Hide most of command line by default

This solution is essentially copied from emacs grep.el
The possibility to hide command line is always on but the default
behavior is controlled by rg-hide-command defcustom.

Related to #25

README.md

@@ -161,6 +161,10 @@ Default value is `nil` (off).
 Variable that controls when case sensitive search is made or not.
 The following values can be set:
 
+### `rg-hide-command`
+Hide most of command line by default. This is enabled by default and
+can be set to `nil` to show full command line by default.
+
 | Symbol | Description |
 |-----|--------|
 | `'case-fold-search` | Smart search based on `case-fold-search` setting. |

rg-result.el

@@ -48,6 +48,11 @@ If nil, the file name is repeated at the beginning of every match line."
   :type 'boolean
   :group 'rg)
 
+(defcustom rg-hide-command t
+  "Hide most of rg command line when non nil."
+  :type 'boolean
+  :group 'rg)
+
 (defvar rg-filter-hook nil
   "Hook for new content in the rg buffer.
 This hook is called every time the rg buffer has been updated with
@@ -132,7 +137,10 @@ Becomes buffer local in `rg-mode' buffers.")
      (2 'rg-error-face nil t))
     ;; "filename-linenumber-" or "linenumber-" format is used for
     ;; context lines in rg
-    ("^\\(?:.+?-\\)?[0-9]+-.*\n" (0 'rg-context-face))))
+    ("^\\(?:.+?-\\)?[0-9]+-.*\n" (0 'rg-context-face))
+    ("^.*rg \\(--color always .*$\\)"
+     (0 '(face rg-context-face))
+     (1 (rg-hide-command-properties)))))
 
 (defvar rg-mode-map
   (let ((map (copy-keymap grep-mode-map)))
@@ -151,8 +159,41 @@ Becomes buffer local in `rg-mode' buffers.")
     map)
   "The keymap for `rg-mode'.")
 
+(defvar rg-ellipsis (if (char-displayable-p ?…) "[…]" "[...]")
+  "Used when hiding command line.")
+
 
 ;; Defuns
+
+;; This solution was mostly copied from emacs grep.el and adjusted to
+;; be more usable.
+(defun rg-hide-command-properties ()
+    "Return properties of button-like ellipsis on part of rg command line."
+  (let ((map (make-sparse-keymap))
+        properties)
+    (define-key map [down-mouse-2] 'mouse-set-point)
+    (define-key map [mouse-2] 'rg-toggle-command-hinding)
+    (define-key map "\C-m" 'rg-toggle-command-hinding)
+    (append
+     `(face nil mouse-face highlight
+            help-echo "RET, mouse-2: show unabbreviated command"
+            keymap ,map rg-command t)
+     (when rg-hide-command
+         `(display ,rg-ellipsis)))))
+
+(defun rg-toggle-command-hinding ()
+  "Toggle showing the hidden part of rg command line."
+  (interactive)
+  (with-silent-modifications
+    (let* ((beg (next-single-property-change (point-min) 'rg-command))
+           (end (when beg
+                  (next-single-property-change beg 'rg-command))))
+      (if end
+          (if (get-text-property beg 'display)
+              (remove-list-of-text-properties beg end '(display))
+            (add-text-properties beg end `(display ,rg-ellipsis)))
+        (user-error "No abbreviated part to hide/show")))))
+
 (defun rg-list-toggle (elem list)
   "Remove ELEM from LIST if present or add it if not present.
 Returns the new list."
@@ -357,7 +398,8 @@ backwards and positive means forwards."
   (rg-rerun))
 
 (defun rg-rerun-change-search-string (literal)
-  "Rerun last search but prompt for new search pattern."
+  "Rerun last search but prompt for new search pattern.
+IF LITERAL is non nil this will trigger a literal search, otherwise a regexp search."
   (let ((pattern (rg-search-pattern rg-cur-search))
         (read-from-minibuffer-orig (symbol-function 'read-from-minibuffer)))
     ;; Override read-from-minibuffer in order to insert the original