fileset: add a 'status(...)' predicate to control evaluation context

Same as 'revs', this predicate does not select files but switches the evaluation
context. This allow to match file according arbitrary status call. We can now
express the same query as 'hg status'.

The API (two 'revsingle' class) have been picked instead of a single 'revs'
revset for multiple reasons:

 * it is less confusing to express
 * it allow to express more query (eg: backward status, cross branch status)

mercurial/fileset.py

@@ -463,6 +463,32 b' def revs(mctx, x):'
                 result.append(f)
     return result
 
+@predicate('status(base, rev, pattern)')
+def status(mctx, x):
+    """``status(base, rev, revspec)``
+
+    Evaluate predicate using status change between ``base`` and
+    ``rev``. Examples:
+
+    - ``status(3, 7, added())`` - matches files added from "3" to "7"
+    """
+    repo = mctx.ctx.repo()
+    # i18n: "status" is a keyword
+    b, r, x = getargs(x, 3, 3, _("status takes three arguments"))
+    # i18n: "status" is a keyword
+    baseerr = _("first argument to status must be a revision")
+    baserevspec = getstring(b, baseerr)
+    if not baserevspec:
+        raise error.ParseError(baseerr)
+    reverr = _("second argument to status must be a revision")
+    revspec = getstring(r, reverr)
+    if not revspec:
+        raise error.ParseError(reverr)
+    basenode, node = scmutil.revpair(repo, [baserevspec, revspec])
+    basectx = repo[basenode]
+    ctx = repo[node]
+    return getset(mctx.switch(ctx, _buildstatus(ctx, x, basectx=basectx)), x)
+
 @predicate('subrepo([pattern])')
 def subrepo(mctx, x):
     """Subrepositories whose paths match the given pattern.
@@ -538,6 +564,7 b' class fullmatchctx(matchctx):'
 # filesets using matchctx.switch()
 _switchcallers = [
     'revs',
+    'status',
 ]
 
 def _intree(funcs, tree):

tests/test-fileset.t

@@ -521,3 +521,101 b' overlapping set'
 
   $ fileset "revs('1+2', modified())"
   b2
+
+test 'status(...)'
+=================
+
+Simple case
+-----------
+
+  $ fileset "status(3, 4, added())"
+  .hgsub
+  .hgsubstate
+
+use rev to restrict matched file
+-----------------------------------------
+
+  $ hg status --removed --rev 0 --rev 1
+  R a2
+  $ fileset "status(0, 1, removed())"
+  a2
+  $ fileset "* and status(0, 1, removed())"
+  $ fileset -r 4 "status(0, 1, removed())"
+  a2
+  $ fileset -r 4 "* and status(0, 1, removed())"
+  $ fileset "revs('4', * and status(0, 1, removed()))"
+  $ fileset "revs('0', * and status(0, 1, removed()))"
+  a2
+
+check wdir()
+------------
+
+  $ hg status --removed  --rev 4
+  R con.xml
+  $ fileset "status(4, 'wdir()', removed())"
+  con.xml
+
+  $ hg status --removed --rev 2
+  R a2
+  $ fileset "status('2', 'wdir()', removed())"
+  a2
+
+test backward status
+--------------------
+
+  $ hg status --removed --rev 0 --rev 4
+  R a2
+  $ hg status --added --rev 4 --rev 0
+  A a2
+  $ fileset "status(4, 0, added())"
+  a2
+
+test cross branch status
+------------------------
+
+  $ hg status --added --rev 1 --rev 2
+  A a2
+  $ fileset "status(1, 2, added())"
+  a2
+
+test with multi revs revset
+---------------------------
+  $ hg status --added --rev 0:1 --rev 3:4
+  A .hgsub
+  A .hgsubstate
+  A 1k
+  A 2k
+  A b2link
+  A bin
+  A c1
+  A con.xml
+  $ fileset "status('0:1', '3:4', added())"
+  .hgsub
+  .hgsubstate
+  1k
+  2k
+  b2link
+  bin
+  c1
+  con.xml
+
+tests with empty value
+----------------------
+
+Fully empty revset
+
+  $ fileset "status('', '4', added())"
+  hg: parse error: first argument to status must be a revision
+  [255]
+  $ fileset "status('2', '', added())"
+  hg: parse error: second argument to status must be a revision
+  [255]
+
+Empty revset will error at the revset layer
+
+  $ fileset "status(' ', '4', added())"
+  hg: parse error at 1: not a prefix: end
+  [255]
+  $ fileset "status('2', ' ', added())"
+  hg: parse error at 1: not a prefix: end
+  [255]