Fix #474 by filtering dabbrev completions at the end

It seems impossible to combine supporting company-dabbrev-char-regexp, with
arbitrary values, with using the "word boundary anchor" (or any of the three
relevant anchors). And without anchors, using the regexp engine without
lookaheads or etc, we must filter completions at the end.

Which is okay, because it can allow us to cache the full list globally and
refresh it less often, as well as implement fuzzy filtering more easily (#418).

diff --git a/company-dabbrev.el b/company-dabbrev.el
index 37dceccce374aac6d91a030375c8f12d6a667297..05c982091fa384beae3e2a9b8771b6a5ec063ef6 100644 (file)
--- a/company-dabbrev.el
+++ b/company-dabbrev.el
@@ -1,6 +1,6 @@
 ;;; company-dabbrev.el --- dabbrev-like company-mode completion backend  -*- lexical-binding: t -*-
 
-;; Copyright (C) 2009, 2011, 2014, 2015  Free Software Foundation, Inc.
+;; Copyright (C) 2009, 2011, 2014, 2015, 2016  Free Software Foundation, Inc.
 
 ;; Author: Nikolaj Schumacher
 
@@ -91,11 +91,8 @@ This variable affects both `company-dabbrev' and `company-dabbrev-code'."
               (> (float-time (time-since ,start)) ,limit)
               (throw 'done 'company-time-out))))))
 
-(defun company-dabbrev--make-regexp (prefix)
-  (concat (if (equal prefix "")
-              (concat "\\(?:" company-dabbrev-char-regexp "\\)")
-            (regexp-quote prefix))
-          "\\(?:" company-dabbrev-char-regexp "\\)*"))
+(defun company-dabbrev--make-regexp ()
+  (concat "\\(?:" company-dabbrev-char-regexp "\\)+"))
 
 (defun company-dabbrev--search-buffer (regexp pos symbols start limit
                                        ignore-comments)
@@ -118,7 +115,7 @@ This variable affects both `company-dabbrev' and `company-dabbrev-code'."
           (save-excursion
             ;; Before, we used backward search, but it matches non-greedily, and
             ;; that forced us to use the "beginning/end of word" anchors in
-            ;; `company-dabbrev--make-regexp'.
+            ;; `company-dabbrev--make-regexp'.  It's also about 2x slower.
             (while (re-search-forward regexp tmp-end t)
               (if (and ignore-comments (save-match-data (company-in-string-or-comment)))
                   (re-search-forward "\\s>\\|\\s!\\|\\s\"" tmp-end t)
@@ -161,6 +158,10 @@ This variable affects both `company-dabbrev' and `company-dabbrev-code'."
                                company-dabbrev-char-regexp)
                        1)))
 
+(defun company-dabbrev--filter (prefix candidates)
+  (let ((completion-ignore-case company-dabbrev-ignore-case))
+    (all-completions prefix candidates)))
+
 ;;;###autoload
 (defun company-dabbrev (command &optional arg &rest ignored)
   "dabbrev-like `company-mode' completion backend."
@@ -170,7 +171,7 @@ This variable affects both `company-dabbrev' and `company-dabbrev-code'."
     (prefix (company-dabbrev--prefix))
     (candidates
      (let* ((case-fold-search company-dabbrev-ignore-case)
-            (words (company-dabbrev--search (company-dabbrev--make-regexp arg)
+            (words (company-dabbrev--search (company-dabbrev--make-regexp)
                                             company-dabbrev-time-limit
                                             (pcase company-dabbrev-other-buffers
                                               (`t (list major-mode))
@@ -178,6 +179,7 @@ This variable affects both `company-dabbrev' and `company-dabbrev-code'."
             (downcase-p (if (eq company-dabbrev-downcase 'case-replace)
                             case-replace
                           company-dabbrev-downcase)))
+       (setq words (company-dabbrev--filter arg words))
        (if downcase-p
            (mapcar 'downcase words)
          words)))