[PATCH 1 of 3] revset: extract a helper to parse integer range

[Yuya Nishihara]

# HG changeset patch
# User Yuya Nishihara <yuya at tcha.org>
# Date 1548562733 -32400
#      Sun Jan 27 13:18:53 2019 +0900
# Node ID 5e5dda247ee2ba8407bc4932118a944c1959b1f9
# Parent  1aa52287973e180eaf23c32dd454d38537facb8e
revset: extract a helper to parse integer range

It's getting common. As a first step, this patch adds getintrange() and
makes followlines() use it.

diff --git a/mercurial/revset.py b/mercurial/revset.py
--- a/mercurial/revset.py
+++ b/mercurial/revset.py
@@ -44,6 +44,7 @@ getinteger = revsetlang.getinteger
 getboolean = revsetlang.getboolean
 getlist = revsetlang.getlist
 getrange = revsetlang.getrange
+getintrange = revsetlang.getintrange
 getargs = revsetlang.getargs
 getargsdict = revsetlang.getargsdict
 
@@ -1067,11 +1068,10 @@ def followlines(repo, subset, x):
     # i18n: "followlines" is a keyword
     msg = _("followlines expects exactly one file")
     fname = scmutil.parsefollowlinespattern(repo, rev, pat, msg)
-    # i18n: "followlines" is a keyword
-    lr = getrange(args['lines'][0], _("followlines expects a line range"))
-    fromline, toline = [getinteger(a, _("line range bounds must be integers"))
-                        for a in lr]
-    fromline, toline = util.processlinerange(fromline, toline)
+    fromline, toline = util.processlinerange(
+        *getintrange(args['lines'][0],
+                     # i18n: "followlines" is a keyword
+                     _("followlines expects an integer line range")))
 
     fctx = repo[rev].filectx(fname)
     descend = False
diff --git a/mercurial/revsetlang.py b/mercurial/revsetlang.py
--- a/mercurial/revsetlang.py
+++ b/mercurial/revsetlang.py
@@ -240,6 +240,15 @@ def getrange(x, err):
         return None, None
     raise error.ParseError(err)
 
+def getintrange(x, err, deffirst=_notset, deflast=_notset):
+    """Get [first, last] integer range (both inclusive) from a parsed tree
+
+    If any of the sides omitted, and if no default provided, ParseError will
+    be raised.
+    """
+    a, b = getrange(x, err)
+    return getinteger(a, err, deffirst), getinteger(b, err, deflast)
+
 def getargs(x, min, max, err):
     l = getlist(x)
     if len(l) < min or (max >= 0 and len(l) > max):
diff --git a/tests/test-annotate.t b/tests/test-annotate.t
--- a/tests/test-annotate.t
+++ b/tests/test-annotate.t
@@ -818,7 +818,7 @@ check error cases
   hg: parse error: followlines requires a line range
   [255]
   $ hg log -r 'followlines(baz, 1)'
-  hg: parse error: followlines expects a line range
+  hg: parse error: followlines expects an integer line range
   [255]
   $ hg log -r 'followlines(baz, 1:2, startrev=desc("b"))'
   hg: parse error: followlines expects exactly one revision
@@ -827,13 +827,13 @@ check error cases
   hg: parse error: followlines expects exactly one file
   [255]
   $ hg log -r 'followlines(baz, 1:)'
-  hg: parse error: line range bounds must be integers
+  hg: parse error: followlines expects an integer line range
   [255]
   $ hg log -r 'followlines(baz, :1)'
-  hg: parse error: line range bounds must be integers
+  hg: parse error: followlines expects an integer line range
   [255]
   $ hg log -r 'followlines(baz, x:4)'
-  hg: parse error: line range bounds must be integers
+  hg: parse error: followlines expects an integer line range
   [255]
   $ hg log -r 'followlines(baz, 5:4)'
   hg: parse error: line range must be positive