New file erlang-edoc.el to support EDoc in erlang-mode

- EDoc markup font-locking and tag completion
- EDoc comment indentation

4 files changed, 179 insertions, 0 deletions

diff --git a/lib/tools/emacs/Makefile b/lib/tools/emacs/Makefile
index 585425e5f1..e1b195ef97 100644
--- a/lib/tools/emacs/Makefile
+++ b/lib/tools/emacs/Makefile
@@ -43,6 +43,7 @@ EMACS_FILES= \
 	erlang_appwiz \
 	erlang-start \
 	erlang-eunit \
+	erlang-edoc \
 	erlang-flymake \
 	erlang
 
diff --git a/lib/tools/emacs/erlang-edoc.el b/lib/tools/emacs/erlang-edoc.el
new file mode 100644
index 0000000000..034036ad04
--- /dev/null
+++ b/lib/tools/emacs/erlang-edoc.el
@@ -0,0 +1,172 @@
+;;; erlang-edoc.el --- EDoc support for Erlang mode  -*- lexical-binding: t; -*-
+
+;; %CopyrightBegin%
+;;
+;; Copyright Ericsson AB 1996-2016. All Rights Reserved.
+;;
+;; Licensed under the Apache License, Version 2.0 (the "License");
+;; you may not use this file except in compliance with the License.
+;; You may obtain a copy of the License at
+;;
+;;     http://www.apache.org/licenses/LICENSE-2.0
+;;
+;; Unless required by applicable law or agreed to in writing, software
+;; distributed under the License is distributed on an "AS IS" BASIS,
+;; WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+;; See the License for the specific language governing permissions and
+;; limitations under the License.
+;;
+;; %CopyrightEnd%
+
+;;; Commentary:
+
+;; Ref: http://www.erlang.org/doc/apps/edoc/users_guide.html
+;;
+;; To use: (add-hook 'erlang-mode-hook 'erlang-edoc-mode)
+
+;;; Code:
+
+(defcustom erlang-edoc-indent-level 2
+  "Indentation level of xhtml in Erlang edoc."
+  :safe 'integerp
+  :group 'erlang)
+
+(defvar erlang-edoc-generic-tags
+  '("clear" "docfile" "end" "headerfile" "todo" "TODO" "type")
+  "Tags that can be used anywhere within a module.")
+
+(defvar erlang-edoc-overview-tags
+  '("author" "copyright" "reference" "see" "since" "title" "version")
+  "Tags that can be used in an overview file.")
+
+(defvar erlang-edoc-module-tags
+  '("author" "copyright" "deprecated" "doc" "hidden" "private" "reference"
+    "see" "since" "version")
+  "Tags that can be used before a module declaration.")
+
+(defvar erlang-edoc-function-tags
+  '("deprecated" "doc" "equiv" "hidden" "private" "see" "since" "spec"
+    "throws" "type")
+  "Tags that can be used before a function definition.")
+
+(defvar erlang-edoc-predefined-macros
+  '("date" "docRoot" "link" "module" "package" "section" "time"
+    "type" "version"))
+
+(defface erlang-edoc-tag '((t (:inherit font-lock-constant-face)))
+  "Face used to highlight edoc tags."
+  :group 'erlang)
+
+(defface erlang-edoc-macro '((t (:inherit font-lock-preprocessor-face)))
+  "Face used to highlight edoc macros."
+  :group 'erlang)
+
+(defface erlang-edoc-verbatim
+  '((t (:family "Monospace" :inherit font-lock-keyword-face)))
+  "Face used to highlight verbatim text."
+  :group 'erlang)
+
+(defface erlang-edoc-todo '((t (:inherit font-lock-warning-face)))
+  "Face used to highlight edoc macros."
+  :group 'erlang)
+
+(defface erlang-edoc-heading '((t (:inherit bold)))
+  "Face used to highlight edoc headings."
+  :group 'erlang)
+
+(defvar erlang-edoc-font-lock-keywords
+  '(("^%+\\s-*\\(@\\w+\\)\\_>" 1 'erlang-edoc-tag prepend)
+    ("^%+\\s-*" ("{\\(@\\w+\\)\\_>" nil nil (1 'erlang-edoc-macro prepend)))
+    ("^%+\\s-*" ("\\(?:@@\\)*\\(@[@{}]\\)" nil nil (1 'escape-glyph prepend)))
+    ("^%+\\s-*@\\(deprecated\\)\\_>" 1 font-lock-warning-face prepend)
+    ;; http://www.erlang.org/doc/apps/edoc/chapter.html#Wiki_notation
+    ("^%+\\s-*" ("[^`]`\\([^`]?\\|[^`].*?[^']\\)'"
+                 (forward-char -1) nil (1 'erlang-edoc-verbatim prepend)))
+    ("^%+\\s-*" ("\\[\\(\\(?:https?\\|file\\|ftp\\)://[^][]+\\)\\]"
+                 nil nil (1 'link prepend)))
+    ("^%+\\s-*\\(?:\\(?1:@todo\\|@TODO\\)\\_>\\|\\(?1:TODO\\):\\)"
+     1 'erlang-edoc-todo prepend)
+    ("^%+\\s-*\\(\\(=\\{2,4\\}\\)[^=\n].*[^=\n]\\2\\)\\s-*$"
+     1 'erlang-edoc-heading prepend)))
+
+(defun erlang-edoc-xml-context ()
+  "Parse edoc x(ht)ml context at comment start of current line."
+  (eval-and-compile (require 'xmltok))
+  (save-excursion
+    (beginning-of-line)
+    (when (looking-at "^%+\\s-*")
+      (let ((pt (match-end 0)) context)
+        (forward-comment (- (point)))
+        (while (< (point) pt)
+          (xmltok-forward)
+          (cond ((eq xmltok-type 'start-tag)
+                 (push (cons xmltok-type xmltok-start) context))
+                ((eq xmltok-type 'end-tag)
+                 (pop context))))
+        (goto-char pt)
+        (xmltok-forward)
+        (push (car (memq xmltok-type '(start-tag end-tag))) context)
+        context))))
+
+(defun erlang-edoc-indent-line ()
+  (let ((context (erlang-edoc-xml-context)))
+    (when context
+      (save-excursion
+        (beginning-of-line)
+        (re-search-forward "^%+\\s-*" (line-end-position))
+        (when (or (car context) (cadr context))
+          (let ((pad (when (cadr context)
+                       (save-excursion
+                         (goto-char (cdr (cadr context)))
+                         (- (current-column)
+                            (progn
+                              (beginning-of-line)
+                              (skip-chars-forward "%")
+                              (current-column)))))))
+            (just-one-space (cond ((not pad) 1)
+                                  ((eq (car context) 'end-tag) pad)
+                                  (t (+ erlang-edoc-indent-level pad)))))))
+      (when (looking-back "^%*\\s-*" (line-beginning-position))
+        (re-search-forward "\\=%*\\s-*")))))
+
+(defun erlang-edoc-before-module-declaration-p ()
+  (save-excursion
+    (beginning-of-line)
+    (forward-comment (point-max))
+    (or (eobp) (re-search-forward "^-module\\s-*(" nil t))))
+
+(defun erlang-edoc-completion-at-point ()
+  (when (eq (syntax-ppss-context (syntax-ppss)) 'comment)
+    (save-excursion
+      (skip-syntax-backward "w_")
+      (when (= (preceding-char) ?@)
+        (let* ((is-tag (looking-back "^%+\\s-*@" (line-beginning-position)))
+               (beg (point))
+               (end (progn (skip-syntax-forward "w_") (point)))
+               (table (cond
+                       ((not is-tag)
+                        erlang-edoc-predefined-macros)
+                       ((erlang-edoc-before-module-declaration-p)
+                        (append erlang-edoc-module-tags
+                                erlang-edoc-generic-tags))
+                       (t (append erlang-edoc-function-tags
+                                  erlang-edoc-generic-tags)))))
+          (list beg end table))))))
+
+;;;###autoload
+(define-minor-mode erlang-edoc-mode nil
+  :lighter " EDoc"
+  (cond (erlang-edoc-mode
+         (add-hook 'erlang-indent-line-hook #'erlang-edoc-indent-line nil t)
+         (font-lock-add-keywords nil erlang-edoc-font-lock-keywords t)
+         (add-hook 'completion-at-point-functions
+                   #'erlang-edoc-completion-at-point nil t))
+        (t
+         (remove-hook 'erlang-indent-line-hook #'erlang-edoc-indent-line t)
+         (font-lock-remove-keywords nil erlang-edoc-font-lock-keywords)
+         (remove-hook 'completion-at-point-functions
+                      #'erlang-edoc-completion-at-point t)))
+  (jit-lock-refontify))
+
+(provide 'erlang-edoc)
+;;; erlang-edoc.el ends here
diff --git a/lib/tools/emacs/erlang-start.el b/lib/tools/emacs/erlang-start.el
index 76e0575e68..f9a6d24b2c 100644
--- a/lib/tools/emacs/erlang-start.el
+++ b/lib/tools/emacs/erlang-start.el
@@ -78,6 +78,7 @@
 (autoload 'erlang-find-tag-other-window "erlang"
   "Like `find-tag-other-window'.  Capable of retreiving Erlang modules.")
 
+(autoload 'erlang-edoc-mode "erlang-edoc" "Toggle Erlang-Edoc mode on or off." t)
 
 ;;
 ;; Associate files extensions ".erl" and ".hrl" with Erlang mode.
diff --git a/lib/tools/emacs/erlang.el b/lib/tools/emacs/erlang.el
index 73c6b8d768..202b3576ab 100644
--- a/lib/tools/emacs/erlang.el
+++ b/lib/tools/emacs/erlang.el
@@ -78,6 +78,10 @@
 
 ;; Variables:
 
+(defgroup erlang nil
+  "The Erlang programming language."
+  :group 'languages)
+
 (defconst erlang-version "2.7"
   "The version number of Erlang mode.")
 
@@ -2446,6 +2450,7 @@ Return the amount the indentation changed by."
     ;; after the indentation. Else stay at same point in text.
     (if (> (- (point-max) pos) (point))
 	(goto-char (- (point-max) pos)))
+    (run-hooks 'erlang-indent-line-hook)
     shift-amt))