/usr/lib/python2.7/lib2to3/patcomp.py is in libpython2.7-stdlib 2.7.6-8.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 | # Copyright 2006 Google, Inc. All Rights Reserved.
# Licensed to PSF under a Contributor Agreement.
"""Pattern compiler.
The grammer is taken from PatternGrammar.txt.
The compiler compiles a pattern to a pytree.*Pattern instance.
"""
__author__ = "Guido van Rossum <guido@python.org>"
# Python imports
import os
import StringIO
# Fairly local imports
from .pgen2 import driver, literals, token, tokenize, parse, grammar
# Really local imports
from . import pytree
from . import pygram
# The pattern grammar file
_PATTERN_GRAMMAR_FILE = os.path.join(os.path.dirname(__file__),
"PatternGrammar.txt")
class PatternSyntaxError(Exception):
pass
def tokenize_wrapper(input):
"""Tokenizes a string suppressing significant whitespace."""
skip = set((token.NEWLINE, token.INDENT, token.DEDENT))
tokens = tokenize.generate_tokens(StringIO.StringIO(input).readline)
for quintuple in tokens:
type, value, start, end, line_text = quintuple
if type not in skip:
yield quintuple
class PatternCompiler(object):
def __init__(self, grammar_file=_PATTERN_GRAMMAR_FILE):
"""Initializer.
Takes an optional alternative filename for the pattern grammar.
"""
self.grammar = driver.load_grammar(grammar_file)
self.syms = pygram.Symbols(self.grammar)
self.pygrammar = pygram.python_grammar
self.pysyms = pygram.python_symbols
self.driver = driver.Driver(self.grammar, convert=pattern_convert)
def compile_pattern(self, input, debug=False, with_tree=False):
"""Compiles a pattern string to a nested pytree.*Pattern object."""
tokens = tokenize_wrapper(input)
try:
root = self.driver.parse_tokens(tokens, debug=debug)
except parse.ParseError as e:
raise PatternSyntaxError(str(e))
if with_tree:
return self.compile_node(root), root
else:
return self.compile_node(root)
def compile_node(self, node):
"""Compiles a node, recursively.
This is one big switch on the node type.
"""
# XXX Optimize certain Wildcard-containing-Wildcard patterns
# that can be merged
if node.type == self.syms.Matcher:
node = node.children[0] # Avoid unneeded recursion
if node.type == self.syms.Alternatives:
# Skip the odd children since they are just '|' tokens
alts = [self.compile_node(ch) for ch in node.children[::2]]
if len(alts) == 1:
return alts[0]
p = pytree.WildcardPattern([[a] for a in alts], min=1, max=1)
return p.optimize()
if node.type == self.syms.Alternative:
units = [self.compile_node(ch) for ch in node.children]
if len(units) == 1:
return units[0]
p = pytree.WildcardPattern([units], min=1, max=1)
return p.optimize()
if node.type == self.syms.NegatedUnit:
pattern = self.compile_basic(node.children[1:])
p = pytree.NegatedPattern(pattern)
return p.optimize()
assert node.type == self.syms.Unit
name = None
nodes = node.children
if len(nodes) >= 3 and nodes[1].type == token.EQUAL:
name = nodes[0].value
nodes = nodes[2:]
repeat = None
if len(nodes) >= 2 and nodes[-1].type == self.syms.Repeater:
repeat = nodes[-1]
nodes = nodes[:-1]
# Now we've reduced it to: STRING | NAME [Details] | (...) | [...]
pattern = self.compile_basic(nodes, repeat)
if repeat is not None:
assert repeat.type == self.syms.Repeater
children = repeat.children
child = children[0]
if child.type == token.STAR:
min = 0
max = pytree.HUGE
elif child.type == token.PLUS:
min = 1
max = pytree.HUGE
elif child.type == token.LBRACE:
assert children[-1].type == token.RBRACE
assert len(children) in (3, 5)
min = max = self.get_int(children[1])
if len(children) == 5:
max = self.get_int(children[3])
else:
assert False
if min != 1 or max != 1:
pattern = pattern.optimize()
pattern = pytree.WildcardPattern([[pattern]], min=min, max=max)
if name is not None:
pattern.name = name
return pattern.optimize()
def compile_basic(self, nodes, repeat=None):
# Compile STRING | NAME [Details] | (...) | [...]
assert len(nodes) >= 1
node = nodes[0]
if node.type == token.STRING:
value = unicode(literals.evalString(node.value))
return pytree.LeafPattern(_type_of_literal(value), value)
elif node.type == token.NAME:
value = node.value
if value.isupper():
if value not in TOKEN_MAP:
raise PatternSyntaxError("Invalid token: %r" % value)
if nodes[1:]:
raise PatternSyntaxError("Can't have details for token")
return pytree.LeafPattern(TOKEN_MAP[value])
else:
if value == "any":
type = None
elif not value.startswith("_"):
type = getattr(self.pysyms, value, None)
if type is None:
raise PatternSyntaxError("Invalid symbol: %r" % value)
if nodes[1:]: # Details present
content = [self.compile_node(nodes[1].children[1])]
else:
content = None
return pytree.NodePattern(type, content)
elif node.value == "(":
return self.compile_node(nodes[1])
elif node.value == "[":
assert repeat is None
subpattern = self.compile_node(nodes[1])
return pytree.WildcardPattern([[subpattern]], min=0, max=1)
assert False, node
def get_int(self, node):
assert node.type == token.NUMBER
return int(node.value)
# Map named tokens to the type value for a LeafPattern
TOKEN_MAP = {"NAME": token.NAME,
"STRING": token.STRING,
"NUMBER": token.NUMBER,
"TOKEN": None}
def _type_of_literal(value):
if value[0].isalpha():
return token.NAME
elif value in grammar.opmap:
return grammar.opmap[value]
else:
return None
def pattern_convert(grammar, raw_node_info):
"""Converts raw node information to a Node or Leaf instance."""
type, value, context, children = raw_node_info
if children or type in grammar.number2symbol:
return pytree.Node(type, children, context=context)
else:
return pytree.Leaf(type, value, context=context)
def compile_pattern(pattern):
return PatternCompiler().compile_pattern(pattern)
|