diff --git a/Lib/sre_compile.py b/Lib/sre_compile.py
index 36986eb..701b267 100644
--- a/Lib/sre_compile.py
+++ b/Lib/sre_compile.py
@@ -10,18 +10,10 @@
 # other compatibility work.
 #
 
-import array
 import _sre
 
 from sre_constants import *
 
-# find an array type code that matches the engine's code size
-for WORDSIZE in "Hil":
-    if len(array.array(WORDSIZE, [0]).tostring()) == _sre.getcodesize():
-        break
-else:
-    raise RuntimeError, "cannot find a useable array type"
-
 MAXCODE = 65535
 
 def _charset(charset, fixup):
@@ -170,7 +162,20 @@
                 emit((group-1)*2+1)
         elif op in (SUCCESS, FAILURE):
             emit(OPCODES[op])
-        elif op in (ASSERT, ASSERT_NOT, CALL):
+        elif op in (ASSERT, ASSERT_NOT):
+            emit(OPCODES[op])
+            skip = len(code); emit(0)
+            if av[0] >= 0:
+                emit(0) # look ahead
+            else:
+                lo, hi = av[1].getwidth()
+                if lo != hi:
+                    raise error, "look-behind requires fixed-width pattern"
+                emit(lo) # look behind
+            _compile(code, av[1], flags)
+            emit(OPCODES[SUCCESS])
+            code[skip] = len(code) - skip
+        elif op is CALL:
             emit(OPCODES[op])
             skip = len(code); emit(0)
             _compile(code, av, flags)
@@ -305,7 +310,7 @@
         indexgroup[i] = k
 
     return _sre.compile(
-        pattern, flags,
-        array.array(WORDSIZE, code).tostring(),
-        p.pattern.groups-1, groupindex, indexgroup
+        pattern, flags, code,
+        p.pattern.groups-1,
+        groupindex, indexgroup
         )
diff --git a/Lib/sre_parse.py b/Lib/sre_parse.py
index d78737f..07ab782 100644
--- a/Lib/sre_parse.py
+++ b/Lib/sre_parse.py
@@ -482,9 +482,15 @@
                         if source.next is None or source.next == ")":
                             break
                         source.get()
-                elif source.next in ("=", "!"):
+                elif source.next in ("=", "!", "<"):
                     # lookahead assertions
                     char = source.get()
+                    dir = 1
+                    if char == "<":
+                        if source.next not in ("=", "!"):
+                            raise error, "syntax error"
+                        dir = -1 # lookbehind
+                        char = source.get()
                     b = []
                     while 1:
                         p = _parse(source, state)
@@ -493,9 +499,9 @@
                                 b.append(p)
                                 p = _branch(state, b)
                             if char == "=":
-                                subpattern.append((ASSERT, p))
+                                subpattern.append((ASSERT, (dir, p)))
                             else:
-                                subpattern.append((ASSERT_NOT, p))
+                                subpattern.append((ASSERT_NOT, (dir, p)))
                             break
                         elif source.match("|"):
                             b.append(p)
diff --git a/Lib/test/test_sre.py b/Lib/test/test_sre.py
index dc42ed1..a22c51a 100644
--- a/Lib/test/test_sre.py
+++ b/Lib/test/test_sre.py
@@ -35,20 +35,20 @@
 
 try:
     assert sre.sub("(?i)b+", "x", "bbbb BBBB") == 'x x'
-    
+
     def bump_num(matchobj):
         int_value = int(matchobj.group(0))
         return str(int_value + 1)
 
     assert sre.sub(r'\d+', bump_num, '08.2 -2 23x99y') == '9.3 -3 24x100y'
     assert sre.sub(r'\d+', bump_num, '08.2 -2 23x99y', 3) == '9.3 -3 23x99y'
-    
+
     assert sre.sub('.', lambda m: r"\n", 'x') == '\\n'
     assert sre.sub('.', r"\n", 'x') == '\n'
 
     s = r"\1\1"
     assert sre.sub('(.)', s, 'x') == 'xx'
-    assert sre.sub('(.)', sre.escape(s), 'x') == s 
+    assert sre.sub('(.)', sre.escape(s), 'x') == s
     assert sre.sub('(.)', lambda m: s, 'x') == s
 
     assert sre.sub('(?P<a>x)', '\g<a>\g<a>', 'xx') == 'xxxx'
@@ -144,7 +144,7 @@
 
 if verbose:
     print 'Running tests on sre.split'
-    
+
 try:
     assert sre.split(":", ":a:b::c") == ['', 'a', 'b', '', 'c']
     assert sre.split(":*", ":a:b::c") == ['', 'a', 'b', 'c']
@@ -164,7 +164,7 @@
     assert sre.split(':', 'a:b:c:d', 2) == ['a', 'b', 'c:d']
 
     assert sre.split("(:)", ":a:b::c", 2) == ['', ':', 'a', ':', 'b::c']
-    assert sre.split("(:*)", ":a:b::c", 2) == ['', ':', 'a', ':', 'b::c']    
+    assert sre.split("(:*)", ":a:b::c", 2) == ['', ':', 'a', ':', 'b::c']
 except AssertionError:
     raise TestFailed, "qualified sre.split"
 
@@ -186,29 +186,29 @@
 
 try:
     # No groups at all
-    m = sre.match('a', 'a') ; assert m.groups() == ()    
+    m = sre.match('a', 'a') ; assert m.groups() == ()
     # A single group
-    m = sre.match('(a)', 'a') ; assert m.groups() == ('a',)      
+    m = sre.match('(a)', 'a') ; assert m.groups() == ('a',)
 
     pat = sre.compile('((a)|(b))(c)?')
-    assert pat.match('a').groups() == ('a', 'a', None, None)    
-    assert pat.match('b').groups() == ('b', None, 'b', None)    
-    assert pat.match('ac').groups() == ('a', 'a', None, 'c')    
-    assert pat.match('bc').groups() == ('b', None, 'b', 'c')    
-    assert pat.match('bc').groups("") == ('b', "", 'b', 'c')    
+    assert pat.match('a').groups() == ('a', 'a', None, None)
+    assert pat.match('b').groups() == ('b', None, 'b', None)
+    assert pat.match('ac').groups() == ('a', 'a', None, 'c')
+    assert pat.match('bc').groups() == ('b', None, 'b', 'c')
+    assert pat.match('bc').groups("") == ('b', "", 'b', 'c')
 except AssertionError:
     raise TestFailed, "match .groups() method"
 
 try:
     # A single group
-    m = sre.match('(a)', 'a') 
-    assert m.group(0) == 'a' ; assert m.group(0) == 'a' 
+    m = sre.match('(a)', 'a')
+    assert m.group(0) == 'a' ; assert m.group(0) == 'a'
     assert m.group(1) == 'a' ; assert m.group(1, 1) == ('a', 'a')
 
     pat = sre.compile('(?:(?P<a1>a)|(?P<b2>b))(?P<c3>c)?')
-    assert pat.match('a').group(1, 2, 3) == ('a', None, None)   
-    assert pat.match('b').group('a1', 'b2', 'c3') == (None, 'b', None)  
-    assert pat.match('ac').group(1, 'b2', 3) == ('a', None, 'c')        
+    assert pat.match('a').group(1, 2, 3) == ('a', None, None)
+    assert pat.match('b').group('a1', 'b2', 'c3') == (None, 'b', None)
+    assert pat.match('ac').group(1, 'b2', 3) == ('a', None, 'c')
 except AssertionError:
     raise TestFailed, "match .group() method"
 
@@ -252,10 +252,10 @@
     assert sre.I == sre.IGNORECASE
     assert sre.L == sre.LOCALE
     assert sre.M == sre.MULTILINE
-    assert sre.S == sre.DOTALL 
-    assert sre.X == sre.VERBOSE 
-    assert sre.T == sre.TEMPLATE 
-    assert sre.U == sre.UNICODE 
+    assert sre.S == sre.DOTALL
+    assert sre.X == sre.VERBOSE
+    assert sre.T == sre.TEMPLATE
+    assert sre.U == sre.UNICODE
 except AssertionError:
     raise TestFailed, 're module constants'
 
@@ -272,7 +272,7 @@
 else:
     # To save time, only run the first and last 10 tests
     #tests = tests[:10] + tests[-10:]
-    pass 
+    pass
 
 for t in tests:
     sys.stdout.flush()
@@ -280,7 +280,7 @@
     if len(t)==5:
         pattern, s, outcome, repl, expected = t
     elif len(t)==3:
-        pattern, s, outcome = t 
+        pattern, s, outcome = t
     else:
         raise ValueError, ('Test tuples should have 3 or 5 fields',t)
 
@@ -288,7 +288,7 @@
         obj=sre.compile(pattern)
     except sre.error:
         if outcome==SYNTAX_ERROR: pass  # Expected a syntax error
-        else: 
+        else:
             print '=== Syntax error:', t
     except KeyboardInterrupt: raise KeyboardInterrupt
     except:
@@ -356,7 +356,7 @@
             # of the match and see if it still succeeds.  \B will
             # break (because it won't match at the end or start of a
             # string), so we'll ignore patterns that feature it.
-            
+
             if pattern[:2]!='\\B' and pattern[-2:]!='\\B':
                 obj=sre.compile(pattern)
                 result=obj.search(s, result.start(0), result.end(0)+1)
diff --git a/Modules/_sre.c b/Modules/_sre.c
index d6f050e..764e155 100644
--- a/Modules/_sre.c
+++ b/Modules/_sre.c
@@ -22,6 +22,7 @@
  * 00-06-30 fl	added fast search optimization (0.9.3)
  * 00-06-30 fl	added assert (lookahead) primitives, etc (0.9.4)
  * 00-07-02 fl	added charset optimizations, etc (0.9.5)
+ * 00-07-03 fl	store code in pattern object, lookbehind, etc
  *
  * Copyright (c) 1997-2000 by Secret Labs AB.  All rights reserved.
  *
@@ -144,14 +145,6 @@
 {
     return (unsigned int) Py_UNICODE_TOLOWER((Py_UNICODE)(ch));
 }
-
-#if !defined(Py_UNICODE_ISALNUM)
-/* FIXME: workaround.  should be fixed in unicodectype.c */
-#define Py_UNICODE_ISALNUM(ch)\
-    (Py_UNICODE_ISLOWER(ch) || Py_UNICODE_ISUPPER(ch) ||\
-     Py_UNICODE_ISTITLE(ch) || Py_UNICODE_ISDIGIT(ch))
-#endif
-
 #define SRE_UNI_IS_DIGIT(ch) Py_UNICODE_ISDIGIT((Py_UNICODE)(ch))
 #define SRE_UNI_IS_SPACE(ch) Py_UNICODE_ISSPACE((Py_UNICODE)(ch))
 #define SRE_UNI_IS_LINEBREAK(ch) Py_UNICODE_ISLINEBREAK((Py_UNICODE)(ch))
@@ -592,7 +585,7 @@
 			/* set index */
 			/* args: <index> */
 			TRACE(("%8d: set index %d\n", PTR(ptr), pattern[0]));
-            state->index = pattern[0];
+            state->lastindex = pattern[0];
 			pattern++;
 			break;
 
@@ -606,10 +599,12 @@
 
 		case SRE_OP_ASSERT:
 			/* assert subpattern */
-			/* args: <skip> <pattern> */
-			TRACE(("%8d: assert subpattern\n", PTR(ptr)));
-			state->ptr = ptr;
-			i = SRE_MATCH(state, pattern + 1);
+			/* args: <skip> <back> <pattern> */
+			TRACE(("%8d: assert subpattern %d\n", PTR(ptr), pattern[1]));
+			state->ptr = ptr - pattern[1];
+            if (state->ptr < state->beginning)
+                goto failure;
+			i = SRE_MATCH(state, pattern + 2);
             if (i < 0)
                 return i;
             if (!i)
@@ -620,9 +615,11 @@
 		case SRE_OP_ASSERT_NOT:
 			/* assert not subpattern */
 			/* args: <skip> <pattern> */
-			TRACE(("%8d: assert not subpattern\n", PTR(ptr)));
-			state->ptr = ptr;
-			i = SRE_MATCH(state, pattern + 1);
+			TRACE(("%8d: assert not subpattern %d\n", PTR(ptr), pattern[1]));
+			state->ptr = ptr - pattern[1];
+            if (state->ptr < state->beginning)
+                goto failure;
+			i = SRE_MATCH(state, pattern + 2);
             if (i < 0)
                 return i;
             if (i)
@@ -1098,6 +1095,7 @@
 	/* "compile" pattern descriptor to pattern object */
 
 	PatternObject* self;
+    int i, n;
 
 	PyObject* pattern;
     int flags = 0;
@@ -1105,24 +1103,37 @@
 	int groups = 0;
 	PyObject* groupindex = NULL;
     PyObject* indexgroup = NULL;
-	if (!PyArg_ParseTuple(args, "OiO!|iOO", &pattern, &flags,
-                          &PyString_Type, &code,
+	if (!PyArg_ParseTuple(args, "OiO|iOO", &pattern, &flags, &code,
                           &groups, &groupindex, &indexgroup))
 		return NULL;
 
-	self = PyObject_NEW(PatternObject, &Pattern_Type);
-	if (self == NULL)
-
+	code = PySequence_Fast(code, "code argument must be a sequence");
+	if (!code)
 		return NULL;
 
+    n = PySequence_Length(code);
+
+	self = PyObject_NEW_VAR(PatternObject, &Pattern_Type, 100*n);
+	if (!self) {
+        Py_DECREF(code);
+		return NULL;
+    }
+
+	for (i = 0; i < n; i++) {
+		PyObject *o = PySequence_Fast_GET_ITEM(code, i);
+        self->code[i] = (SRE_CODE) PyInt_AsLong(o);
+	}
+
+    Py_DECREF(code);
+
+    if (PyErr_Occurred())
+        return NULL;
+
 	Py_INCREF(pattern);
 	self->pattern = pattern;
 
     self->flags = flags;
 
-	Py_INCREF(code);
-	self->code = code;
-
 	self->groups = groups;
 
 	Py_XINCREF(groupindex);
@@ -1217,7 +1228,7 @@
 	for (i = 0; i < SRE_MARK_SIZE; i++)
 		state->mark[i] = NULL;
 
-    state->index = -1;
+    state->lastindex = -1;
 
 	state->stack = NULL;
 	state->stackbase = 0;
@@ -1274,8 +1285,9 @@
 	if (status > 0) {
 
 		/* create match object (with room for extra group marks) */
-		match = PyObject_NEW_VAR(MatchObject, &Match_Type, 2*pattern->groups);
-		if (match == NULL)
+		match = PyObject_NEW_VAR(MatchObject, &Match_Type,
+                                 2*(pattern->groups+1));
+		if (!match)
 			return NULL;
 
 		Py_INCREF(pattern);
@@ -1301,7 +1313,10 @@
 			} else
 				match->mark[j+2] = match->mark[j+3] = -1; /* undefined */
 
-        match->index = state->index;
+        match->lastindex = state->lastindex;
+
+        match->pos = ((char*) state->start - base) / n;
+        match->endpos = ((char*) state->end - base) / n;
 
 		return (PyObject*) match;
 
@@ -1329,12 +1344,12 @@
 
     /* create match object (with room for extra group marks) */
     self = PyObject_NEW(ScannerObject, &Scanner_Type);
-    if (self == NULL)
+    if (!self)
         return NULL;
 
     string = state_init(&self->state, pattern, args);
     if (!string) {
-        PyObject_DEL(self);
+        PyObject_Del(self);
         return NULL;
     }
 
@@ -1350,10 +1365,9 @@
 static void
 pattern_dealloc(PatternObject* self)
 {
-	Py_XDECREF(self->code);
 	Py_XDECREF(self->pattern);
 	Py_XDECREF(self->groupindex);
-	PyMem_DEL(self);
+	PyObject_DEL(self);
 }
 
 static PyObject*
@@ -1614,10 +1628,11 @@
 
 statichere PyTypeObject Pattern_Type = {
 	PyObject_HEAD_INIT(NULL)
-	0, "SRE_Pattern", sizeof(PatternObject), 0,
+	0, "SRE_Pattern",
+    sizeof(PatternObject), sizeof(SRE_CODE),
 	(destructor)pattern_dealloc, /*tp_dealloc*/
 	0, /*tp_print*/
-	(getattrfunc)pattern_getattr, /*tp_getattr*/
+	(getattrfunc)pattern_getattr /*tp_getattr*/
 };
 
 /* -------------------------------------------------------------------- */
@@ -1628,7 +1643,7 @@
 {
 	Py_XDECREF(self->string);
 	Py_DECREF(self->pattern);
-	PyMem_DEL(self);
+	PyObject_DEL(self);
 }
 
 static PyObject*
@@ -1643,31 +1658,40 @@
 		return NULL;
 	}
 
-	if (self->string == Py_None || self->mark[index+index] < 0) {
+    index *= 2;
+
+	if (self->string == Py_None || self->mark[index] < 0) {
 		/* return default value if the string or group is undefined */
 		Py_INCREF(def);
 		return def;
 	}
 
 	return PySequence_GetSlice(
-		self->string, self->mark[index+index], self->mark[index+index+1]
+		self->string, self->mark[index], self->mark[index+1]
 		);
 }
 
 static int
 match_getindex(MatchObject* self, PyObject* index)
 {
-	if (!PyInt_Check(index) && self->pattern->groupindex != NULL) {
-		/* FIXME: resource leak? */
-		index = PyObject_GetItem(self->pattern->groupindex, index);
-		if (!index)
-			return -1;
-	}
+    int i;
 
 	if (PyInt_Check(index))
         return (int) PyInt_AS_LONG(index);
 
-    return -1;
+    i = -1;
+
+	if (self->pattern->groupindex) {
+		index = PyObject_GetItem(self->pattern->groupindex, index);
+		if (index) {
+            if (PyInt_Check(index))
+                i = (int) PyInt_AS_LONG(index);
+            Py_DECREF(index);
+        } else
+            PyErr_Clear();
+	}
+
+    return i;
 }
 
 static PyObject*
@@ -1889,17 +1913,17 @@
 
 	if (!strcmp(name, "lastindex")) {
         /* experimental */
-        if (self->index >= 0)
-            return Py_BuildValue("i", self->index);
+        if (self->lastindex >= 0)
+            return Py_BuildValue("i", self->lastindex);
         Py_INCREF(Py_None);
         return Py_None;
     }
 
     if (!strcmp(name, "lastgroup")) {
         /* experimental */
-        if (self->pattern->indexgroup) {
+        if (self->pattern->indexgroup && self->lastindex >= 0) {
             PyObject* result = PySequence_GetItem(
-                self->pattern->indexgroup, self->index
+                self->pattern->indexgroup, self->lastindex
                 );
             if (result)
                 return result;
@@ -1920,10 +1944,10 @@
     }
 
 	if (!strcmp(name, "pos"))
-		return Py_BuildValue("i", 0); /* FIXME */
+		return Py_BuildValue("i", self->pos);
 
 	if (!strcmp(name, "endpos"))
-		return Py_BuildValue("i", 0); /* FIXME */
+		return Py_BuildValue("i", self->endpos);
 
 	PyErr_SetString(PyExc_AttributeError, name);
 	return NULL;
@@ -1935,11 +1959,10 @@
 statichere PyTypeObject Match_Type = {
 	PyObject_HEAD_INIT(NULL)
 	0, "SRE_Match",
-	sizeof(MatchObject), /* size of basic object */
-	sizeof(int), /* space for group item */
+	sizeof(MatchObject), sizeof(int),
 	(destructor)match_dealloc, /*tp_dealloc*/
 	0, /*tp_print*/
-	(getattrfunc)match_getattr, /*tp_getattr*/
+	(getattrfunc)match_getattr /*tp_getattr*/
 };
 
 /* -------------------------------------------------------------------- */
@@ -1951,7 +1974,7 @@
 	state_fini(&self->state);
     Py_DECREF(self->string);
     Py_DECREF(self->pattern);
-	PyMem_DEL(self);
+	PyObject_DEL(self);
 }
 
 static PyObject*
@@ -2041,8 +2064,7 @@
 statichere PyTypeObject Scanner_Type = {
 	PyObject_HEAD_INIT(NULL)
 	0, "SRE_Scanner",
-	sizeof(ScannerObject), /* size of basic object */
-	0,
+	sizeof(ScannerObject), 0,
 	(destructor)scanner_dealloc, /*tp_dealloc*/
 	0, /*tp_print*/
 	(getattrfunc)scanner_getattr, /*tp_getattr*/
diff --git a/Modules/sre.h b/Modules/sre.h
index f66d608..d4e93da 100644
--- a/Modules/sre.h
+++ b/Modules/sre.h
@@ -17,26 +17,27 @@
 #define SRE_CODE unsigned short
 
 typedef struct {
-    PyObject_HEAD
-    PyObject* code; /* link to the code string object */
+    PyObject_VAR_HEAD
     int groups;
     PyObject* groupindex;
     PyObject* indexgroup;
     /* compatibility */
     PyObject* pattern; /* pattern source (or None) */
     int flags; /* flags used when compiling pattern source */
+    /* pattern code */
+    SRE_CODE code[1];
 } PatternObject;
 
-#define PatternObject_GetCode(o)\
-    ((void*) PyString_AS_STRING(((PatternObject*)(o))->code))
+#define PatternObject_GetCode(o) (((PatternObject*)(o))->code)
 
 typedef struct {
-    PyObject_HEAD
+    PyObject_VAR_HEAD
     PyObject* string; /* link to the target string */
     PatternObject* pattern; /* link to the regex (pattern) object */
-    int index; /* last index marker seen by the engine (-1 if none) */
+    int pos, endpos; /* current target slice */
+    int lastindex; /* last index marker seen by the engine (-1 if none) */
     int groups; /* number of groups (start/end marks) */
-    int mark[2];
+    int mark[1];
 } MatchObject;
 
 typedef unsigned int (*SRE_TOLOWER_HOOK)(unsigned int ch);
@@ -59,7 +60,7 @@
     /* character size */
     int charsize;
     /* registers */
-    int index;
+    int lastindex;
     int lastmark;
     void* mark[SRE_MARK_SIZE];
     /* backtracking stack */