match: make _fileroots a @propertycache and rename it to _fileset

match: make _fileroots a @propertycache and rename it to _fileset

The files in the set are not necesserily roots of anything. Making it
a @propertycache will help towards extracting a base class for
matchers.

--- a/hgext/largefiles/overrides.py	Wed May 17 23:54:43 2017 -0700
+++ b/hgext/largefiles/overrides.py	Thu May 18 09:04:37 2017 -0700
@@ -41,7 +41,7 @@
     m = copy.copy(match)
     lfile = lambda f: lfutil.standin(f) in manifest
     m._files = filter(lfile, m._files)
-    m._fileroots = set(m._files)
+    m._fileset = set(m._files)
     m._always = False
     origmatchfn = m.matchfn
     m.matchfn = lambda f: lfile(f) and origmatchfn(f)
@@ -56,7 +56,7 @@
     notlfile = lambda f: not (lfutil.isstandin(f) or lfutil.standin(f) in
             manifest or f in excluded)
     m._files = filter(notlfile, m._files)
-    m._fileroots = set(m._files)
+    m._fileset = set(m._files)
     m._always = False
     origmatchfn = m.matchfn
     m.matchfn = lambda f: notlfile(f) and origmatchfn(f)
@@ -368,7 +368,7 @@
             elif m._files[i] not in ctx and repo.wvfs.isdir(standin):
                 m._files.append(standin)
 
-        m._fileroots = set(m._files)
+        m._fileset = set(m._files)
         m._always = False
         origmatchfn = m.matchfn
         def lfmatchfn(f):
@@ -644,7 +644,7 @@
             m = copy.copy(match)
             lfile = lambda f: lfutil.standin(f) in manifest
             m._files = [lfutil.standin(f) for f in m._files if lfile(f)]
-            m._fileroots = set(m._files)
+            m._fileset = set(m._files)
             origmatchfn = m.matchfn
             def matchfn(f):
                 lfile = lfutil.splitstandin(f)
@@ -767,7 +767,7 @@
                 else:
                     matchfiles.append(f)
             m._files = matchfiles
-            m._fileroots = set(m._files)
+            m._fileset = set(m._files)
             origmatchfn = m.matchfn
             def matchfn(f):
                 lfile = lfutil.splitstandin(f)

--- a/mercurial/match.py	Wed May 17 23:54:43 2017 -0700
+++ b/mercurial/match.py	Thu May 18 09:04:37 2017 -0700
@@ -188,7 +188,6 @@
                 return True
 
         self.matchfn = m
-        self._fileroots = set(self._files)
 
     def __call__(self, fn):
         return self.matchfn(fn)
@@ -235,8 +234,12 @@
         return self._files
 
     @propertycache
+    def _fileset(self):
+        return set(self._files)
+
+    @propertycache
     def _dirs(self):
-        return set(util.dirs(self._fileroots)) | {'.'}
+        return set(util.dirs(self._fileset)) | {'.'}
 
     def visitdir(self, dir):
         '''Decides whether a directory should be visited based on whether it
@@ -250,7 +253,7 @@
         This function's behavior is undefined if it has returned False for
         one of the dir's parent directories.
         '''
-        if self.prefix() and dir in self._fileroots:
+        if self.prefix() and dir in self._fileset:
             return 'all'
         if dir in self._excluderoots:
             return False
@@ -261,16 +264,16 @@
             not any(parent in self._includeroots
                     for parent in util.finddirs(dir))):
             return False
-        return (not self._fileroots or
-                '.' in self._fileroots or
-                dir in self._fileroots or
+        return (not self._fileset or
+                '.' in self._fileset or
+                dir in self._fileset or
                 dir in self._dirs or
-                any(parentdir in self._fileroots
+                any(parentdir in self._fileset
                     for parentdir in util.finddirs(dir)))
 
     def exact(self, f):
         '''Returns True if f is in .files().'''
-        return f in self._fileroots
+        return f in self._fileset
 
     def anypats(self):
         '''Matcher uses patterns or include/exclude.'''
@@ -399,7 +402,6 @@
                 return matcher.visitdir(self._path)
             return matcher.visitdir(self._path + "/" + dir)
         self.visitdir = visitdir
-        self._fileroots = set(self._files)
 
     def abs(self, f):
         return self._matcher.abs(self._path + "/" + f)
@@ -428,8 +430,8 @@
         # inexact case matches are treated as exact, and not noted without -v.
         if self._files:
             roots, dirs = _rootsanddirs(self._kp)
-            self._fileroots = set(roots)
-            self._fileroots.update(dirs)
+            self._fileset = set(roots)
+            self._fileset.update(dirs)
 
     def _normalize(self, patterns, default, root, cwd, auditor):
         self._kp = super(icasefsmatcher, self)._normalize(patterns, default,