ffap-string-at-point: Limit max length of active region

Prevents that 'ffap-guesser' waste time checking large strings
which are likely not valid candidates (Bug#25243).
* lisp/ffap.el (ffap-max-region-length): New variable.
(ffap-string-at-point): Use it.
* test/lisp/ffap-tests.el: New test suite.
(ffap-tests-25243): Add test for this bug.

1 files changed, 54 insertions, 0 deletions

diff --git a/test/lisp/ffap-tests.el b/test/lisp/ffap-tests.el
new file mode 100644
index 00000000000..61fa891fe72
--- /dev/null
+++ b/test/lisp/ffap-tests.el
@@ -0,0 +1,54 @@
+;;; ffap-tests.el --- Test suite for ffap.el -*- lexical-binding: t -*-
+
+;; Copyright (C) 2016 Free Software Foundation, Inc.
+
+;; Author: Tino Calancha <tino.calancha@gmail.com>
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs is free software: you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; GNU Emacs is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;;; Code:
+
+(require 'ert)
+(require 'ffap)
+
+(ert-deftest ffap-tests-25243 ()
+  "Test for http://debbugs.gnu.org/25243 ."
+  (let ((file (make-temp-file "test-Bug#25243")))
+    (unwind-protect
+        (with-temp-file file
+          (let ((str "diff --git b/lisp/ffap.el a/lisp/ffap.el
+index 3d7cebadcf..ad4b70d737 100644
+--- b/lisp/ffap.el
++++ a/lisp/ffap.el
+@@ -203,6 +203,9 @@ ffap-foo-at-bar-prefix
+"))
+            (transient-mark-mode 1)
+            (when (natnump ffap-max-region-length)
+              (insert
+               (concat
+                str
+                (make-string ffap-max-region-length #xa)
+                (format "%s ENDS HERE" file)))
+              (mark-whole-buffer)
+              (should (equal "" (ffap-string-at-point)))
+              (should (equal '(1 1) ffap-string-at-point-region)))))
+      (and (file-exists-p file) (delete-file file)))))
+
+(provide 'ffap-tests)
+
+;;; ffap-tests.el ends here