
static void symtable_funcdef(struct symtable *, node *);
static void symtable_default_args(struct symtable *, node *);
static void symtable_params(struct symtable *, node *);
static void symtable_params_fplist(struct symtable *, node *n);
static void symtable_global(struct symtable *, node *);
static void symtable_import(struct symtable *, node *);
static void symtable_assign(struct symtable *, node *, int);
static void symtable_list_comprehension(struct symtable *, node *);

static int symtable_update_free_vars(struct symtable *);
static int symtable_undo_free(struct symtable *, PyObject *, PyObject *);
static int symtable_check_global(struct symtable *, PyObject *, PyObject *);

/* helper */
static void
do_pad(int pad)
{
	int i;
	for (i = 0; i < pad; ++i)
		fprintf(stderr, "  ");
}

static void
dump(node *n, int pad, int depth)
{
	int i;
	if (depth == 0)
	    return;
	do_pad(pad);
	fprintf(stderr, "%d: %s\n", TYPE(n), STR(n));
	if (depth > 0)
	    depth--;
	for (i = 0; i < NCH(n); ++i)
		dump(CHILD(n, i), pad + 1, depth);
}

#define DUMP(N) dump(N, 0, -1)

static int
com_init(struct compiling *c, char *filename)
{
	memset((void *)c, '\0', sizeof(struct compiling));
	if ((c->c_code = PyString_FromStringAndSize((char *)NULL,
						    1000)) == NULL)
		goto fail;
	if ((c->c_consts = PyList_New(0)) == NULL)
		goto fail;
	if ((c->c_const_dict = PyDict_New()) == NULL)
		goto fail;
	if ((c->c_names = PyList_New(0)) == NULL)
		goto fail;
	if ((c->c_name_dict = PyDict_New()) == NULL)
		goto fail;
	if ((c->c_locals = PyDict_New()) == NULL)
		goto fail;
	if ((c->c_lnotab = PyString_FromStringAndSize((char *)NULL,
						      1000)) == NULL)
		goto fail;
	c->c_globals = NULL;
	c->c_varnames = NULL;
	c->c_freevars = NULL;
	c->c_cellvars = NULL;
	c->c_nlocals = 0;
	c->c_argcount = 0;
	c->c_flags = 0;
	c->c_nexti = 0;
	c->c_errors = 0;
	c->c_infunction = 0;
	c->c_interactive = 0;
	c->c_loops = 0;
	c->c_begin = 0;
	c->c_nblocks = 0;
	c->c_filename = filename;
	c->c_name = "?";
	c->c_lineno = 0;
	c->c_stacklevel = 0;
	c->c_maxstacklevel = 0;
	c->c_firstlineno = 0;
	c->c_last_addr = 0;
	c->c_last_line = 0;
	c->c_lnotab_next = 0;
	c->c_tmpname = 0;
	c->c_nested = 0;
	c->c_closure = 0;
	c->c_symtable = NULL;
	return 1;
	
  fail:
	com_free(c);
 	return 0;
}

static void
com_free(struct compiling *c)
{
	Py_XDECREF(c->c_code);
	Py_XDECREF(c->c_consts);
	Py_XDECREF(c->c_const_dict);
	Py_XDECREF(c->c_names);
	Py_XDECREF(c->c_name_dict);
	Py_XDECREF(c->c_globals);
	Py_XDECREF(c->c_locals);
	Py_XDECREF(c->c_varnames);
	Py_XDECREF(c->c_freevars);
	Py_XDECREF(c->c_cellvars);
	Py_XDECREF(c->c_lnotab);
	if (c->c_future)
		PyMem_Free((void *)c->c_future);
}

static void
com_push(struct compiling *c, int n)
{
	c->c_stacklevel += n;
	if (c->c_stacklevel > c->c_maxstacklevel) {
		c->c_maxstacklevel = c->c_stacklevel;
		/*
		fprintf(stderr, "%s:%s:%d max stack nexti=%d level=%d n=%d\n",
			c->c_filename, c->c_name, c->c_lineno,
			c->c_nexti, c->c_stacklevel, n);
		*/
	}
}

static void
com_pop(struct compiling *c, int n)
{
	if (c->c_stacklevel < n) 
		c->c_stacklevel = 0;
	else
		c->c_stacklevel -= n;
}

static void
com_done(struct compiling *c)
{
	if (c->c_code != NULL)
		_PyString_Resize(&c->c_code, c->c_nexti);
	if (c->c_lnotab != NULL)
		_PyString_Resize(&c->c_lnotab, c->c_lnotab_next);
}

static int
com_check_size(PyObject **s, int offset)
{
	int len = PyString_GET_SIZE(*s);
	if (offset >= len) 
		return _PyString_Resize(s, len * 2);
	return 0;
}

static void
com_addbyte(struct compiling *c, int byte)
{
	/*fprintf(stderr, "%3d: %3d\n", c->c_nexti, byte);*/
	assert(byte >= 0 && byte <= 255);
	assert(c->c_code != 0);
	if (com_check_size(&c->c_code, c->c_nexti)) {
		c->c_errors++;
		return;
	}
	PyString_AS_STRING(c->c_code)[c->c_nexti++] = byte;
}

static void
com_addint(struct compiling *c, int x)
{
	com_addbyte(c, x & 0xff);
	com_addbyte(c, x >> 8); /* XXX x should be positive */
}

static void
com_add_lnotab(struct compiling *c, int addr, int line)
{
	char *p;
	if (c->c_lnotab == NULL)
		return;
	if (com_check_size(&c->c_lnotab, c->c_lnotab_next + 2)) {
		c->c_errors++;
		return;
	}
	p = PyString_AS_STRING(c->c_lnotab) + c->c_lnotab_next;
	*p++ = addr;
	*p++ = line;
	c->c_lnotab_next += 2;
}

static void
com_set_lineno(struct compiling *c, int lineno)
{
	c->c_lineno = lineno;
	if (c->c_firstlineno == 0) {
		c->c_firstlineno = c->c_last_line = lineno;
	}
	else {
		int incr_addr = c->c_nexti - c->c_last_addr;
		int incr_line = lineno - c->c_last_line;
		while (incr_addr > 255) {
			com_add_lnotab(c, 255, 0);
			incr_addr -= 255;
		}
		while (incr_line > 255) {
			com_add_lnotab(c, incr_addr, 255);
			incr_line -=255;
			incr_addr = 0;
		}
		if (incr_addr > 0 || incr_line > 0)
			com_add_lnotab(c, incr_addr, incr_line);
		c->c_last_addr = c->c_nexti;
		c->c_last_line = lineno;
	}
}

static void
com_addoparg(struct compiling *c, int op, int arg)
{
	int extended_arg = arg >> 16;
	if (op == SET_LINENO) {
		com_set_lineno(c, arg);
		if (Py_OptimizeFlag)
			return;
	}
	if (extended_arg){
		com_addbyte(c, EXTENDED_ARG);
		com_addint(c, extended_arg);
		arg &= 0xffff;
	}
	com_addbyte(c, op);
	com_addint(c, arg);
}

static void
com_addfwref(struct compiling *c, int op, int *p_anchor)
{
	/* Compile a forward reference for backpatching */
	int here;
	int anchor;
	com_addbyte(c, op);
	here = c->c_nexti;
	anchor = *p_anchor;
	*p_anchor = here;
	com_addint(c, anchor == 0 ? 0 : here - anchor);
}

static void
com_backpatch(struct compiling *c, int anchor)
{
	unsigned char *code = (unsigned char *) PyString_AS_STRING(c->c_code);
	int target = c->c_nexti;
	int dist;
	int prev;
	for (;;) {
		/* Make the JUMP instruction at anchor point to target */
		prev = code[anchor] + (code[anchor+1] << 8);
		dist = target - (anchor+2);
		code[anchor] = dist & 0xff;
		dist >>= 8;
		code[anchor+1] = dist;
		dist >>= 8;
		if (dist) {
			com_error(c, PyExc_SystemError,
				  "com_backpatch: offset too large");
			break;
		}
		if (!prev)
			break;
		anchor -= prev;
	}
}

/* Handle literals and names uniformly */

static int
com_add(struct compiling *c, PyObject *list, PyObject *dict, PyObject *v)
{
	PyObject *w, *t, *np=NULL;
	long n;
	
	t = Py_BuildValue("(OO)", v, v->ob_type);
	if (t == NULL)
	    goto fail;
	w = PyDict_GetItem(dict, t);
	if (w != NULL) {
		n = PyInt_AsLong(w);
	} else {
		n = PyList_Size(list);
		np = PyInt_FromLong(n);
		if (np == NULL)
		    goto fail;
		if (PyList_Append(list, v) != 0)
		    goto fail;
		if (PyDict_SetItem(dict, t, np) != 0)
		    goto fail;
		Py_DECREF(np);
	}
	Py_DECREF(t);
	return n;
  fail:
	Py_XDECREF(np);
	Py_XDECREF(t);
	c->c_errors++;
	return 0;
}

static int
com_addconst(struct compiling *c, PyObject *v)
{
	return com_add(c, c->c_consts, c->c_const_dict, v);
}

static int
com_addname(struct compiling *c, PyObject *v)
{
	return com_add(c, c->c_names, c->c_name_dict, v);
}

static int
mangle(char *p, char *name, char *buffer, size_t maxlen)
{
	/* Name mangling: __private becomes _classname__private.
	   This is independent from how the name is used. */
	size_t nlen, plen;
	if (p == NULL || name == NULL || name[0] != '_' || name[1] != '_')
		return 0;
	nlen = strlen(name);
	if (nlen+2 >= maxlen)
		return 0; /* Don't mangle __extremely_long_names */
	if (name[nlen-1] == '_' && name[nlen-2] == '_')
		return 0; /* Don't mangle __whatever__ */
	/* Strip leading underscores from class name */
	while (*p == '_')
		p++;
	if (*p == '\0')
		return 0; /* Don't mangle if class is just underscores */
	plen = strlen(p);
	if (plen + nlen >= maxlen)
		plen = maxlen-nlen-2; /* Truncate class name if too long */
	/* buffer = "_" + p[:plen] + name # i.e. 1+plen+nlen bytes */
	buffer[0] = '_';
	strncpy(buffer+1, p, plen);
	strcpy(buffer+1+plen, name);
	return 1;
}

static void
com_addop_name(struct compiling *c, int op, char *name)
{
	PyObject *v;
	int i;
	char buffer[MANGLE_LEN];

	if (mangle(c->c_private, name, buffer, sizeof(buffer)))
		name = buffer;
	if (name == NULL || (v = PyString_InternFromString(name)) == NULL) {
		c->c_errors++;
		i = 255;
	}
	else {
		i = com_addname(c, v);
		Py_DECREF(v);
	}
	com_addoparg(c, op, i);
}

#define NAME_LOCAL 0
#define NAME_GLOBAL 1
#define NAME_DEFAULT 2
#define NAME_CLOSURE 3

static int
com_lookup_arg(PyObject *dict, PyObject *name)
{
	PyObject *v = PyDict_GetItem(dict, name);
	if (v == NULL)
		return -1;
	else
		return PyInt_AS_LONG(v);
}

static void
com_addop_varname(struct compiling *c, int kind, char *name)
{
	PyObject *v;
	int i, reftype;
	int scope = NAME_DEFAULT;
	int op = STOP_CODE;
	char buffer[MANGLE_LEN];

	if (mangle(c->c_private, name, buffer, sizeof(buffer)))
		name = buffer;
	if (name == NULL || (v = PyString_InternFromString(name)) == NULL) {
		c->c_errors++;
		i = 255;
		goto done;
	}

	reftype = get_ref_type(c, name);
	switch (reftype) {
	case LOCAL:
		if (c->c_symtable->st_cur->ste_type == TYPE_FUNCTION)
			scope = NAME_LOCAL;
		break;
	case GLOBAL_EXPLICIT:
		scope = NAME_GLOBAL;
		break;
	case GLOBAL_IMPLICIT:
		if (c->c_flags & CO_OPTIMIZED)
			scope = NAME_GLOBAL;
		break;
	case FREE:
	case CELL:
		scope = NAME_CLOSURE;
		break;
	}

	i = com_addname(c, v);
	if (scope == NAME_LOCAL)
		i = com_lookup_arg(c->c_locals, v);
	else if (reftype == FREE)
		i = com_lookup_arg(c->c_freevars, v);
	else if (reftype == CELL)
		i = com_lookup_arg(c->c_cellvars, v);
	if (i == -1) {
		c->c_errors++; /* XXX no exception set */
		i = 255;
		goto done;
	}
	Py_DECREF(v);

	switch (kind) {
	case VAR_LOAD:
		switch (scope) {
		case NAME_LOCAL:
			op = LOAD_FAST;
			break;
		case NAME_GLOBAL:
			op = LOAD_GLOBAL;
			break;
		case NAME_DEFAULT:
			op = LOAD_NAME;
			break;
		case NAME_CLOSURE:
			op = LOAD_DEREF;
			break;
		}
		break;
	case VAR_STORE:
		switch (scope) {
		case NAME_LOCAL:
			op = STORE_FAST;
			break;
		case NAME_GLOBAL:
			op = STORE_GLOBAL;
			break;
		case NAME_DEFAULT:
			op = STORE_NAME;
			break;
		case NAME_CLOSURE:
			op = STORE_DEREF;
			break;
		}
		break;
	case VAR_DELETE:
		switch (scope) {
		case NAME_LOCAL:
			op = DELETE_FAST;
			break;
		case NAME_GLOBAL:
			op = DELETE_GLOBAL;
			break;
		case NAME_DEFAULT:
			op = DELETE_NAME;
			break;
		case NAME_CLOSURE: {
			char buf[500];
			PyOS_snprintf(buf, sizeof(buf),
				      DEL_CLOSURE_ERROR, name);
			com_error(c, PyExc_SyntaxError, buf);
			i = 255;
			break;
		}
		}
		break;
	}
done:
	com_addoparg(c, op, i);
}

static void
com_addopname(struct compiling *c, int op, node *n)
{
	char *name;
	char buffer[1000];
	/* XXX it is possible to write this code without the 1000
	   chars on the total length of dotted names, I just can't be
	   bothered right now */
	if (TYPE(n) == STAR)
		name = "*";
	else if (TYPE(n) == dotted_name) {
		char *p = buffer;
		int i;
		name = buffer;
		for (i = 0; i < NCH(n); i += 2) {
			char *s = STR(CHILD(n, i));
			if (p + strlen(s) > buffer + (sizeof buffer) - 2) {
				com_error(c, PyExc_MemoryError,
					  "dotted_name too long");
				name = NULL;
				break;
			}
			if (p != buffer)
				*p++ = '.';
			strcpy(p, s);
			p = strchr(p, '\0');
		}
	}
	else {
		REQ(n, NAME);
		name = STR(n);
	}
	com_addop_name(c, op, name);
}

static PyObject *
parsenumber(struct compiling *co, char *s)
{
	char *end;
	long x;
	double dx;
#ifndef WITHOUT_COMPLEX
	Py_complex c;
	int imflag;
#endif

	errno = 0;
	end = s + strlen(s) - 1;
#ifndef WITHOUT_COMPLEX
	imflag = *end == 'j' || *end == 'J';
#endif
	if (*end == 'l' || *end == 'L')
		return PyLong_FromString(s, (char **)0, 0);
	if (s[0] == '0')
		x = (long) PyOS_strtoul(s, &end, 0);
	else
		x = PyOS_strtol(s, &end, 0);
	if (*end == '\0') {
		if (errno != 0)
			return PyLong_FromString(s, (char **)0, 0);
		return PyInt_FromLong(x);
	}
	/* XXX Huge floats may silently fail */
#ifndef WITHOUT_COMPLEX
	if (imflag) {
		c.real = 0.;
		PyFPE_START_PROTECT("atof", return 0)
		c.imag = atof(s);
		PyFPE_END_PROTECT(c)
		return PyComplex_FromCComplex(c);
	}
	else
#endif
	{
		PyFPE_START_PROTECT("atof", return 0)
		dx = atof(s);
		PyFPE_END_PROTECT(dx)
		return PyFloat_FromDouble(dx);
	}
}

static PyObject *
parsestr(struct compiling *com, char *s)
{
	PyObject *v;
	size_t len;
	char *buf;
	char *p;
	char *end;
	int c;
	int first = *s;
	int quote = first;
	int rawmode = 0;
#ifdef Py_USING_UNICODE
	int unicode = 0;
#endif
	if (isalpha(quote) || quote == '_') {
		if (quote == 'u' || quote == 'U') {
#ifdef Py_USING_UNICODE
			quote = *++s;
			unicode = 1;
#else
			com_error(com, PyExc_SyntaxError,
				  "Unicode literals not supported in this Python");
			return NULL;
#endif
		}
		if (quote == 'r' || quote == 'R') {
			quote = *++s;
			rawmode = 1;
		}
	}
	if (quote != '\'' && quote != '\"') {
		PyErr_BadInternalCall();
		return NULL;
	}
	s++;
	len = strlen(s);
	if (len > INT_MAX) {
		com_error(com, PyExc_OverflowError, 
			  "string to parse is too long");
		return NULL;
	}
	if (s[--len] != quote) {
		PyErr_BadInternalCall();
		return NULL;
	}
	if (len >= 4 && s[0] == quote && s[1] == quote) {
		s += 2;
		len -= 2;
		if (s[--len] != quote || s[--len] != quote) {
			PyErr_BadInternalCall();
			return NULL;
		}
	}
#ifdef Py_USING_UNICODE
	if (unicode || Py_UnicodeFlag) {
		if (rawmode)
			v = PyUnicode_DecodeRawUnicodeEscape(
				 s, len, NULL);
		else
			v = PyUnicode_DecodeUnicodeEscape(
				s, len, NULL);
		if (v == NULL)
			PyErr_SyntaxLocation(com->c_filename, com->c_lineno);
		return v;
			
	}
#endif
	if (rawmode || strchr(s, '\\') == NULL)
		return PyString_FromStringAndSize(s, len);
	v = PyString_FromStringAndSize((char *)NULL, len);
	if (v == NULL)
		return NULL;
	p = buf = PyString_AsString(v);
	end = s + len;
	while (s < end) {
		if (*s != '\\') {
			*p++ = *s++;
			continue;
		}
		s++;
		switch (*s++) {
		/* XXX This assumes ASCII! */
		case '\n': break;
		case '\\': *p++ = '\\'; break;
		case '\'': *p++ = '\''; break;
		case '\"': *p++ = '\"'; break;
		case 'b': *p++ = '\b'; break;
		case 'f': *p++ = '\014'; break; /* FF */
		case 't': *p++ = '\t'; break;
		case 'n': *p++ = '\n'; break;
		case 'r': *p++ = '\r'; break;
		case 'v': *p++ = '\013'; break; /* VT */
		case 'a': *p++ = '\007'; break; /* BEL, not classic C */
		case '0': case '1': case '2': case '3':
		case '4': case '5': case '6': case '7':
			c = s[-1] - '0';
			if ('0' <= *s && *s <= '7') {
				c = (c<<3) + *s++ - '0';
				if ('0' <= *s && *s <= '7')
					c = (c<<3) + *s++ - '0';
			}
			*p++ = c;
			break;
		case 'x':
			if (isxdigit(Py_CHARMASK(s[0])) 
			    && isxdigit(Py_CHARMASK(s[1]))) {
				unsigned int x = 0;
				c = Py_CHARMASK(*s);
				s++;
				if (isdigit(c))
					x = c - '0';
				else if (islower(c))
					x = 10 + c - 'a';
				else
					x = 10 + c - 'A';
				x = x << 4;
				c = Py_CHARMASK(*s);
				s++;
				if (isdigit(c))
					x += c - '0';
				else if (islower(c))
					x += 10 + c - 'a';
				else
					x += 10 + c - 'A';
				*p++ = x;
				break;
			}
			Py_DECREF(v);
			com_error(com, PyExc_ValueError, 
				  "invalid \\x escape");
			return NULL;
		default:
			*p++ = '\\';
			*p++ = s[-1];
			break;
		}
	}
	_PyString_Resize(&v, (int)(p - buf));
	return v;
}

static PyObject *
parsestrplus(struct compiling* c, node *n)
{
	PyObject *v;
	int i;
	REQ(CHILD(n, 0), STRING);
	if ((v = parsestr(c, STR(CHILD(n, 0)))) != NULL) {
		/* String literal concatenation */
		for (i = 1; i < NCH(n); i++) {
		    PyObject *s;
		    s = parsestr(c, STR(CHILD(n, i)));
		    if (s == NULL)
			goto onError;
		    if (PyString_Check(v) && PyString_Check(s)) {
			PyString_ConcatAndDel(&v, s);
			if (v == NULL)
			    goto onError;
		    }
#ifdef Py_USING_UNICODE
		    else {
			PyObject *temp;
			temp = PyUnicode_Concat(v, s);
			Py_DECREF(s);
			if (temp == NULL)
			    goto onError;
			Py_DECREF(v);
			v = temp;
		    }
#endif
		}
	}
	return v;

 onError:
	Py_XDECREF(v);
	return NULL;
}

static void
com_list_for(struct compiling *c, node *n, node *e, char *t)
{
	int anchor = 0;
	int save_begin = c->c_begin;

	/* list_iter: for v in expr [list_iter] */
	com_node(c, CHILD(n, 3)); /* expr */
	com_addbyte(c, GET_ITER);
	c->c_begin = c->c_nexti;
	com_addoparg(c, SET_LINENO, n->n_lineno);
	com_addfwref(c, FOR_ITER, &anchor);
	com_push(c, 1);
	com_assign(c, CHILD(n, 1), OP_ASSIGN, NULL);
	c->c_loops++;
	com_list_iter(c, n, e, t);
	c->c_loops--;
	com_addoparg(c, JUMP_ABSOLUTE, c->c_begin);
	c->c_begin = save_begin;
	com_backpatch(c, anchor);
	com_pop(c, 1); /* FOR_ITER has popped this */
}  

static void
com_list_if(struct compiling *c, node *n, node *e, char *t)
{
	int anchor = 0;
	int a = 0;
	/* list_iter: 'if' test [list_iter] */
	com_addoparg(c, SET_LINENO, n->n_lineno);
	com_node(c, CHILD(n, 1));
	com_addfwref(c, JUMP_IF_FALSE, &a);
	com_addbyte(c, POP_TOP);
	com_pop(c, 1);
	com_list_iter(c, n, e, t);
	com_addfwref(c, JUMP_FORWARD, &anchor);
	com_backpatch(c, a);
	/* We jump here with an extra entry which we now pop */
	com_addbyte(c, POP_TOP);
	com_backpatch(c, anchor);
}

static void
com_list_iter(struct compiling *c,
	      node *p,		/* parent of list_iter node */
	      node *e,		/* element expression node */
	      char *t		/* name of result list temp local */)
{
	/* list_iter is the last child in a listmaker, list_for, or list_if */
	node *n = CHILD(p, NCH(p)-1);
	if (TYPE(n) == list_iter) {
		n = CHILD(n, 0);
		switch (TYPE(n)) {
		case list_for: 
			com_list_for(c, n, e, t);
			break;
		case list_if:
			com_list_if(c, n, e, t);
			break;
		default:
			com_error(c, PyExc_SystemError,
				  "invalid list_iter node type");
		}
	}
	else {
		com_addop_varname(c, VAR_LOAD, t);
		com_push(c, 1);
		com_node(c, e);
		com_addoparg(c, CALL_FUNCTION, 1);
		com_addbyte(c, POP_TOP);
		com_pop(c, 2);
	}
}

static void
com_list_comprehension(struct compiling *c, node *n)
{
	/* listmaker: test list_for */
	char tmpname[30];
	PyOS_snprintf(tmpname, sizeof(tmpname), "_[%d]", ++c->c_tmpname);
	com_addoparg(c, BUILD_LIST, 0);
	com_addbyte(c, DUP_TOP); /* leave the result on the stack */
	com_push(c, 2);
	com_addop_name(c, LOAD_ATTR, "append");
	com_addop_varname(c, VAR_STORE, tmpname);
	com_pop(c, 1);
	com_list_for(c, CHILD(n, 1), CHILD(n, 0), tmpname);
	com_addop_varname(c, VAR_DELETE, tmpname);
	--c->c_tmpname;
}

static void
com_listmaker(struct compiling *c, node *n)
{
	/* listmaker: test ( list_for | (',' test)* [','] ) */
	if (NCH(n) > 1 && TYPE(CHILD(n, 1)) == list_for)
		com_list_comprehension(c, n);
	else {
		int len = 0;
		int i;
		for (i = 0; i < NCH(n); i += 2, len++)
			com_node(c, CHILD(n, i));
		com_addoparg(c, BUILD_LIST, len);
		com_pop(c, len-1);
	}
}

static void
com_dictmaker(struct compiling *c, node *n)
{
	int i;
	/* dictmaker: test ':' test (',' test ':' value)* [','] */
	for (i = 0; i+2 < NCH(n); i += 4) {
		/* We must arrange things just right for STORE_SUBSCR.
		   It wants the stack to look like (value) (dict) (key) */
		com_addbyte(c, DUP_TOP);
		com_push(c, 1);
		com_node(c, CHILD(n, i+2)); /* value */
		com_addbyte(c, ROT_TWO);
		com_node(c, CHILD(n, i)); /* key */
		com_addbyte(c, STORE_SUBSCR);
		com_pop(c, 3);
	}
}

static void
com_atom(struct compiling *c, node *n)
{
	node *ch;
	PyObject *v;
	int i;
	REQ(n, atom);
	ch = CHILD(n, 0);
	switch (TYPE(ch)) {
	case LPAR:
		if (TYPE(CHILD(n, 1)) == RPAR) {
			com_addoparg(c, BUILD_TUPLE, 0);
			com_push(c, 1);
		}
		else
			com_node(c, CHILD(n, 1));
		break;
	case LSQB: /* '[' [listmaker] ']' */
		if (TYPE(CHILD(n, 1)) == RSQB) {
			com_addoparg(c, BUILD_LIST, 0);
			com_push(c, 1);
		}
		else
			com_listmaker(c, CHILD(n, 1));
		break;
	case LBRACE: /* '{' [dictmaker] '}' */
		com_addoparg(c, BUILD_MAP, 0);
		com_push(c, 1);
		if (TYPE(CHILD(n, 1)) == dictmaker)
			com_dictmaker(c, CHILD(n, 1));
		break;
	case BACKQUOTE:
		com_node(c, CHILD(n, 1));
		com_addbyte(c, UNARY_CONVERT);
		break;
	case NUMBER:
		if ((v = parsenumber(c, STR(ch))) == NULL) {
			i = 255;
		}
		else {
			i = com_addconst(c, v);
			Py_DECREF(v);
		}
		com_addoparg(c, LOAD_CONST, i);
		com_push(c, 1);
		break;
	case STRING:
		v = parsestrplus(c, n);
		if (v == NULL) {
			c->c_errors++;
			i = 255;
		}
		else {
			i = com_addconst(c, v);
			Py_DECREF(v);
		}
		com_addoparg(c, LOAD_CONST, i);
		com_push(c, 1);
		break;
	case NAME:
		com_addop_varname(c, VAR_LOAD, STR(ch));
		com_push(c, 1);
		break;
	default:
		com_error(c, PyExc_SystemError,
			  "com_atom: unexpected node type");
	}
}

static void
com_slice(struct compiling *c, node *n, int op)
{
	if (NCH(n) == 1) {
		com_addbyte(c, op);
	}
	else if (NCH(n) == 2) {
		if (TYPE(CHILD(n, 0)) != COLON) {
			com_node(c, CHILD(n, 0));
			com_addbyte(c, op+1);
		}
		else {
			com_node(c, CHILD(n, 1));
			com_addbyte(c, op+2);
		}
		com_pop(c, 1);
	}
	else {
		com_node(c, CHILD(n, 0));
		com_node(c, CHILD(n, 2));
		com_addbyte(c, op+3);
		com_pop(c, 2);
	}
}

static void
com_augassign_slice(struct compiling *c, node *n, int opcode, node *augn)
{
	if (NCH(n) == 1) {
		com_addbyte(c, DUP_TOP);
		com_push(c, 1);
		com_addbyte(c, SLICE);
		com_node(c, augn);
		com_addbyte(c, opcode);
		com_pop(c, 1);
		com_addbyte(c, ROT_TWO);
		com_addbyte(c, STORE_SLICE);
		com_pop(c, 2);
	} else if (NCH(n) == 2 && TYPE(CHILD(n, 0)) != COLON) {
		com_node(c, CHILD(n, 0));
		com_addoparg(c, DUP_TOPX, 2);
		com_push(c, 2);
		com_addbyte(c, SLICE+1);
		com_pop(c, 1);
		com_node(c, augn);
		com_addbyte(c, opcode);
		com_pop(c, 1);
		com_addbyte(c, ROT_THREE);
		com_addbyte(c, STORE_SLICE+1);
		com_pop(c, 3);
	} else if (NCH(n) == 2) {
		com_node(c, CHILD(n, 1));
		com_addoparg(c, DUP_TOPX, 2);
		com_push(c, 2);
		com_addbyte(c, SLICE+2);
		com_pop(c, 1);
		com_node(c, augn);
		com_addbyte(c, opcode);
		com_pop(c, 1);
		com_addbyte(c, ROT_THREE);
		com_addbyte(c, STORE_SLICE+2);
		com_pop(c, 3);
	} else {
		com_node(c, CHILD(n, 0));
		com_node(c, CHILD(n, 2));
		com_addoparg(c, DUP_TOPX, 3);
		com_push(c, 3);
		com_addbyte(c, SLICE+3);
		com_pop(c, 2);
		com_node(c, augn);
		com_addbyte(c, opcode);
		com_pop(c, 1);
		com_addbyte(c, ROT_FOUR);
		com_addbyte(c, STORE_SLICE+3);
		com_pop(c, 4);
	}
}

static void
com_argument(struct compiling *c, node *n, PyObject **pkeywords)
{
	node *m;
	REQ(n, argument); /* [test '='] test; really [keyword '='] test */
	if (NCH(n) == 1) {
		if (*pkeywords != NULL) {
			com_error(c, PyExc_SyntaxError,
				  "non-keyword arg after keyword arg");
		}
		else {
			com_node(c, CHILD(n, 0));
		}
		return;
	}
	m = n;
	do {
		m = CHILD(m, 0);
	} while (NCH(m) == 1);
	if (TYPE(m) != NAME) {
		/* f(lambda x: x[0] = 3) ends up getting parsed with
		 * LHS test = lambda x: x[0], and RHS test = 3.
		 * SF bug 132313 points out that complaining about a keyword
		 * then is very confusing.
		 */
		com_error(c, PyExc_SyntaxError,
			  TYPE(m) == lambdef ?
				  "lambda cannot contain assignment" :
				  "keyword can't be an expression");
	}
	else {
		PyObject *v = PyString_InternFromString(STR(m));
		if (v != NULL && *pkeywords == NULL)
			*pkeywords = PyDict_New();
		if (v == NULL)
			c->c_errors++;
		else if (*pkeywords == NULL) {
			c->c_errors++;
			Py_DECREF(v);
		} else {
			if (PyDict_GetItem(*pkeywords, v) != NULL)
				com_error(c, PyExc_SyntaxError,
					  "duplicate keyword argument");
			else
				if (PyDict_SetItem(*pkeywords, v, v) != 0)
					c->c_errors++;
			com_addoparg(c, LOAD_CONST, com_addconst(c, v));
			com_push(c, 1);
			Py_DECREF(v);
		}
	}
	com_node(c, CHILD(n, 2));
}

static void
com_call_function(struct compiling *c, node *n)
{
	if (TYPE(n) == RPAR) {
		com_addoparg(c, CALL_FUNCTION, 0);
	}
	else {
		PyObject *keywords = NULL;
		int i, na, nk;
		int lineno = n->n_lineno;
		int star_flag = 0;
		int starstar_flag = 0;
		int opcode;
		REQ(n, arglist);
		na = 0;
		nk = 0;
		for (i = 0; i < NCH(n); i += 2) {
			node *ch = CHILD(n, i);
			if (TYPE(ch) == STAR ||
			    TYPE(ch) == DOUBLESTAR)
			  break;
			if (ch->n_lineno != lineno) {
				lineno = ch->n_lineno;
				com_addoparg(c, SET_LINENO, lineno);
			}
			com_argument(c, ch, &keywords);
			if (keywords == NULL)
				na++;
			else
				nk++;
		}
		Py_XDECREF(keywords);
		while (i < NCH(n)) {
		    node *tok = CHILD(n, i);
		    node *ch = CHILD(n, i+1);
		    i += 3;
		    switch (TYPE(tok)) {
		    case STAR:       star_flag = 1;     break;
		    case DOUBLESTAR: starstar_flag = 1;	break;
		    }
		    com_node(c, ch);
		}
		if (na > 255 || nk > 255) {
			com_error(c, PyExc_SyntaxError,
				  "more than 255 arguments");
		}
		if (star_flag || starstar_flag)
		    opcode = CALL_FUNCTION_VAR - 1 + 
			star_flag + (starstar_flag << 1);
		else
		    opcode = CALL_FUNCTION;
		com_addoparg(c, opcode, na | (nk << 8));
		com_pop(c, na + 2*nk + star_flag + starstar_flag);
	}
}

static void
com_select_member(struct compiling *c, node *n)
{
	com_addopname(c, LOAD_ATTR, n);
}

static void
com_sliceobj(struct compiling *c, node *n)
{
	int i=0;
	int ns=2; /* number of slice arguments */
	node *ch;

	/* first argument */
	if (TYPE(CHILD(n,i)) == COLON) {
		com_addoparg(c, LOAD_CONST, com_addconst(c, Py_None));
		com_push(c, 1);
		i++;
	}
	else {
		com_node(c, CHILD(n,i));
		i++;
		REQ(CHILD(n,i),COLON);
		i++;
	}
	/* second argument */
	if (i < NCH(n) && TYPE(CHILD(n,i)) == test) {
		com_node(c, CHILD(n,i));
		i++;
	}
	else {
		com_addoparg(c, LOAD_CONST, com_addconst(c, Py_None));
		com_push(c, 1);
	}
	/* remaining arguments */
	for (; i < NCH(n); i++) {
		ns++;
		ch=CHILD(n,i);
		REQ(ch, sliceop);
		if (NCH(ch) == 1) {
			/* right argument of ':' missing */
			com_addoparg(c, LOAD_CONST, com_addconst(c, Py_None));
			com_push(c, 1);
		}
		else
			com_node(c, CHILD(ch,1));
	}
	com_addoparg(c, BUILD_SLICE, ns);
	com_pop(c, 1 + (ns == 3));
}

static void
com_subscript(struct compiling *c, node *n)
{
	node *ch;
	REQ(n, subscript);
	ch = CHILD(n,0);
	/* check for rubber index */
	if (TYPE(ch) == DOT && TYPE(CHILD(n,1)) == DOT) {
		com_addoparg(c, LOAD_CONST, com_addconst(c, Py_Ellipsis));
		com_push(c, 1);
	}
	else {
		/* check for slice */
		if ((TYPE(ch) == COLON || NCH(n) > 1))
			com_sliceobj(c, n);
		else {
			REQ(ch, test);
			com_node(c, ch);
		}
	}
}

static void
com_subscriptlist(struct compiling *c, node *n, int assigning, node *augn)
{
	int i, op;
	REQ(n, subscriptlist);
	/* Check to make backward compatible slice behavior for '[i:j]' */
	if (NCH(n) == 1) {
		node *sub = CHILD(n, 0); /* subscript */
		/* 'Basic' slice, should have exactly one colon. */
		if ((TYPE(CHILD(sub, 0)) == COLON
		     || (NCH(sub) > 1 && TYPE(CHILD(sub, 1)) == COLON))
		    && (TYPE(CHILD(sub,NCH(sub)-1)) != sliceop))
		{
			switch (assigning) {
			case OP_DELETE:
				op = DELETE_SLICE;
				break;
			case OP_ASSIGN:
				op = STORE_SLICE;
				break;
			case OP_APPLY:
				op = SLICE;
				break;
			default:
				com_augassign_slice(c, sub, assigning, augn);
				return;
			}
			com_slice(c, sub, op);
			if (op == STORE_SLICE)
				com_pop(c, 2);
			else if (op == DELETE_SLICE)
				com_pop(c, 1);
			return;
		}
	}
	/* Else normal subscriptlist.  Compile each subscript. */
	for (i = 0; i < NCH(n); i += 2)
		com_subscript(c, CHILD(n, i));
	/* Put multiple subscripts into a tuple */
	if (NCH(n) > 1) {
		i = (NCH(n)+1) / 2;
		com_addoparg(c, BUILD_TUPLE, i);
		com_pop(c, i-1);
	}
	switch (assigning) {
	case OP_DELETE:
		op = DELETE_SUBSCR;
		i = 2;
		break;
	default:
	case OP_ASSIGN:
		op = STORE_SUBSCR;
		i = 3;
		break;
	case OP_APPLY:
		op = BINARY_SUBSCR;
		i = 1;
		break;
	}
	if (assigning > OP_APPLY) {
		com_addoparg(c, DUP_TOPX, 2);
		com_push(c, 2);
		com_addbyte(c, BINARY_SUBSCR);
		com_pop(c, 1);
		com_node(c, augn);
		com_addbyte(c, assigning);
		com_pop(c, 1);
		com_addbyte(c, ROT_THREE);
	}
	com_addbyte(c, op);
	com_pop(c, i);
}

static void
com_apply_trailer(struct compiling *c, node *n)
{
	REQ(n, trailer);
	switch (TYPE(CHILD(n, 0))) {
	case LPAR:
		com_call_function(c, CHILD(n, 1));
		break;
	case DOT:
		com_select_member(c, CHILD(n, 1));
		break;
	case LSQB:
		com_subscriptlist(c, CHILD(n, 1), OP_APPLY, NULL);
		break;
	default:
		com_error(c, PyExc_SystemError,
			  "com_apply_trailer: unknown trailer type");
	}
}

static void
com_power(struct compiling *c, node *n)
{
	int i;
	REQ(n, power);
	com_atom(c, CHILD(n, 0));
	for (i = 1; i < NCH(n); i++) {
		if (TYPE(CHILD(n, i)) == DOUBLESTAR) {
			com_factor(c, CHILD(n, i+1));
			com_addbyte(c, BINARY_POWER);
			com_pop(c, 1);
			break;
		}
		else
			com_apply_trailer(c, CHILD(n, i));
	}
}

static void
com_invert_constant(struct compiling *c, node *n)
{
	/* Compute the inverse of int and longs and use them directly,
	   but be prepared to generate code for all other
	   possibilities (invalid numbers, floats, complex).
	*/
	PyObject *num, *inv = NULL;
	int i;

	REQ(n, NUMBER);
	num = parsenumber(c, STR(n));
	if (num == NULL) 
		i = 255;
	else {
		inv = PyNumber_Invert(num);
		if (inv == NULL) {
			PyErr_Clear();
			i = com_addconst(c, num);
		} else {
			i = com_addconst(c, inv);
			Py_DECREF(inv);
		}
		Py_DECREF(num);
	}
	com_addoparg(c, LOAD_CONST, i);
	com_push(c, 1);
	if (num != NULL && inv == NULL)
		com_addbyte(c, UNARY_INVERT);
}

static int
is_float_zero(const char *p)
{
	int found_radix_point = 0;
	int ch;
	while ((ch = Py_CHARMASK(*p++)) != '\0') {
		switch (ch) {
		case '0':
			/* no reason to believe it's not 0 -- continue */
			break;

		case 'e': case 'E': case 'j': case 'J':
			/* If this was a hex constant, we already would have
			   returned 0 due to the 'x' or 'X', so 'e' or 'E'
			   must be an exponent marker, and we haven't yet
			   seen a non-zero digit, and it doesn't matter what
			   the exponent is then.  For 'j' or 'J' similarly,
			   except that this is an imaginary 0 then. */
			return 1;

		case '.':
			found_radix_point = 1;
			break;

		default:
			return 0;
		}
	}
	return found_radix_point;
}

static void
com_factor(struct compiling *c, node *n)
{
	int childtype = TYPE(CHILD(n, 0));
	node *pfactor, *ppower, *patom, *pnum;
	REQ(n, factor);
	/* If the unary +, -, or ~ operator is applied to a constant,
	   don't generate a UNARY_xxx opcode.  Just store the
	   approriate value as a constant.  If the value is negative,
	   extend the string containing the constant and insert a
	   negative in the 0th position -- unless we're doing unary minus
	   of a floating zero!  In that case the sign is significant, but
	   the const dict can't distinguish +0.0 from -0.0.
	 */
	if ((childtype == PLUS || childtype == MINUS || childtype == TILDE)
	    && NCH(n) == 2
	    && TYPE((pfactor = CHILD(n, 1))) == factor
 	    && NCH(pfactor) == 1
	    && TYPE((ppower = CHILD(pfactor, 0))) == power
 	    && NCH(ppower) == 1
	    && TYPE((patom = CHILD(ppower, 0))) == atom
	    && TYPE((pnum = CHILD(patom, 0))) == NUMBER
	    && !(childtype == MINUS && is_float_zero(STR(pnum)))) {
		if (childtype == TILDE) {
			com_invert_constant(c, pnum);
			return;
		}
		if (childtype == MINUS) {
			char *s = PyMem_Malloc(strlen(STR(pnum)) + 2);
			if (s == NULL) {
				com_error(c, PyExc_MemoryError, "");
				com_addbyte(c, 255);
				return;
			}
			s[0] = '-';
			strcpy(s + 1, STR(pnum));
			PyMem_Free(STR(pnum));
			STR(pnum) = s;
		}
		com_atom(c, patom);
	}
	else if (childtype == PLUS) {
		com_factor(c, CHILD(n, 1));
		com_addbyte(c, UNARY_POSITIVE);
	}
	else if (childtype == MINUS) {
		com_factor(c, CHILD(n, 1));
		com_addbyte(c, UNARY_NEGATIVE);
	}
	else if (childtype == TILDE) {
		com_factor(c, CHILD(n, 1));
		com_addbyte(c, UNARY_INVERT);
	}
	else {
		com_power(c, CHILD(n, 0));
	}
}

static void
com_term(struct compiling *c, node *n)
{
	int i;
	int op;
	REQ(n, term);
	com_factor(c, CHILD(n, 0));
	for (i = 2; i < NCH(n); i += 2) {
		com_factor(c, CHILD(n, i));
		switch (TYPE(CHILD(n, i-1))) {
		case STAR:
			op = BINARY_MULTIPLY;
			break;
		case SLASH:
			if (c->c_flags & CO_FUTURE_DIVISION)
				op = BINARY_TRUE_DIVIDE;
			else
				op = BINARY_DIVIDE;
			break;
		case PERCENT:
			op = BINARY_MODULO;
			break;
		case DOUBLESLASH:
			op = BINARY_FLOOR_DIVIDE;
			break;
		default:
			com_error(c, PyExc_SystemError,
				  "com_term: operator not *, /, // or %");
			op = 255;
		}
		com_addbyte(c, op);
		com_pop(c, 1);
	}
}

static void
com_arith_expr(struct compiling *c, node *n)
{
	int i;
	int op;
	REQ(n, arith_expr);
	com_term(c, CHILD(n, 0));
	for (i = 2; i < NCH(n); i += 2) {
		com_term(c, CHILD(n, i));
		switch (TYPE(CHILD(n, i-1))) {
		case PLUS:
			op = BINARY_ADD;
			break;
		case MINUS:
			op = BINARY_SUBTRACT;
			break;
		default:
			com_error(c, PyExc_SystemError,
				  "com_arith_expr: operator not + or -");
			op = 255;
		}
		com_addbyte(c, op);
		com_pop(c, 1);
	}
}

static void
com_shift_expr(struct compiling *c, node *n)
{
	int i;
	int op;
	REQ(n, shift_expr);
	com_arith_expr(c, CHILD(n, 0));
	for (i = 2; i < NCH(n); i += 2) {
		com_arith_expr(c, CHILD(n, i));
		switch (TYPE(CHILD(n, i-1))) {
		case LEFTSHIFT:
			op = BINARY_LSHIFT;
			break;
		case RIGHTSHIFT:
			op = BINARY_RSHIFT;
			break;
		default:
			com_error(c, PyExc_SystemError,
				  "com_shift_expr: operator not << or >>");
			op = 255;
		}
		com_addbyte(c, op);
		com_pop(c, 1);
	}
}

static void
com_and_expr(struct compiling *c, node *n)
{
	int i;
	int op;
	REQ(n, and_expr);
	com_shift_expr(c, CHILD(n, 0));
	for (i = 2; i < NCH(n); i += 2) {
		com_shift_expr(c, CHILD(n, i));
		if (TYPE(CHILD(n, i-1)) == AMPER) {
			op = BINARY_AND;
		}
		else {
			com_error(c, PyExc_SystemError,
				  "com_and_expr: operator not &");
			op = 255;
		}
		com_addbyte(c, op);
		com_pop(c, 1);
	}
}

static void
com_xor_expr(struct compiling *c, node *n)
{
	int i;
	int op;
	REQ(n, xor_expr);
	com_and_expr(c, CHILD(n, 0));
	for (i = 2; i < NCH(n); i += 2) {
		com_and_expr(c, CHILD(n, i));
		if (TYPE(CHILD(n, i-1)) == CIRCUMFLEX) {
			op = BINARY_XOR;
		}
		else {
			com_error(c, PyExc_SystemError,
				  "com_xor_expr: operator not ^");
			op = 255;
		}
		com_addbyte(c, op);
		com_pop(c, 1);
	}
}

static void
com_expr(struct compiling *c, node *n)
{
	int i;
	int op;
	REQ(n, expr);
	com_xor_expr(c, CHILD(n, 0));
	for (i = 2; i < NCH(n); i += 2) {
		com_xor_expr(c, CHILD(n, i));
		if (TYPE(CHILD(n, i-1)) == VBAR) {
			op = BINARY_OR;
		}
		else {
			com_error(c, PyExc_SystemError,
				  "com_expr: expr operator not |");
			op = 255;
		}
		com_addbyte(c, op);
		com_pop(c, 1);
	}
}

static enum cmp_op
cmp_type(node *n)
{
	REQ(n, comp_op);
	/* comp_op: '<' | '>' | '=' | '>=' | '<=' | '<>' | '!=' | '=='
	          | 'in' | 'not' 'in' | 'is' | 'is' not' */
	if (NCH(n) == 1) {
		n = CHILD(n, 0);
		switch (TYPE(n)) {
		case LESS:	return PyCmp_LT;
		case GREATER:	return PyCmp_GT;
		case EQEQUAL:			/* == */
		case EQUAL:	return PyCmp_EQ;
		case LESSEQUAL:	return PyCmp_LE;
		case GREATEREQUAL: return PyCmp_GE;
		case NOTEQUAL:	return PyCmp_NE;	/* <> or != */
		case NAME:	if (strcmp(STR(n), "in") == 0) return PyCmp_IN;
				if (strcmp(STR(n), "is") == 0) return PyCmp_IS;
		}
	}
	else if (NCH(n) == 2) {
		switch (TYPE(CHILD(n, 0))) {
		case NAME:	if (strcmp(STR(CHILD(n, 1)), "in") == 0)
					return PyCmp_NOT_IN;
				if (strcmp(STR(CHILD(n, 0)), "is") == 0)
					return PyCmp_IS_NOT;
		}
	}
	return PyCmp_BAD;
}

static void
com_comparison(struct compiling *c, node *n)
{
	int i;
	enum cmp_op op;
	int anchor;
	REQ(n, comparison); /* comparison: expr (comp_op expr)* */
	com_expr(c, CHILD(n, 0));
	if (NCH(n) == 1)
		return;
	
	/****************************************************************
	   The following code is generated for all but the last
	   comparison in a chain:
	   
	   label:	on stack:	opcode:		jump to:
	   
			a		<code to load b>
			a, b		DUP_TOP
			a, b, b		ROT_THREE
			b, a, b		COMPARE_OP
			b, 0-or-1	JUMP_IF_FALSE	L1
			b, 1		POP_TOP
			b		
	
	   We are now ready to repeat this sequence for the next
	   comparison in the chain.
	   
	   For the last we generate:
	   
	   		b		<code to load c>
	   		b, c		COMPARE_OP
	   		0-or-1		
	   
	   If there were any jumps to L1 (i.e., there was more than one
	   comparison), we generate:
	   
	   		0-or-1		JUMP_FORWARD	L2
	   L1:		b, 0		ROT_TWO
	   		0, b		POP_TOP
	   		0
	   L2:		0-or-1
	****************************************************************/
	
	anchor = 0;
	
	for (i = 2; i < NCH(n); i += 2) {
		com_expr(c, CHILD(n, i));
		if (i+2 < NCH(n)) {
			com_addbyte(c, DUP_TOP);
			com_push(c, 1);
			com_addbyte(c, ROT_THREE);
		}
		op = cmp_type(CHILD(n, i-1));
		if (op == PyCmp_BAD) {
			com_error(c, PyExc_SystemError,
				  "com_comparison: unknown comparison op");
		}
		com_addoparg(c, COMPARE_OP, op);
		com_pop(c, 1);
		if (i+2 < NCH(n)) {
			com_addfwref(c, JUMP_IF_FALSE, &anchor);
			com_addbyte(c, POP_TOP);
			com_pop(c, 1);
		}
	}
	
	if (anchor) {
		int anchor2 = 0;
		com_addfwref(c, JUMP_FORWARD, &anchor2);
		com_backpatch(c, anchor);
		com_addbyte(c, ROT_TWO);
		com_addbyte(c, POP_TOP);
		com_backpatch(c, anchor2);
	}
}

static void
com_not_test(struct compiling *c, node *n)
{
	REQ(n, not_test); /* 'not' not_test | comparison */
	if (NCH(n) == 1) {
		com_comparison(c, CHILD(n, 0));
	}
	else {
		com_not_test(c, CHILD(n, 1));
		com_addbyte(c, UNARY_NOT);
	}
}

static void
com_and_test(struct compiling *c, node *n)
{
	int i;
	int anchor;
	REQ(n, and_test); /* not_test ('and' not_test)* */
	anchor = 0;
	i = 0;
	for (;;) {
		com_not_test(c, CHILD(n, i));
		if ((i += 2) >= NCH(n))
			break;
		com_addfwref(c, JUMP_IF_FALSE, &anchor);
		com_addbyte(c, POP_TOP);
		com_pop(c, 1);
	}
	if (anchor)
		com_backpatch(c, anchor);
}

static int
com_make_closure(struct compiling *c, PyCodeObject *co)
{
	int i, free = PyCode_GetNumFree(co);
	if (free == 0)
		return 0;
	for (i = 0; i < free; ++i) {
		/* Bypass com_addop_varname because it will generate
		   LOAD_DEREF but LOAD_CLOSURE is needed. 
		*/
		PyObject *name = PyTuple_GET_ITEM(co->co_freevars, i);
		int arg, reftype;

		/* Special case: If a class contains a method with a
		   free variable that has the same name as a method,
		   the name will be considered free *and* local in the
		   class.  It should be handled by the closure, as
		   well as by the normal name loookup logic.
		*/
		reftype = get_ref_type(c, PyString_AS_STRING(name));	
		if (reftype == CELL)
			arg = com_lookup_arg(c->c_cellvars, name);
		else /* (reftype == FREE) */
			arg = com_lookup_arg(c->c_freevars, name);
		if (arg == -1) {
			fprintf(stderr, "lookup %s in %s %d %d\n"
				"freevars of %s: %s\n",
				PyObject_REPR(name), 
				c->c_name, 
				reftype, arg,
				PyString_AS_STRING(co->co_name),
				PyObject_REPR(co->co_freevars));
			Py_FatalError("com_make_closure()");
		}
		com_addoparg(c, LOAD_CLOSURE, arg);

	}
	com_push(c, free);
	return 1;
}

static void
com_test(struct compiling *c, node *n)
{
	REQ(n, test); /* and_test ('or' and_test)* | lambdef */
	if (NCH(n) == 1 && TYPE(CHILD(n, 0)) == lambdef) {
		PyCodeObject *co;
		int i, closure;
		int ndefs = com_argdefs(c, CHILD(n, 0));
		symtable_enter_scope(c->c_symtable, "lambda", lambdef,
				     n->n_lineno);
		co = icompile(CHILD(n, 0), c);
		if (co == NULL) {
			c->c_errors++;
			return;
		}
		symtable_exit_scope(c->c_symtable);
		i = com_addconst(c, (PyObject *)co);
		closure = com_make_closure(c, co);
		com_addoparg(c, LOAD_CONST, i);
		com_push(c, 1);
		if (closure) {
			com_addoparg(c, MAKE_CLOSURE, ndefs);
			com_pop(c, PyCode_GetNumFree(co));
		} else
			com_addoparg(c, MAKE_FUNCTION, ndefs);
		Py_DECREF(co);
		com_pop(c, ndefs);
	}
	else {
		int anchor = 0;
		int i = 0;
		for (;;) {
			com_and_test(c, CHILD(n, i));
			if ((i += 2) >= NCH(n))
				break;
			com_addfwref(c, JUMP_IF_TRUE, &anchor);
			com_addbyte(c, POP_TOP);
			com_pop(c, 1);
		}
		if (anchor)
			com_backpatch(c, anchor);
	}
}

static void
com_list(struct compiling *c, node *n, int toplevel)
{
	/* exprlist: expr (',' expr)* [',']; likewise for testlist */
	if (NCH(n) == 1 && !toplevel) {
		com_node(c, CHILD(n, 0));
	}
	else {
		int i;
		int len;
		len = (NCH(n) + 1) / 2;
		for (i = 0; i < NCH(n); i += 2)
			com_node(c, CHILD(n, i));
		com_addoparg(c, BUILD_TUPLE, len);
		com_pop(c, len-1);
	}
}


/* Begin of assignment compilation */


static void
com_augassign_attr(struct compiling *c, node *n, int opcode, node *augn)
{
	com_addbyte(c, DUP_TOP);
	com_push(c, 1);
	com_addopname(c, LOAD_ATTR, n);
	com_node(c, augn);
	com_addbyte(c, opcode);
	com_pop(c, 1);
	com_addbyte(c, ROT_TWO);
	com_addopname(c, STORE_ATTR, n);
	com_pop(c, 2);
}

static void
com_assign_attr(struct compiling *c, node *n, int assigning)
{
	com_addopname(c, assigning ? STORE_ATTR : DELETE_ATTR, n);
	com_pop(c, assigning ? 2 : 1);
}

static void
com_assign_trailer(struct compiling *c, node *n, int assigning, node *augn)
{
	REQ(n, trailer);
	switch (TYPE(CHILD(n, 0))) {
	case LPAR: /* '(' [exprlist] ')' */
		com_error(c, PyExc_SyntaxError,
			  "can't assign to function call");
		break;
	case DOT: /* '.' NAME */
		if (assigning > OP_APPLY)
			com_augassign_attr(c, CHILD(n, 1), assigning, augn);
		else
			com_assign_attr(c, CHILD(n, 1), assigning);
		break;
	case LSQB: /* '[' subscriptlist ']' */
		com_subscriptlist(c, CHILD(n, 1), assigning, augn);
		break;
	default:
		com_error(c, PyExc_SystemError, "unknown trailer type");
	}
}

static void
com_assign_sequence(struct compiling *c, node *n, int assigning)
{
	int i;
	if (TYPE(n) != testlist && TYPE(n) != listmaker)
		REQ(n, exprlist);
	if (assigning) {
		i = (NCH(n)+1)/2;
		com_addoparg(c, UNPACK_SEQUENCE, i);
		com_push(c, i-1);
	}
	for (i = 0; i < NCH(n); i += 2)
		com_assign(c, CHILD(n, i), assigning, NULL);
}

static void
com_augassign_name(struct compiling *c, node *n, int opcode, node *augn)
{
	REQ(n, NAME);
	com_addop_varname(c, VAR_LOAD, STR(n));
	com_push(c, 1);
	com_node(c, augn);
	com_addbyte(c, opcode);
	com_pop(c, 1);
	com_assign_name(c, n, OP_ASSIGN);
}

static void
com_assign_name(struct compiling *c, node *n, int assigning)
{
	REQ(n, NAME);
	com_addop_varname(c, assigning ? VAR_STORE : VAR_DELETE, STR(n));
	if (assigning)
		com_pop(c, 1);
}

static void
com_assign(struct compiling *c, node *n, int assigning, node *augn)
{
	/* Loop to avoid trivial recursion */
	for (;;) {
		switch (TYPE(n)) {
		
		case exprlist:
		case testlist:
			if (NCH(n) > 1) {
				if (assigning > OP_APPLY) {
					com_error(c, PyExc_SyntaxError,
				  "augmented assign to tuple not possible");
					return;
				}
				com_assign_sequence(c, n, assigning);
				return;
			}
			n = CHILD(n, 0);
			break;
		
		case test:
		case and_test:
		case not_test:
		case comparison:
		case expr:
		case xor_expr:
		case and_expr:
		case shift_expr:
		case arith_expr:
		case term:
		case factor:
			if (NCH(n) > 1) {
				com_error(c, PyExc_SyntaxError,
					  "can't assign to operator");
				return;
			}
			n = CHILD(n, 0);
			break;
		
		case power: /* atom trailer* ('**' power)*
                              ('+'|'-'|'~') factor | atom trailer* */
			if (TYPE(CHILD(n, 0)) != atom) {
				com_error(c, PyExc_SyntaxError,
					  "can't assign to operator");
				return;
			}
			if (NCH(n) > 1) { /* trailer or exponent present */
				int i;
				com_node(c, CHILD(n, 0));
				for (i = 1; i+1 < NCH(n); i++) {
					if (TYPE(CHILD(n, i)) == DOUBLESTAR) {
						com_error(c, PyExc_SyntaxError,
						  "can't assign to operator");
						return;
					}
					com_apply_trailer(c, CHILD(n, i));
				} /* NB i is still alive */
				com_assign_trailer(c,
						CHILD(n, i), assigning, augn);
				return;
			}
			n = CHILD(n, 0);
			break;
		
		case atom:
			switch (TYPE(CHILD(n, 0))) {
			case LPAR:
				n = CHILD(n, 1);
				if (TYPE(n) == RPAR) {
					/* XXX Should allow () = () ??? */
					com_error(c, PyExc_SyntaxError,
						  "can't assign to ()");
					return;
				}
				if (assigning > OP_APPLY) {
					com_error(c, PyExc_SyntaxError,
				  "augmented assign to tuple not possible");
					return;
				}
				break;
			case LSQB:
				n = CHILD(n, 1);
				if (TYPE(n) == RSQB) {
					com_error(c, PyExc_SyntaxError,
						  "can't assign to []");
					return;
				}
				if (assigning > OP_APPLY) {
					com_error(c, PyExc_SyntaxError,
				  "augmented assign to list not possible");
					return;
				}
				if (NCH(n) > 1 
				    && TYPE(CHILD(n, 1)) == list_for) {
					com_error(c, PyExc_SyntaxError,
				  "can't assign to list comprehension");
					return;
				}
				com_assign_sequence(c, n, assigning);
				return;
			case NAME:
				if (assigning > OP_APPLY)
					com_augassign_name(c, CHILD(n, 0),
							   assigning, augn);
				else
					com_assign_name(c, CHILD(n, 0),
							assigning);
				return;
			default:
				com_error(c, PyExc_SyntaxError,
					  "can't assign to literal");
				return;
			}
			break;

		case lambdef:
			com_error(c, PyExc_SyntaxError,
				  "can't assign to lambda");
			return;
		
		default:
			com_error(c, PyExc_SystemError,
				  "com_assign: bad node");
			return;
		
		}
	}
}

static void
com_augassign(struct compiling *c, node *n)
{
	int opcode;

	switch (STR(CHILD(CHILD(n, 1), 0))[0]) {
	case '+': opcode = INPLACE_ADD; break;
	case '-': opcode = INPLACE_SUBTRACT; break;
	case '/':
		if (STR(CHILD(CHILD(n, 1), 0))[1] == '/')
			opcode = INPLACE_FLOOR_DIVIDE;
		else if (c->c_flags & CO_FUTURE_DIVISION)
			opcode = INPLACE_TRUE_DIVIDE;
		else
			opcode = INPLACE_DIVIDE;
		break;
	case '%': opcode = INPLACE_MODULO; break;
	case '<': opcode = INPLACE_LSHIFT; break;
	case '>': opcode = INPLACE_RSHIFT; break;
	case '&': opcode = INPLACE_AND; break;
	case '^': opcode = INPLACE_XOR; break;
	case '|': opcode = INPLACE_OR; break;
	case '*':
		if (STR(CHILD(CHILD(n, 1), 0))[1] == '*')
			opcode = INPLACE_POWER;
		else
			opcode = INPLACE_MULTIPLY;
		break;
	default:
		com_error(c, PyExc_SystemError, "com_augassign: bad operator");
		return;
	}
	com_assign(c, CHILD(n, 0), opcode, CHILD(n, 2));
}

static void
com_expr_stmt(struct compiling *c, node *n)
{
	REQ(n, expr_stmt);
	/* testlist (('=' testlist)* | augassign testlist) */
	/* Forget it if we have just a doc string here */
	if (!c->c_interactive && NCH(n) == 1 && get_rawdocstring(n) != NULL)
		return;
 	if (NCH(n) == 1) {
		com_node(c, CHILD(n, NCH(n)-1));
		if (c->c_interactive)
			com_addbyte(c, PRINT_EXPR);
		else
			com_addbyte(c, POP_TOP);
		com_pop(c, 1);
	}
	else if (TYPE(CHILD(n,1)) == augassign)
		com_augassign(c, n);
	else {
		int i;
		com_node(c, CHILD(n, NCH(n)-1));
		for (i = 0; i < NCH(n)-2; i+=2) {
			if (i+2 < NCH(n)-2) {
				com_addbyte(c, DUP_TOP);
				com_push(c, 1);
			}
			com_assign(c, CHILD(n, i), OP_ASSIGN, NULL);
		}
	}
}

static void
com_assert_stmt(struct compiling *c, node *n)
{
	int a = 0;
	int i;
	REQ(n, assert_stmt); /* 'assert' test [',' test] */
	if (Py_OptimizeFlag)
		return;
	/* Generate code like
	   
	     if not <test>:
	         raise AssertionError [, <message>]

	   where <message> is the second test, if present.
	*/
	com_node(c, CHILD(n, 1));
	com_addfwref(c, JUMP_IF_TRUE, &a);
	com_addbyte(c, POP_TOP);
	com_pop(c, 1);
	/* Raise that exception! */
	com_addop_name(c, LOAD_GLOBAL, "AssertionError");
	com_push(c, 1);
	i = NCH(n)/2; /* Either 2 or 4 */
	if (i > 1)
		com_node(c, CHILD(n, 3));
	com_addoparg(c, RAISE_VARARGS, i);
	com_pop(c, i);
	/* The interpreter does not fall through */
	/* Jump ends up here */
	com_backpatch(c, a);
	com_addbyte(c, POP_TOP);
}

static void
com_print_stmt(struct compiling *c, node *n)
{
	int i = 1;
	node* stream = NULL;

	REQ(n, print_stmt); /* 'print' (test ',')* [test] */

	/* are we using the extended print form? */
	if (NCH(n) >= 2 && TYPE(CHILD(n, 1)) == RIGHTSHIFT) {
		stream = CHILD(n, 2);
		com_node(c, stream);
		/* stack: [...] => [... stream] */
		com_push(c, 1);
		if (NCH(n) > 3 && TYPE(CHILD(n, 3)) == COMMA)
			i = 4;
		else
			i = 3;
	}
	for (; i < NCH(n); i += 2) {
		if (stream != NULL) {
			com_addbyte(c, DUP_TOP);
			/* stack: [stream] => [stream stream] */
			com_push(c, 1);
			com_node(c, CHILD(n, i));
			/* stack: [stream stream] => [stream stream obj] */
			com_addbyte(c, ROT_TWO);
			/* stack: [stream stream obj] => [stream obj stream] */
			com_addbyte(c, PRINT_ITEM_TO);
			/* stack: [stream obj stream] => [stream] */
			com_pop(c, 2);
		}
		else {
			com_node(c, CHILD(n, i));
			/* stack: [...] => [... obj] */
			com_addbyte(c, PRINT_ITEM);
			com_pop(c, 1);
		}
	}
	/* XXX Alternatively, LOAD_CONST '\n' and then PRINT_ITEM */
	if (TYPE(CHILD(n, NCH(n)-1)) == COMMA) {
		if (stream != NULL) {
			/* must pop the extra stream object off the stack */
			com_addbyte(c, POP_TOP);
			/* stack: [... stream] => [...] */
			com_pop(c, 1);
		}
	}
	else {
		if (stream != NULL) {
			/* this consumes the last stream object on stack */
			com_addbyte(c, PRINT_NEWLINE_TO);
			/* stack: [... stream] => [...] */
			com_pop(c, 1);
		}
		else
			com_addbyte(c, PRINT_NEWLINE);
	}
}

static void
com_return_stmt(struct compiling *c, node *n)
{
	REQ(n, return_stmt); /* 'return' [testlist] */
	if (!c->c_infunction) {
		com_error(c, PyExc_SyntaxError, "'return' outside function");
	}
	if (c->c_flags & CO_GENERATOR) {
		if (NCH(n) > 1) {
			com_error(c, PyExc_SyntaxError,
				  "'return' with argument inside generator");
		}
	}
	if (NCH(n) < 2) {
		com_addoparg(c, LOAD_CONST, com_addconst(c, Py_None));
		com_push(c, 1);
	}
	else
		com_node(c, CHILD(n, 1));
	com_addbyte(c, RETURN_VALUE);
	com_pop(c, 1);
}

static void
com_yield_stmt(struct compiling *c, node *n)
{
	int i;
	REQ(n, yield_stmt); /* 'yield' testlist */
	if (!c->c_infunction) {
		com_error(c, PyExc_SyntaxError, "'yield' outside function");
	}
	
	for (i = 0; i < c->c_nblocks; ++i) {
		if (c->c_block[i] == SETUP_FINALLY) {
			com_error(c, PyExc_SyntaxError,
				  "'yield' not allowed in a 'try' block "
				  "with a 'finally' clause");
			return;
		}
	}
	com_node(c, CHILD(n, 1));
	com_addbyte(c, YIELD_VALUE);
	com_pop(c, 1);
}

static void
com_raise_stmt(struct compiling *c, node *n)
{
	int i;
	REQ(n, raise_stmt); /* 'raise' [test [',' test [',' test]]] */
	if (NCH(n) > 1) {
		com_node(c, CHILD(n, 1));
		if (NCH(n) > 3) {
			com_node(c, CHILD(n, 3));
			if (NCH(n) > 5)
				com_node(c, CHILD(n, 5));
		}
	}
	i = NCH(n)/2;
	com_addoparg(c, RAISE_VARARGS, i);
	com_pop(c, i);
}

static void
com_from_import(struct compiling *c, node *n)
{
	com_addopname(c, IMPORT_FROM, CHILD(n, 0));
	com_push(c, 1);
	if (NCH(n) > 1) {
		if (strcmp(STR(CHILD(n, 1)), "as") != 0) {
			com_error(c, PyExc_SyntaxError, "invalid syntax");
			return;
		}
		com_addop_varname(c, VAR_STORE, STR(CHILD(n, 2)));
	} else
		com_addop_varname(c, VAR_STORE, STR(CHILD(n, 0)));
	com_pop(c, 1);
}

static void
com_import_stmt(struct compiling *c, node *n)
{
	int i;
	REQ(n, import_stmt);
	/* 'import' dotted_name (',' dotted_name)* |
	   'from' dotted_name 'import' ('*' | NAME (',' NAME)*) */
	if (STR(CHILD(n, 0))[0] == 'f') {
		PyObject *tup;
		/* 'from' dotted_name 'import' ... */
		REQ(CHILD(n, 1), dotted_name);
		
		if (TYPE(CHILD(n, 3)) == STAR) {
			tup = Py_BuildValue("(s)", "*");
		} else {
			tup = PyTuple_New((NCH(n) - 2)/2);
			for (i = 3; i < NCH(n); i += 2) {
				PyTuple_SET_ITEM(tup, (i-3)/2, 
					PyString_FromString(STR(
						CHILD(CHILD(n, i), 0))));
			}
		}
		com_addoparg(c, LOAD_CONST, com_addconst(c, tup));
		Py_DECREF(tup);
		com_push(c, 1);
		com_addopname(c, IMPORT_NAME, CHILD(n, 1));
		if (TYPE(CHILD(n, 3)) == STAR) 
			com_addbyte(c, IMPORT_STAR);
		else {
			for (i = 3; i < NCH(n); i += 2) 
				com_from_import(c, CHILD(n, i));
			com_addbyte(c, POP_TOP);
		}
		com_pop(c, 1);
	}
	else {
		/* 'import' ... */
		for (i = 1; i < NCH(n); i += 2) {
			node *subn = CHILD(n, i);
			REQ(subn, dotted_as_name);
			com_addoparg(c, LOAD_CONST, com_addconst(c, Py_None));
			com_push(c, 1);
			com_addopname(c, IMPORT_NAME, CHILD(subn, 0));
			if (NCH(subn) > 1) {
				int j;
				if (strcmp(STR(CHILD(subn, 1)), "as") != 0) {
					com_error(c, PyExc_SyntaxError,
						  "invalid syntax");
					return;
				}
				for (j=2 ; j < NCH(CHILD(subn, 0)); j += 2)
					com_addopname(c, LOAD_ATTR,
						      CHILD(CHILD(subn, 0),
							    j));
				com_addop_varname(c, VAR_STORE,
						  STR(CHILD(subn, 2)));
			} else
				com_addop_varname(c, VAR_STORE,
						  STR(CHILD(CHILD(subn, 0),
							    0))); 
			com_pop(c, 1);
		}
	}
}

static void
com_exec_stmt(struct compiling *c, node *n)
{
	REQ(n, exec_stmt);
	/* exec_stmt: 'exec' expr ['in' expr [',' expr]] */
	com_node(c, CHILD(n, 1));
	if (NCH(n) >= 4)
		com_node(c, CHILD(n, 3));
	else {
		com_addoparg(c, LOAD_CONST, com_addconst(c, Py_None));
		com_push(c, 1);
	}
	if (NCH(n) >= 6)
		com_node(c, CHILD(n, 5));
	else {
		com_addbyte(c, DUP_TOP);
		com_push(c, 1);
	}
	com_addbyte(c, EXEC_STMT);
	com_pop(c, 3);
}

static int
is_constant_false(struct compiling *c, node *n)
{
	PyObject *v;
	int i;
	/* argument c will be NULL when called from symtable_node() */

  /* Label to avoid tail recursion */
  next:
	switch (TYPE(n)) {

	case suite:
		if (NCH(n) == 1) {
			n = CHILD(n, 0);
			goto next;
		}
		/* Fall through */
	case file_input:
		for (i = 0; i < NCH(n); i++) {
			node *ch = CHILD(n, i);
			if (TYPE(ch) == stmt) {
				n = ch;
				goto next;
			}
		}
		break;

	case stmt:
	case simple_stmt:
	case small_stmt:
		n = CHILD(n, 0);
		goto next;

	case expr_stmt:
	case testlist:
	case test:
	case and_test:
	case not_test:
	case comparison:
	case expr:
	case xor_expr:
	case and_expr:
	case shift_expr:
	case arith_expr:
	case term:
	case factor:
	case power:
	case atom:
		if (NCH(n) == 1) {
			n = CHILD(n, 0);
			goto next;
		}
		break;

	case NAME:
		if (Py_OptimizeFlag && strcmp(STR(n), "__debug__") == 0)
			return 1;
		break;

	case NUMBER:
		v = parsenumber(c, STR(n));
		if (v == NULL) {
			PyErr_Clear();
			break;
		}
		i = PyObject_IsTrue(v);
		Py_DECREF(v);
		return i == 0;

	case STRING:
		v = parsestr(c, STR(n));
		if (v == NULL) {
			PyErr_Clear();
			break;
		}
		i = PyObject_IsTrue(v);
		Py_DECREF(v);
		return i == 0;

	}
	return 0;
}


/* Look under n for a return stmt with an expression.
 * This hack is used to find illegal returns under "if 0:" blocks in
 * functions already known to be generators (as determined by the symtable
 * pass).
 * Return the offending return node if found, else NULL.
 */
static node *
look_for_offending_return(node *n)
{
	int i;

	for (i = 0; i < NCH(n); ++i) {
		node *kid = CHILD(n, i);

		switch (TYPE(kid)) {
			case classdef:
			case funcdef:
			case lambdef:
				/* Stuff in nested functions & classes doesn't
				   affect the code block we started in. */
				return NULL;

			case return_stmt:
				if (NCH(kid) > 1)
					return kid;
				break;

			default: {
				node *bad = look_for_offending_return(kid);
				if (bad != NULL)
					return bad;
			}
		}
	}

	return NULL;
}			

static void
com_if_stmt(struct compiling *c, node *n)
{
	int i;
	int anchor = 0;
	REQ(n, if_stmt);
	/*'if' test ':' suite ('elif' test ':' suite)* ['else' ':' suite] */
	for (i = 0; i+3 < NCH(n); i+=4) {
		int a = 0;
		node *ch = CHILD(n, i+1);
		if (is_constant_false(c, ch)) {
			/* We're going to skip this block.  However, if this
			   is a generator, we have to check the dead code
			   anyway to make sure there aren't any return stmts
			   with expressions, in the same scope. */
			if (c->c_flags & CO_GENERATOR) {
				node *p = look_for_offending_return(n);
				if (p != NULL) {
					int savelineno = c->c_lineno;
					c->c_lineno = p->n_lineno;
					com_error(c, PyExc_SyntaxError,
			  	   		"'return' with argument "
			  	   		"inside generator");
			  	   	c->c_lineno = savelineno;
				}
			}
			continue;
		}
		if (i > 0)
			com_addoparg(c, SET_LINENO, ch->n_lineno);
		com_node(c, ch);
		com_addfwref(c, JUMP_IF_FALSE, &a);
		com_addbyte(c, POP_TOP);
		com_pop(c, 1);
		com_node(c, CHILD(n, i+3));
		com_addfwref(c, JUMP_FORWARD, &anchor);
		com_backpatch(c, a);
		/* We jump here with an extra entry which we now pop */
		com_addbyte(c, POP_TOP);
	}
	if (i+2 < NCH(n))
		com_node(c, CHILD(n, i+2));
	if (anchor)
		com_backpatch(c, anchor);
}

static void
com_while_stmt(struct compiling *c, node *n)
{
	int break_anchor = 0;
	int anchor = 0;
	int save_begin = c->c_begin;
	REQ(n, while_stmt); /* 'while' test ':' suite ['else' ':' suite] */
	com_addfwref(c, SETUP_LOOP, &break_anchor);
	block_push(c, SETUP_LOOP);
	c->c_begin = c->c_nexti;
	com_addoparg(c, SET_LINENO, n->n_lineno);
	com_node(c, CHILD(n, 1));
	com_addfwref(c, JUMP_IF_FALSE, &anchor);
	com_addbyte(c, POP_TOP);
	com_pop(c, 1);
	c->c_loops++;
	com_node(c, CHILD(n, 3));
	c->c_loops--;
	com_addoparg(c, JUMP_ABSOLUTE, c->c_begin);
	c->c_begin = save_begin;
	com_backpatch(c, anchor);
	/* We jump here with one entry more on the stack */
	com_addbyte(c, POP_TOP);
	com_addbyte(c, POP_BLOCK);
	block_pop(c, SETUP_LOOP);
	if (NCH(n) > 4)
		com_node(c, CHILD(n, 6));
	com_backpatch(c, break_anchor);
}

static void
com_for_stmt(struct compiling *c, node *n)
{
	int break_anchor = 0;
	int anchor = 0;
	int save_begin = c->c_begin;
	REQ(n, for_stmt);
	/* 'for' exprlist 'in' exprlist ':' suite ['else' ':' suite] */
	com_addfwref(c, SETUP_LOOP, &break_anchor);
	block_push(c, SETUP_LOOP);
	com_node(c, CHILD(n, 3));
	com_addbyte(c, GET_ITER);
	c->c_begin = c->c_nexti;
	com_addoparg(c, SET_LINENO, n->n_lineno);
	com_addfwref(c, FOR_ITER, &anchor);
	com_push(c, 1);
	com_assign(c, CHILD(n, 1), OP_ASSIGN, NULL);
	c->c_loops++;
	com_node(c, CHILD(n, 5));
	c->c_loops--;
	com_addoparg(c, JUMP_ABSOLUTE, c->c_begin);
	c->c_begin = save_begin;
	com_backpatch(c, anchor);
	com_pop(c, 1); /* FOR_ITER has popped this */
	com_addbyte(c, POP_BLOCK);
	block_pop(c, SETUP_LOOP);
	if (NCH(n) > 8)
		com_node(c, CHILD(n, 8));
	com_backpatch(c, break_anchor);
}

/* Code generated for "try: S finally: Sf" is as follows:
   
		SETUP_FINALLY	L
		<code for S>
		POP_BLOCK
		LOAD_CONST	<nil>
	L:	<code for Sf>
		END_FINALLY
   
   The special instructions use the block stack.  Each block
   stack entry contains the instruction that created it (here
   SETUP_FINALLY), the level of the value stack at the time the
   block stack entry was created, and a label (here L).
   
   SETUP_FINALLY:
	Pushes the current value stack level and the label
	onto the block stack.
   POP_BLOCK:
	Pops en entry from the block stack, and pops the value
	stack until its level is the same as indicated on the
	block stack.  (The label is ignored.)
   END_FINALLY:
	Pops a variable number of entries from the *value* stack
	and re-raises the exception they specify.  The number of
	entries popped depends on the (pseudo) exception type.
   
   The block stack is unwound when an exception is raised:
   when a SETUP_FINALLY entry is found, the exception is pushed
   onto the value stack (and the exception condition is cleared),
   and the interpreter jumps to the label gotten from the block
   stack.
   
   Code generated for "try: S except E1, V1: S1 except E2, V2: S2 ...":
   (The contents of the value stack is shown in [], with the top
   at the right; 'tb' is trace-back info, 'val' the exception's
   associated value, and 'exc' the exception.)
   
   Value stack		Label	Instruction	Argument
   []				SETUP_EXCEPT	L1
   []				<code for S>
   []				POP_BLOCK
   []				JUMP_FORWARD	L0
   
   [tb, val, exc]	L1:	DUP				)
   [tb, val, exc, exc]		<evaluate E1>			)
   [tb, val, exc, exc, E1]	COMPARE_OP	EXC_MATCH	) only if E1
   [tb, val, exc, 1-or-0]	JUMP_IF_FALSE	L2		)
   [tb, val, exc, 1]		POP				)
   [tb, val, exc]		POP
   [tb, val]			<assign to V1>	(or POP if no V1)
   [tb]				POP
   []				<code for S1>
   				JUMP_FORWARD	L0
   
   [tb, val, exc, 0]	L2:	POP
   [tb, val, exc]		DUP
   .............................etc.......................

   [tb, val, exc, 0]	Ln+1:	POP
   [tb, val, exc]	   	END_FINALLY	# re-raise exception
   
   []			L0:	<next statement>
   
   Of course, parts are not generated if Vi or Ei is not present.
*/

static void
com_try_except(struct compiling *c, node *n)
{
	int except_anchor = 0;
	int end_anchor = 0;
	int else_anchor = 0;
	int i;
	node *ch;

	com_addfwref(c, SETUP_EXCEPT, &except_anchor);
	block_push(c, SETUP_EXCEPT);
	com_node(c, CHILD(n, 2));
	com_addbyte(c, POP_BLOCK);
	block_pop(c, SETUP_EXCEPT);
	com_addfwref(c, JUMP_FORWARD, &else_anchor);
	com_backpatch(c, except_anchor);
	for (i = 3;
	     i < NCH(n) && TYPE(ch = CHILD(n, i)) == except_clause;
	     i += 3) {
		/* except_clause: 'except' [expr [',' var]] */
		if (except_anchor == 0) {
			com_error(c, PyExc_SyntaxError,
				  "default 'except:' must be last");
			break;
		}
		except_anchor = 0;
		com_push(c, 3); /* tb, val, exc pushed by exception */
		com_addoparg(c, SET_LINENO, ch->n_lineno);
		if (NCH(ch) > 1) {
			com_addbyte(c, DUP_TOP);
			com_push(c, 1);
			com_node(c, CHILD(ch, 1));
			com_addoparg(c, COMPARE_OP, PyCmp_EXC_MATCH);
			com_pop(c, 1);
			com_addfwref(c, JUMP_IF_FALSE, &except_anchor);
			com_addbyte(c, POP_TOP);
			com_pop(c, 1);
		}
		com_addbyte(c, POP_TOP);
		com_pop(c, 1);
		if (NCH(ch) > 3)
			com_assign(c, CHILD(ch, 3), OP_ASSIGN, NULL);
		else {
			com_addbyte(c, POP_TOP);
			com_pop(c, 1);
		}
		com_addbyte(c, POP_TOP);
		com_pop(c, 1);
		com_node(c, CHILD(n, i+2));
		com_addfwref(c, JUMP_FORWARD, &end_anchor);
		if (except_anchor) {
			com_backpatch(c, except_anchor);
			/* We come in with [tb, val, exc, 0] on the
			   stack; one pop and it's the same as
			   expected at the start of the loop */
			com_addbyte(c, POP_TOP);
		}
	}
	/* We actually come in here with [tb, val, exc] but the
	   END_FINALLY will zap those and jump around.
	   The c_stacklevel does not reflect them so we need not pop
	   anything. */
	com_addbyte(c, END_FINALLY);
	com_backpatch(c, else_anchor);
	if (i < NCH(n))
		com_node(c, CHILD(n, i+2));
	com_backpatch(c, end_anchor);
}

static void
com_try_finally(struct compiling *c, node *n)
{
	int finally_anchor = 0;
	node *ch;

	com_addfwref(c, SETUP_FINALLY, &finally_anchor);
	block_push(c, SETUP_FINALLY);
	com_node(c, CHILD(n, 2));
	com_addbyte(c, POP_BLOCK);
	block_pop(c, SETUP_FINALLY);
	block_push(c, END_FINALLY);
	com_addoparg(c, LOAD_CONST, com_addconst(c, Py_None));
	/* While the generated code pushes only one item,
	   the try-finally handling can enter here with
	   up to three items.  OK, here are the details:
	   3 for an exception, 2 for RETURN, 1 for BREAK. */
	com_push(c, 3);
	com_backpatch(c, finally_anchor);
	ch = CHILD(n, NCH(n)-1);
	com_addoparg(c, SET_LINENO, ch->n_lineno);
	com_node(c, ch);
	com_addbyte(c, END_FINALLY);
	block_pop(c, END_FINALLY);
	com_pop(c, 3); /* Matches the com_push above */
}

static void
com_try_stmt(struct compiling *c, node *n)
{
	REQ(n, try_stmt);
	/* 'try' ':' suite (except_clause ':' suite)+ ['else' ':' suite]
	 | 'try' ':' suite 'finally' ':' suite */
	if (TYPE(CHILD(n, 3)) != except_clause)
		com_try_finally(c, n);
	else
		com_try_except(c, n);
}

static node *
get_rawdocstring(node *n)
{
	int i;

  /* Label to avoid tail recursion */
  next:
	switch (TYPE(n)) {

	case suite:
		if (NCH(n) == 1) {
			n = CHILD(n, 0);
			goto next;
		}
		/* Fall through */
	case file_input:
		for (i = 0; i < NCH(n); i++) {
			node *ch = CHILD(n, i);
			if (TYPE(ch) == stmt) {
				n = ch;
				goto next;
			}
		}
		break;

	case stmt:
	case simple_stmt:
	case small_stmt:
		n = CHILD(n, 0);
		goto next;

	case expr_stmt:
	case testlist:
	case test:
	case and_test:
	case not_test:
	case comparison:
	case expr:
	case xor_expr:
	case and_expr:
	case shift_expr:
	case arith_expr:
	case term:
	case factor:
	case power:
		if (NCH(n) == 1) {
			n = CHILD(n, 0);
			goto next;
		}
		break;

	case atom:
		if (TYPE(CHILD(n, 0)) == STRING)
			return n;
		break;

	}
	return NULL;
}

static PyObject *
get_docstring(struct compiling *c, node *n)
{
	/* Don't generate doc-strings if run with -OO */
	if (Py_OptimizeFlag > 1)
		return NULL;
	n = get_rawdocstring(n);
	if (n == NULL)
		return NULL;
	return parsestrplus(c, n);
}

static void
com_suite(struct compiling *c, node *n)
{
	REQ(n, suite);
	/* simple_stmt | NEWLINE INDENT NEWLINE* (stmt NEWLINE*)+ DEDENT */
	if (NCH(n) == 1) {
		com_node(c, CHILD(n, 0));
	}
	else {
		int i;
		for (i = 0; i < NCH(n) && c->c_errors == 0; i++) {
			node *ch = CHILD(n, i);
			if (TYPE(ch) == stmt)
				com_node(c, ch);
		}
	}
}

/* ARGSUSED */
static void
com_continue_stmt(struct compiling *c, node *n)
{
	int i = c->c_nblocks;
	if (i-- > 0 && c->c_block[i] == SETUP_LOOP) {
		com_addoparg(c, JUMP_ABSOLUTE, c->c_begin);
	}
	else if (i <= 0) {
		/* at the outer level */
		com_error(c, PyExc_SyntaxError,
			  "'continue' not properly in loop");
	}
	else {
		int j;
		for (j = i-1; j >= 0; --j) {
			if (c->c_block[j] == SETUP_LOOP)
				break;
		}
		if (j >= 0) {
			/* there is a loop, but something interferes */
			for (; i > j; --i) {
				if (c->c_block[i] == SETUP_EXCEPT ||
				    c->c_block[i] == SETUP_FINALLY) {
					com_addoparg(c, CONTINUE_LOOP,
						     c->c_begin);
					return;
				}
				if (c->c_block[i] == END_FINALLY) {
					com_error(c, PyExc_SyntaxError,
			  "'continue' not supported inside 'finally' clause");
			  		return;
			  	}
			}
		}
		com_error(c, PyExc_SyntaxError,
			  "'continue' not properly in loop");
	}
	/* XXX Could allow it inside a 'finally' clause
	   XXX if we could pop the exception still on the stack */
}

static int
com_argdefs(struct compiling *c, node *n)
{
	int i, nch, nargs, ndefs;
	if (TYPE(n) == lambdef) {
		/* lambdef: 'lambda' [varargslist] ':' test */
		n = CHILD(n, 1);
	}
	else {
		REQ(n, funcdef); /* funcdef: 'def' NAME parameters ... */
		n = CHILD(n, 2);
		REQ(n, parameters); /* parameters: '(' [varargslist] ')' */
		n = CHILD(n, 1);
	}
	if (TYPE(n) != varargslist)
		    return 0;
	/* varargslist:
		(fpdef ['=' test] ',')* '*' ....... |
		fpdef ['=' test] (',' fpdef ['=' test])* [','] */
	nch = NCH(n);
	nargs = 0;
	ndefs = 0;
	for (i = 0; i < nch; i++) {
		int t;
		if (TYPE(CHILD(n, i)) == STAR ||
		    TYPE(CHILD(n, i)) == DOUBLESTAR)
			break;
		nargs++;
		i++;
		if (i >= nch)
			t = RPAR; /* Anything except EQUAL or COMMA */
		else
			t = TYPE(CHILD(n, i));
		if (t == EQUAL) {
			i++;
			ndefs++;
			com_node(c, CHILD(n, i));
			i++;
			if (i >= nch)
				break;
			t = TYPE(CHILD(n, i));
		}
		else {
			/* Treat "(a=1, b)" as an error */
			if (ndefs)
				com_error(c, PyExc_SyntaxError,
			    "non-default argument follows default argument");
		}
		if (t != COMMA)
			break;
	}
	return ndefs;
}

static void
com_funcdef(struct compiling *c, node *n)
{
	PyObject *co;
	int ndefs;
	REQ(n, funcdef); /* funcdef: 'def' NAME parameters ':' suite */
	ndefs = com_argdefs(c, n);
	symtable_enter_scope(c->c_symtable, STR(CHILD(n, 1)), TYPE(n),
			     n->n_lineno);
	co = (PyObject *)icompile(n, c);
	symtable_exit_scope(c->c_symtable);
	if (co == NULL)
		c->c_errors++;
	else {
		int closure = com_make_closure(c, (PyCodeObject *)co);
		int i = com_addconst(c, co);
		com_addoparg(c, LOAD_CONST, i);
		com_push(c, 1);
		if (closure)
			com_addoparg(c, MAKE_CLOSURE, ndefs);
		else
			com_addoparg(c, MAKE_FUNCTION, ndefs);
		com_pop(c, ndefs);
		com_addop_varname(c, VAR_STORE, STR(CHILD(n, 1)));
		com_pop(c, 1);
		Py_DECREF(co);
	}
}

static void
com_bases(struct compiling *c, node *n)
{
	int i;
	REQ(n, testlist);
	/* testlist: test (',' test)* [','] */
	for (i = 0; i < NCH(n); i += 2)
		com_node(c, CHILD(n, i));
	i = (NCH(n)+1) / 2;
	com_addoparg(c, BUILD_TUPLE, i);
	com_pop(c, i-1);
}

static void
com_classdef(struct compiling *c, node *n)
{
	int i;
	PyObject *v;
	PyCodeObject *co;
	char *name;

	REQ(n, classdef);
	/* classdef: class NAME ['(' testlist ')'] ':' suite */
	if ((v = PyString_InternFromString(STR(CHILD(n, 1)))) == NULL) {
		c->c_errors++;
		return;
	}
	/* Push the class name on the stack */
	i = com_addconst(c, v);
	com_addoparg(c, LOAD_CONST, i);
	com_push(c, 1);
	Py_DECREF(v);
	/* Push the tuple of base classes on the stack */
	if (TYPE(CHILD(n, 2)) != LPAR) {
		com_addoparg(c, BUILD_TUPLE, 0);
		com_push(c, 1);
	}
	else
		com_bases(c, CHILD(n, 3));
	name = STR(CHILD(n, 1));
	symtable_enter_scope(c->c_symtable, name, TYPE(n), n->n_lineno);
	co = icompile(n, c);
	symtable_exit_scope(c->c_symtable);
	if (co == NULL)
		c->c_errors++;
	else {
		int closure = com_make_closure(c, co);
		i = com_addconst(c, (PyObject *)co);
		com_addoparg(c, LOAD_CONST, i);
		com_push(c, 1);
		if (closure) {
			com_addoparg(c, MAKE_CLOSURE, 0);
			com_pop(c, PyCode_GetNumFree(co));
		} else
			com_addoparg(c, MAKE_FUNCTION, 0);
		com_addoparg(c, CALL_FUNCTION, 0);
		com_addbyte(c, BUILD_CLASS);
		com_pop(c, 2);
		com_addop_varname(c, VAR_STORE, STR(CHILD(n, 1)));
		com_pop(c, 1);
		Py_DECREF(co);
	}
}

static void
com_node(struct compiling *c, node *n)
{
 loop:
	if (c->c_errors)
		return;
	switch (TYPE(n)) {
	
	/* Definition nodes */
	
	case funcdef:
		com_funcdef(c, n);
		break;
	case classdef:
		com_classdef(c, n);
		break;
	
	/* Trivial parse tree nodes */
	
	case stmt:
	case small_stmt:
	case flow_stmt:
		n = CHILD(n, 0);
		goto loop;

	case simple_stmt:
		/* small_stmt (';' small_stmt)* [';'] NEWLINE */
		com_addoparg(c, SET_LINENO, n->n_lineno);
		{
			int i;
			for (i = 0; i < NCH(n)-1; i += 2)
				com_node(c, CHILD(n, i));
		}
		break;
	
	case compound_stmt:
		com_addoparg(c, SET_LINENO, n->n_lineno);
		n = CHILD(n, 0);
		goto loop;

	/* Statement nodes */
	
	case expr_stmt:
		com_expr_stmt(c, n);
		break;
	case print_stmt:
		com_print_stmt(c, n);
		break;
	case del_stmt: /* 'del' exprlist */
		com_assign(c, CHILD(n, 1), OP_DELETE, NULL);
		break;
	case pass_stmt:
		break;
	case break_stmt:
		if (c->c_loops == 0) {
			com_error(c, PyExc_SyntaxError,
				  "'break' outside loop");
		}
		com_addbyte(c, BREAK_LOOP);
		break;
	case continue_stmt:
		com_continue_stmt(c, n);
		break;
	case return_stmt:
		com_return_stmt(c, n);
		break;
	case yield_stmt:
		com_yield_stmt(c, n);
		break;
	case raise_stmt:
		com_raise_stmt(c, n);
		break;
	case import_stmt:
		com_import_stmt(c, n);
		break;
	case global_stmt:
		break;
	case exec_stmt:
		com_exec_stmt(c, n);
		break;
	case assert_stmt:
		com_assert_stmt(c, n);
		break;
	case if_stmt:
		com_if_stmt(c, n);
		break;
	case while_stmt:
		com_while_stmt(c, n);
		break;
	case for_stmt:
		com_for_stmt(c, n);
		break;
	case try_stmt:
		com_try_stmt(c, n);
		break;
	case suite:
		com_suite(c, n);
		break;
	
	/* Expression nodes */
	
	case testlist:
	case testlist_safe:
		com_list(c, n, 0);
		break;
	case test:
		com_test(c, n);
		break;
	case and_test:
		com_and_test(c, n);
		break;
	case not_test:
		com_not_test(c, n);
		break;
	case comparison:
		com_comparison(c, n);
		break;
	case exprlist:
		com_list(c, n, 0);
		break;
	case expr:
		com_expr(c, n);
		break;
	case xor_expr:
		com_xor_expr(c, n);
		break;
	case and_expr:
		com_and_expr(c, n);
		break;
	case shift_expr:
		com_shift_expr(c, n);
		break;
	case arith_expr:
		com_arith_expr(c, n);
		break;
	case term:
		com_term(c, n);
		break;
	case factor:
		com_factor(c, n);
		break;
	case power:
		com_power(c, n);
		break;
	case atom:
		com_atom(c, n);
		break;
	
	default:
		com_error(c, PyExc_SystemError,
			  "com_node: unexpected node type");
	}
}

static void com_fplist(struct compiling *, node *);

static void
com_fpdef(struct compiling *c, node *n)
{
	REQ(n, fpdef); /* fpdef: NAME | '(' fplist ')' */
	if (TYPE(CHILD(n, 0)) == LPAR)
		com_fplist(c, CHILD(n, 1));
	else {
		com_addop_varname(c, VAR_STORE, STR(CHILD(n, 0)));
		com_pop(c, 1);
	}
}

static void
com_fplist(struct compiling *c, node *n)
{
	REQ(n, fplist); /* fplist: fpdef (',' fpdef)* [','] */
	if (NCH(n) == 1) {
		com_fpdef(c, CHILD(n, 0));
	}
	else {
		int i = (NCH(n)+1)/2;
		com_addoparg(c, UNPACK_SEQUENCE, i);
		com_push(c, i-1);
		for (i = 0; i < NCH(n); i += 2)
			com_fpdef(c, CHILD(n, i));
	}
}

static void
com_arglist(struct compiling *c, node *n)
{
	int nch, i, narg;
	int complex = 0;
	char nbuf[30];
	REQ(n, varargslist);
	/* varargslist:
		(fpdef ['=' test] ',')* (fpdef ['=' test] | '*' .....) */
	nch = NCH(n);
	/* Enter all arguments in table of locals */
	for (i = 0, narg = 0; i < nch; i++) {
		node *ch = CHILD(n, i);
		node *fp;
		if (TYPE(ch) == STAR || TYPE(ch) == DOUBLESTAR)
			break;
		REQ(ch, fpdef); /* fpdef: NAME | '(' fplist ')' */
		fp = CHILD(ch, 0);
		if (TYPE(fp) != NAME) {
			PyOS_snprintf(nbuf, sizeof(nbuf), ".%d", i);
			complex = 1;
		}
		narg++;
		/* all name updates handled by symtable */
		if (++i >= nch)
			break;
		ch = CHILD(n, i);
		if (TYPE(ch) == EQUAL)
			i += 2;
		else
			REQ(ch, COMMA);
	}
	if (complex) {
		/* Generate code for complex arguments only after
		   having counted the simple arguments */
		int ilocal = 0;
		for (i = 0; i < nch; i++) {
			node *ch = CHILD(n, i);
			node *fp;
			if (TYPE(ch) == STAR || TYPE(ch) == DOUBLESTAR)
				break;
			REQ(ch, fpdef); /* fpdef: NAME | '(' fplist ')' */
			fp = CHILD(ch, 0);
			if (TYPE(fp) != NAME) {
				com_addoparg(c, LOAD_FAST, ilocal);
				com_push(c, 1);
				com_fpdef(c, ch);
			}
			ilocal++;
			if (++i >= nch)
				break;
			ch = CHILD(n, i);
			if (TYPE(ch) == EQUAL)
				i += 2;
			else
				REQ(ch, COMMA);
		}
	}
}

static void
com_file_input(struct compiling *c, node *n)
{
	int i;
	PyObject *doc;
	REQ(n, file_input); /* (NEWLINE | stmt)* ENDMARKER */
	doc = get_docstring(c, n);
	if (doc != NULL) {
		int i = com_addconst(c, doc);
		Py_DECREF(doc);
		com_addoparg(c, LOAD_CONST, i);
		com_push(c, 1);
		com_addop_name(c, STORE_NAME, "__doc__");
		com_pop(c, 1);
	}
	for (i = 0; i < NCH(n); i++) {
		node *ch = CHILD(n, i);
		if (TYPE(ch) != ENDMARKER && TYPE(ch) != NEWLINE)
			com_node(c, ch);
	}
}

/* Top-level compile-node interface */

static void
compile_funcdef(struct compiling *c, node *n)
{
	PyObject *doc;
	node *ch;
	REQ(n, funcdef); /* funcdef: 'def' NAME parameters ':' suite */
	c->c_name = STR(CHILD(n, 1));
	doc = get_docstring(c, CHILD(n, 4));
	if (doc != NULL) {
		(void) com_addconst(c, doc);
		Py_DECREF(doc);
	}
	else
		(void) com_addconst(c, Py_None); /* No docstring */
	ch = CHILD(n, 2); /* parameters: '(' [varargslist] ')' */
	ch = CHILD(ch, 1); /* ')' | varargslist */
	if (TYPE(ch) == varargslist)
		com_arglist(c, ch);
	c->c_infunction = 1;
	com_node(c, CHILD(n, 4));
	c->c_infunction = 0;
	com_addoparg(c, LOAD_CONST, com_addconst(c, Py_None));
	com_push(c, 1);
	com_addbyte(c, RETURN_VALUE);
	com_pop(c, 1);
}

static void
compile_lambdef(struct compiling *c, node *n)
{
	node *ch;
	REQ(n, lambdef); /* lambdef: 'lambda' [varargslist] ':' test */
	c->c_name = "<lambda>";

	ch = CHILD(n, 1);
	(void) com_addconst(c, Py_None); /* No docstring */
	if (TYPE(ch) == varargslist) {
		com_arglist(c, ch);
		ch = CHILD(n, 3);
	}
	else
		ch = CHILD(n, 2);
	com_node(c, ch);
	com_addbyte(c, RETURN_VALUE);
	com_pop(c, 1);
}

static void
compile_classdef(struct compiling *c, node *n)
{
	node *ch;
	PyObject *doc;
	REQ(n, classdef);
	/* classdef: 'class' NAME ['(' testlist ')'] ':' suite */
	c->c_name = STR(CHILD(n, 1));
	c->c_private = c->c_name;
	/* Initialize local __module__ from global __name__ */
	com_addop_name(c, LOAD_GLOBAL, "__name__");
	com_addop_name(c, STORE_NAME, "__module__");
	ch = CHILD(n, NCH(n)-1); /* The suite */
	doc = get_docstring(c, ch);
	if (doc != NULL) {
		int i = com_addconst(c, doc);
		Py_DECREF(doc);
		com_addoparg(c, LOAD_CONST, i);
		com_push(c, 1);
		com_addop_name(c, STORE_NAME, "__doc__");
		com_pop(c, 1);
	}
	else
		(void) com_addconst(c, Py_None);
	com_node(c, ch);
	com_addbyte(c, LOAD_LOCALS);
	com_push(c, 1);
	com_addbyte(c, RETURN_VALUE);
	com_pop(c, 1);
}

static void
compile_node(struct compiling *c, node *n)
{
	com_addoparg(c, SET_LINENO, n->n_lineno);
	
	switch (TYPE(n)) {
	
	case single_input: /* One interactive command */
		/* NEWLINE | simple_stmt | compound_stmt NEWLINE */
		c->c_interactive++;
		n = CHILD(n, 0);
		if (TYPE(n) != NEWLINE)
			com_node(c, n);
		com_addoparg(c, LOAD_CONST, com_addconst(c, Py_None));
		com_push(c, 1);
		com_addbyte(c, RETURN_VALUE);
		com_pop(c, 1);
		c->c_interactive--;
		break;
	
	case file_input: /* A whole file, or built-in function exec() */
		com_file_input(c, n);
		com_addoparg(c, LOAD_CONST, com_addconst(c, Py_None));
		com_push(c, 1);
		com_addbyte(c, RETURN_VALUE);
		com_pop(c, 1);
		break;
	
	case eval_input: /* Built-in function input() */
		com_node(c, CHILD(n, 0));
		com_addbyte(c, RETURN_VALUE);
		com_pop(c, 1);
		break;
	
	case lambdef: /* anonymous function definition */
		compile_lambdef(c, n);
		break;

	case funcdef: /* A function definition */
		compile_funcdef(c, n);
		break;
	
	case classdef: /* A class definition */
		compile_classdef(c, n);
		break;
	
	default:
		com_error(c, PyExc_SystemError,
			  "compile_node: unexpected node type");
	}
}

static PyObject *
dict_keys_inorder(PyObject *dict, int offset)
{
	PyObject *tuple, *k, *v;
	int i, pos = 0, size = PyDict_Size(dict);

	tuple = PyTuple_New(size);
	if (tuple == NULL)
		return NULL;
	while (PyDict_Next(dict, &pos, &k, &v)) {
		i = PyInt_AS_LONG(v);
		Py_INCREF(k);
		assert((i - offset) < size);
		PyTuple_SET_ITEM(tuple, i - offset, k);
	}
	return tuple;
}

PyCodeObject *
PyNode_Compile(node *n, char *filename)
{
	return PyNode_CompileFlags(n, filename, NULL);
}

PyCodeObject *
PyNode_CompileFlags(node *n, char *filename, PyCompilerFlags *flags)
{
	return jcompile(n, filename, NULL, flags);
}

struct symtable *
PyNode_CompileSymtable(node *n, char *filename)
{
	struct symtable *st;
	PyFutureFeatures *ff;

	ff = PyNode_Future(n, filename);
	if (ff == NULL)
		return NULL;

	st = symtable_init();
	if (st == NULL) {
		PyMem_Free((void *)ff);
		return NULL;
	}
	st->st_future = ff;
	symtable_enter_scope(st, TOP, TYPE(n), n->n_lineno);
	if (st->st_errors > 0)
		goto fail;
	symtable_node(st, n);
	if (st->st_errors > 0)
		goto fail;
	
	return st;
 fail:
	PyMem_Free((void *)ff);
	st->st_future = NULL;
	PySymtable_Free(st);
	return NULL;
}

static PyCodeObject *
icompile(node *n, struct compiling *base)
{
	return jcompile(n, base->c_filename, base, NULL);
}

static PyCodeObject *
jcompile(node *n, char *filename, struct compiling *base,
	 PyCompilerFlags *flags)
{
	struct compiling sc;
	PyCodeObject *co;
	if (!com_init(&sc, filename))
		return NULL;
	if (base) {
		sc.c_private = base->c_private;
		sc.c_symtable = base->c_symtable;
		/* c_symtable still points to parent's symbols */
		if (base->c_nested 
		    || (sc.c_symtable->st_cur->ste_type == TYPE_FUNCTION))
			sc.c_nested = 1;
		sc.c_flags |= base->c_flags & PyCF_MASK;
	} else {
		sc.c_private = NULL;
		sc.c_future = PyNode_Future(n, filename);
		if (sc.c_future == NULL) {
			com_free(&sc);
			return NULL;
		}
		if (flags) {
			int merged = sc.c_future->ff_features |
				flags->cf_flags;
			sc.c_future->ff_features = merged;
			flags->cf_flags = merged;
		}
		if (symtable_build(&sc, n) < 0) {
			com_free(&sc);
			return NULL;
		}
	}
	co = NULL;
	if (symtable_load_symbols(&sc) < 0) {
		sc.c_errors++;
		goto exit;
	}
	compile_node(&sc, n);
	com_done(&sc);
	if (sc.c_errors == 0) {
		PyObject *consts, *names, *varnames, *filename, *name,
			*freevars, *cellvars;
		consts = PyList_AsTuple(sc.c_consts);
		names = PyList_AsTuple(sc.c_names);
		varnames = PyList_AsTuple(sc.c_varnames);
		cellvars = dict_keys_inorder(sc.c_cellvars, 0);
		freevars = dict_keys_inorder(sc.c_freevars,
					     PyTuple_GET_SIZE(cellvars));
		filename = PyString_InternFromString(sc.c_filename);
		name = PyString_InternFromString(sc.c_name);
		if (!PyErr_Occurred())
			co = PyCode_New(sc.c_argcount,
					sc.c_nlocals,
					sc.c_maxstacklevel,
					sc.c_flags,
					sc.c_code,
					consts,
					names,
					varnames,
					freevars,
					cellvars,
					filename,
					name,
					sc.c_firstlineno,
					sc.c_lnotab);
		Py_XDECREF(consts);
		Py_XDECREF(names);
		Py_XDECREF(varnames);
		Py_XDECREF(freevars);
		Py_XDECREF(cellvars);
		Py_XDECREF(filename);
		Py_XDECREF(name);
	}
	else if (!PyErr_Occurred()) {
		/* This could happen if someone called PyErr_Clear() after an
		   error was reported above.  That's not supposed to happen,
		   but I just plugged one case and I'm not sure there can't be
		   others.  In that case, raise SystemError so that at least
		   it gets reported instead dumping core. */
		PyErr_SetString(PyExc_SystemError, "lost syntax error");
	}
 exit:
	if (base == NULL) {
		PySymtable_Free(sc.c_symtable);
		sc.c_symtable = NULL;
	}
	com_free(&sc);
	return co;
}

int
PyCode_Addr2Line(PyCodeObject *co, int addrq)
{
	int size = PyString_Size(co->co_lnotab) / 2;
	unsigned char *p = (unsigned char*)PyString_AsString(co->co_lnotab);
	int line = co->co_firstlineno;
	int addr = 0;
	while (--size >= 0) {
		addr += *p++;
		if (addr > addrq)
			break;
		line += *p++;
	}
	return line;
}

/* The test for LOCAL must come before the test for FREE in order to
   handle classes where name is both local and free.  The local var is
   a method and the free var is a free var referenced within a method.
*/

static int
get_ref_type(struct compiling *c, char *name)
{
	char buf[350];
	PyObject *v;

	if (PyDict_GetItemString(c->c_cellvars, name) != NULL)
		return CELL;
	if (PyDict_GetItemString(c->c_locals, name) != NULL)
		return LOCAL;
	if (PyDict_GetItemString(c->c_freevars, name) != NULL)
		return FREE;
	v = PyDict_GetItemString(c->c_globals, name);
	if (v) {
		if (v == Py_None)
			return GLOBAL_EXPLICIT;
		else {
			return GLOBAL_IMPLICIT;
		}
	}
	PyOS_snprintf(buf, sizeof(buf),
		"unknown scope for %.100s in %.100s(%s) "
		"in %s\nsymbols: %s\nlocals: %s\nglobals: %s\n",
		name, c->c_name, 
		PyObject_REPR(c->c_symtable->st_cur->ste_id),
		c->c_filename,
		PyObject_REPR(c->c_symtable->st_cur->ste_symbols),
		PyObject_REPR(c->c_locals),
		PyObject_REPR(c->c_globals)
		);

	Py_FatalError(buf);
	return -1;
}

/* Helper functions to issue warnings */

static int
issue_warning(char *msg, char *filename, int lineno)
{
	if (PyErr_WarnExplicit(PyExc_SyntaxWarning, msg, filename,
			       lineno, NULL, NULL) < 0)	{
		if (PyErr_ExceptionMatches(PyExc_SyntaxWarning)) {
			PyErr_SetString(PyExc_SyntaxError, msg);
			PyErr_SyntaxLocation(filename, lineno);
		}
		return -1;
	}
	return 0;
}

static int
symtable_warn(struct symtable *st, char *msg)
{
	if (issue_warning(msg, st->st_filename, st->st_cur->ste_lineno) < 0) {
		st->st_errors++;
		return -1;
	}
	return 0;
}

/* Helper function for setting lineno and filename */

static int
symtable_build(struct compiling *c, node *n)
{
	if ((c->c_symtable = symtable_init()) == NULL)
		return -1;
	c->c_symtable->st_future = c->c_future;
	c->c_symtable->st_filename = c->c_filename;
	symtable_enter_scope(c->c_symtable, TOP, TYPE(n), n->n_lineno);
	if (c->c_symtable->st_errors > 0)
		return -1;
	symtable_node(c->c_symtable, n);
	if (c->c_symtable->st_errors > 0)
		return -1;
	/* reset for second pass */
	c->c_symtable->st_nscopes = 1;
	c->c_symtable->st_pass = 2;
	return 0;
}

static int
symtable_init_compiling_symbols(struct compiling *c)
{
	PyObject *varnames;

	varnames = c->c_symtable->st_cur->ste_varnames;
	if (varnames == NULL) {
		varnames = PyList_New(0);
		if (varnames == NULL)
			return -1;
		c->c_symtable->st_cur->ste_varnames = varnames;
		Py_INCREF(varnames);
	} else
		Py_INCREF(varnames);
	c->c_varnames = varnames;

	c->c_globals = PyDict_New();
	if (c->c_globals == NULL)
		return -1;
	c->c_freevars = PyDict_New();
	if (c->c_freevars == NULL)
		return -1;
	c->c_cellvars = PyDict_New();
	if (c->c_cellvars == NULL)
		return -1;
	return 0;
}

struct symbol_info {
	int si_nlocals;
	int si_ncells;
	int si_nfrees;
	int si_nimplicit;
};

static void
symtable_init_info(struct symbol_info *si)
{
	si->si_nlocals = 0;
	si->si_ncells = 0;
	si->si_nfrees = 0;
	si->si_nimplicit = 0;
}

static int
symtable_resolve_free(struct compiling *c, PyObject *name, int flags,
		      struct symbol_info *si)
{
	PyObject *dict, *v;

	/* Seperate logic for DEF_FREE.  If it occurs in a function,
	   it indicates a local that we must allocate storage for (a
	   cell var).  If it occurs in a class, then the class has a
	   method and a free variable with the same name.
	*/
	if (c->c_symtable->st_cur->ste_type == TYPE_FUNCTION) {
		/* If it isn't declared locally, it can't be a cell. */
		if (!(flags & (DEF_LOCAL | DEF_PARAM)))
			return 0;
		v = PyInt_FromLong(si->si_ncells++);
		dict = c->c_cellvars;
	} else {
		/* If it is free anyway, then there is no need to do
		   anything here.
		*/
		if (is_free(flags ^ DEF_FREE_CLASS) 
		    || (flags == DEF_FREE_CLASS))
			return 0;
		v = PyInt_FromLong(si->si_nfrees++);
		dict = c->c_freevars;
	}
	if (v == NULL)
		return -1;
	if (PyDict_SetItem(dict, name, v) < 0) {
		Py_DECREF(v);
		return -1;
	}
	Py_DECREF(v);
	return 0;
}

/* If a variable is a cell and an argument, make sure that appears in
   co_cellvars before any variable to its right in varnames. 
*/


static int
symtable_cellvar_offsets(PyObject **cellvars, int argcount, 
			 PyObject *varnames, int flags) 
{
	PyObject *v, *w, *d, *list = NULL;
	int i, pos;

	if (flags & CO_VARARGS)
		argcount++;
	if (flags & CO_VARKEYWORDS)
		argcount++;
	for (i = argcount; --i >= 0; ) {
		v = PyList_GET_ITEM(varnames, i);
		if (PyDict_GetItem(*cellvars, v)) {
			if (list == NULL) {
				list = PyList_New(1);
				if (list == NULL)
					return -1;
				PyList_SET_ITEM(list, 0, v);
				Py_INCREF(v);
			} else
				PyList_Insert(list, 0, v);
		}
	}
	if (list == NULL || PyList_GET_SIZE(list) == 0)
		return 0;
	/* There are cellvars that are also arguments.  Create a dict
	   to replace cellvars and put the args at the front.
	*/
	d = PyDict_New();
	for (i = PyList_GET_SIZE(list); --i >= 0; ) {
		v = PyInt_FromLong(i);
		if (v == NULL) 
			goto fail;
		if (PyDict_SetItem(d, PyList_GET_ITEM(list, i), v) < 0)
			goto fail;
		if (PyDict_DelItem(*cellvars, PyList_GET_ITEM(list, i)) < 0)
			goto fail;
	}
	pos = 0;
	i = PyList_GET_SIZE(list);
	Py_DECREF(list);
	while (PyDict_Next(*cellvars, &pos, &v, &w)) {
		w = PyInt_FromLong(i++);  /* don't care about the old key */
		if (PyDict_SetItem(d, v, w) < 0) {
			Py_DECREF(w);
			goto fail;
		}
		Py_DECREF(w);
	}
	Py_DECREF(*cellvars);
	*cellvars = d;
	return 1;
 fail:
	Py_DECREF(d);
	return -1;
}

static int
symtable_freevar_offsets(PyObject *freevars, int offset)
{
	PyObject *name, *v;
	int pos;

	/* The cell vars are the first elements of the closure,
	   followed by the free vars.  Update the offsets in
	   c_freevars to account for number of cellvars. */  
	pos = 0;
	while (PyDict_Next(freevars, &pos, &name, &v)) {
		int i = PyInt_AS_LONG(v) + offset;
		PyObject *o = PyInt_FromLong(i);
		if (o == NULL)
			return -1;
		if (PyDict_SetItem(freevars, name, o) < 0) {
			Py_DECREF(o);
			return -1;
		}
		Py_DECREF(o);
	}
	return 0;
}

static int
symtable_check_unoptimized(struct compiling *c,
			   PySymtableEntryObject *ste, 
			   struct symbol_info *si)
{
	char buf[300];

	if (!(si->si_ncells || si->si_nfrees || ste->ste_child_free
	      || (ste->ste_nested && si->si_nimplicit)))
		return 0;

#define ILLEGAL_CONTAINS "contains a nested function with free variables"

#define ILLEGAL_IS "is a nested function"

#define ILLEGAL_IMPORT_STAR \
"import * is not allowed in function '%.100s' because it %s"

#define ILLEGAL_BARE_EXEC \
"unqualified exec is not allowed in function '%.100s' it %s"

#define ILLEGAL_EXEC_AND_IMPORT_STAR \
"function '%.100s' uses import * and bare exec, which are illegal " \
"because it %s"

	/* XXX perhaps the linenos for these opt-breaking statements
	   should be stored so the exception can point to them. */

	if (ste->ste_child_free) {
		if (ste->ste_optimized == OPT_IMPORT_STAR)
			PyOS_snprintf(buf, sizeof(buf),
				      ILLEGAL_IMPORT_STAR, 
				      PyString_AS_STRING(ste->ste_name),
				      ILLEGAL_CONTAINS);
		else if (ste->ste_optimized == (OPT_BARE_EXEC | OPT_EXEC))
			PyOS_snprintf(buf, sizeof(buf),
				      ILLEGAL_BARE_EXEC,
				      PyString_AS_STRING(ste->ste_name),
				      ILLEGAL_CONTAINS);
		else {
			PyOS_snprintf(buf, sizeof(buf),
				      ILLEGAL_EXEC_AND_IMPORT_STAR,
				      PyString_AS_STRING(ste->ste_name),
				      ILLEGAL_CONTAINS);
		}
	} else {
		if (ste->ste_optimized == OPT_IMPORT_STAR)
			PyOS_snprintf(buf, sizeof(buf),
				      ILLEGAL_IMPORT_STAR, 
				      PyString_AS_STRING(ste->ste_name),
				      ILLEGAL_IS);
		else if (ste->ste_optimized == (OPT_BARE_EXEC | OPT_EXEC))
			PyOS_snprintf(buf, sizeof(buf),
				      ILLEGAL_BARE_EXEC,
				      PyString_AS_STRING(ste->ste_name),
				      ILLEGAL_IS);
		else {
			PyOS_snprintf(buf, sizeof(buf),
				      ILLEGAL_EXEC_AND_IMPORT_STAR,
				      PyString_AS_STRING(ste->ste_name),
				      ILLEGAL_IS);
		}
	}

	PyErr_SetString(PyExc_SyntaxError, buf);
	PyErr_SyntaxLocation(c->c_symtable->st_filename,
			     ste->ste_opt_lineno);
	return -1;
}

static int
symtable_update_flags(struct compiling *c, PySymtableEntryObject *ste,
		      struct symbol_info *si)
{
	if (c->c_future)
		c->c_flags |= c->c_future->ff_features;
	if (ste->ste_generator)
		c->c_flags |= CO_GENERATOR;
	if (ste->ste_type != TYPE_MODULE)
		c->c_flags |= CO_NEWLOCALS;
	if (ste->ste_type == TYPE_FUNCTION) {
		c->c_nlocals = si->si_nlocals;
		if (ste->ste_optimized == 0)
			c->c_flags |= CO_OPTIMIZED;
		else if (ste->ste_optimized != OPT_EXEC) 
			return symtable_check_unoptimized(c, ste, si);
	}
	return 0;
}

static int
symtable_load_symbols(struct compiling *c)
{
	static PyObject *implicit = NULL;
	struct symtable *st = c->c_symtable;
	PySymtableEntryObject *ste = st->st_cur;
	PyObject *name, *varnames, *v;
	int i, flags, pos;
	struct symbol_info si;

	if (implicit == NULL) {
		implicit = PyInt_FromLong(1);
		if (implicit == NULL)
			return -1;
	}
	v = NULL;

	if (symtable_init_compiling_symbols(c) < 0)
		goto fail;
	symtable_init_info(&si);
	varnames = st->st_cur->ste_varnames;
	si.si_nlocals = PyList_GET_SIZE(varnames);
	c->c_argcount = si.si_nlocals;

	for (i = 0; i < si.si_nlocals; ++i) {
		v = PyInt_FromLong(i);
		if (PyDict_SetItem(c->c_locals, 
				   PyList_GET_ITEM(varnames, i), v) < 0)
			goto fail;
		Py_DECREF(v);
	}

	/* XXX The cases below define the rules for whether a name is
	   local or global.  The logic could probably be clearer. */
	pos = 0;
	while (PyDict_Next(ste->ste_symbols, &pos, &name, &v)) {
		flags = PyInt_AS_LONG(v);

		if (flags & DEF_FREE_GLOBAL)
			/* undo the original DEF_FREE */
			flags &= ~(DEF_FREE | DEF_FREE_CLASS);

		/* Deal with names that need two actions:
		   1. Cell variables that are also locals.
		   2. Free variables in methods that are also class
		   variables or declared global.
		*/
		if (flags & (DEF_FREE | DEF_FREE_CLASS))
			symtable_resolve_free(c, name, flags, &si);

		if (flags & DEF_STAR) {
			c->c_argcount--;
			c->c_flags |= CO_VARARGS;
		} else if (flags & DEF_DOUBLESTAR) {
			c->c_argcount--;
			c->c_flags |= CO_VARKEYWORDS;
		} else if (flags & DEF_INTUPLE) 
			c->c_argcount--;
		else if (flags & DEF_GLOBAL) {
			if (flags & DEF_PARAM) {
				PyErr_Format(PyExc_SyntaxError, LOCAL_GLOBAL,
					     PyString_AS_STRING(name));
				PyErr_SyntaxLocation(st->st_filename, 
						   ste->ste_lineno);
				st->st_errors++;
				goto fail;
			}
			if (PyDict_SetItem(c->c_globals, name, Py_None) < 0)
				goto fail;
		} else if (flags & DEF_FREE_GLOBAL) {
			si.si_nimplicit++;
			if (PyDict_SetItem(c->c_globals, name, implicit) < 0)
				goto fail;
		} else if ((flags & DEF_LOCAL) && !(flags & DEF_PARAM)) {
			v = PyInt_FromLong(si.si_nlocals++);
			if (v == NULL)
				goto fail;
			if (PyDict_SetItem(c->c_locals, name, v) < 0)
				goto fail;
			Py_DECREF(v);
			if (ste->ste_type != TYPE_CLASS) 
				if (PyList_Append(c->c_varnames, name) < 0)
					goto fail;
		} else if (is_free(flags)) {
			if (ste->ste_nested) {
				v = PyInt_FromLong(si.si_nfrees++);
				if (v == NULL)
					goto fail;
				if (PyDict_SetItem(c->c_freevars, name, v) < 0)
					goto fail;
				Py_DECREF(v);
			} else {
				si.si_nimplicit++;
 				if (PyDict_SetItem(c->c_globals, name,
 						   implicit) < 0)
 					goto fail;
 				if (st->st_nscopes != 1) {
 					v = PyInt_FromLong(flags);
 					if (PyDict_SetItem(st->st_global, 
 							   name, v)) 
 						goto fail;
 					Py_DECREF(v);
 				}
			}
		}
	}

	assert(PyDict_Size(c->c_freevars) == si.si_nfrees);

	if (si.si_ncells > 1) { /* one cell is always in order */
		if (symtable_cellvar_offsets(&c->c_cellvars, c->c_argcount,
					     c->c_varnames, c->c_flags) < 0)
			return -1;
	}
	if (symtable_freevar_offsets(c->c_freevars, si.si_ncells) < 0)
		return -1;
	return symtable_update_flags(c, ste, &si);
 fail:
	/* is this always the right thing to do? */
	Py_XDECREF(v);
	return -1;
}

static struct symtable *
symtable_init()
{
	struct symtable *st;

	st = (struct symtable *)PyMem_Malloc(sizeof(struct symtable));
	if (st == NULL)
		return NULL;
	st->st_pass = 1;

	st->st_filename = NULL;
	if ((st->st_stack = PyList_New(0)) == NULL)
		goto fail;
	if ((st->st_symbols = PyDict_New()) == NULL)
		goto fail; 
	st->st_cur = NULL;
	st->st_nscopes = 0;
	st->st_errors = 0;
	st->st_tmpname = 0;
	st->st_private = NULL;
	return st;
 fail:
	PySymtable_Free(st);
	return NULL;
}

void
PySymtable_Free(struct symtable *st)
{
	Py_XDECREF(st->st_symbols);
	Py_XDECREF(st->st_stack);
	Py_XDECREF(st->st_cur);
	PyMem_Free((void *)st);
}

/* When the compiler exits a scope, it must should update the scope's
   free variable information with the list of free variables in its
   children.

   Variables that are free in children and defined in the current
   scope are cellvars.

   If the scope being exited is defined at the top-level (ste_nested is
   false), free variables in children that are not defined here are
   implicit globals.

*/

static int
symtable_update_free_vars(struct symtable *st)
{
	int i, j, def;
	PyObject *o, *name, *list = NULL;
	PySymtableEntryObject *child, *ste = st->st_cur;

	if (ste->ste_type == TYPE_CLASS)
		def = DEF_FREE_CLASS;
	else
		def = DEF_FREE;
	for (i = 0; i < PyList_GET_SIZE(ste->ste_children); ++i) {
		int pos = 0;

		if (list)
			PyList_SetSlice(list, 0, 
					((PyVarObject*)list)->ob_size, 0);
		child = (PySymtableEntryObject *)
			PyList_GET_ITEM(ste->ste_children, i);
		while (PyDict_Next(child->ste_symbols, &pos, &name, &o)) {
			int flags = PyInt_AS_LONG(o);
			if (!(is_free(flags)))
				continue; /* avoids indentation */
			if (list == NULL) {
				list = PyList_New(0);
				if (list == NULL)
					return -1;
			}
			ste->ste_child_free = 1;
			if (PyList_Append(list, name) < 0) {
				Py_DECREF(list);
				return -1;
			}
		}
		for (j = 0; list && j < PyList_GET_SIZE(list); j++) {
			PyObject *v;
			name = PyList_GET_ITEM(list, j);
			v = PyDict_GetItem(ste->ste_symbols, name);
			/* If a name N is declared global in scope A and
			   referenced in scope B contained (perhaps
			   indirectly) in A and there are no scopes
			   with bindings for N between B and A, then N
			   is global in B.  Unless A is a class scope,
			   because class scopes are not considered for
			   nested scopes.
			*/
			if (v && (ste->ste_type != TYPE_CLASS)) {
				int flags = PyInt_AS_LONG(v); 
				if (flags & DEF_GLOBAL) {
					symtable_undo_free(st, child->ste_id,
							   name);
					continue;
				}
			}
			if (ste->ste_nested) {
				if (symtable_add_def_o(st, ste->ste_symbols,
						       name, def) < 0) {
				    Py_DECREF(list);
				    return -1;
				}
			} else {
				if (symtable_check_global(st, child->ste_id, 
							  name) < 0) {
				    Py_DECREF(list);
				    return -1;
				}
			}
		}
	}

	Py_XDECREF(list);
	return 0;
}

/* If the current scope is a non-nested class or if name is not
   defined in the current, non-nested scope, then it is an implicit
   global in all nested scopes.
*/

static int
symtable_check_global(struct symtable *st, PyObject *child, PyObject *name)
{
	PyObject *o;
	int v;
	PySymtableEntryObject *ste = st->st_cur;
			
	if (ste->ste_type == TYPE_CLASS)
		return symtable_undo_free(st, child, name);
	o = PyDict_GetItem(ste->ste_symbols, name);
	if (o == NULL)
		return symtable_undo_free(st, child, name);
	v = PyInt_AS_LONG(o);

	if (is_free(v) || (v & DEF_GLOBAL)) 
		return symtable_undo_free(st, child, name);
	else
		return symtable_add_def_o(st, ste->ste_symbols,
					  name, DEF_FREE);
}

static int
symtable_undo_free(struct symtable *st, PyObject *id, 
		      PyObject *name)
{
	int i, v, x;
	PyObject *info;
	PySymtableEntryObject *ste;

	ste = (PySymtableEntryObject *)PyDict_GetItem(st->st_symbols, id);
	if (ste == NULL)
		return -1;

	info = PyDict_GetItem(ste->ste_symbols, name);
	if (info == NULL)
		return 0;
	v = PyInt_AS_LONG(info);
	if (is_free(v)) {
		if (symtable_add_def_o(st, ste->ste_symbols, name,
				       DEF_FREE_GLOBAL) < 0)
			return -1;
	} else
		/* If the name is defined here or declared global,
		   then the recursion stops. */
		return 0;
	
	for (i = 0; i < PyList_GET_SIZE(ste->ste_children); ++i) {
		PySymtableEntryObject *child;
		child = (PySymtableEntryObject *)
			PyList_GET_ITEM(ste->ste_children, i);
		x = symtable_undo_free(st, child->ste_id, name);
		if (x < 0)
			return x;
	}
	return 0;
}

/* symtable_enter_scope() gets a reference via PySymtableEntry_New().
   This reference is released when the scope is exited, via the DECREF
   in symtable_exit_scope().
*/

static int
symtable_exit_scope(struct symtable *st)
{
	int end;

	if (st->st_pass == 1)
		symtable_update_free_vars(st);
	Py_DECREF(st->st_cur);
	end = PyList_GET_SIZE(st->st_stack) - 1;
	st->st_cur = (PySymtableEntryObject *)PyList_GET_ITEM(st->st_stack, 
							      end);
	if (PySequence_DelItem(st->st_stack, end) < 0)
		return -1;
	return 0;
}

static void
symtable_enter_scope(struct symtable *st, char *name, int type,
		     int lineno)
{
	PySymtableEntryObject *prev = NULL;

	if (st->st_cur) {
		prev = st->st_cur;
		if (PyList_Append(st->st_stack, (PyObject *)st->st_cur) < 0) {
			Py_DECREF(st->st_cur);
			st->st_errors++;
			return;
		}
	}
	st->st_cur = (PySymtableEntryObject *)
		PySymtableEntry_New(st, name, type, lineno);
	if (strcmp(name, TOP) == 0)
		st->st_global = st->st_cur->ste_symbols;
	if (prev && st->st_pass == 1) {
		if (PyList_Append(prev->ste_children, 
				  (PyObject *)st->st_cur) < 0)
			st->st_errors++;
	}
}

static int
symtable_lookup(struct symtable *st, char *name)
{
	char buffer[MANGLE_LEN];
	PyObject *v;
	int flags;

	if (mangle(st->st_private, name, buffer, sizeof(buffer)))
		name = buffer;
	v = PyDict_GetItemString(st->st_cur->ste_symbols, name);
	if (v == NULL) {
		if (PyErr_Occurred())
			return -1;
		else
			return 0;
	}

	flags = PyInt_AS_LONG(v);
	return flags;
}

static int
symtable_add_def(struct symtable *st, char *name, int flag)
{
	PyObject *s;
	char buffer[MANGLE_LEN];
	int ret;

	if (mangle(st->st_private, name, buffer, sizeof(buffer)))
		name = buffer;
	if ((s = PyString_InternFromString(name)) == NULL)
		return -1;
	ret = symtable_add_def_o(st, st->st_cur->ste_symbols, s, flag);
	Py_DECREF(s);
	return ret;
}

/* Must only be called with mangled names */

static int
symtable_add_def_o(struct symtable *st, PyObject *dict, 
		   PyObject *name, int flag) 
{
	PyObject *o;
	int val;

	if ((o = PyDict_GetItem(dict, name))) {
	    val = PyInt_AS_LONG(o);
	    if ((flag & DEF_PARAM) && (val & DEF_PARAM)) {
		    PyErr_Format(PyExc_SyntaxError, DUPLICATE_ARGUMENT,
				 PyString_AsString(name));
		    PyErr_SyntaxLocation(st->st_filename,
				       st->st_cur->ste_lineno);
		    return -1;
	    }
	    val |= flag;
	} else
	    val = flag;
	o = PyInt_FromLong(val);
	if (PyDict_SetItem(dict, name, o) < 0) {
		Py_DECREF(o);
		return -1;
	}
	Py_DECREF(o);

	if (flag & DEF_PARAM) {
		if (PyList_Append(st->st_cur->ste_varnames, name) < 0) 
			return -1;
	} else	if (flag & DEF_GLOBAL) {
		/* XXX need to update DEF_GLOBAL for other flags too;
		   perhaps only DEF_FREE_GLOBAL */
		if ((o = PyDict_GetItem(st->st_global, name))) {
			val = PyInt_AS_LONG(o);
			val |= flag;
		} else
			val = flag;
		o = PyInt_FromLong(val);
		if (PyDict_SetItem(st->st_global, name, o) < 0) {
			Py_DECREF(o);
			return -1;
		}
		Py_DECREF(o);
	}
	return 0;
}

#define symtable_add_use(ST, NAME) symtable_add_def((ST), (NAME), USE)

/* Look for a yield stmt under n.  Return 1 if found, else 0.
   This hack is used to look inside "if 0:" blocks (which are normally
   ignored) in case those are the only places a yield occurs (so that this
   function is a generator). */
static int
look_for_yield(node *n)
{
	int i;

	for (i = 0; i < NCH(n); ++i) {
		node *kid = CHILD(n, i);

		switch (TYPE(kid)) {

		case classdef:
		case funcdef:
		case lambdef:
			/* Stuff in nested functions and classes can't make
			   the parent a generator. */
			return 0;

		case yield_stmt:
			return 1;

		default:
			if (look_for_yield(kid))
				return 1;
		}
	}
	return 0;
}			

static void
symtable_node(struct symtable *st, node *n)
{
	int i;

 loop:
	switch (TYPE(n)) {
	case funcdef: {
		char *func_name = STR(CHILD(n, 1));
		symtable_add_def(st, func_name, DEF_LOCAL);
		symtable_default_args(st, CHILD(n, 2));
		symtable_enter_scope(st, func_name, TYPE(n), n->n_lineno);
		symtable_funcdef(st, n);
		symtable_exit_scope(st);
		break;
	}
	case lambdef:
		if (NCH(n) == 4)
			symtable_default_args(st, CHILD(n, 1));
		symtable_enter_scope(st, "lambda", TYPE(n), n->n_lineno);
		symtable_funcdef(st, n);
		symtable_exit_scope(st);
		break;
	case classdef: {
		char *tmp, *class_name = STR(CHILD(n, 1));
		symtable_add_def(st, class_name, DEF_LOCAL);
		if (TYPE(CHILD(n, 2)) == LPAR) {
			node *bases = CHILD(n, 3);
			int i;
			for (i = 0; i < NCH(bases); i += 2) {
				symtable_node(st, CHILD(bases, i));
			}
		}
		symtable_enter_scope(st, class_name, TYPE(n), n->n_lineno);
		tmp = st->st_private;
		st->st_private = class_name;
		symtable_node(st, CHILD(n, NCH(n) - 1));
		st->st_private = tmp;
		symtable_exit_scope(st);
		break;
	}
	case if_stmt:
		for (i = 0; i + 3 < NCH(n); i += 4) {
			if (is_constant_false(NULL, (CHILD(n, i + 1)))) {
				if (st->st_cur->ste_generator == 0)
					st->st_cur->ste_generator =
						look_for_yield(CHILD(n, i+3));
				continue;
			}
			symtable_node(st, CHILD(n, i + 1));
			symtable_node(st, CHILD(n, i + 3));
		}
		if (i + 2 < NCH(n))
			symtable_node(st, CHILD(n, i + 2));
		break;
	case global_stmt:
		symtable_global(st, n);
		break;
	case import_stmt:
		symtable_import(st, n);
		break;
	case exec_stmt: {
		st->st_cur->ste_optimized |= OPT_EXEC;
		symtable_node(st, CHILD(n, 1));
		if (NCH(n) > 2)
			symtable_node(st, CHILD(n, 3));
		else {
			st->st_cur->ste_optimized |= OPT_BARE_EXEC;
			st->st_cur->ste_opt_lineno = n->n_lineno;
		}
		if (NCH(n) > 4)
			symtable_node(st, CHILD(n, 5));
		break;

	}
	case assert_stmt: 
		if (Py_OptimizeFlag)
			return;
		if (NCH(n) == 2) {
			n = CHILD(n, 1);
			goto loop;
		} else {
			symtable_node(st, CHILD(n, 1));
			n = CHILD(n, 3);
			goto loop;
		}
	case except_clause:
		if (NCH(n) == 4)
			symtable_assign(st, CHILD(n, 3), 0);
		if (NCH(n) > 1) {
			n = CHILD(n, 1);
			goto loop;
		}
		break;
	case del_stmt:
		symtable_assign(st, CHILD(n, 1), 0);
		break;
	case yield_stmt:
		st->st_cur->ste_generator = 1;
		n = CHILD(n, 1);
		goto loop;
	case expr_stmt:
		if (NCH(n) == 1)
			n = CHILD(n, 0);
		else {
			if (TYPE(CHILD(n, 1)) == augassign) {
				symtable_assign(st, CHILD(n, 0), 0);
				symtable_node(st, CHILD(n, 2));
				break;
			} else {
				int i;
				for (i = 0; i < NCH(n) - 2; i += 2) 
					symtable_assign(st, CHILD(n, i), 0);
				n = CHILD(n, NCH(n) - 1);
			}
		}
		goto loop;
	case list_iter:
		n = CHILD(n, 0);
		if (TYPE(n) == list_for) {
			st->st_tmpname++;
			symtable_list_comprehension(st, n);
			st->st_tmpname--;
		} else {
			REQ(n, list_if);
			symtable_node(st, CHILD(n, 1));
			if (NCH(n) == 3) {
				n = CHILD(n, 2); 
				goto loop;
			}
		}
		break;
	case for_stmt:
		symtable_assign(st, CHILD(n, 1), 0);
		for (i = 3; i < NCH(n); ++i)
			if (TYPE(CHILD(n, i)) >= single_input)
				symtable_node(st, CHILD(n, i));
		break;
	/* The remaining cases fall through to default except in
	   special circumstances.  This requires the individual cases
	   to be coded with great care, even though they look like
	   rather innocuous.  Each case must double-check TYPE(n).
	*/
	case argument:
		if (TYPE(n) == argument && NCH(n) == 3) {
			n = CHILD(n, 2);
			goto loop;
		}
		/* fall through */
	case listmaker:
		if (NCH(n) > 1 && TYPE(CHILD(n, 1)) == list_for) {
			st->st_tmpname++;
			symtable_list_comprehension(st, CHILD(n, 1));
			symtable_node(st, CHILD(n, 0));
			st->st_tmpname--;
			break;
		}
		/* fall through */
	case atom:
		if (TYPE(n) == atom && TYPE(CHILD(n, 0)) == NAME) {
			symtable_add_use(st, STR(CHILD(n, 0)));
			break;
		}
		/* fall through */
	default:
		/* Walk over every non-token child with a special case
		   for one child.
		*/
		if (NCH(n) == 1) {
			n = CHILD(n, 0);
			goto loop;
		}
		for (i = 0; i < NCH(n); ++i)
			if (TYPE(CHILD(n, i)) >= single_input)
				symtable_node(st, CHILD(n, i));
	}
}

static void
symtable_funcdef(struct symtable *st, node *n)
{
	node *body;

	if (TYPE(n) == lambdef) {
		if (NCH(n) == 4)
			symtable_params(st, CHILD(n, 1));
	} else
		symtable_params(st, CHILD(n, 2));
	body = CHILD(n, NCH(n) - 1);
	symtable_node(st, body);
}

/* The next two functions parse the argument tuple.
   symtable_default_arg() checks for names in the default arguments,
   which are references in the defining scope.  symtable_params()
   parses the parameter names, which are defined in the function's
   body. 

   varargslist: 
       (fpdef ['=' test] ',')* ('*' NAME [',' '**' NAME] | '**' NAME) 
	| fpdef ['=' test] (',' fpdef ['=' test])* [',']
*/

static void
symtable_default_args(struct symtable *st, node *n)
{
	node *c;
	int i;

	if (TYPE(n) == parameters) {
		n = CHILD(n, 1);
		if (TYPE(n) == RPAR)
			return;
	}
	REQ(n, varargslist);
	for (i = 0; i < NCH(n); i += 2) {
		c = CHILD(n, i);
		if (TYPE(c) == STAR || TYPE(c) == DOUBLESTAR) {
			break;
		}
		if (i > 0 && (TYPE(CHILD(n, i - 1)) == EQUAL))
			symtable_node(st, CHILD(n, i));
	}
}

static void
symtable_params(struct symtable *st, node *n)
{
	int i, complex = -1, ext = 0;
	node *c = NULL;

	if (TYPE(n) == parameters) {
		n = CHILD(n, 1);
		if (TYPE(n) == RPAR)
			return;
	}
	REQ(n, varargslist);
	for (i = 0; i < NCH(n); i += 2) {
		c = CHILD(n, i);
		if (TYPE(c) == STAR || TYPE(c) == DOUBLESTAR) {
			ext = 1;
			break;
		}
		if (TYPE(c) == test) {
			continue;
		}
		if (TYPE(CHILD(c, 0)) == NAME)
			symtable_add_def(st, STR(CHILD(c, 0)), DEF_PARAM);
		else {
			char nbuf[30];
			PyOS_snprintf(nbuf, sizeof(nbuf), ".%d", i);
			symtable_add_def(st, nbuf, DEF_PARAM);
			complex = i;
		}
	}
	if (ext) {
		c = CHILD(n, i);
		if (TYPE(c) == STAR) {
			i++;
			symtable_add_def(st, STR(CHILD(n, i)), 
					 DEF_PARAM | DEF_STAR);
			i += 2;
			if (i >= NCH(n))
				c = NULL;
			else
				c = CHILD(n, i);
		}
		if (c && TYPE(c) == DOUBLESTAR) {
			i++;
			symtable_add_def(st, STR(CHILD(n, i)), 
					 DEF_PARAM | DEF_DOUBLESTAR);
		}
	}
	if (complex >= 0) {
		int j;
		for (j = 0; j <= complex; j++) {
			c = CHILD(n, j);
			if (TYPE(c) == COMMA)
				c = CHILD(n, ++j);
			else if (TYPE(c) == EQUAL)
				c = CHILD(n, j += 3);
			if (TYPE(CHILD(c, 0)) == LPAR)
				symtable_params_fplist(st, CHILD(c, 1));
		} 
	}
}

static void
symtable_params_fplist(struct symtable *st, node *n)
{
	int i;
	node *c;

	REQ(n, fplist);
	for (i = 0; i < NCH(n); i += 2) {
		c = CHILD(n, i);
		REQ(c, fpdef);
		if (NCH(c) == 1)
			symtable_add_def(st, STR(CHILD(c, 0)), 
					 DEF_PARAM | DEF_INTUPLE);
		else
			symtable_params_fplist(st, CHILD(c, 1));
	}
	
}

static void
symtable_global(struct symtable *st, node *n)
{
	int i;

	/* XXX It might be helpful to warn about module-level global
	   statements, but it's hard to tell the difference between
	   module-level and a string passed to exec.
	*/

	for (i = 1; i < NCH(n); i += 2) {
		char *name = STR(CHILD(n, i));
		int flags;

		flags = symtable_lookup(st, name);
		if (flags < 0)
			continue;
		if (flags && flags != DEF_GLOBAL) {
			char buf[500];
			if (flags & DEF_PARAM) {
				PyErr_Format(PyExc_SyntaxError,
				     "name '%.400s' is local and global",
					     name);
				PyErr_SyntaxLocation(st->st_filename,
						   st->st_cur->ste_lineno);
				st->st_errors++;
				return;
			}
			else {
				if (flags & DEF_LOCAL)
					PyOS_snprintf(buf, sizeof(buf),
						      GLOBAL_AFTER_ASSIGN,
						      name);
				else
					PyOS_snprintf(buf, sizeof(buf),
						      GLOBAL_AFTER_USE, name);
				symtable_warn(st, buf);
			}
		}
		symtable_add_def(st, name, DEF_GLOBAL);
	}
}

static void
symtable_list_comprehension(struct symtable *st, node *n)
{
	char tmpname[30];

	PyOS_snprintf(tmpname, sizeof(tmpname), "_[%d]", st->st_tmpname);
	symtable_add_def(st, tmpname, DEF_LOCAL);
	symtable_assign(st, CHILD(n, 1), 0);
	symtable_node(st, CHILD(n, 3));
	if (NCH(n) == 5)
		symtable_node(st, CHILD(n, 4));
}

static void
symtable_import(struct symtable *st, node *n)
{
	int i;
	/* import_stmt: 'import' dotted_as_name (',' dotted_as_name)* 
              | 'from' dotted_name 'import' 
                                ('*' | import_as_name (',' import_as_name)*)
	   import_as_name: NAME [NAME NAME]
	*/
	if (STR(CHILD(n, 0))[0] == 'f') {  /* from */
		node *dotname = CHILD(n, 1);
		if (strcmp(STR(CHILD(dotname, 0)), "__future__") == 0) {
			/* check for bogus imports */
			if (n->n_lineno >= st->st_future->ff_last_lineno) {
				PyErr_SetString(PyExc_SyntaxError,
						LATE_FUTURE);
 				PyErr_SyntaxLocation(st->st_filename,
						   n->n_lineno);
				st->st_errors++;
				return;
			}
		}
		if (TYPE(CHILD(n, 3)) == STAR) {
			if (st->st_cur->ste_type != TYPE_MODULE) {
				if (symtable_warn(st,
				  "import * only allowed at module level") < 0)
					return;
			}
			st->st_cur->ste_optimized |= OPT_IMPORT_STAR;
			st->st_cur->ste_opt_lineno = n->n_lineno;
		} else {
			for (i = 3; i < NCH(n); i += 2) {
				node *c = CHILD(n, i);
				if (NCH(c) > 1) /* import as */
					symtable_assign(st, CHILD(c, 2),
							DEF_IMPORT);
				else
					symtable_assign(st, CHILD(c, 0),
							DEF_IMPORT);
			}
		}
	} else { 
		for (i = 1; i < NCH(n); i += 2) {
			symtable_assign(st, CHILD(n, i), DEF_IMPORT);
		}
	}
}

/* The third argument to symatble_assign() is a flag to be passed to
   symtable_add_def() if it is eventually called.  The flag is useful
   to specify the particular type of assignment that should be
   recorded, e.g. an assignment caused by import.
 */

static void 
symtable_assign(struct symtable *st, node *n, int def_flag)
{
	node *tmp;
	int i;

 loop:
	switch (TYPE(n)) {
	case lambdef:
		/* invalid assignment, e.g. lambda x:x=2.  The next
		   pass will catch this error. */
		return;
	case power:
		if (NCH(n) > 2) {
			for (i = 2; i < NCH(n); ++i)
				if (TYPE(CHILD(n, i)) != DOUBLESTAR)
					symtable_node(st, CHILD(n, i));
		}
		if (NCH(n) > 1) { 
			symtable_node(st, CHILD(n, 0));
			symtable_node(st, CHILD(n, 1));
		} else {
			n = CHILD(n, 0);
			goto loop;
		}
		return;
	case listmaker:
		if (NCH(n) > 1 && TYPE(CHILD(n, 1)) == list_for) {
			/* XXX This is an error, but the next pass
			   will catch it. */ 
			return;
		} else {
			for (i = 0; i < NCH(n); i += 2)
				symtable_assign(st, CHILD(n, i), def_flag);
		}
		return;
	case exprlist:
	case testlist:
		if (NCH(n) == 1) {
			n = CHILD(n, 0);
			goto loop;
		}
		else {
			int i;
			for (i = 0; i < NCH(n); i += 2)
				symtable_assign(st, CHILD(n, i), def_flag);
			return;
		}
	case atom:
		tmp = CHILD(n, 0);
		if (TYPE(tmp) == LPAR || TYPE(tmp) == LSQB) {
			n = CHILD(n, 1);
			goto loop;
		} else if (TYPE(tmp) == NAME) {
			if (strcmp(STR(tmp), "__debug__") == 0) {
				PyErr_SetString(PyExc_SyntaxError, 
						ASSIGN_DEBUG);
				PyErr_SyntaxLocation(st->st_filename,
						     n->n_lineno);
				st->st_errors++;
			}
			symtable_add_def(st, STR(tmp), DEF_LOCAL | def_flag);
		}
		return;
	case dotted_as_name:
		if (NCH(n) == 3)
			symtable_add_def(st, STR(CHILD(n, 2)),
					 DEF_LOCAL | def_flag);
		else
			symtable_add_def(st,
					 STR(CHILD(CHILD(n,
							 0), 0)),
					 DEF_LOCAL | def_flag);
		return;
	case dotted_name:
		symtable_add_def(st, STR(CHILD(n, 0)), DEF_LOCAL | def_flag);
		return;
	case NAME:
		symtable_add_def(st, STR(n), DEF_LOCAL | def_flag);
		return;
	default:
		if (NCH(n) == 0)
			return;
		if (NCH(n) == 1) {
			n = CHILD(n, 0);
			goto loop;
		}
		/* Should only occur for errors like x + 1 = 1,
		   which will be caught in the next pass. */
		for (i = 0; i < NCH(n); ++i)
			if (TYPE(CHILD(n, i)) >= single_input)
				symtable_assign(st, CHILD(n, i), def_flag);
	}
}