[PATCH 3 of 3] revset: add a changes(file, fromline, toline[, rev]) revset

[Denis Laxalde]

# HG changeset patch
# User Denis Laxalde <denis.laxalde at logilab.fr>
# Date 1480086890 -3600
#      Fri Nov 25 16:14:50 2016 +0100
# Node ID e88a112076294d9b1639a486e7ef0ec9c1ffa660
# Parent  6dd93ae7b35002531308444c87dcf47beb773648
# EXP-Topic linerange-log/revset
revset: add a changes(file, fromline, toline[, rev]) revset

This relies on `filectx.blocksancetors(fromline, toline)`.

diff --git a/mercurial/revset.py b/mercurial/revset.py
--- a/mercurial/revset.py
+++ b/mercurial/revset.py
@@ -18,6 +18,7 @@ from . import (
     error,
     hbisect,
     match as matchmod,
+    mdiff,
     node,
     obsolete as obsmod,
     parser,
@@ -1350,6 +1351,34 @@ def modifies(repo, subset, x):
     pat = getstring(x, _("modifies requires a pattern"))
     return checkstatus(repo, subset, pat, 0)
 
+ at predicate('changes(file, fromline, toline, rev)', safe=True)
+def changes(repo, subset, x):
+    """Changesets modifying 'file' in line range ('fromline', 'toline').
+
+    Line range corresponds to 'file' content at 'rev'. If rev is not
+    specified, working directory's parent is used.
+    """
+    args = map(getsymbol,
+               getargs(x, 3, 4, _('changes takes at least three arguments')))
+    fname = args[0]
+
+    try:
+        fromline, toline = map(int, args[1:3])
+    except ValueError:
+        raise error.ParseError(_('line range bounds must be integers'))
+    if toline - fromline < 0:
+        raise error.Abort("line range must be positive")
+    if fromline < 1:
+        raise error.Abort("fromline must be > 0")
+    fromline -= 1
+
+    rev = '.'
+    if len(args) == 4:
+        rev = args[3]
+    fctx = repo[rev].filectx(fname)
+    revs = (c.rev() for c in fctx.blockancestors(fromline, toline))
+    return subset & generatorset(revs, iterasc=False)
+
 @predicate('named(namespace)')
 def named(repo, subset, x):
     """The changesets in a given namespace.