| Current File : //usr/lib64/python3.6/sre_parse.py |
#
# Secret Labs' Regular Expression Engine
#
# convert re-style regular expression to sre pattern
#
# Copyright (c) 1998-2001 by Secret Labs AB. All rights reserved.
#
# See the sre.py file for information on usage and redistribution.
#
"""Internal support module for sre"""
# XXX: show string offset and offending character for all errors
from sre_constants import *
SPECIAL_CHARS = ".\\[{()*+?^$|"
REPEAT_CHARS = "*+?{"
DIGITS = frozenset("0123456789")
OCTDIGITS = frozenset("01234567")
HEXDIGITS = frozenset("0123456789abcdefABCDEF")
ASCIILETTERS = frozenset("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
WHITESPACE = frozenset(" \t\n\r\v\f")
_REPEATCODES = frozenset({MIN_REPEAT, MAX_REPEAT})
_UNITCODES = frozenset({ANY, RANGE, IN, LITERAL, NOT_LITERAL, CATEGORY})
ESCAPES = {
r"\a": (LITERAL, ord("\a")),
r"\b": (LITERAL, ord("\b")),
r"\f": (LITERAL, ord("\f")),
r"\n": (LITERAL, ord("\n")),
r"\r": (LITERAL, ord("\r")),
r"\t": (LITERAL, ord("\t")),
r"\v": (LITERAL, ord("\v")),
r"\\": (LITERAL, ord("\\"))
}
CATEGORIES = {
r"\A": (AT, AT_BEGINNING_STRING), # start of string
r"\b": (AT, AT_BOUNDARY),
r"\B": (AT, AT_NON_BOUNDARY),
r"\d": (IN, [(CATEGORY, CATEGORY_DIGIT)]),
r"\D": (IN, [(CATEGORY, CATEGORY_NOT_DIGIT)]),
r"\s": (IN, [(CATEGORY, CATEGORY_SPACE)]),
r"\S": (IN, [(CATEGORY, CATEGORY_NOT_SPACE)]),
r"\w": (IN, [(CATEGORY, CATEGORY_WORD)]),
r"\W": (IN, [(CATEGORY, CATEGORY_NOT_WORD)]),
r"\Z": (AT, AT_END_STRING), # end of string
}
FLAGS = {
# standard flags
"i": SRE_FLAG_IGNORECASE,
"L": SRE_FLAG_LOCALE,
"m": SRE_FLAG_MULTILINE,
"s": SRE_FLAG_DOTALL,
"x": SRE_FLAG_VERBOSE,
# extensions
"a": SRE_FLAG_ASCII,
"t": SRE_FLAG_TEMPLATE,
"u": SRE_FLAG_UNICODE,
}
GLOBAL_FLAGS = (SRE_FLAG_ASCII | SRE_FLAG_LOCALE | SRE_FLAG_UNICODE |
SRE_FLAG_DEBUG | SRE_FLAG_TEMPLATE)
class Verbose(Exception):
pass
class Pattern:
# master pattern object. keeps track of global attributes
def __init__(self):
self.flags = 0
self.groupdict = {}
self.groupwidths = [None] # group 0
self.lookbehindgroups = None
@property
def groups(self):
return len(self.groupwidths)
def opengroup(self, name=None):
gid = self.groups
self.groupwidths.append(None)
if self.groups > MAXGROUPS:
raise error("too many groups")
if name is not None:
ogid = self.groupdict.get(name, None)
if ogid is not None:
raise error("redefinition of group name %r as group %d; "
"was group %d" % (name, gid, ogid))
self.groupdict[name] = gid
return gid
def closegroup(self, gid, p):
self.groupwidths[gid] = p.getwidth()
def checkgroup(self, gid):
return gid < self.groups and self.groupwidths[gid] is not None
def checklookbehindgroup(self, gid, source):
if self.lookbehindgroups is not None:
if not self.checkgroup(gid):
raise source.error('cannot refer to an open group')
if gid >= self.lookbehindgroups:
raise source.error('cannot refer to group defined in the same '
'lookbehind subpattern')
class SubPattern:
# a subpattern, in intermediate form
def __init__(self, pattern, data=None):
self.pattern = pattern
if data is None:
data = []
self.data = data
self.width = None
def dump(self, level=0):
nl = True
seqtypes = (tuple, list)
for op, av in self.data:
print(level*" " + str(op), end='')
if op is IN:
# member sublanguage
print()
for op, a in av:
print((level+1)*" " + str(op), a)
elif op is BRANCH:
print()
for i, a in enumerate(av[1]):
if i:
print(level*" " + "OR")
a.dump(level+1)
elif op is GROUPREF_EXISTS:
condgroup, item_yes, item_no = av
print('', condgroup)
item_yes.dump(level+1)
if item_no:
print(level*" " + "ELSE")
item_no.dump(level+1)
elif isinstance(av, seqtypes):
nl = False
for a in av:
if isinstance(a, SubPattern):
if not nl:
print()
a.dump(level+1)
nl = True
else:
if not nl:
print(' ', end='')
print(a, end='')
nl = False
if not nl:
print()
else:
print('', av)
def __repr__(self):
return repr(self.data)
def __len__(self):
return len(self.data)
def __delitem__(self, index):
del self.data[index]
def __getitem__(self, index):
if isinstance(index, slice):
return SubPattern(self.pattern, self.data[index])
return self.data[index]
def __setitem__(self, index, code):
self.data[index] = code
def insert(self, index, code):
self.data.insert(index, code)
def append(self, code):
self.data.append(code)
def getwidth(self):
# determine the width (min, max) for this subpattern
if self.width is not None:
return self.width
lo = hi = 0
for op, av in self.data:
if op is BRANCH:
i = MAXREPEAT - 1
j = 0
for av in av[1]:
l, h = av.getwidth()
i = min(i, l)
j = max(j, h)
lo = lo + i
hi = hi + j
elif op is CALL:
i, j = av.getwidth()
lo = lo + i
hi = hi + j
elif op is SUBPATTERN:
i, j = av[-1].getwidth()
lo = lo + i
hi = hi + j
elif op in _REPEATCODES:
i, j = av[2].getwidth()
lo = lo + i * av[0]
hi = hi + j * av[1]
elif op in _UNITCODES:
lo = lo + 1
hi = hi + 1
elif op is GROUPREF:
i, j = self.pattern.groupwidths[av]
lo = lo + i
hi = hi + j
elif op is GROUPREF_EXISTS:
i, j = av[1].getwidth()
if av[2] is not None:
l, h = av[2].getwidth()
i = min(i, l)
j = max(j, h)
else:
i = 0
lo = lo + i
hi = hi + j
elif op is SUCCESS:
break
self.width = min(lo, MAXREPEAT - 1), min(hi, MAXREPEAT)
return self.width
class Tokenizer:
def __init__(self, string):
self.istext = isinstance(string, str)
self.string = string
if not self.istext:
string = str(string, 'latin1')
self.decoded_string = string
self.index = 0
self.next = None
self.__next()
def __next(self):
index = self.index
try:
char = self.decoded_string[index]
except IndexError:
self.next = None
return
if char == "\\":
index += 1
try:
char += self.decoded_string[index]
except IndexError:
raise error("bad escape (end of pattern)",
self.string, len(self.string) - 1) from None
self.index = index + 1
self.next = char
def match(self, char):
if char == self.next:
self.__next()
return True
return False
def get(self):
this = self.next
self.__next()
return this
def getwhile(self, n, charset):
result = ''
for _ in range(n):
c = self.next
if c not in charset:
break
result += c
self.__next()
return result
def getuntil(self, terminator):
result = ''
while True:
c = self.next
self.__next()
if c is None:
if not result:
raise self.error("missing group name")
raise self.error("missing %s, unterminated name" % terminator,
len(result))
if c == terminator:
if not result:
raise self.error("missing group name", 1)
break
result += c
return result
@property
def pos(self):
return self.index - len(self.next or '')
def tell(self):
return self.index - len(self.next or '')
def seek(self, index):
self.index = index
self.__next()
def error(self, msg, offset=0):
return error(msg, self.string, self.tell() - offset)
def _class_escape(source, escape):
# handle escape code inside character class
code = ESCAPES.get(escape)
if code:
return code
code = CATEGORIES.get(escape)
if code and code[0] is IN:
return code
try:
c = escape[1:2]
if c == "x":
# hexadecimal escape (exactly two digits)
escape += source.getwhile(2, HEXDIGITS)
if len(escape) != 4:
raise source.error("incomplete escape %s" % escape, len(escape))
return LITERAL, int(escape[2:], 16)
elif c == "u" and source.istext:
# unicode escape (exactly four digits)
escape += source.getwhile(4, HEXDIGITS)
if len(escape) != 6:
raise source.error("incomplete escape %s" % escape, len(escape))
return LITERAL, int(escape[2:], 16)
elif c == "U" and source.istext:
# unicode escape (exactly eight digits)
escape += source.getwhile(8, HEXDIGITS)
if len(escape) != 10:
raise source.error("incomplete escape %s" % escape, len(escape))
c = int(escape[2:], 16)
chr(c) # raise ValueError for invalid code
return LITERAL, c
elif c in OCTDIGITS:
# octal escape (up to three digits)
escape += source.getwhile(2, OCTDIGITS)
c = int(escape[1:], 8)
if c > 0o377:
raise source.error('octal escape value %s outside of '
'range 0-0o377' % escape, len(escape))
return LITERAL, c
elif c in DIGITS:
raise ValueError
if len(escape) == 2:
if c in ASCIILETTERS:
raise source.error('bad escape %s' % escape, len(escape))
return LITERAL, ord(escape[1])
except ValueError:
pass
raise source.error("bad escape %s" % escape, len(escape))
def _escape(source, escape, state):
# handle escape code in expression
code = CATEGORIES.get(escape)
if code:
return code
code = ESCAPES.get(escape)
if code:
return code
try:
c = escape[1:2]
if c == "x":
# hexadecimal escape
escape += source.getwhile(2, HEXDIGITS)
if len(escape) != 4:
raise source.error("incomplete escape %s" % escape, len(escape))
return LITERAL, int(escape[2:], 16)
elif c == "u" and source.istext:
# unicode escape (exactly four digits)
escape += source.getwhile(4, HEXDIGITS)
if len(escape) != 6:
raise source.error("incomplete escape %s" % escape, len(escape))
return LITERAL, int(escape[2:], 16)
elif c == "U" and source.istext:
# unicode escape (exactly eight digits)
escape += source.getwhile(8, HEXDIGITS)
if len(escape) != 10:
raise source.error("incomplete escape %s" % escape, len(escape))
c = int(escape[2:], 16)
chr(c) # raise ValueError for invalid code
return LITERAL, c
elif c == "0":
# octal escape
escape += source.getwhile(2, OCTDIGITS)
return LITERAL, int(escape[1:], 8)
elif c in DIGITS:
# octal escape *or* decimal group reference (sigh)
if source.next in DIGITS:
escape += source.get()
if (escape[1] in OCTDIGITS and escape[2] in OCTDIGITS and
source.next in OCTDIGITS):
# got three octal digits; this is an octal escape
escape += source.get()
c = int(escape[1:], 8)
if c > 0o377:
raise source.error('octal escape value %s outside of '
'range 0-0o377' % escape,
len(escape))
return LITERAL, c
# not an octal escape, so this is a group reference
group = int(escape[1:])
if group < state.groups:
if not state.checkgroup(group):
raise source.error("cannot refer to an open group",
len(escape))
state.checklookbehindgroup(group, source)
return GROUPREF, group
raise source.error("invalid group reference %d" % group, len(escape) - 1)
if len(escape) == 2:
if c in ASCIILETTERS:
raise source.error("bad escape %s" % escape, len(escape))
return LITERAL, ord(escape[1])
except ValueError:
pass
raise source.error("bad escape %s" % escape, len(escape))
def _parse_sub(source, state, verbose, nested):
# parse an alternation: a|b|c
items = []
itemsappend = items.append
sourcematch = source.match
start = source.tell()
while True:
itemsappend(_parse(source, state, verbose, nested + 1,
not nested and not items))
if not sourcematch("|"):
break
if len(items) == 1:
return items[0]
subpattern = SubPattern(state)
subpatternappend = subpattern.append
# check if all items share a common prefix
while True:
prefix = None
for item in items:
if not item:
break
if prefix is None:
prefix = item[0]
elif item[0] != prefix:
break
else:
# all subitems start with a common "prefix".
# move it out of the branch
for item in items:
del item[0]
subpatternappend(prefix)
continue # check next one
break
# check if the branch can be replaced by a character set
for item in items:
if len(item) != 1 or item[0][0] is not LITERAL:
break
else:
# we can store this as a character set instead of a
# branch (the compiler may optimize this even more)
subpatternappend((IN, [item[0] for item in items]))
return subpattern
subpattern.append((BRANCH, (None, items)))
return subpattern
def _parse_sub_cond(source, state, condgroup, verbose, nested):
item_yes = _parse(source, state, verbose, nested + 1)
if source.match("|"):
item_no = _parse(source, state, verbose, nested + 1)
if source.next == "|":
raise source.error("conditional backref with more than two branches")
else:
item_no = None
subpattern = SubPattern(state)
subpattern.append((GROUPREF_EXISTS, (condgroup, item_yes, item_no)))
return subpattern
def _parse(source, state, verbose, nested, first=False):
# parse a simple pattern
subpattern = SubPattern(state)
# precompute constants into local variables
subpatternappend = subpattern.append
sourceget = source.get
sourcematch = source.match
_len = len
_ord = ord
while True:
this = source.next
if this is None:
break # end of pattern
if this in "|)":
break # end of subpattern
sourceget()
if verbose:
# skip whitespace and comments
if this in WHITESPACE:
continue
if this == "#":
while True:
this = sourceget()
if this is None or this == "\n":
break
continue
if this[0] == "\\":
code = _escape(source, this, state)
subpatternappend(code)
elif this not in SPECIAL_CHARS:
subpatternappend((LITERAL, _ord(this)))
elif this == "[":
here = source.tell() - 1
# character set
set = []
setappend = set.append
## if sourcematch(":"):
## pass # handle character classes
if sourcematch("^"):
setappend((NEGATE, None))
# check remaining characters
start = set[:]
while True:
this = sourceget()
if this is None:
raise source.error("unterminated character set",
source.tell() - here)
if this == "]" and set != start:
break
elif this[0] == "\\":
code1 = _class_escape(source, this)
else:
code1 = LITERAL, _ord(this)
if sourcematch("-"):
# potential range
that = sourceget()
if that is None:
raise source.error("unterminated character set",
source.tell() - here)
if that == "]":
if code1[0] is IN:
code1 = code1[1][0]
setappend(code1)
setappend((LITERAL, _ord("-")))
break
if that[0] == "\\":
code2 = _class_escape(source, that)
else:
code2 = LITERAL, _ord(that)
if code1[0] != LITERAL or code2[0] != LITERAL:
msg = "bad character range %s-%s" % (this, that)
raise source.error(msg, len(this) + 1 + len(that))
lo = code1[1]
hi = code2[1]
if hi < lo:
msg = "bad character range %s-%s" % (this, that)
raise source.error(msg, len(this) + 1 + len(that))
setappend((RANGE, (lo, hi)))
else:
if code1[0] is IN:
code1 = code1[1][0]
setappend(code1)
# XXX: <fl> should move set optimization to compiler!
if _len(set)==1 and set[0][0] is LITERAL:
subpatternappend(set[0]) # optimization
elif _len(set)==2 and set[0][0] is NEGATE and set[1][0] is LITERAL:
subpatternappend((NOT_LITERAL, set[1][1])) # optimization
else:
# XXX: <fl> should add charmap optimization here
subpatternappend((IN, set))
elif this in REPEAT_CHARS:
# repeat previous item
here = source.tell()
if this == "?":
min, max = 0, 1
elif this == "*":
min, max = 0, MAXREPEAT
elif this == "+":
min, max = 1, MAXREPEAT
elif this == "{":
if source.next == "}":
subpatternappend((LITERAL, _ord(this)))
continue
min, max = 0, MAXREPEAT
lo = hi = ""
while source.next in DIGITS:
lo += sourceget()
if sourcematch(","):
while source.next in DIGITS:
hi += sourceget()
else:
hi = lo
if not sourcematch("}"):
subpatternappend((LITERAL, _ord(this)))
source.seek(here)
continue
if lo:
min = int(lo)
if min >= MAXREPEAT:
raise OverflowError("the repetition number is too large")
if hi:
max = int(hi)
if max >= MAXREPEAT:
raise OverflowError("the repetition number is too large")
if max < min:
raise source.error("min repeat greater than max repeat",
source.tell() - here)
else:
raise AssertionError("unsupported quantifier %r" % (char,))
# figure out which item to repeat
if subpattern:
item = subpattern[-1:]
else:
item = None
if not item or (_len(item) == 1 and item[0][0] is AT):
raise source.error("nothing to repeat",
source.tell() - here + len(this))
if item[0][0] in _REPEATCODES:
raise source.error("multiple repeat",
source.tell() - here + len(this))
if sourcematch("?"):
subpattern[-1] = (MIN_REPEAT, (min, max, item))
else:
subpattern[-1] = (MAX_REPEAT, (min, max, item))
elif this == ".":
subpatternappend((ANY, None))
elif this == "(":
start = source.tell() - 1
group = True
name = None
condgroup = None
add_flags = 0
del_flags = 0
if sourcematch("?"):
# options
char = sourceget()
if char is None:
raise source.error("unexpected end of pattern")
if char == "P":
# python extensions
if sourcematch("<"):
# named group: skip forward to end of name
name = source.getuntil(">")
if not name.isidentifier():
msg = "bad character in group name %r" % name
raise source.error(msg, len(name) + 1)
elif sourcematch("="):
# named backreference
name = source.getuntil(")")
if not name.isidentifier():
msg = "bad character in group name %r" % name
raise source.error(msg, len(name) + 1)
gid = state.groupdict.get(name)
if gid is None:
msg = "unknown group name %r" % name
raise source.error(msg, len(name) + 1)
if not state.checkgroup(gid):
raise source.error("cannot refer to an open group",
len(name) + 1)
state.checklookbehindgroup(gid, source)
subpatternappend((GROUPREF, gid))
continue
else:
char = sourceget()
if char is None:
raise source.error("unexpected end of pattern")
raise source.error("unknown extension ?P" + char,
len(char) + 2)
elif char == ":":
# non-capturing group
group = None
elif char == "#":
# comment
while True:
if source.next is None:
raise source.error("missing ), unterminated comment",
source.tell() - start)
if sourceget() == ")":
break
continue
elif char in "=!<":
# lookahead assertions
dir = 1
if char == "<":
char = sourceget()
if char is None:
raise source.error("unexpected end of pattern")
if char not in "=!":
raise source.error("unknown extension ?<" + char,
len(char) + 2)
dir = -1 # lookbehind
lookbehindgroups = state.lookbehindgroups
if lookbehindgroups is None:
state.lookbehindgroups = state.groups
p = _parse_sub(source, state, verbose, nested + 1)
if dir < 0:
if lookbehindgroups is None:
state.lookbehindgroups = None
if not sourcematch(")"):
raise source.error("missing ), unterminated subpattern",
source.tell() - start)
if char == "=":
subpatternappend((ASSERT, (dir, p)))
else:
subpatternappend((ASSERT_NOT, (dir, p)))
continue
elif char == "(":
# conditional backreference group
condname = source.getuntil(")")
group = None
if condname.isidentifier():
condgroup = state.groupdict.get(condname)
if condgroup is None:
msg = "unknown group name %r" % condname
raise source.error(msg, len(condname) + 1)
else:
try:
condgroup = int(condname)
if condgroup < 0:
raise ValueError
except ValueError:
msg = "bad character in group name %r" % condname
raise source.error(msg, len(condname) + 1) from None
if not condgroup:
raise source.error("bad group number",
len(condname) + 1)
if condgroup >= MAXGROUPS:
msg = "invalid group reference %d" % condgroup
raise source.error(msg, len(condname) + 1)
state.checklookbehindgroup(condgroup, source)
elif char in FLAGS or char == "-":
# flags
flags = _parse_flags(source, state, char)
if flags is None: # global flags
if not first or subpattern:
import warnings
warnings.warn(
'Flags not at the start of the expression %r%s' % (
source.string[:20], # truncate long regexes
' (truncated)' if len(source.string) > 20 else '',
),
DeprecationWarning, stacklevel=nested + 6
)
if (state.flags & SRE_FLAG_VERBOSE) and not verbose:
raise Verbose
continue
add_flags, del_flags = flags
group = None
else:
raise source.error("unknown extension ?" + char,
len(char) + 1)
# parse group contents
if group is not None:
try:
group = state.opengroup(name)
except error as err:
raise source.error(err.msg, len(name) + 1) from None
if condgroup:
p = _parse_sub_cond(source, state, condgroup, verbose, nested + 1)
else:
sub_verbose = ((verbose or (add_flags & SRE_FLAG_VERBOSE)) and
not (del_flags & SRE_FLAG_VERBOSE))
p = _parse_sub(source, state, sub_verbose, nested + 1)
if not source.match(")"):
raise source.error("missing ), unterminated subpattern",
source.tell() - start)
if group is not None:
state.closegroup(group, p)
subpatternappend((SUBPATTERN, (group, add_flags, del_flags, p)))
elif this == "^":
subpatternappend((AT, AT_BEGINNING))
elif this == "$":
subpattern.append((AT, AT_END))
else:
raise AssertionError("unsupported special character %r" % (char,))
return subpattern
def _parse_flags(source, state, char):
sourceget = source.get
add_flags = 0
del_flags = 0
if char != "-":
while True:
add_flags |= FLAGS[char]
char = sourceget()
if char is None:
raise source.error("missing -, : or )")
if char in ")-:":
break
if char not in FLAGS:
msg = "unknown flag" if char.isalpha() else "missing -, : or )"
raise source.error(msg, len(char))
if char == ")":
state.flags |= add_flags
return None
if add_flags & GLOBAL_FLAGS:
raise source.error("bad inline flags: cannot turn on global flag", 1)
if char == "-":
char = sourceget()
if char is None:
raise source.error("missing flag")
if char not in FLAGS:
msg = "unknown flag" if char.isalpha() else "missing flag"
raise source.error(msg, len(char))
while True:
del_flags |= FLAGS[char]
char = sourceget()
if char is None:
raise source.error("missing :")
if char == ":":
break
if char not in FLAGS:
msg = "unknown flag" if char.isalpha() else "missing :"
raise source.error(msg, len(char))
assert char == ":"
if del_flags & GLOBAL_FLAGS:
raise source.error("bad inline flags: cannot turn off global flag", 1)
if add_flags & del_flags:
raise source.error("bad inline flags: flag turned on and off", 1)
return add_flags, del_flags
def fix_flags(src, flags):
# Check and fix flags according to the type of pattern (str or bytes)
if isinstance(src, str):
if flags & SRE_FLAG_LOCALE:
raise ValueError("cannot use LOCALE flag with a str pattern")
if not flags & SRE_FLAG_ASCII:
flags |= SRE_FLAG_UNICODE
elif flags & SRE_FLAG_UNICODE:
raise ValueError("ASCII and UNICODE flags are incompatible")
else:
if flags & SRE_FLAG_UNICODE:
raise ValueError("cannot use UNICODE flag with a bytes pattern")
if flags & SRE_FLAG_LOCALE and flags & SRE_FLAG_ASCII:
raise ValueError("ASCII and LOCALE flags are incompatible")
return flags
def parse(str, flags=0, pattern=None):
# parse 're' pattern into list of (opcode, argument) tuples
source = Tokenizer(str)
if pattern is None:
pattern = Pattern()
pattern.flags = flags
pattern.str = str
try:
p = _parse_sub(source, pattern, flags & SRE_FLAG_VERBOSE, 0)
except Verbose:
# the VERBOSE flag was switched on inside the pattern. to be
# on the safe side, we'll parse the whole thing again...
pattern = Pattern()
pattern.flags = flags | SRE_FLAG_VERBOSE
pattern.str = str
source.seek(0)
p = _parse_sub(source, pattern, True, 0)
p.pattern.flags = fix_flags(str, p.pattern.flags)
if source.next is not None:
assert source.next == ")"
raise source.error("unbalanced parenthesis")
if flags & SRE_FLAG_DEBUG:
p.dump()
return p
def parse_template(source, pattern):
# parse 're' replacement string into list of literals and
# group references
s = Tokenizer(source)
sget = s.get
groups = []
literals = []
literal = []
lappend = literal.append
def addgroup(index, pos):
if index > pattern.groups:
raise s.error("invalid group reference %d" % index, pos)
if literal:
literals.append(''.join(literal))
del literal[:]
groups.append((len(literals), index))
literals.append(None)
groupindex = pattern.groupindex
while True:
this = sget()
if this is None:
break # end of replacement string
if this[0] == "\\":
# group
c = this[1]
if c == "g":
name = ""
if not s.match("<"):
raise s.error("missing <")
name = s.getuntil(">")
if name.isidentifier():
try:
index = groupindex[name]
except KeyError:
raise IndexError("unknown group name %r" % name)
else:
try:
index = int(name)
if index < 0:
raise ValueError
except ValueError:
raise s.error("bad character in group name %r" % name,
len(name) + 1) from None
if index >= MAXGROUPS:
raise s.error("invalid group reference %d" % index,
len(name) + 1)
addgroup(index, len(name) + 1)
elif c == "0":
if s.next in OCTDIGITS:
this += sget()
if s.next in OCTDIGITS:
this += sget()
lappend(chr(int(this[1:], 8) & 0xff))
elif c in DIGITS:
isoctal = False
if s.next in DIGITS:
this += sget()
if (c in OCTDIGITS and this[2] in OCTDIGITS and
s.next in OCTDIGITS):
this += sget()
isoctal = True
c = int(this[1:], 8)
if c > 0o377:
raise s.error('octal escape value %s outside of '
'range 0-0o377' % this, len(this))
lappend(chr(c))
if not isoctal:
addgroup(int(this[1:]), len(this) - 1)
else:
try:
this = chr(ESCAPES[this][1])
except KeyError:
if c in ASCIILETTERS:
import warnings
warnings.warn('bad escape %s' % this,
DeprecationWarning, stacklevel=4)
lappend(this)
else:
lappend(this)
if literal:
literals.append(''.join(literal))
if not isinstance(source, str):
# The tokenizer implicitly decodes bytes objects as latin-1, we must
# therefore re-encode the final representation.
literals = [None if s is None else s.encode('latin-1') for s in literals]
return groups, literals
def expand_template(template, match):
g = match.group
empty = match.string[:0]
groups, literals = template
literals = literals[:]
try:
for index, group in groups:
literals[index] = g(group) or empty
except IndexError:
raise error("invalid group reference %d" % index)
return empty.join(literals)