Add cape-dict-grep customization option (Fix #147)

2 files changed, 42 insertions, 13 deletions

diff --git a/CHANGELOG.org b/CHANGELOG.org
index 79a0cbd..38700e3 100644
--- a/CHANGELOG.org
+++ b/CHANGELOG.org
@@ -4,8 +4,10 @@
 
 * Development
 
+- ~cape-dict~: Add new customization variable ~cape-dict-grep~. Set to ~nil~ to filter
+  the dictionary in Lisp.
 - ~cape-file~: Improve handling of environment variables as part of the path,
-  e.g., $HOME.
+  e.g., ~$HOME~.
 - ~cape-company-to-capf~: Handle updated return value convention of the ~prefix~
   action of Company backends.
 
diff --git a/cape.el b/cape.el
index 1142e72..38de07a 100644
--- a/cape.el
+++ b/cape.el
@@ -67,6 +67,11 @@
   "Maximal number of completion candidates returned by `cape-dict'."
   :type '(choice (const nil) natnum))
 
+(defcustom cape-dict-grep t
+  "Filter the dictionary via grep instead of in Lisp.
+It may be beneficial to disable this setting depending on your system."
+  :type 'boolean)
+
 (defcustom cape-dict-file "/usr/share/dict/words"
   "Path to dictionary word list file.
 This variable can also be a list of paths or
@@ -617,6 +622,8 @@ See the user options `cape-dabbrev-min-length' and
         :category 'cape-dict)
   "Completion extra properties for `cape-dict'.")
 
+(defvar cape--dict-cache nil)
+
 (defun cape--dict-list (input)
   "Return all words from `cape-dict-file' matching INPUT."
   (let* ((inhibit-message t)
@@ -626,18 +633,38 @@ See the user options `cape-dabbrev-min-length' and
                    (file-directory-p default-directory))
               default-directory
             user-emacs-directory))
-         (files (mapcar #'expand-file-name
-                        (ensure-list
-                         (if (functionp cape-dict-file)
-                             (funcall cape-dict-file)
-                           cape-dict-file))))
-         (words
-          (apply #'process-lines-ignore-status
-                 "grep"
-                 (concat "-Fh"
-                         (and (cape--case-fold-p cape-dict-case-fold) "i")
-                         (and cape-dict-limit (format "m%d" cape-dict-limit)))
-                 input files)))
+         (files (sort (mapcar #'expand-file-name
+                              (ensure-list
+                               (if (functionp cape-dict-file)
+                                   (funcall cape-dict-file)
+                                 cape-dict-file)))
+                      #'string<))
+         (words nil))
+    (if cape-dict-grep
+        (setq words (apply #'process-lines-ignore-status
+                           "grep"
+                           (concat "-Fh"
+                                   (and (cape--case-fold-p cape-dict-case-fold) "i")
+                                   (and cape-dict-limit (format "m%d" cape-dict-limit)))
+                           input files))
+      (let ((completion-ignore-case (cape--case-fold-p cape-dict-case-fold))
+            (completion-regexp-list (list (regexp-quote input)))
+            (count 0))
+        (catch 'limit
+          (all-completions
+           ""
+           (with-memoization (alist-get files cape--dict-cache nil nil #'equal)
+             (with-temp-buffer
+               (dolist (file files)
+                 (insert-file-contents file)
+                 (insert "\n"))
+               (split-string (buffer-string) "[\r\n]+" t)))
+           (lambda (word)
+             (when cape-dict-limit
+               (when (>= count cape-dict-limit) (throw 'limit nil))
+               (cl-incf count))
+             (push word words)
+             nil)))))
     (cons
      (apply-partially
       (if (and cape-dict-limit (length= words cape-dict-limit))