New option company-abort-manual-when-too-short

For manually started completions, backspacing to a prefix shorter
than company-minimum-prefix-length still shows completions.

Setting the new option to t turns that off, so that completions
disappear whenever your prefix gets too short.

With either value of the new option, even if the user changes the
selection, that no longer suffices to make any prefix valid in this
completion invocation.

diff --git a/company.el b/company.el
index a633af3aee97cc0d6b24b394f6892b9786c5ed04..704b83bf0f67b9f953c754d64c230a314c4dda1b 100644 (file)
--- a/company.el
+++ b/company.el
@@ -445,6 +445,14 @@ back-end, consider using the `post-completion' command instead."
   "The minimum prefix length for idle completion."
   :type '(integer :tag "prefix length"))
 
+(defcustom company-abort-manual-when-too-short nil
+  "If enabled, cancel a manually started completion when the prefix gets
+shorter than both `company-minimum-prefix-length' and the length of the
+prefix it was started from."
+  :group 'company
+  :type '(choice (const :tag "Off" nil)
+                 (const :tag "On" t)))
+
 (defcustom company-require-match 'company-explicit-action-p
   "If enabled, disallow non-matching input.
 This can be a function do determine if a match is required.
@@ -851,6 +859,9 @@ means that `company-mode' is always turned on except in `message-mode' buffers."
   "Non-nil, if explicit completion took place.")
 (make-variable-buffer-local 'company--explicit-action)
 
+(defvar company--manual-prefix nil)
+(make-variable-buffer-local 'company--manual-prefix)
+
 (defvar company--auto-completion nil
   "Non-nil when current candidate is being inserted automatically.
 Controlled by `company-auto-complete'.")
@@ -1187,7 +1198,13 @@ Keywords and function definition names are ignored."
      (t (company-cancel)))))
 
 (defun company--good-prefix-p (prefix)
-  (and (or (company-explicit-action-p)
+  (and (or (and company--manual-prefix
+                ;; changed selection not enough for valid prefix
+                (not (and company-abort-manual-when-too-short
+                          ;; must not be less than minimum or initial length
+                          (< (or (cdr-safe prefix) (length prefix))
+                             (min company-minimum-prefix-length
+                                  (length company--manual-prefix))))))
            (unless (eq prefix 'stop)
              (or (eq (cdr-safe prefix) t)
                  (>= (or (cdr-safe prefix) (length prefix))
@@ -1242,6 +1259,8 @@ Keywords and function definition names are ignored."
               (when company--explicit-action
                 (message "No completion found"))
             (setq company-prefix prefix)
+            (when company--explicit-action
+              (setq company--manual-prefix prefix))
             (when (symbolp backend)
               (setq company-lighter (concat " " (symbol-name backend))))
             (company-update-candidates c)
@@ -1292,6 +1311,7 @@ Keywords and function definition names are ignored."
         company-selection 0
         company-selection-changed nil
         company--explicit-action nil
+        company--manual-prefix nil
         company-lighter company-default-lighter
         company--point-max nil
         company-point nil)