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diff --git a/Lib/pre.py b/Lib/pre.py new file mode 100644 index 0000000..602980a --- /dev/null +++ b/Lib/pre.py @@ -0,0 +1,652 @@ +# module 're' -- A collection of regular expression operations + +"""Support for regular expressions (RE). + +This module provides regular expression matching operations similar to +those found in Perl. It's 8-bit clean: the strings being processed may +contain both null bytes and characters whose high bit is set. Regular +expression pattern strings may not contain null bytes, but can specify +the null byte using the \\number notation. Characters with the high +bit set may be included. + +Regular expressions can contain both special and ordinary +characters. Most ordinary characters, like "A", "a", or "0", are the +simplest regular expressions; they simply match themselves. You can +concatenate ordinary characters, so last matches the string 'last'. + +The special characters are: + "." Matches any character except a newline. + "^" Matches the start of the string. + "$" Matches the end of the string. + "*" Matches 0 or more (greedy) repetitions of the preceding RE. + Greedy means that it will match as many repetitions as possible. + "+" Matches 1 or more (greedy) repetitions of the preceding RE. + "?" Matches 0 or 1 (greedy) of the preceding RE. + *?,+?,?? Non-greedy versions of the previous three special characters. + {m,n} Matches from m to n repetitions of the preceding RE. + {m,n}? Non-greedy version of the above. + "\\" Either escapes special characters or signals a special sequence. + [] Indicates a set of characters. + A "^" as the first character indicates a complementing set. + "|" A|B, creates an RE that will match either A or B. + (...) Matches the RE inside the parentheses. + The contents can be retrieved or matched later in the string. + (?iLmsx) Set the I, L, M, S, or X flag for the RE. + (?:...) Non-grouping version of regular parentheses. + (?P<name>...) The substring matched by the group is accessible by name. + (?P=name) Matches the text matched earlier by the group named name. + (?#...) A comment; ignored. + (?=...) Matches if ... matches next, but doesn't consume the string. + (?!...) Matches if ... doesn't match next. + +The special sequences consist of "\\" and a character from the list +below. If the ordinary character is not on the list, then the +resulting RE will match the second character. + \\number Matches the contents of the group of the same number. + \\A Matches only at the start of the string. + \\Z Matches only at the end of the string. + \\b Matches the empty string, but only at the start or end of a word. + \\B Matches the empty string, but not at the start or end of a word. + \\d Matches any decimal digit; equivalent to the set [0-9]. + \\D Matches any non-digit character; equivalent to the set [^0-9]. + \\s Matches any whitespace character; equivalent to [ \\t\\n\\r\\f\\v]. + \\S Matches any non-whitespace character; equiv. to [^ \\t\\n\\r\\f\\v]. + \\w Matches any alphanumeric character; equivalent to [a-zA-Z0-9_]. + With LOCALE, it will match the set [0-9_] plus characters defined + as letters for the current locale. + \\W Matches the complement of \\w. + \\\\ Matches a literal backslash. + +This module exports the following functions: + match Match a regular expression pattern to the beginning of a string. + search Search a string for the presence of a pattern. + sub Substitute occurrences of a pattern found in a string. + subn Same as sub, but also return the number of substitutions made. + split Split a string by the occurrences of a pattern. + findall Find all occurrences of a pattern in a string. + compile Compile a pattern into a RegexObject. + escape Backslash all non-alphanumerics in a string. + +This module exports the following classes: + RegexObject Holds a compiled regular expression pattern. + MatchObject Contains information about pattern matches. + +Some of the functions in this module takes flags as optional parameters: + I IGNORECASE Perform case-insensitive matching. + L LOCALE Make \w, \W, \b, \B, dependent on the current locale. + M MULTILINE "^" matches the beginning of lines as well as the string. + "$" matches the end of lines as well as the string. + S DOTALL "." matches any character at all, including the newline. + X VERBOSE Ignore whitespaces and comments for nicer looking RE's. + +This module also defines an exception 'error'. + +""" + + +import sys +import string +from pcre import * + +# +# First, the public part of the interface: +# + +# pcre.error and re.error should be the same, since exceptions can be +# raised from either module. + +# compilation flags + +I = IGNORECASE +L = LOCALE +M = MULTILINE +S = DOTALL +X = VERBOSE + + +# +# +# + +_cache = {} +_MAXCACHE = 20 + +def _cachecompile(pattern, flags=0): + key = (pattern, flags) + try: + return _cache[key] + except KeyError: + pass + value = compile(pattern, flags) + if len(_cache) >= _MAXCACHE: + _cache.clear() + _cache[key] = value + return value + +def match(pattern, string, flags=0): + """match (pattern, string[, flags]) -> MatchObject or None + + If zero or more characters at the beginning of string match the + regular expression pattern, return a corresponding MatchObject + instance. Return None if the string does not match the pattern; + note that this is different from a zero-length match. + + Note: If you want to locate a match anywhere in string, use + search() instead. + + """ + + return _cachecompile(pattern, flags).match(string) + +def search(pattern, string, flags=0): + """search (pattern, string[, flags]) -> MatchObject or None + + Scan through string looking for a location where the regular + expression pattern produces a match, and return a corresponding + MatchObject instance. Return None if no position in the string + matches the pattern; note that this is different from finding a + zero-length match at some point in the string. + + """ + return _cachecompile(pattern, flags).search(string) + +def sub(pattern, repl, string, count=0): + """sub(pattern, repl, string[, count=0]) -> string + + Return the string obtained by replacing the leftmost + non-overlapping occurrences of pattern in string by the + replacement repl. If the pattern isn't found, string is returned + unchanged. repl can be a string or a function; if a function, it + is called for every non-overlapping occurrence of pattern. The + function takes a single match object argument, and returns the + replacement string. + + The pattern may be a string or a regex object; if you need to + specify regular expression flags, you must use a regex object, or + use embedded modifiers in a pattern; e.g. + sub("(?i)b+", "x", "bbbb BBBB") returns 'x x'. + + The optional argument count is the maximum number of pattern + occurrences to be replaced; count must be a non-negative integer, + and the default value of 0 means to replace all occurrences. + + """ + if type(pattern) == type(''): + pattern = _cachecompile(pattern) + return pattern.sub(repl, string, count) + +def subn(pattern, repl, string, count=0): + """subn(pattern, repl, string[, count=0]) -> (string, num substitutions) + + Perform the same operation as sub(), but return a tuple + (new_string, number_of_subs_made). + + """ + if type(pattern) == type(''): + pattern = _cachecompile(pattern) + return pattern.subn(repl, string, count) + +def split(pattern, string, maxsplit=0): + """split(pattern, string[, maxsplit=0]) -> list of strings + + Split string by the occurrences of pattern. If capturing + parentheses are used in pattern, then the text of all groups in + the pattern are also returned as part of the resulting list. If + maxsplit is nonzero, at most maxsplit splits occur, and the + remainder of the string is returned as the final element of the + list. + + """ + if type(pattern) == type(''): + pattern = _cachecompile(pattern) + return pattern.split(string, maxsplit) + +def findall(pattern, string): + """findall(pattern, string) -> list + + Return a list of all non-overlapping matches of pattern in + string. If one or more groups are present in the pattern, return a + list of groups; this will be a list of tuples if the pattern has + more than one group. Empty matches are included in the result. + + """ + if type(pattern) == type(''): + pattern = _cachecompile(pattern) + return pattern.findall(string) + +def escape(pattern): + """escape(string) -> string + + Return string with all non-alphanumerics backslashed; this is + useful if you want to match an arbitrary literal string that may + have regular expression metacharacters in it. + + """ + result = list(pattern) + alphanum=string.letters+'_'+string.digits + for i in range(len(pattern)): + char = pattern[i] + if char not in alphanum: + if char=='\000': result[i] = '\\000' + else: result[i] = '\\'+char + return string.join(result, '') + +def compile(pattern, flags=0): + """compile(pattern[, flags]) -> RegexObject + + Compile a regular expression pattern into a regular expression + object, which can be used for matching using its match() and + search() methods. + + """ + groupindex={} + code=pcre_compile(pattern, flags, groupindex) + return RegexObject(pattern, flags, code, groupindex) + + +# +# Class definitions +# + +class RegexObject: + """Holds a compiled regular expression pattern. + + Methods: + match Match the pattern to the beginning of a string. + search Search a string for the presence of the pattern. + sub Substitute occurrences of the pattern found in a string. + subn Same as sub, but also return the number of substitutions made. + split Split a string by the occurrences of the pattern. + findall Find all occurrences of the pattern in a string. + + """ + + def __init__(self, pattern, flags, code, groupindex): + self.code = code + self.flags = flags + self.pattern = pattern + self.groupindex = groupindex + + def search(self, string, pos=0, endpos=None): + """search(string[, pos][, endpos]) -> MatchObject or None + + Scan through string looking for a location where this regular + expression produces a match, and return a corresponding + MatchObject instance. Return None if no position in the string + matches the pattern; note that this is different from finding + a zero-length match at some point in the string. The optional + pos and endpos parameters have the same meaning as for the + match() method. + + """ + if endpos is None or endpos>len(string): + endpos=len(string) + if endpos<pos: endpos=pos + regs = self.code.match(string, pos, endpos, 0) + if regs is None: + return None + self._num_regs=len(regs) + + return MatchObject(self, + string, + pos, endpos, + regs) + + def match(self, string, pos=0, endpos=None): + """match(string[, pos][, endpos]) -> MatchObject or None + + If zero or more characters at the beginning of string match + this regular expression, return a corresponding MatchObject + instance. Return None if the string does not match the + pattern; note that this is different from a zero-length match. + + Note: If you want to locate a match anywhere in string, use + search() instead. + + The optional second parameter pos gives an index in the string + where the search is to start; it defaults to 0. This is not + completely equivalent to slicing the string; the '' pattern + character matches at the real beginning of the string and at + positions just after a newline, but not necessarily at the + index where the search is to start. + + The optional parameter endpos limits how far the string will + be searched; it will be as if the string is endpos characters + long, so only the characters from pos to endpos will be + searched for a match. + + """ + if endpos is None or endpos>len(string): + endpos=len(string) + if endpos<pos: endpos=pos + regs = self.code.match(string, pos, endpos, ANCHORED) + if regs is None: + return None + self._num_regs=len(regs) + return MatchObject(self, + string, + pos, endpos, + regs) + + def sub(self, repl, string, count=0): + """sub(repl, string[, count=0]) -> string + + Return the string obtained by replacing the leftmost + non-overlapping occurrences of the compiled pattern in string + by the replacement repl. If the pattern isn't found, string is + returned unchanged. + + Identical to the sub() function, using the compiled pattern. + + """ + return self.subn(repl, string, count)[0] + + def subn(self, repl, source, count=0): + """subn(repl, string[, count=0]) -> tuple + + Perform the same operation as sub(), but return a tuple + (new_string, number_of_subs_made). + + """ + if count < 0: + raise error, "negative substitution count" + if count == 0: + count = sys.maxint + n = 0 # Number of matches + pos = 0 # Where to start searching + lastmatch = -1 # End of last match + results = [] # Substrings making up the result + end = len(source) + + if type(repl) is type(''): + # See if repl contains group references + try: + repl = pcre_expand(_Dummy, repl) + except: + m = MatchObject(self, source, 0, end, []) + repl = lambda m, repl=repl, expand=pcre_expand: expand(m, repl) + else: + m = None + else: + m = MatchObject(self, source, 0, end, []) + + match = self.code.match + append = results.append + while n < count and pos <= end: + regs = match(source, pos, end, 0) + if not regs: + break + self._num_regs = len(regs) + i, j = regs[0] + if i == j == lastmatch: + # Empty match adjacent to previous match + pos = pos + 1 + append(source[lastmatch:pos]) + continue + if pos < i: + append(source[pos:i]) + if m: + m.pos = pos + m.regs = regs + append(repl(m)) + else: + append(repl) + pos = lastmatch = j + if i == j: + # Last match was empty; don't try here again + pos = pos + 1 + append(source[lastmatch:pos]) + n = n + 1 + append(source[pos:]) + return (string.join(results, ''), n) + + def split(self, source, maxsplit=0): + """split(source[, maxsplit=0]) -> list of strings + + Split string by the occurrences of the compiled pattern. If + capturing parentheses are used in the pattern, then the text + of all groups in the pattern are also returned as part of the + resulting list. If maxsplit is nonzero, at most maxsplit + splits occur, and the remainder of the string is returned as + the final element of the list. + + """ + if maxsplit < 0: + raise error, "negative split count" + if maxsplit == 0: + maxsplit = sys.maxint + n = 0 + pos = 0 + lastmatch = 0 + results = [] + end = len(source) + match = self.code.match + append = results.append + while n < maxsplit: + regs = match(source, pos, end, 0) + if not regs: + break + i, j = regs[0] + if i == j: + # Empty match + if pos >= end: + break + pos = pos+1 + continue + append(source[lastmatch:i]) + rest = regs[1:] + if rest: + for a, b in rest: + if a == -1 or b == -1: + group = None + else: + group = source[a:b] + append(group) + pos = lastmatch = j + n = n + 1 + append(source[lastmatch:]) + return results + + def findall(self, source): + """findall(source) -> list + + Return a list of all non-overlapping matches of the compiled + pattern in string. If one or more groups are present in the + pattern, return a list of groups; this will be a list of + tuples if the pattern has more than one group. Empty matches + are included in the result. + + """ + pos = 0 + end = len(source) + results = [] + match = self.code.match + append = results.append + while pos <= end: + regs = match(source, pos, end, 0) + if not regs: + break + i, j = regs[0] + rest = regs[1:] + if not rest: + gr = source[i:j] + elif len(rest) == 1: + a, b = rest[0] + gr = source[a:b] + else: + gr = [] + for (a, b) in rest: + gr.append(source[a:b]) + gr = tuple(gr) + append(gr) + pos = max(j, pos+1) + return results + + # The following 3 functions were contributed by Mike Fletcher, and + # allow pickling and unpickling of RegexObject instances. + def __getinitargs__(self): + return (None,None,None,None) # any 4 elements, to work around + # problems with the + # pickle/cPickle modules not yet + # ignoring the __init__ function + def __getstate__(self): + return self.pattern, self.flags, self.groupindex + def __setstate__(self, statetuple): + self.pattern = statetuple[0] + self.flags = statetuple[1] + self.groupindex = statetuple[2] + self.code = apply(pcre_compile, statetuple) + +class _Dummy: + # Dummy class used by _subn_string(). Has 'group' to avoid core dump. + group = None + +class MatchObject: + """Holds a compiled regular expression pattern. + + Methods: + start Return the index of the start of a matched substring. + end Return the index of the end of a matched substring. + span Return a tuple of (start, end) of a matched substring. + groups Return a tuple of all the subgroups of the match. + group Return one or more subgroups of the match. + groupdict Return a dictionary of all the named subgroups of the match. + + """ + + def __init__(self, re, string, pos, endpos, regs): + self.re = re + self.string = string + self.pos = pos + self.endpos = endpos + self.regs = regs + + def start(self, g = 0): + """start([group=0]) -> int or None + + Return the index of the start of the substring matched by + group; group defaults to zero (meaning the whole matched + substring). Return None if group exists but did not contribute + to the match. + + """ + if type(g) == type(''): + try: + g = self.re.groupindex[g] + except (KeyError, TypeError): + raise IndexError, 'group %s is undefined' % `g` + return self.regs[g][0] + + def end(self, g = 0): + """end([group=0]) -> int or None + + Return the indices of the end of the substring matched by + group; group defaults to zero (meaning the whole matched + substring). Return None if group exists but did not contribute + to the match. + + """ + if type(g) == type(''): + try: + g = self.re.groupindex[g] + except (KeyError, TypeError): + raise IndexError, 'group %s is undefined' % `g` + return self.regs[g][1] + + def span(self, g = 0): + """span([group=0]) -> tuple + + Return the 2-tuple (m.start(group), m.end(group)). Note that + if group did not contribute to the match, this is (None, + None). Group defaults to zero (meaning the whole matched + substring). + + """ + if type(g) == type(''): + try: + g = self.re.groupindex[g] + except (KeyError, TypeError): + raise IndexError, 'group %s is undefined' % `g` + return self.regs[g] + + def groups(self, default=None): + """groups([default=None]) -> tuple + + Return a tuple containing all the subgroups of the match, from + 1 up to however many groups are in the pattern. The default + argument is used for groups that did not participate in the + match. + + """ + result = [] + for g in range(1, self.re._num_regs): + a, b = self.regs[g] + if a == -1 or b == -1: + result.append(default) + else: + result.append(self.string[a:b]) + return tuple(result) + + def group(self, *groups): + """group([group1, group2, ...]) -> string or tuple + + Return one or more subgroups of the match. If there is a + single argument, the result is a single string; if there are + multiple arguments, the result is a tuple with one item per + argument. Without arguments, group1 defaults to zero (i.e. the + whole match is returned). If a groupN argument is zero, the + corresponding return value is the entire matching string; if + it is in the inclusive range [1..99], it is the string + matching the the corresponding parenthesized group. If a group + number is negative or larger than the number of groups defined + in the pattern, an IndexError exception is raised. If a group + is contained in a part of the pattern that did not match, the + corresponding result is None. If a group is contained in a + part of the pattern that matched multiple times, the last + match is returned. + + If the regular expression uses the (?P<name>...) syntax, the + groupN arguments may also be strings identifying groups by + their group name. If a string argument is not used as a group + name in the pattern, an IndexError exception is raised. + + """ + if len(groups) == 0: + groups = (0,) + result = [] + for g in groups: + if type(g) == type(''): + try: + g = self.re.groupindex[g] + except (KeyError, TypeError): + raise IndexError, 'group %s is undefined' % `g` + if g >= len(self.regs): + raise IndexError, 'group %s is undefined' % `g` + a, b = self.regs[g] + if a == -1 or b == -1: + result.append(None) + else: + result.append(self.string[a:b]) + if len(result) > 1: + return tuple(result) + elif len(result) == 1: + return result[0] + else: + return () + + def groupdict(self, default=None): + """groupdict([default=None]) -> dictionary + + Return a dictionary containing all the named subgroups of the + match, keyed by the subgroup name. The default argument is + used for groups that did not participate in the match. + + """ + dict = {} + for name, index in self.re.groupindex.items(): + a, b = self.regs[index] + if a == -1 or b == -1: + dict[name] = default + else: + dict[name] = self.string[a:b] + return dict |