match: simplify brittle predicate construction

In match.__init__(), we create the matchfn predicate by and-ing
together the individual predicates for includes, excludes (negated)
and patterns. Instead of the current set of nested if/else blocks, we
can simplify by adding the predicates to a list and defining the
overall predicate in a generic way based on the components. We can
still optimize it for the 0-length and 1-length cases. This way, there
is no combinatorial explosion to deal with if new component predicates
are added, and there is less risk of getting the overall predicate
wrong.

mercurial/match.py

@@ -1,416 +1,408 b''
 # match.py - filename matching
 #
 #  Copyright 2008, 2009 Matt Mackall <[e-mail]> and others
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 import re
 import util, pathutil
 from i18n import _
 
 def _rematcher(regex):
     '''compile the regexp with the best available regexp engine and return a
     matcher function'''
     m = util.re.compile(regex)
     try:
         # slightly faster, provided by facebook's re2 bindings
         return m.test_match
     except AttributeError:
         return m.match
 
 def _expandsets(kindpats, ctx):
     '''Returns the kindpats list with the 'set' patterns expanded.'''
     fset = set()
     other = []
 
     for kind, pat in kindpats:
         if kind == 'set':
             if not ctx:
                 raise util.Abort("fileset expression with no context")
             s = ctx.getfileset(pat)
             fset.update(s)
             continue
         other.append((kind, pat))
     return fset, other
 
 class match(object):
     def __init__(self, root, cwd, patterns, include=[], exclude=[],
                  default='glob', exact=False, auditor=None, ctx=None):
         """build an object to match a set of file patterns
 
         arguments:
         root - the canonical root of the tree you're matching against
         cwd - the current working directory, if relevant
         patterns - patterns to find
         include - patterns to include (unless they are excluded)
         exclude - patterns to exclude (even if they are included)
         default - if a pattern in patterns has no explicit type, assume this one
         exact - patterns are actually filenames (include/exclude still apply)
 
         a pattern is one of:
         'glob:<glob>' - a glob relative to cwd
         're:<regexp>' - a regular expression
         'path:<path>' - a path relative to repository root
         'relglob:<glob>' - an unrooted glob (*.c matches C files in all dirs)
         'relpath:<path>' - a path relative to cwd
         'relre:<regexp>' - a regexp that needn't match the start of a name
         'set:<fileset>' - a fileset expression
         '<something>' - a pattern of the specified default type
         """
 
         self._root = root
         self._cwd = cwd
         self._files = [] # exact files and roots of patterns
         self._anypats = bool(include or exclude)
         self._ctx = ctx
         self._always = False
 
+        matchfns = []
         if include:
             kindpats = _normalize(include, 'glob', root, cwd, auditor)
             self.includepat, im = _buildmatch(ctx, kindpats, '(?:/|$)')
+            matchfns.append(im)
         if exclude:
             kindpats = _normalize(exclude, 'glob', root, cwd, auditor)
             self.excludepat, em = _buildmatch(ctx, kindpats, '(?:/|$)')
+            matchfns.append(lambda f: not em(f))
         if exact:
             if isinstance(patterns, list):
                 self._files = patterns
             else:
                 self._files = list(patterns)
-            pm = self.exact
+            matchfns.append(self.exact)
         elif patterns:
             kindpats = _normalize(patterns, default, root, cwd, auditor)
             self._files = _roots(kindpats)
             self._anypats = self._anypats or _anypats(kindpats)
             self.patternspat, pm = _buildmatch(ctx, kindpats, '$')
+            matchfns.append(pm)
 
-        if patterns or exact:
-            if include:
-                if exclude:
-                    m = lambda f: im(f) and not em(f) and pm(f)
-                else:
-                    m = lambda f: im(f) and pm(f)
-            else:
-                if exclude:
-                    m = lambda f: not em(f) and pm(f)
-                else:
-                    m = pm
+        if not matchfns:
+            m = util.always
+            self._always = True
+        elif len(matchfns) == 1:
+            m = matchfns[0]
         else:
-            if include:
-                if exclude:
-                    m = lambda f: im(f) and not em(f)
-                else:
-                    m = im
-            else:
-                if exclude:
-                    m = lambda f: not em(f)
-                else:
-                    m = lambda f: True
-                    self._always = True
+            def m(f):
+                for matchfn in matchfns:
+                    if not matchfn(f):
+                        return False
+                return True
 
         self.matchfn = m
         self._fmap = set(self._files)
 
     def __call__(self, fn):
         return self.matchfn(fn)
     def __iter__(self):
         for f in self._files:
             yield f
 
     # Callbacks related to how the matcher is used by dirstate.walk.
     # Subscribers to these events must monkeypatch the matcher object.
     def bad(self, f, msg):
         '''Callback from dirstate.walk for each explicit file that can't be
         found/accessed, with an error message.'''
         pass
 
     # If an explicitdir is set, it will be called when an explicitly listed
     # directory is visited.
     explicitdir = None
 
     # If an traversedir is set, it will be called when a directory discovered
     # by recursive traversal is visited.
     traversedir = None
 
     def rel(self, f):
         '''Convert repo path back to path that is relative to cwd of matcher.'''
         return util.pathto(self._root, self._cwd, f)
 
     def files(self):
         '''Explicitly listed files or patterns or roots:
         if no patterns or .always(): empty list,
         if exact: list exact files,
         if not .anypats(): list all files and dirs,
         else: optimal roots'''
         return self._files
 
     def exact(self, f):
         '''Returns True if f is in .files().'''
         return f in self._fmap
 
     def anypats(self):
         '''Matcher uses patterns or include/exclude.'''
         return self._anypats
 
     def always(self):
         '''Matcher will match everything and .files() will be empty
         - optimization might be possible and necessary.'''
         return self._always
 
 class exact(match):
     def __init__(self, root, cwd, files):
         match.__init__(self, root, cwd, files, exact=True)
 
 class always(match):
     def __init__(self, root, cwd):
         match.__init__(self, root, cwd, [])
         self._always = True
 
 class narrowmatcher(match):
     """Adapt a matcher to work on a subdirectory only.
 
     The paths are remapped to remove/insert the path as needed:
 
     >>> m1 = match('root', '', ['a.txt', 'sub/b.txt'])
     >>> m2 = narrowmatcher('sub', m1)
     >>> bool(m2('a.txt'))
     False
     >>> bool(m2('b.txt'))
     True
     >>> bool(m2.matchfn('a.txt'))
     False
     >>> bool(m2.matchfn('b.txt'))
     True
     >>> m2.files()
     ['b.txt']
     >>> m2.exact('b.txt')
     True
     >>> m2.rel('b.txt')
     'b.txt'
     >>> def bad(f, msg):
     ...     print "%s: %s" % (f, msg)
     >>> m1.bad = bad
     >>> m2.bad('x.txt', 'No such file')
     sub/x.txt: No such file
     """
 
     def __init__(self, path, matcher):
         self._root = matcher._root
         self._cwd = matcher._cwd
         self._path = path
         self._matcher = matcher
         self._always = matcher._always
 
         self._files = [f[len(path) + 1:] for f in matcher._files
                        if f.startswith(path + "/")]
         self._anypats = matcher._anypats
         self.matchfn = lambda fn: matcher.matchfn(self._path + "/" + fn)
         self._fmap = set(self._files)
 
     def bad(self, f, msg):
         self._matcher.bad(self._path + "/" + f, msg)
 
 def patkind(pattern, default=None):
     '''If pattern is 'kind:pat' with a known kind, return kind.'''
     return _patsplit(pattern, default)[0]
 
 def _patsplit(pattern, default):
     """Split a string into the optional pattern kind prefix and the actual
     pattern."""
     if ':' in pattern:
         kind, pat = pattern.split(':', 1)
         if kind in ('re', 'glob', 'path', 'relglob', 'relpath', 'relre',
                     'listfile', 'listfile0', 'set'):
             return kind, pat
     return default, pattern
 
 def _globre(pat):
     r'''Convert an extended glob string to a regexp string.
 
     >>> print _globre(r'?')
     .
     >>> print _globre(r'*')
     [^/]*
     >>> print _globre(r'**')
     .*
     >>> print _globre(r'**/a')
     (?:.*/)?a
     >>> print _globre(r'a/**/b')
     a\/(?:.*/)?b
     >>> print _globre(r'[a*?!^][^b][!c]')
     [a*?!^][\^b][^c]
     >>> print _globre(r'{a,b}')
     (?:a|b)
     >>> print _globre(r'.\*\?')
     \.\*\?
     '''
     i, n = 0, len(pat)
     res = ''
     group = 0
     escape = util.re.escape
     def peek():
         return i < n and pat[i]
     while i < n:
         c = pat[i]
         i += 1
         if c not in '*?[{},\\':
             res += escape(c)
         elif c == '*':
             if peek() == '*':
                 i += 1
                 if peek() == '/':
                     i += 1
                     res += '(?:.*/)?'
                 else:
                     res += '.*'
             else:
                 res += '[^/]*'
         elif c == '?':
             res += '.'
         elif c == '[':
             j = i
             if j < n and pat[j] in '!]':
                 j += 1
             while j < n and pat[j] != ']':
                 j += 1
             if j >= n:
                 res += '\\['
             else:
                 stuff = pat[i:j].replace('\\','\\\\')
                 i = j + 1
                 if stuff[0] == '!':
                     stuff = '^' + stuff[1:]
                 elif stuff[0] == '^':
                     stuff = '\\' + stuff
                 res = '%s[%s]' % (res, stuff)
         elif c == '{':
             group += 1
             res += '(?:'
         elif c == '}' and group:
             res += ')'
             group -= 1
         elif c == ',' and group:
             res += '|'
         elif c == '\\':
             p = peek()
             if p:
                 i += 1
                 res += escape(p)
             else:
                 res += escape(c)
         else:
             res += escape(c)
     return res
 
 def _regex(kind, pat, globsuffix):
     '''Convert a (normalized) pattern of any kind into a regular expression.
     globsuffix is appended to the regexp of globs.'''
     if not pat:
         return ''
     if kind == 're':
         return pat
     if kind == 'path':
         return '^' + util.re.escape(pat) + '(?:/|$)'
     if kind == 'relglob':
         return '(?:|.*/)' + _globre(pat) + globsuffix
     if kind == 'relpath':
         return util.re.escape(pat) + '(?:/|$)'
     if kind == 'relre':
         if pat.startswith('^'):
             return pat
         return '.*' + pat
     return _globre(pat) + globsuffix
 
 def _buildmatch(ctx, kindpats, globsuffix):
     '''Return regexp string and a matcher function for kindpats.
     globsuffix is appended to the regexp of globs.'''
     fset, kindpats = _expandsets(kindpats, ctx)
     if not kindpats:
         return "", fset.__contains__
 
     regex, mf = _buildregexmatch(kindpats, globsuffix)
     if fset:
         return regex, lambda f: f in fset or mf(f)
     return regex, mf
 
 def _buildregexmatch(kindpats, globsuffix):
     """Build a match function from a list of kinds and kindpats,
     return regexp string and a matcher function."""
     try:
         regex = '(?:%s)' % '|'.join([_regex(k, p, globsuffix)
                                      for (k, p) in kindpats])
         if len(regex) > 20000:
             raise OverflowError
         return regex, _rematcher(regex)
     except OverflowError:
         # We're using a Python with a tiny regex engine and we
         # made it explode, so we'll divide the pattern list in two
         # until it works
         l = len(kindpats)
         if l < 2:
             raise
         regexa, a = _buildregexmatch(kindpats[:l//2], globsuffix)
         regexb, b = _buildregexmatch(kindpats[l//2:], globsuffix)
         return regex, lambda s: a(s) or b(s)
     except re.error:
         for k, p in kindpats:
             try:
                 _rematcher('(?:%s)' % _regex(k, p, globsuffix))
             except re.error:
                 raise util.Abort(_("invalid pattern (%s): %s") % (k, p))
         raise util.Abort(_("invalid pattern"))
 
 def _normalize(patterns, default, root, cwd, auditor):
     '''Convert 'kind:pat' from the patterns list to tuples with kind and
     normalized and rooted patterns and with listfiles expanded.'''
     kindpats = []
     for kind, pat in [_patsplit(p, default) for p in patterns]:
         if kind in ('glob', 'relpath'):
             pat = pathutil.canonpath(root, cwd, pat, auditor)
         elif kind in ('relglob', 'path'):
             pat = util.normpath(pat)
         elif kind in ('listfile', 'listfile0'):
             try:
                 files = util.readfile(pat)
                 if kind == 'listfile0':
                     files = files.split('\0')
                 else:
                     files = files.splitlines()
                 files = [f for f in files if f]
             except EnvironmentError:
                 raise util.Abort(_("unable to read file list (%s)") % pat)
             kindpats += _normalize(files, default, root, cwd, auditor)
             continue
         # else: re or relre - which cannot be normalized
         kindpats.append((kind, pat))
     return kindpats
 
 def _roots(kindpats):
     '''return roots and exact explicitly listed files from patterns
 
     >>> _roots([('glob', 'g/*'), ('glob', 'g'), ('glob', 'g*')])
     ['g', 'g', '.']
     >>> _roots([('relpath', 'r'), ('path', 'p/p'), ('path', '')])
     ['r', 'p/p', '.']
     >>> _roots([('relglob', 'rg*'), ('re', 're/'), ('relre', 'rr')])
     ['.', '.', '.']
     '''
     r = []
     for kind, pat in kindpats:
         if kind == 'glob': # find the non-glob prefix
             root = []
             for p in pat.split('/'):
                 if '[' in p or '{' in p or '*' in p or '?' in p:
                     break
                 root.append(p)
             r.append('/'.join(root) or '.')
         elif kind in ('relpath', 'path'):
             r.append(pat or '.')
         else: # relglob, re, relre
             r.append('.')
     return r
 
 def _anypats(kindpats):
     for kind, pat in kindpats:
         if kind in ('glob', 're', 'relglob', 'relre', 'set'):
             return True