Merged revisions 61596-61597 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk
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r61596 | martin.v.loewis | 2008-03-18 23:43:46 -0500 (Di, 18 Mär 2008) | 2 lines
Import lib2to3.
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r61597 | martin.v.loewis | 2008-03-18 23:58:04 -0500 (Di, 18 Mär 2008) | 3 lines
Initialized merge tracking via "svnmerge" with revisions "1-61595" from
svn+ssh://pythondev@svn.python.org/sandbox/trunk/2to3/lib2to3
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diff --git a/Lib/lib2to3/pgen2/conv.py b/Lib/lib2to3/pgen2/conv.py
new file mode 100644
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+++ b/Lib/lib2to3/pgen2/conv.py
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+# Copyright 2004-2005 Elemental Security, Inc. All Rights Reserved.
+# Licensed to PSF under a Contributor Agreement.
+
+"""Convert graminit.[ch] spit out by pgen to Python code.
+
+Pgen is the Python parser generator. It is useful to quickly create a
+parser from a grammar file in Python's grammar notation. But I don't
+want my parsers to be written in C (yet), so I'm translating the
+parsing tables to Python data structures and writing a Python parse
+engine.
+
+Note that the token numbers are constants determined by the standard
+Python tokenizer. The standard token module defines these numbers and
+their names (the names are not used much). The token numbers are
+hardcoded into the Python tokenizer and into pgen. A Python
+implementation of the Python tokenizer is also available, in the
+standard tokenize module.
+
+On the other hand, symbol numbers (representing the grammar's
+non-terminals) are assigned by pgen based on the actual grammar
+input.
+
+Note: this module is pretty much obsolete; the pgen module generates
+equivalent grammar tables directly from the Grammar.txt input file
+without having to invoke the Python pgen C program.
+
+"""
+
+# Python imports
+import re
+
+# Local imports
+from pgen2 import grammar, token
+
+
+class Converter(grammar.Grammar):
+ """Grammar subclass that reads classic pgen output files.
+
+ The run() method reads the tables as produced by the pgen parser
+ generator, typically contained in two C files, graminit.h and
+ graminit.c. The other methods are for internal use only.
+
+ See the base class for more documentation.
+
+ """
+
+ def run(self, graminit_h, graminit_c):
+ """Load the grammar tables from the text files written by pgen."""
+ self.parse_graminit_h(graminit_h)
+ self.parse_graminit_c(graminit_c)
+ self.finish_off()
+
+ def parse_graminit_h(self, filename):
+ """Parse the .h file writen by pgen. (Internal)
+
+ This file is a sequence of #define statements defining the
+ nonterminals of the grammar as numbers. We build two tables
+ mapping the numbers to names and back.
+
+ """
+ try:
+ f = open(filename)
+ except IOError, err:
+ print "Can't open %s: %s" % (filename, err)
+ return False
+ self.symbol2number = {}
+ self.number2symbol = {}
+ lineno = 0
+ for line in f:
+ lineno += 1
+ mo = re.match(r"^#define\s+(\w+)\s+(\d+)$", line)
+ if not mo and line.strip():
+ print "%s(%s): can't parse %s" % (filename, lineno,
+ line.strip())
+ else:
+ symbol, number = mo.groups()
+ number = int(number)
+ assert symbol not in self.symbol2number
+ assert number not in self.number2symbol
+ self.symbol2number[symbol] = number
+ self.number2symbol[number] = symbol
+ return True
+
+ def parse_graminit_c(self, filename):
+ """Parse the .c file writen by pgen. (Internal)
+
+ The file looks as follows. The first two lines are always this:
+
+ #include "pgenheaders.h"
+ #include "grammar.h"
+
+ After that come four blocks:
+
+ 1) one or more state definitions
+ 2) a table defining dfas
+ 3) a table defining labels
+ 4) a struct defining the grammar
+
+ A state definition has the following form:
+ - one or more arc arrays, each of the form:
+ static arc arcs_<n>_<m>[<k>] = {
+ {<i>, <j>},
+ ...
+ };
+ - followed by a state array, of the form:
+ static state states_<s>[<t>] = {
+ {<k>, arcs_<n>_<m>},
+ ...
+ };
+
+ """
+ try:
+ f = open(filename)
+ except IOError, err:
+ print "Can't open %s: %s" % (filename, err)
+ return False
+ # The code below essentially uses f's iterator-ness!
+ lineno = 0
+
+ # Expect the two #include lines
+ lineno, line = lineno+1, f.next()
+ assert line == '#include "pgenheaders.h"\n', (lineno, line)
+ lineno, line = lineno+1, f.next()
+ assert line == '#include "grammar.h"\n', (lineno, line)
+
+ # Parse the state definitions
+ lineno, line = lineno+1, f.next()
+ allarcs = {}
+ states = []
+ while line.startswith("static arc "):
+ while line.startswith("static arc "):
+ mo = re.match(r"static arc arcs_(\d+)_(\d+)\[(\d+)\] = {$",
+ line)
+ assert mo, (lineno, line)
+ n, m, k = map(int, mo.groups())
+ arcs = []
+ for _ in range(k):
+ lineno, line = lineno+1, f.next()
+ mo = re.match(r"\s+{(\d+), (\d+)},$", line)
+ assert mo, (lineno, line)
+ i, j = map(int, mo.groups())
+ arcs.append((i, j))
+ lineno, line = lineno+1, f.next()
+ assert line == "};\n", (lineno, line)
+ allarcs[(n, m)] = arcs
+ lineno, line = lineno+1, f.next()
+ mo = re.match(r"static state states_(\d+)\[(\d+)\] = {$", line)
+ assert mo, (lineno, line)
+ s, t = map(int, mo.groups())
+ assert s == len(states), (lineno, line)
+ state = []
+ for _ in range(t):
+ lineno, line = lineno+1, f.next()
+ mo = re.match(r"\s+{(\d+), arcs_(\d+)_(\d+)},$", line)
+ assert mo, (lineno, line)
+ k, n, m = map(int, mo.groups())
+ arcs = allarcs[n, m]
+ assert k == len(arcs), (lineno, line)
+ state.append(arcs)
+ states.append(state)
+ lineno, line = lineno+1, f.next()
+ assert line == "};\n", (lineno, line)
+ lineno, line = lineno+1, f.next()
+ self.states = states
+
+ # Parse the dfas
+ dfas = {}
+ mo = re.match(r"static dfa dfas\[(\d+)\] = {$", line)
+ assert mo, (lineno, line)
+ ndfas = int(mo.group(1))
+ for i in range(ndfas):
+ lineno, line = lineno+1, f.next()
+ mo = re.match(r'\s+{(\d+), "(\w+)", (\d+), (\d+), states_(\d+),$',
+ line)
+ assert mo, (lineno, line)
+ symbol = mo.group(2)
+ number, x, y, z = map(int, mo.group(1, 3, 4, 5))
+ assert self.symbol2number[symbol] == number, (lineno, line)
+ assert self.number2symbol[number] == symbol, (lineno, line)
+ assert x == 0, (lineno, line)
+ state = states[z]
+ assert y == len(state), (lineno, line)
+ lineno, line = lineno+1, f.next()
+ mo = re.match(r'\s+("(?:\\\d\d\d)*")},$', line)
+ assert mo, (lineno, line)
+ first = {}
+ rawbitset = eval(mo.group(1))
+ for i, c in enumerate(rawbitset):
+ byte = ord(c)
+ for j in range(8):
+ if byte & (1<<j):
+ first[i*8 + j] = 1
+ dfas[number] = (state, first)
+ lineno, line = lineno+1, f.next()
+ assert line == "};\n", (lineno, line)
+ self.dfas = dfas
+
+ # Parse the labels
+ labels = []
+ lineno, line = lineno+1, f.next()
+ mo = re.match(r"static label labels\[(\d+)\] = {$", line)
+ assert mo, (lineno, line)
+ nlabels = int(mo.group(1))
+ for i in range(nlabels):
+ lineno, line = lineno+1, f.next()
+ mo = re.match(r'\s+{(\d+), (0|"\w+")},$', line)
+ assert mo, (lineno, line)
+ x, y = mo.groups()
+ x = int(x)
+ if y == "0":
+ y = None
+ else:
+ y = eval(y)
+ labels.append((x, y))
+ lineno, line = lineno+1, f.next()
+ assert line == "};\n", (lineno, line)
+ self.labels = labels
+
+ # Parse the grammar struct
+ lineno, line = lineno+1, f.next()
+ assert line == "grammar _PyParser_Grammar = {\n", (lineno, line)
+ lineno, line = lineno+1, f.next()
+ mo = re.match(r"\s+(\d+),$", line)
+ assert mo, (lineno, line)
+ ndfas = int(mo.group(1))
+ assert ndfas == len(self.dfas)
+ lineno, line = lineno+1, f.next()
+ assert line == "\tdfas,\n", (lineno, line)
+ lineno, line = lineno+1, f.next()
+ mo = re.match(r"\s+{(\d+), labels},$", line)
+ assert mo, (lineno, line)
+ nlabels = int(mo.group(1))
+ assert nlabels == len(self.labels), (lineno, line)
+ lineno, line = lineno+1, f.next()
+ mo = re.match(r"\s+(\d+)$", line)
+ assert mo, (lineno, line)
+ start = int(mo.group(1))
+ assert start in self.number2symbol, (lineno, line)
+ self.start = start
+ lineno, line = lineno+1, f.next()
+ assert line == "};\n", (lineno, line)
+ try:
+ lineno, line = lineno+1, f.next()
+ except StopIteration:
+ pass
+ else:
+ assert 0, (lineno, line)
+
+ def finish_off(self):
+ """Create additional useful structures. (Internal)."""
+ self.keywords = {} # map from keyword strings to arc labels
+ self.tokens = {} # map from numeric token values to arc labels
+ for ilabel, (type, value) in enumerate(self.labels):
+ if type == token.NAME and value is not None:
+ self.keywords[value] = ilabel
+ elif value is None:
+ self.tokens[type] = ilabel