# # Secret Labs' Regular Expression Engine # # Copyright (c) 1998-2001 by Secret Labs AB. All rights reserved. # # This version of the SRE library can be redistributed under CNRI's # Python 1.6 license. For any other use, please contact Secret Labs # AB (info@pythonware.com). # # Portions of this engine have been developed in cooperation with # CNRI. Hewlett-Packard provided funding for 1.6 integration and # other compatibility work. # # 2010-01-16 mrab Python front-end re-written and extended r"""Support for regular expressions (RE). This module provides regular expression matching operations similar to those found in Perl. It supports both 8-bit and Unicode strings; both the pattern and the strings being processed can contain null bytes and characters outside the US ASCII range. 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'. There are a few differences between the old (legacy) behaviour and the new (enhanced) behaviour, which are indicated by VERSION0 or VERSION1. The special characters are: "." Matches any character except a newline. "^" Matches the start of the string. "$" Matches the end of the string or just before the newline at 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. *+,++,?+ Possessive 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. {m,n}+ Possessive version of the above. {...} Fuzzy matching constraints. "\\" 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 are captured and can be retrieved or matched later in the string. (?flags-flags) VERSION1: Sets/clears the flags for the remainder of the group or pattern; VERSION0: Sets the flags for the entire pattern. (?:...) Non-capturing version of regular parentheses. (?>...) Atomic non-capturing version of regular parentheses. (?flags-flags:...) Non-capturing version of regular parentheses with local flags. (?P...) The substring matched by the group is accessible by 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. (?<=...) Matches if preceded by .... (? Matches the text matched by the group named name. \G Matches the empty string, but only at the position where the search started. \h Matches horizontal whitespace. \K Keeps only what follows for the entire match. \L Named list. The list is provided as a keyword argument. \m Matches the empty string, but only at the start of a word. \M Matches the empty string, but only at the end of a word. \n Matches the newline character. \N{name} Matches the named character. \p{name=value} Matches the character if its property has the specified value. \P{name=value} Matches the character if its property hasn't the specified value. \r Matches the carriage-return character. \s Matches any whitespace character; equivalent to [ \t\n\r\f\v]. \S Matches any non-whitespace character; equivalent to [^\s]. \t Matches the tab character. \uXXXX Matches the Unicode codepoint with 4-digit hex code XXXX. \UXXXXXXXX Matches the Unicode codepoint with 8-digit hex code XXXXXXXX. \v Matches the vertical tab character. \w Matches any alphanumeric character; equivalent to [a-zA-Z0-9_] when matching a bytestring or a Unicode string with the ASCII flag, or the whole range of Unicode alphanumeric characters (letters plus digits plus underscore) when matching a Unicode string. With LOCALE, it will match the set [0-9_] plus characters defined as letters for the current locale. \W Matches the complement of \w; equivalent to [^\w]. \xXX Matches the character with 2-digit hex code XX. \X Matches a grapheme. \Z Matches only at the end of the string. \\ Matches a literal backslash. This module exports the following functions: match Match a regular expression pattern at the beginning of a string. fullmatch Match a regular expression pattern against all of a string. search Search a string for the presence of a pattern. sub Substitute occurrences of a pattern found in a string using a template string. subf Substitute occurrences of a pattern found in a string using a format string. subn Same as sub, but also return the number of substitutions made. subfn Same as subf, but also return the number of substitutions made. split Split a string by the occurrences of a pattern. VERSION1: will split at zero-width match; VERSION0: won't split at zero-width match. splititer Return an iterator yielding the parts of a split string. findall Find all occurrences of a pattern in a string. finditer Return an iterator yielding a match object for each match. compile Compile a pattern into a Pattern object. purge Clear the regular expression cache. escape Backslash all non-alphanumerics or special characters in a string. Most of the functions support a concurrent parameter: if True, the GIL will be released during matching, allowing other Python threads to run concurrently. If the string changes during matching, the behaviour is undefined. This parameter is not needed when working on the builtin (immutable) string classes. Some of the functions in this module take flags as optional parameters. Most of these flags can also be set within an RE: A a ASCII Make \w, \W, \b, \B, \d, and \D match the corresponding ASCII character categories. Default when matching a bytestring. B b BESTMATCH Find the best fuzzy match (default is first). D DEBUG Print the parsed pattern. E e ENHANCEMATCH Attempt to improve the fit after finding the first fuzzy match. F f FULLCASE Use full case-folding when performing case-insensitive matching in Unicode. I i IGNORECASE Perform case-insensitive matching. L L LOCALE Make \w, \W, \b, \B, \d, and \D dependent on the current locale. (One byte per character only.) M m MULTILINE "^" matches the beginning of lines (after a newline) as well as the string. "$" matches the end of lines (before a newline) as well as the end of the string. P p POSIX Perform POSIX-standard matching (leftmost longest). R r REVERSE Searches backwards. S s DOTALL "." matches any character at all, including the newline. U u UNICODE Make \w, \W, \b, \B, \d, and \D dependent on the Unicode locale. Default when matching a Unicode string. V0 V0 VERSION0 Turn on the old legacy behaviour. V1 V1 VERSION1 Turn on the new enhanced behaviour. This flag includes the FULLCASE flag. W w WORD Make \b and \B work with default Unicode word breaks and make ".", "^" and "$" work with Unicode line breaks. X x VERBOSE Ignore whitespace and comments for nicer looking REs. This module also defines an exception 'error'. """ # Public symbols. __all__ = ["cache_all", "compile", "DEFAULT_VERSION", "escape", "findall", "finditer", "fullmatch", "match", "purge", "search", "split", "splititer", "sub", "subf", "subfn", "subn", "template", "Scanner", "A", "ASCII", "B", "BESTMATCH", "D", "DEBUG", "E", "ENHANCEMATCH", "S", "DOTALL", "F", "FULLCASE", "I", "IGNORECASE", "L", "LOCALE", "M", "MULTILINE", "P", "POSIX", "R", "REVERSE", "T", "TEMPLATE", "U", "UNICODE", "V0", "VERSION0", "V1", "VERSION1", "X", "VERBOSE", "W", "WORD", "error", "Regex", "__version__", "__doc__", "RegexFlag"] __version__ = "2.5.142" # -------------------------------------------------------------------- # Public interface. def match(pattern, string, flags=0, pos=None, endpos=None, partial=False, concurrent=None, timeout=None, ignore_unused=False, **kwargs): """Try to apply the pattern at the start of the string, returning a match object, or None if no match was found.""" pat = _compile(pattern, flags, ignore_unused, kwargs, True) return pat.match(string, pos, endpos, concurrent, partial, timeout) def fullmatch(pattern, string, flags=0, pos=None, endpos=None, partial=False, concurrent=None, timeout=None, ignore_unused=False, **kwargs): """Try to apply the pattern against all of the string, returning a match object, or None if no match was found.""" pat = _compile(pattern, flags, ignore_unused, kwargs, True) return pat.fullmatch(string, pos, endpos, concurrent, partial, timeout) def search(pattern, string, flags=0, pos=None, endpos=None, partial=False, concurrent=None, timeout=None, ignore_unused=False, **kwargs): """Search through string looking for a match to the pattern, returning a match object, or None if no match was found.""" pat = _compile(pattern, flags, ignore_unused, kwargs, True) return pat.search(string, pos, endpos, concurrent, partial, timeout) def sub(pattern, repl, string, count=0, flags=0, pos=None, endpos=None, concurrent=None, timeout=None, ignore_unused=False, **kwargs): """Return the string obtained by replacing the leftmost (or rightmost with a reverse pattern) non-overlapping occurrences of the pattern in string by the replacement repl. repl can be either a string or a callable; if a string, backslash escapes in it are processed; if a callable, it's passed the match object and must return a replacement string to be used.""" pat = _compile(pattern, flags, ignore_unused, kwargs, True) return pat.sub(repl, string, count, pos, endpos, concurrent, timeout) def subf(pattern, format, string, count=0, flags=0, pos=None, endpos=None, concurrent=None, timeout=None, ignore_unused=False, **kwargs): """Return the string obtained by replacing the leftmost (or rightmost with a reverse pattern) non-overlapping occurrences of the pattern in string by the replacement format. format can be either a string or a callable; if a string, it's treated as a format string; if a callable, it's passed the match object and must return a replacement string to be used.""" pat = _compile(pattern, flags, ignore_unused, kwargs, True) return pat.subf(format, string, count, pos, endpos, concurrent, timeout) def subn(pattern, repl, string, count=0, flags=0, pos=None, endpos=None, concurrent=None, timeout=None, ignore_unused=False, **kwargs): """Return a 2-tuple containing (new_string, number). new_string is the string obtained by replacing the leftmost (or rightmost with a reverse pattern) non-overlapping occurrences of the pattern in the source string by the replacement repl. number is the number of substitutions that were made. repl can be either a string or a callable; if a string, backslash escapes in it are processed; if a callable, it's passed the match object and must return a replacement string to be used.""" pat = _compile(pattern, flags, ignore_unused, kwargs, True) return pat.subn(repl, string, count, pos, endpos, concurrent, timeout) def subfn(pattern, format, string, count=0, flags=0, pos=None, endpos=None, concurrent=None, timeout=None, ignore_unused=False, **kwargs): """Return a 2-tuple containing (new_string, number). new_string is the string obtained by replacing the leftmost (or rightmost with a reverse pattern) non-overlapping occurrences of the pattern in the source string by the replacement format. number is the number of substitutions that were made. format can be either a string or a callable; if a string, it's treated as a format string; if a callable, it's passed the match object and must return a replacement string to be used.""" pat = _compile(pattern, flags, ignore_unused, kwargs, True) return pat.subfn(format, string, count, pos, endpos, concurrent, timeout) def split(pattern, string, maxsplit=0, flags=0, concurrent=None, timeout=None, ignore_unused=False, **kwargs): """Split the source string by the occurrences of the pattern, returning a list containing the resulting substrings. 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.""" pat = _compile(pattern, flags, ignore_unused, kwargs, True) return pat.split(string, maxsplit, concurrent, timeout) def splititer(pattern, string, maxsplit=0, flags=0, concurrent=None, timeout=None, ignore_unused=False, **kwargs): "Return an iterator yielding the parts of a split string." pat = _compile(pattern, flags, ignore_unused, kwargs, True) return pat.splititer(string, maxsplit, concurrent, timeout) def findall(pattern, string, flags=0, pos=None, endpos=None, overlapped=False, concurrent=None, timeout=None, ignore_unused=False, **kwargs): """Return a list of all matches in the string. The matches may be overlapped if overlapped is True. 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.""" pat = _compile(pattern, flags, ignore_unused, kwargs, True) return pat.findall(string, pos, endpos, overlapped, concurrent, timeout) def finditer(pattern, string, flags=0, pos=None, endpos=None, overlapped=False, partial=False, concurrent=None, timeout=None, ignore_unused=False, **kwargs): """Return an iterator over all matches in the string. The matches may be overlapped if overlapped is True. For each match, the iterator returns a match object. Empty matches are included in the result.""" pat = _compile(pattern, flags, ignore_unused, kwargs, True) return pat.finditer(string, pos, endpos, overlapped, concurrent, partial, timeout) def compile(pattern, flags=0, ignore_unused=False, cache_pattern=None, **kwargs): "Compile a regular expression pattern, returning a pattern object." if cache_pattern is None: cache_pattern = _cache_all return _compile(pattern, flags, ignore_unused, kwargs, cache_pattern) def purge(): "Clear the regular expression cache" _cache.clear() _locale_sensitive.clear() # Whether to cache all patterns. _cache_all = True def cache_all(value=True): """Sets whether to cache all patterns, even those are compiled explicitly. Passing None has no effect, but returns the current setting.""" global _cache_all if value is None: return _cache_all _cache_all = value def template(pattern, flags=0): "Compile a template pattern, returning a pattern object." return _compile(pattern, flags | TEMPLATE, False, {}, False) def escape(pattern, special_only=True, literal_spaces=False): """Escape a string for use as a literal in a pattern. If special_only is True, escape only special characters, else escape all non-alphanumeric characters. If literal_spaces is True, don't escape spaces.""" # Convert it to Unicode. if isinstance(pattern, bytes): p = pattern.decode("latin-1") else: p = pattern s = [] if special_only: for c in p: if c == " " and literal_spaces: s.append(c) elif c in _METACHARS or c.isspace(): s.append("\\") s.append(c) else: s.append(c) else: for c in p: if c == " " and literal_spaces: s.append(c) elif c in _ALNUM: s.append(c) else: s.append("\\") s.append(c) r = "".join(s) # Convert it back to bytes if necessary. if isinstance(pattern, bytes): r = r.encode("latin-1") return r # -------------------------------------------------------------------- # Internals. import regex._regex_core as _regex_core import regex._regex as _regex from threading import RLock as _RLock from locale import getpreferredencoding as _getpreferredencoding from regex._regex_core import * from regex._regex_core import (_ALL_VERSIONS, _ALL_ENCODINGS, _FirstSetError, _UnscopedFlagSet, _check_group_features, _compile_firstset, _compile_replacement, _flatten_code, _fold_case, _get_required_string, _parse_pattern, _shrink_cache) from regex._regex_core import (ALNUM as _ALNUM, Info as _Info, OP as _OP, Source as _Source, Fuzzy as _Fuzzy) # Version 0 is the old behaviour, compatible with the original 're' module. # Version 1 is the new behaviour, which differs slightly. DEFAULT_VERSION = VERSION0 _METACHARS = frozenset("()[]{}?*+|^$\\.-#&~") _regex_core.DEFAULT_VERSION = DEFAULT_VERSION # Caches for the patterns and replacements. _cache = {} _cache_lock = _RLock() _named_args = {} _replacement_cache = {} _locale_sensitive = {} # Maximum size of the cache. _MAXCACHE = 500 _MAXREPCACHE = 500 def _compile(pattern, flags, ignore_unused, kwargs, cache_it): "Compiles a regular expression to a PatternObject." global DEFAULT_VERSION try: from regex import DEFAULT_VERSION except ImportError: pass # We won't bother to cache the pattern if we're debugging. if (flags & DEBUG) != 0: cache_it = False # What locale is this pattern using? locale_key = (type(pattern), pattern) if _locale_sensitive.get(locale_key, True) or (flags & LOCALE) != 0: # This pattern is, or might be, locale-sensitive. pattern_locale = _getpreferredencoding() else: # This pattern is definitely not locale-sensitive. pattern_locale = None def complain_unused_args(): if ignore_unused: return # Complain about any unused keyword arguments, possibly resulting from a typo. unused_kwargs = set(kwargs) - {k for k, v in args_needed} if unused_kwargs: any_one = next(iter(unused_kwargs)) raise ValueError('unused keyword argument {!a}'.format(any_one)) if cache_it: try: # Do we know what keyword arguments are needed? args_key = pattern, type(pattern), flags args_needed = _named_args[args_key] # Are we being provided with its required keyword arguments? args_supplied = set() if args_needed: for k, v in args_needed: try: args_supplied.add((k, frozenset(kwargs[k]))) except KeyError: raise error("missing named list: {!r}".format(k)) complain_unused_args() args_supplied = frozenset(args_supplied) # Have we already seen this regular expression and named list? pattern_key = (pattern, type(pattern), flags, args_supplied, DEFAULT_VERSION, pattern_locale) return _cache[pattern_key] except KeyError: # It's a new pattern, or new named list for a known pattern. pass # Guess the encoding from the class of the pattern string. if isinstance(pattern, str): guess_encoding = UNICODE elif isinstance(pattern, bytes): guess_encoding = ASCII elif isinstance(pattern, Pattern): if flags: raise ValueError("cannot process flags argument with a compiled pattern") return pattern else: raise TypeError("first argument must be a string or compiled pattern") # Set the default version in the core code in case it has been changed. _regex_core.DEFAULT_VERSION = DEFAULT_VERSION global_flags = flags while True: caught_exception = None try: source = _Source(pattern) info = _Info(global_flags, source.char_type, kwargs) info.guess_encoding = guess_encoding source.ignore_space = bool(info.flags & VERBOSE) parsed = _parse_pattern(source, info) break except _UnscopedFlagSet: # Remember the global flags for the next attempt. global_flags = info.global_flags except error as e: caught_exception = e if caught_exception: raise error(caught_exception.msg, caught_exception.pattern, caught_exception.pos) if not source.at_end(): raise error("unbalanced parenthesis", pattern, source.pos) # Check the global flags for conflicts. version = (info.flags & _ALL_VERSIONS) or DEFAULT_VERSION if version not in (0, VERSION0, VERSION1): raise ValueError("VERSION0 and VERSION1 flags are mutually incompatible") if (info.flags & _ALL_ENCODINGS) not in (0, ASCII, LOCALE, UNICODE): raise ValueError("ASCII, LOCALE and UNICODE flags are mutually incompatible") if isinstance(pattern, bytes) and (info.flags & UNICODE): raise ValueError("cannot use UNICODE flag with a bytes pattern") if not (info.flags & _ALL_ENCODINGS): if isinstance(pattern, str): info.flags |= UNICODE else: info.flags |= ASCII reverse = bool(info.flags & REVERSE) fuzzy = isinstance(parsed, _Fuzzy) # Remember whether this pattern as an inline locale flag. _locale_sensitive[locale_key] = info.inline_locale # Fix the group references. caught_exception = None try: parsed.fix_groups(pattern, reverse, False) except error as e: caught_exception = e if caught_exception: raise error(caught_exception.msg, caught_exception.pattern, caught_exception.pos) # Should we print the parsed pattern? if flags & DEBUG: parsed.dump(indent=0, reverse=reverse) # Optimise the parsed pattern. parsed = parsed.optimise(info, reverse) parsed = parsed.pack_characters(info) # Get the required string. req_offset, req_chars, req_flags = _get_required_string(parsed, info.flags) # Build the named lists. named_lists = {} named_list_indexes = [None] * len(info.named_lists_used) args_needed = set() for key, index in info.named_lists_used.items(): name, case_flags = key values = frozenset(kwargs[name]) if case_flags: items = frozenset(_fold_case(info, v) for v in values) else: items = values named_lists[name] = values named_list_indexes[index] = items args_needed.add((name, values)) complain_unused_args() # Check the features of the groups. _check_group_features(info, parsed) # Compile the parsed pattern. The result is a list of tuples. code = parsed.compile(reverse) # Is there a group call to the pattern as a whole? key = (0, reverse, fuzzy) ref = info.call_refs.get(key) if ref is not None: code = [(_OP.CALL_REF, ref)] + code + [(_OP.END, )] # Add the final 'success' opcode. code += [(_OP.SUCCESS, )] # Compile the additional copies of the groups that we need. for group, rev, fuz in info.additional_groups: code += group.compile(rev, fuz) # Flatten the code into a list of ints. code = _flatten_code(code) if not parsed.has_simple_start(): # Get the first set, if possible. try: fs_code = _compile_firstset(info, parsed.get_firstset(reverse)) fs_code = _flatten_code(fs_code) code = fs_code + code except _FirstSetError: pass # The named capture groups. index_group = dict((v, n) for n, v in info.group_index.items()) # Create the PatternObject. # # Local flags like IGNORECASE affect the code generation, but aren't needed # by the PatternObject itself. Conversely, global flags like LOCALE _don't_ # affect the code generation but _are_ needed by the PatternObject. compiled_pattern = _regex.compile(pattern, info.flags | version, code, info.group_index, index_group, named_lists, named_list_indexes, req_offset, req_chars, req_flags, info.group_count) # Do we need to reduce the size of the cache? if len(_cache) >= _MAXCACHE: with _cache_lock: _shrink_cache(_cache, _named_args, _locale_sensitive, _MAXCACHE) if cache_it: if (info.flags & LOCALE) == 0: pattern_locale = None args_needed = frozenset(args_needed) # Store this regular expression and named list. pattern_key = (pattern, type(pattern), flags, args_needed, DEFAULT_VERSION, pattern_locale) _cache[pattern_key] = compiled_pattern # Store what keyword arguments are needed. _named_args[args_key] = args_needed return compiled_pattern def _compile_replacement_helper(pattern, template): "Compiles a replacement template." # This function is called by the _regex module. # Have we seen this before? key = pattern.pattern, pattern.flags, template compiled = _replacement_cache.get(key) if compiled is not None: return compiled if len(_replacement_cache) >= _MAXREPCACHE: _replacement_cache.clear() is_unicode = isinstance(template, str) source = _Source(template) if is_unicode: def make_string(char_codes): return "".join(chr(c) for c in char_codes) else: def make_string(char_codes): return bytes(char_codes) compiled = [] literal = [] while True: ch = source.get() if not ch: break if ch == "\\": # '_compile_replacement' will return either an int group reference # or a string literal. It returns items (plural) in order to handle # a 2-character literal (an invalid escape sequence). is_group, items = _compile_replacement(source, pattern, is_unicode) if is_group: # It's a group, so first flush the literal. if literal: compiled.append(make_string(literal)) literal = [] compiled.extend(items) else: literal.extend(items) else: literal.append(ord(ch)) # Flush the literal. if literal: compiled.append(make_string(literal)) _replacement_cache[key] = compiled return compiled # We define Pattern here after all the support objects have been defined. _pat = _compile('', 0, False, {}, False) Pattern = type(_pat) Match = type(_pat.match('')) del _pat # Make Pattern public for typing annotations. __all__.append("Pattern") __all__.append("Match") # We'll define an alias for the 'compile' function so that the repr of a # pattern object is eval-able. Regex = compile # Register myself for pickling. import copyreg as _copy_reg def _pickle(pattern): return _regex.compile, pattern._pickled_data _copy_reg.pickle(Pattern, _pickle)