--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mylisp/ag.el	Sat Jan 02 00:33:04 2021 +0200
@@ -0,0 +1,144 @@
+;;; ag.el --- Ag frontend
+
+;;; Commentary:
+;;
+
+(defgroup my-ag nil
+  "My own ag search front-end."
+  :prefix "my-ag"
+  :group 'tools
+  :group 'processes)
+
+(defun my-ag-goto ()
+  (interactive)
+  (save-excursion
+    (let ( lineno end )
+      (forward-line 1)
+      (backward-char 1)
+      (setq end (point))
+      (forward-line 0)
+      (if (not (search-forward-regexp "^\\([1-9][0-9]*\\)[:-]" end t))
+          (message "Not at line number...")
+        (setq lineno (string-to-number (match-string 1)))
+        (if (search-backward-regexp "^$" nil t)
+            (forward-char)
+          (goto-char (point-min)))
+        (search-forward-regexp "^.*")
+        (find-file-other-window (match-string 0))
+        (goto-char (point-min))
+        (forward-line (1- lineno))))))
+
+(defun my-ag-kill-process ()
+  (interactive)
+  (let ( (proc (get-buffer-process (current-buffer))) )
+    (if proc
+	(interrupt-process proc)
+      (error "The %s process is not running" (downcase mode-name)))))
+
+(defvar my-ag-mode-map (make-sparse-keymap))
+
+(define-key my-ag-mode-map (kbd "RET") 'my-ag-goto)
+(define-key my-ag-mode-map (kbd "C-c C-k") 'my-ag-kill-process)
+
+(defface my-ag/lineno-face
+  '((t :inherit warning))
+  "Face for line number."
+  :group 'my-ag)
+(defface my-ag/path-face
+  '((t :inherit success))
+  "Face for line number."
+  :group 'my-ag)
+
+(defvar my-ag/keywords
+  '(("^[1-9][0-9]\\{0,5\\}[-:]" . (0 'my-ag/lineno-face))
+    ("^[^:]\\{6\\}.*" . (0 'my-ag/path-face))))
+
+(define-derived-mode my-ag-mode fundamental-mode "Ag"
+  "Major mode for Ag parsing."
+  (setq font-lock-defaults '(my-ag/keywords t nil nil)) ;  (font-lock-multiline . t)
+  (use-local-map my-ag-mode-map))
+
+(defvar my-ag/buffer-name "*ag*")
+(defvar my-ag/buffer nil)
+
+(defun my-ag/filter (proc str)
+  (when (buffer-live-p (process-buffer proc))
+    (with-current-buffer (process-buffer proc)
+      (save-excursion
+        (goto-char (process-mark proc))
+        (insert str)
+        (set-marker (process-mark proc) (point)))
+      )))
+
+(defvar my-ag/regex-history nil)
+
+(defun my-ag/setup-buffer (dir)
+  (setq my-ag/buffer (get-buffer-create my-ag/buffer-name))
+  (with-current-buffer my-ag/buffer
+    (setq default-directory dir)
+    (erase-buffer)
+    (my-ag-mode))
+  (display-buffer my-ag/buffer))
+
+(defun my-ag/run (regex &optional args)
+  (let ((default-directory (buffer-local-value 'default-directory my-ag/buffer))
+        (cmd (list "ag" "--group" "--nocolor" "--hidden")))
+    (when args
+      (nconc cmd (split-string args)))
+    (nconc cmd (list "--" regex))
+    (make-process
+     :name "ag"
+     :buffer my-ag/buffer
+     :filter 'my-ag/filter
+     :command cmd)))
+
+(defun my-ag/project-root ()
+  (condition-case err
+      (let ( backend )
+        (setq backend (vc-responsible-backend default-directory))
+        (if backend
+            (vc-call-backend backend 'root default-directory)
+          default-directory))
+    (error default-directory)))
+
+(defun my-ag/read-regex ()
+  (let* ( (def (when my-ag/regex-history (car my-ag/regex-history)))
+          (part (when def (if (< (length def) 20)
+                              def
+                            (concat (substring def 0 20) "...")))) )
+    (read-string
+     (if part (format "Regex [%s]: " part) "Regex: ")
+     ""  'my-ag/regex-history  def  t)))
+
+(defvar my-ag/extra-history nil)
+
+(defun my-ag/read-extra ()
+  (let* ( (def (when my-ag/extra-history (car my-ag/extra-history)))
+          (part (when def (if (< (length def) 20)
+                              def
+                            (concat (substring def 0 20) "...")))) )
+    (read-string
+     (if part (format "Extra args [%s]: " part) "Extra args: ")
+     ""  'my-ag/extra-history  def  t)))
+
+;;;###autoload
+(defun my-ag (regex &optional args)
+  "Search in 'ag' recursively from VCS root directory and fall to
+current directory if VCS root is not defined."
+  (interactive (if (equal current-prefix-arg '(16))
+                   (list (my-ag/read-regex) (my-ag/read-extra))
+                 (list (my-ag/read-regex))))
+  (my-ag/setup-buffer (if current-prefix-arg default-directory (my-ag/project-root)))
+  (my-ag/run regex args))
+
+;;;###autoload
+(defun my-ag-default-directory (regex)
+  "Search in 'ag' recursively from current directory."
+  (interactive (list (my-ag/read-regex)))
+  (my-ag/setup-buffer default-directory)
+  (my-ag/run regex))
+
+
+(provide 'ag)
+
+;;; ag.el ends here