diff options
Diffstat (limited to 'AppPkg/Applications/Python/Python-2.7.10/Lib/sre_parse.py')
| -rw-r--r-- | AppPkg/Applications/Python/Python-2.7.10/Lib/sre_parse.py | 834 |
1 files changed, 834 insertions, 0 deletions
diff --git a/AppPkg/Applications/Python/Python-2.7.10/Lib/sre_parse.py b/AppPkg/Applications/Python/Python-2.7.10/Lib/sre_parse.py new file mode 100644 index 0000000000..803c09d81f --- /dev/null +++ b/AppPkg/Applications/Python/Python-2.7.10/Lib/sre_parse.py @@ -0,0 +1,834 @@ +#
+# 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
+
+import sys
+
+from sre_constants import *
+
+SPECIAL_CHARS = ".\\[{()*+?^$|"
+REPEAT_CHARS = "*+?{"
+
+DIGITS = set("0123456789")
+
+OCTDIGITS = set("01234567")
+HEXDIGITS = set("0123456789abcdefABCDEF")
+
+WHITESPACE = set(" \t\n\r\v\f")
+
+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
+ "t": SRE_FLAG_TEMPLATE,
+ "u": SRE_FLAG_UNICODE,
+}
+
+class Pattern:
+ # master pattern object. keeps track of global attributes
+ def __init__(self):
+ self.flags = 0
+ self.open = []
+ self.groups = 1
+ self.groupdict = {}
+ self.lookbehind = 0
+
+ def opengroup(self, name=None):
+ gid = self.groups
+ self.groups = gid + 1
+ if name is not None:
+ ogid = self.groupdict.get(name, None)
+ if ogid is not None:
+ raise error, ("redefinition of group name %s as group %d; "
+ "was group %d" % (repr(name), gid, ogid))
+ self.groupdict[name] = gid
+ self.open.append(gid)
+ return gid
+ def closegroup(self, gid):
+ self.open.remove(gid)
+ def checkgroup(self, gid):
+ return gid < self.groups and gid not in self.open
+
+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):
+ seqtypes = (tuple, list)
+ for op, av in self.data:
+ print level*" " + op,
+ if op == IN:
+ # member sublanguage
+ print
+ for op, a in av:
+ print (level+1)*" " + op, a
+ elif op == BRANCH:
+ print
+ for i, a in enumerate(av[1]):
+ if i:
+ print level*" " + "or"
+ a.dump(level+1)
+ elif op == 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 = 0
+ for a in av:
+ if isinstance(a, SubPattern):
+ if not nl:
+ print
+ a.dump(level+1)
+ nl = 1
+ else:
+ print a,
+ nl = 0
+ 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:
+ return self.width
+ lo = hi = 0
+ UNITCODES = (ANY, RANGE, IN, LITERAL, NOT_LITERAL, CATEGORY)
+ REPEATCODES = (MIN_REPEAT, MAX_REPEAT)
+ 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 == SUCCESS:
+ break
+ self.width = min(lo, MAXREPEAT - 1), min(hi, MAXREPEAT)
+ return self.width
+
+class Tokenizer:
+ def __init__(self, string):
+ self.string = string
+ self.index = 0
+ self.__next()
+ def __next(self):
+ if self.index >= len(self.string):
+ self.next = None
+ return
+ char = self.string[self.index]
+ if char[0] == "\\":
+ try:
+ c = self.string[self.index + 1]
+ except IndexError:
+ raise error, "bogus escape (end of line)"
+ char = char + c
+ self.index = self.index + len(char)
+ self.next = char
+ def match(self, char, skip=1):
+ if char == self.next:
+ if skip:
+ self.__next()
+ return 1
+ return 0
+ def get(self):
+ this = self.next
+ self.__next()
+ return this
+ def tell(self):
+ return self.index, self.next
+ def seek(self, index):
+ self.index, self.next = index
+
+def isident(char):
+ return "a" <= char <= "z" or "A" <= char <= "Z" or char == "_"
+
+def isdigit(char):
+ return "0" <= char <= "9"
+
+def isname(name):
+ # check that group name is a valid string
+ if not isident(name[0]):
+ return False
+ for char in name[1:]:
+ if not isident(char) and not isdigit(char):
+ return False
+ return True
+
+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] == IN:
+ return code
+ try:
+ c = escape[1:2]
+ if c == "x":
+ # hexadecimal escape (exactly two digits)
+ while source.next in HEXDIGITS and len(escape) < 4:
+ escape = escape + source.get()
+ escape = escape[2:]
+ if len(escape) != 2:
+ raise error, "bogus escape: %s" % repr("\\" + escape)
+ return LITERAL, int(escape, 16) & 0xff
+ elif c in OCTDIGITS:
+ # octal escape (up to three digits)
+ while source.next in OCTDIGITS and len(escape) < 4:
+ escape = escape + source.get()
+ escape = escape[1:]
+ return LITERAL, int(escape, 8) & 0xff
+ elif c in DIGITS:
+ raise error, "bogus escape: %s" % repr(escape)
+ if len(escape) == 2:
+ return LITERAL, ord(escape[1])
+ except ValueError:
+ pass
+ raise error, "bogus escape: %s" % repr(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
+ while source.next in HEXDIGITS and len(escape) < 4:
+ escape = escape + source.get()
+ if len(escape) != 4:
+ raise ValueError
+ return LITERAL, int(escape[2:], 16) & 0xff
+ elif c == "0":
+ # octal escape
+ while source.next in OCTDIGITS and len(escape) < 4:
+ escape = escape + source.get()
+ return LITERAL, int(escape[1:], 8) & 0xff
+ elif c in DIGITS:
+ # octal escape *or* decimal group reference (sigh)
+ if source.next in DIGITS:
+ escape = 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 = escape + source.get()
+ return LITERAL, int(escape[1:], 8) & 0xff
+ # not an octal escape, so this is a group reference
+ group = int(escape[1:])
+ if group < state.groups:
+ if not state.checkgroup(group):
+ raise error, "cannot refer to open group"
+ if state.lookbehind:
+ import warnings
+ warnings.warn('group references in lookbehind '
+ 'assertions are not supported',
+ RuntimeWarning)
+ return GROUPREF, group
+ raise ValueError
+ if len(escape) == 2:
+ return LITERAL, ord(escape[1])
+ except ValueError:
+ pass
+ raise error, "bogus escape: %s" % repr(escape)
+
+def _parse_sub(source, state, nested=1):
+ # parse an alternation: a|b|c
+
+ items = []
+ itemsappend = items.append
+ sourcematch = source.match
+ while 1:
+ itemsappend(_parse(source, state))
+ if sourcematch("|"):
+ continue
+ if not nested:
+ break
+ if not source.next or sourcematch(")", 0):
+ break
+ else:
+ raise error, "pattern not properly closed"
+
+ if len(items) == 1:
+ return items[0]
+
+ subpattern = SubPattern(state)
+ subpatternappend = subpattern.append
+
+ # check if all items share a common prefix
+ while 1:
+ 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] != LITERAL:
+ break
+ else:
+ # we can store this as a character set instead of a
+ # branch (the compiler may optimize this even more)
+ set = []
+ setappend = set.append
+ for item in items:
+ setappend(item[0])
+ subpatternappend((IN, set))
+ return subpattern
+
+ subpattern.append((BRANCH, (None, items)))
+ return subpattern
+
+def _parse_sub_cond(source, state, condgroup):
+ item_yes = _parse(source, state)
+ if source.match("|"):
+ item_no = _parse(source, state)
+ if source.match("|"):
+ raise error, "conditional backref with more than two branches"
+ else:
+ item_no = None
+ if source.next and not source.match(")", 0):
+ raise error, "pattern not properly closed"
+ subpattern = SubPattern(state)
+ subpattern.append((GROUPREF_EXISTS, (condgroup, item_yes, item_no)))
+ return subpattern
+
+_PATTERNENDERS = set("|)")
+_ASSERTCHARS = set("=!<")
+_LOOKBEHINDASSERTCHARS = set("=!")
+_REPEATCODES = set([MIN_REPEAT, MAX_REPEAT])
+
+def _parse(source, state):
+ # parse a simple pattern
+ subpattern = SubPattern(state)
+
+ # precompute constants into local variables
+ subpatternappend = subpattern.append
+ sourceget = source.get
+ sourcematch = source.match
+ _len = len
+ PATTERNENDERS = _PATTERNENDERS
+ ASSERTCHARS = _ASSERTCHARS
+ LOOKBEHINDASSERTCHARS = _LOOKBEHINDASSERTCHARS
+ REPEATCODES = _REPEATCODES
+
+ while 1:
+
+ if source.next in PATTERNENDERS:
+ break # end of subpattern
+ this = sourceget()
+ if this is None:
+ break # end of pattern
+
+ if state.flags & SRE_FLAG_VERBOSE:
+ # skip whitespace and comments
+ if this in WHITESPACE:
+ continue
+ if this == "#":
+ while 1:
+ this = sourceget()
+ if this in (None, "\n"):
+ break
+ continue
+
+ if this and this[0] not in SPECIAL_CHARS:
+ subpatternappend((LITERAL, ord(this)))
+
+ elif this == "[":
+ # character set
+ set = []
+ setappend = set.append
+## if sourcematch(":"):
+## pass # handle character classes
+ if sourcematch("^"):
+ setappend((NEGATE, None))
+ # check remaining characters
+ start = set[:]
+ while 1:
+ this = sourceget()
+ if this == "]" and set != start:
+ break
+ elif this and this[0] == "\\":
+ code1 = _class_escape(source, this)
+ elif this:
+ code1 = LITERAL, ord(this)
+ else:
+ raise error, "unexpected end of regular expression"
+ if sourcematch("-"):
+ # potential range
+ this = sourceget()
+ if this == "]":
+ if code1[0] is IN:
+ code1 = code1[1][0]
+ setappend(code1)
+ setappend((LITERAL, ord("-")))
+ break
+ elif this:
+ if this[0] == "\\":
+ code2 = _class_escape(source, this)
+ else:
+ code2 = LITERAL, ord(this)
+ if code1[0] != LITERAL or code2[0] != LITERAL:
+ raise error, "bad character range"
+ lo = code1[1]
+ hi = code2[1]
+ if hi < lo:
+ raise error, "bad character range"
+ setappend((RANGE, (lo, hi)))
+ else:
+ raise error, "unexpected end of regular expression"
+ 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 and this[0] in REPEAT_CHARS:
+ # repeat previous item
+ 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
+ here = source.tell()
+ min, max = 0, MAXREPEAT
+ lo = hi = ""
+ while source.next in DIGITS:
+ lo = lo + source.get()
+ if sourcematch(","):
+ while source.next in DIGITS:
+ hi = 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 error("bad repeat interval")
+ else:
+ raise error, "not supported"
+ # 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] == AT):
+ raise error, "nothing to repeat"
+ if item[0][0] in REPEATCODES:
+ raise error, "multiple repeat"
+ if sourcematch("?"):
+ subpattern[-1] = (MIN_REPEAT, (min, max, item))
+ else:
+ subpattern[-1] = (MAX_REPEAT, (min, max, item))
+
+ elif this == ".":
+ subpatternappend((ANY, None))
+
+ elif this == "(":
+ group = 1
+ name = None
+ condgroup = None
+ if sourcematch("?"):
+ group = 0
+ # options
+ if sourcematch("P"):
+ # python extensions
+ if sourcematch("<"):
+ # named group: skip forward to end of name
+ name = ""
+ while 1:
+ char = sourceget()
+ if char is None:
+ raise error, "unterminated name"
+ if char == ">":
+ break
+ name = name + char
+ group = 1
+ if not name:
+ raise error("missing group name")
+ if not isname(name):
+ raise error("bad character in group name %r" %
+ name)
+ elif sourcematch("="):
+ # named backreference
+ name = ""
+ while 1:
+ char = sourceget()
+ if char is None:
+ raise error, "unterminated name"
+ if char == ")":
+ break
+ name = name + char
+ if not name:
+ raise error("missing group name")
+ if not isname(name):
+ raise error("bad character in backref group name "
+ "%r" % name)
+ gid = state.groupdict.get(name)
+ if gid is None:
+ msg = "unknown group name: {0!r}".format(name)
+ raise error(msg)
+ if state.lookbehind:
+ import warnings
+ warnings.warn('group references in lookbehind '
+ 'assertions are not supported',
+ RuntimeWarning)
+ subpatternappend((GROUPREF, gid))
+ continue
+ else:
+ char = sourceget()
+ if char is None:
+ raise error, "unexpected end of pattern"
+ raise error, "unknown specifier: ?P%s" % char
+ elif sourcematch(":"):
+ # non-capturing group
+ group = 2
+ elif sourcematch("#"):
+ # comment
+ while 1:
+ if source.next is None or source.next == ")":
+ break
+ sourceget()
+ if not sourcematch(")"):
+ raise error, "unbalanced parenthesis"
+ continue
+ elif source.next in ASSERTCHARS:
+ # lookahead assertions
+ char = sourceget()
+ dir = 1
+ if char == "<":
+ if source.next not in LOOKBEHINDASSERTCHARS:
+ raise error, "syntax error"
+ dir = -1 # lookbehind
+ char = sourceget()
+ state.lookbehind += 1
+ p = _parse_sub(source, state)
+ if dir < 0:
+ state.lookbehind -= 1
+ if not sourcematch(")"):
+ raise error, "unbalanced parenthesis"
+ if char == "=":
+ subpatternappend((ASSERT, (dir, p)))
+ else:
+ subpatternappend((ASSERT_NOT, (dir, p)))
+ continue
+ elif sourcematch("("):
+ # conditional backreference group
+ condname = ""
+ while 1:
+ char = sourceget()
+ if char is None:
+ raise error, "unterminated name"
+ if char == ")":
+ break
+ condname = condname + char
+ group = 2
+ if not condname:
+ raise error("missing group name")
+ if isname(condname):
+ condgroup = state.groupdict.get(condname)
+ if condgroup is None:
+ msg = "unknown group name: {0!r}".format(condname)
+ raise error(msg)
+ else:
+ try:
+ condgroup = int(condname)
+ except ValueError:
+ raise error, "bad character in group name"
+ if state.lookbehind:
+ import warnings
+ warnings.warn('group references in lookbehind '
+ 'assertions are not supported',
+ RuntimeWarning)
+ else:
+ # flags
+ if not source.next in FLAGS:
+ raise error, "unexpected end of pattern"
+ while source.next in FLAGS:
+ state.flags = state.flags | FLAGS[sourceget()]
+ if group:
+ # parse group contents
+ if group == 2:
+ # anonymous group
+ group = None
+ else:
+ group = state.opengroup(name)
+ if condgroup:
+ p = _parse_sub_cond(source, state, condgroup)
+ else:
+ p = _parse_sub(source, state)
+ if not sourcematch(")"):
+ raise error, "unbalanced parenthesis"
+ if group is not None:
+ state.closegroup(group)
+ subpatternappend((SUBPATTERN, (group, p)))
+ else:
+ while 1:
+ char = sourceget()
+ if char is None:
+ raise error, "unexpected end of pattern"
+ if char == ")":
+ break
+ raise error, "unknown extension"
+
+ elif this == "^":
+ subpatternappend((AT, AT_BEGINNING))
+
+ elif this == "$":
+ subpattern.append((AT, AT_END))
+
+ elif this and this[0] == "\\":
+ code = _escape(source, this, state)
+ subpatternappend(code)
+
+ else:
+ raise error, "parser error"
+
+ return subpattern
+
+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
+
+ p = _parse_sub(source, pattern, 0)
+
+ tail = source.get()
+ if tail == ")":
+ raise error, "unbalanced parenthesis"
+ elif tail:
+ raise error, "bogus characters at end of regular expression"
+
+ if flags & SRE_FLAG_DEBUG:
+ p.dump()
+
+ if not (flags & SRE_FLAG_VERBOSE) and p.pattern.flags & SRE_FLAG_VERBOSE:
+ # the VERBOSE flag was switched on inside the pattern. to be
+ # on the safe side, we'll parse the whole thing again...
+ return parse(str, p.pattern.flags)
+
+ return p
+
+def parse_template(source, pattern):
+ # parse 're' replacement string into list of literals and
+ # group references
+ s = Tokenizer(source)
+ sget = s.get
+ p = []
+ a = p.append
+ def literal(literal, p=p, pappend=a):
+ if p and p[-1][0] is LITERAL:
+ p[-1] = LITERAL, p[-1][1] + literal
+ else:
+ pappend((LITERAL, literal))
+ sep = source[:0]
+ if type(sep) is type(""):
+ makechar = chr
+ else:
+ makechar = unichr
+ while 1:
+ this = sget()
+ if this is None:
+ break # end of replacement string
+ if this and this[0] == "\\":
+ # group
+ c = this[1:2]
+ if c == "g":
+ name = ""
+ if s.match("<"):
+ while 1:
+ char = sget()
+ if char is None:
+ raise error, "unterminated group name"
+ if char == ">":
+ break
+ name = name + char
+ if not name:
+ raise error, "missing group name"
+ try:
+ index = int(name)
+ if index < 0:
+ raise error, "negative group number"
+ except ValueError:
+ if not isname(name):
+ raise error, "bad character in group name"
+ try:
+ index = pattern.groupindex[name]
+ except KeyError:
+ msg = "unknown group name: {0!r}".format(name)
+ raise IndexError(msg)
+ a((MARK, index))
+ elif c == "0":
+ if s.next in OCTDIGITS:
+ this = this + sget()
+ if s.next in OCTDIGITS:
+ this = this + sget()
+ literal(makechar(int(this[1:], 8) & 0xff))
+ elif c in DIGITS:
+ isoctal = False
+ if s.next in DIGITS:
+ this = this + sget()
+ if (c in OCTDIGITS and this[2] in OCTDIGITS and
+ s.next in OCTDIGITS):
+ this = this + sget()
+ isoctal = True
+ literal(makechar(int(this[1:], 8) & 0xff))
+ if not isoctal:
+ a((MARK, int(this[1:])))
+ else:
+ try:
+ this = makechar(ESCAPES[this][1])
+ except KeyError:
+ pass
+ literal(this)
+ else:
+ literal(this)
+ # convert template to groups and literals lists
+ i = 0
+ groups = []
+ groupsappend = groups.append
+ literals = [None] * len(p)
+ for c, s in p:
+ if c is MARK:
+ groupsappend((i, s))
+ # literal[i] is already None
+ else:
+ literals[i] = s
+ i = i + 1
+ return groups, literals
+
+def expand_template(template, match):
+ g = match.group
+ sep = match.string[:0]
+ groups, literals = template
+ literals = literals[:]
+ try:
+ for index, group in groups:
+ literals[index] = s = g(group)
+ if s is None:
+ raise error, "unmatched group"
+ except IndexError:
+ raise error, "invalid group reference"
+ return sep.join(literals)
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