fileset: use decorator to mark a predicate as "status caller"

fileset: use decorator to mark a predicate as "status caller"

Before this patch, predicates calling 'matchctx.status()' are listed
up by immediate list value in 'getfileset()'.

This prevents 3rd party extensions from adding specific predicate
calling 'matchctx.status()'.

This uses decorator to mark a predicate as "status caller".

This can also localize changes for adding (or removing) a "status
caller" predicate function in source code.

--- a/mercurial/fileset.py	Mon Dec 21 22:31:16 2015 +0900
+++ b/mercurial/fileset.py	Mon Dec 21 22:31:16 2015 +0900
@@ -137,11 +137,17 @@
 #  x - argument in tree form
 symbols = {}
 
-def predicate(decl):
+# filesets using matchctx.status()
+_statuscallers = []
+
+def predicate(decl, callstatus=False):
     """Return a decorator for fileset predicate function
 
     'decl' argument is the declaration (including argument list like
     'adds(pattern)') or the name (for internal use only) of predicate.
+
+    Optional 'callstatus' argument indicates whether predicate implies
+    'matchctx.status()' at runtime or not (False, by default).
     """
     def decorator(func):
         i = decl.find('(')
@@ -150,12 +156,14 @@
         else:
             name = decl
         symbols[name] = func
+        if callstatus:
+            _statuscallers.append(name)
         if func.__doc__:
             func.__doc__ = "``%s``\n    %s" % (decl, func.__doc__.strip())
         return func
     return decorator
 
-@predicate('modified()')
+@predicate('modified()', callstatus=True)
 def modified(mctx, x):
     """File that is modified according to :hg:`status`.
     """
@@ -164,7 +172,7 @@
     s = mctx.status().modified
     return [f for f in mctx.subset if f in s]
 
-@predicate('added()')
+@predicate('added()', callstatus=True)
 def added(mctx, x):
     """File that is added according to :hg:`status`.
     """
@@ -173,7 +181,7 @@
     s = mctx.status().added
     return [f for f in mctx.subset if f in s]
 
-@predicate('removed()')
+@predicate('removed()', callstatus=True)
 def removed(mctx, x):
     """File that is removed according to :hg:`status`.
     """
@@ -182,7 +190,7 @@
     s = mctx.status().removed
     return [f for f in mctx.subset if f in s]
 
-@predicate('deleted()')
+@predicate('deleted()', callstatus=True)
 def deleted(mctx, x):
     """Alias for ``missing()``.
     """
@@ -191,7 +199,7 @@
     s = mctx.status().deleted
     return [f for f in mctx.subset if f in s]
 
-@predicate('missing()')
+@predicate('missing()', callstatus=True)
 def missing(mctx, x):
     """File that is missing according to :hg:`status`.
     """
@@ -200,7 +208,7 @@
     s = mctx.status().deleted
     return [f for f in mctx.subset if f in s]
 
-@predicate('unknown()')
+@predicate('unknown()', callstatus=True)
 def unknown(mctx, x):
     """File that is unknown according to :hg:`status`. These files will only be
     considered if this predicate is used.
@@ -210,7 +218,7 @@
     s = mctx.status().unknown
     return [f for f in mctx.subset if f in s]
 
-@predicate('ignored()')
+@predicate('ignored()', callstatus=True)
 def ignored(mctx, x):
     """File that is ignored according to :hg:`status`. These files will only be
     considered if this predicate is used.
@@ -220,7 +228,7 @@
     s = mctx.status().ignored
     return [f for f in mctx.subset if f in s]
 
-@predicate('clean()')
+@predicate('clean()', callstatus=True)
 def clean(mctx, x):
     """File that is clean according to :hg:`status`.
     """
@@ -523,8 +531,7 @@
     tree = parse(expr)
 
     # do we need status info?
-    if (_intree(['modified', 'added', 'removed', 'deleted',
-                 'missing', 'unknown', 'ignored', 'clean'], tree) or
+    if (_intree(_statuscallers, tree) or
         # Using matchctx.existing() on a workingctx requires us to check
         # for deleted files.
         (ctx.rev() is None and _intree(_existingcallers, tree))):