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go-mode.el
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;;; go-mode.el --- Major mode for the Go programming language
;; Copyright 2013 The go-mode Authors. All rights reserved.
;; Use of this source code is governed by a BSD-style
;; license that can be found in the LICENSE file.
;; Author: The go-mode Authors
;; Version: 1.0.0
;; Keywords: languages go
;; URL: https://github.com/dominikh/go-mode.el
;;
;; This file is not part of GNU Emacs.
;;; Code:
(require 'cl)
(require 'etags)
(require 'ffap)
(require 'find-file)
(require 'ring)
(require 'url)
;; XEmacs compatibility guidelines
;; - Minimum required version of XEmacs: 21.5.32
;; - Feature that cannot be backported: POSIX character classes in
;; regular expressions
;; - Functions that could be backported but won't because 21.5.32
;; covers them: plenty.
;; - Features that are still partly broken:
;; - godef will not work correctly if multibyte characters are
;; being used
;; - Fontification will not handle unicode correctly
;;
;; - Do not use \_< and \_> regexp delimiters directly; use
;; go--regexp-enclose-in-symbol
;;
;; - The character `_` must not be a symbol constituent but a
;; character constituent
;;
;; - Do not use process-lines
;;
;; - Use go--old-completion-list-style when using a plain list as the
;; collection for completing-read
;;
;; - Use go--position-bytes instead of position-bytes
(defmacro go--xemacs-p ()
`(featurep 'xemacs))
;; Delete the current line without putting it in the kill-ring.
(defun go--delete-whole-line (&optional arg)
;; Derived from `kill-whole-line'.
;; ARG is defined as for that function.
(setq arg (or arg 1))
(if (and (> arg 0)
(eobp)
(save-excursion (forward-visible-line 0) (eobp)))
(signal 'end-of-buffer nil))
(if (and (< arg 0)
(bobp)
(save-excursion (end-of-visible-line) (bobp)))
(signal 'beginning-of-buffer nil))
(cond ((zerop arg)
(delete-region (progn (forward-visible-line 0) (point))
(progn (end-of-visible-line) (point))))
((< arg 0)
(delete-region (progn (end-of-visible-line) (point))
(progn (forward-visible-line (1+ arg))
(unless (bobp)
(backward-char))
(point))))
(t
(delete-region (progn (forward-visible-line 0) (point))
(progn (forward-visible-line arg) (point))))))
;; declare-function is an empty macro that only byte-compile cares
;; about. Wrap in always false if to satisfy Emacsen without that
;; macro.
(if nil
(declare-function go--position-bytes "go-mode" (point)))
;; XEmacs unfortunately does not offer position-bytes. We can fall
;; back to just using (point), but it will be incorrect as soon as
;; multibyte characters are being used.
(if (fboundp 'position-bytes)
(defalias 'go--position-bytes #'position-bytes)
(defun go--position-bytes (point) point))
(defun go--old-completion-list-style (list)
(mapcar (lambda (x) (cons x nil)) list))
;; GNU Emacs 24 has prog-mode, older GNU Emacs and XEmacs do not, so
;; copy its definition for those.
(if (not (fboundp 'prog-mode))
(define-derived-mode prog-mode fundamental-mode "Prog"
"Major mode for editing source code."
(set (make-local-variable 'require-final-newline) mode-require-final-newline)
(set (make-local-variable 'parse-sexp-ignore-comments) t)
(setq bidi-paragraph-direction 'left-to-right)))
(defun go--regexp-enclose-in-symbol (s)
;; XEmacs does not support \_<, GNU Emacs does. In GNU Emacs we make
;; extensive use of \_< to support unicode in identifiers. Until we
;; come up with a better solution for XEmacs, this solution will
;; break fontification in XEmacs for identifiers such as "typeµ".
;; XEmacs will consider "type" a keyword, GNU Emacs won't.
(if (go--xemacs-p)
(concat "\\<" s "\\>")
(concat "\\_<" s "\\_>")))
;; Move up one level of parentheses.
(defun go-goto-opening-parenthesis (&optional legacy-unused)
;; The old implementation of go-goto-opening-parenthesis had an
;; optional argument to speed up the function. It didn't change the
;; function's outcome.
;; Silently fail if there's no matching opening parenthesis.
(condition-case nil
(backward-up-list)
(scan-error nil)))
(defconst go-dangling-operators-regexp "[^-]-\\|[^+]\\+\\|[/*&><.=|^]")
(defconst go-identifier-regexp "[[:word:][:multibyte:]]+")
(defconst go-type-name-no-prefix-regexp "\\(?:[[:word:][:multibyte:]]+\\.\\)?[[:word:][:multibyte:]]+")
(defconst go-qualified-identifier-regexp (concat go-identifier-regexp "\\." go-identifier-regexp))
(defconst go-label-regexp go-identifier-regexp)
(defconst go-type-regexp "[[:word:][:multibyte:]*]+")
(defconst go-func-regexp (concat (go--regexp-enclose-in-symbol "func") "\\s *\\(" go-identifier-regexp "\\)"))
(defconst go-func-meth-regexp (concat
(go--regexp-enclose-in-symbol "func") "\\s *\\(?:(\\s *"
"\\(" go-identifier-regexp "\\s +\\)?" go-type-regexp
"\\s *)\\s *\\)?\\("
go-identifier-regexp
"\\)("))
(defconst go-builtins
'("append" "cap" "close" "complex" "copy"
"delete" "imag" "len" "make" "new"
"panic" "print" "println" "real" "recover")
"All built-in functions in the Go language. Used for font locking.")
(defconst go-mode-keywords
'("break" "default" "func" "interface" "select"
"case" "defer" "go" "map" "struct"
"chan" "else" "goto" "package" "switch"
"const" "fallthrough" "if" "range" "type"
"continue" "for" "import" "return" "var")
"All keywords in the Go language. Used for font locking.")
(defconst go-constants '("nil" "true" "false" "iota"))
(defconst go-type-name-regexp (concat "\\(?:[*(]\\)*\\(\\(?:" go-identifier-regexp "\\.\\)?" go-identifier-regexp "\\)"))
;; Maximum number of identifiers that can be highlighted as type names
;; in one function type/declaration.
(defconst go--font-lock-func-param-num-groups 16)
(defvar go-dangling-cache)
(defvar go-godoc-history nil)
(defvar go--coverage-current-file-name)
(defgroup go nil
"Major mode for editing Go code"
:group 'languages)
(defgroup go-cover nil
"Options specific to `cover`"
:group 'go)
(defcustom go-fontify-function-calls t
"Fontify function and method calls if this is non-nil."
:type 'boolean
:group 'go)
(defcustom go-mode-hook nil
"Hook called by `go-mode'."
:type 'hook
:group 'go)
(defcustom go-command "go"
"The 'go' command. Some users have multiple Go development
trees and invoke the 'go' tool via a wrapper that sets GOROOT and
GOPATH based on the current directory. Such users should
customize this variable to point to the wrapper script."
:type 'string
:group 'go)
(defcustom gofmt-command "gofmt"
"The 'gofmt' command. Some users may replace this with 'goimports'
from https://github.com/bradfitz/goimports."
:type 'string
:group 'go)
(defcustom gofmt-show-errors 'buffer
"Where to display gofmt error output. It can either be
displayed in its own buffer, in the echo area, or not at all.
Please note that Emacs outputs to the echo area when writing
files and will overwrite gofmt's echo output if used from inside
a before-save-hook."
:type '(choice
(const :tag "Own buffer" buffer)
(const :tag "Echo area" echo)
(const :tag "None" nil))
:group 'go)
(defcustom godef-command "godef"
"The 'godef' command."
:type 'string
:group 'go)
(defcustom go-other-file-alist
'(("_test\\.go\\'" (".go"))
("\\.go\\'" ("_test.go")))
"See the documentation of `ff-other-file-alist' for details."
:type '(repeat (list regexp (choice (repeat string) function)))
:group 'go)
(defcustom go-coverage-display-buffer-func 'display-buffer-reuse-window
"How go-coverage should display the coverage buffer. See
`display-buffer' for a list of possible functions."
:type 'function
:group 'go-cover)
(defface go-coverage-untracked
'((t (:foreground "#505050")))
"Coverage color of untracked code."
:group 'go-cover)
(defface go-coverage-0
'((t (:foreground "#c00000")))
"Coverage color for uncovered code."
:group 'go-cover)
(defface go-coverage-1
'((t (:foreground "#808080")))
"Coverage color for covered code with weight 1."
:group 'go-cover)
(defface go-coverage-2
'((t (:foreground "#748c83")))
"Coverage color for covered code with weight 2."
:group 'go-cover)
(defface go-coverage-3
'((t (:foreground "#689886")))
"Coverage color for covered code with weight 3."
:group 'go-cover)
(defface go-coverage-4
'((t (:foreground "#5ca489")))
"Coverage color for covered code with weight 4."
:group 'go-cover)
(defface go-coverage-5
'((t (:foreground "#50b08c")))
"Coverage color for covered code with weight 5."
:group 'go-cover)
(defface go-coverage-6
'((t (:foreground "#44bc8f")))
"Coverage color for covered code with weight 6."
:group 'go-cover)
(defface go-coverage-7
'((t (:foreground "#38c892")))
"Coverage color for covered code with weight 7."
:group 'go-cover)
(defface go-coverage-8
'((t (:foreground "#2cd495")))
"Coverage color for covered code with weight 8.
For mode=set, all covered lines will have this weight."
:group 'go-cover)
(defface go-coverage-9
'((t (:foreground "#20e098")))
"Coverage color for covered code with weight 9."
:group 'go-cover)
(defface go-coverage-10
'((t (:foreground "#14ec9b")))
"Coverage color for covered code with weight 10."
:group 'go-cover)
(defface go-coverage-covered
'((t (:foreground "#2cd495")))
"Coverage color of covered code."
:group 'go-cover)
(defvar go-mode-syntax-table
(let ((st (make-syntax-table)))
(modify-syntax-entry ?+ "." st)
(modify-syntax-entry ?- "." st)
(modify-syntax-entry ?% "." st)
(modify-syntax-entry ?& "." st)
(modify-syntax-entry ?| "." st)
(modify-syntax-entry ?^ "." st)
(modify-syntax-entry ?! "." st)
(modify-syntax-entry ?= "." st)
(modify-syntax-entry ?< "." st)
(modify-syntax-entry ?> "." st)
(modify-syntax-entry ?/ (if (go--xemacs-p) ". 1456" ". 124b") st)
(modify-syntax-entry ?* ". 23" st)
(modify-syntax-entry ?\n "> b" st)
(modify-syntax-entry ?\" "\"" st)
(modify-syntax-entry ?\' "\"" st)
(modify-syntax-entry ?` "\"" st)
(modify-syntax-entry ?\\ "\\" st)
;; It would be nicer to have _ as a symbol constituent, but that
;; would trip up XEmacs, which does not support the \_< anchor
(modify-syntax-entry ?_ "w" st)
st)
"Syntax table for Go mode.")
(defun go--build-font-lock-keywords ()
;; we cannot use 'symbols in regexp-opt because GNU Emacs <24
;; doesn't understand that
(append
`((go--match-func
,@(mapcar (lambda (x) `(,x font-lock-type-face))
(number-sequence 1 go--font-lock-func-param-num-groups)))
(,(go--regexp-enclose-in-symbol (regexp-opt go-mode-keywords t)) . font-lock-keyword-face)
(,(concat "\\(" (go--regexp-enclose-in-symbol (regexp-opt go-builtins t)) "\\)[[:space:]]*(") 1 font-lock-builtin-face)
(,(go--regexp-enclose-in-symbol (regexp-opt go-constants t)) . font-lock-constant-face)
(,go-func-regexp 1 font-lock-function-name-face)) ;; function (not method) name
(if go-fontify-function-calls
`((,(concat "\\(" go-identifier-regexp "\\)[[:space:]]*(") 1 font-lock-function-name-face) ;; function call/method name
(,(concat "[^[:word:][:multibyte:]](\\(" go-identifier-regexp "\\))[[:space:]]*(") 1 font-lock-function-name-face)) ;; bracketed function call
`((,go-func-meth-regexp 2 font-lock-function-name-face))) ;; method name
`(
("\\(`[^`]*`\\)" 1 font-lock-multiline) ;; raw string literal, needed for font-lock-syntactic-keywords
(,(concat (go--regexp-enclose-in-symbol "type") "[[:space:]]+\\([^[:space:]]+\\)") 1 font-lock-type-face) ;; types
(,(concat (go--regexp-enclose-in-symbol "type") "[[:space:]]+" go-identifier-regexp "[[:space:]]*" go-type-name-regexp) 1 font-lock-type-face) ;; types
(,(concat "[^[:word:][:multibyte:]]\\[\\([[:digit:]]+\\|\\.\\.\\.\\)?\\]" go-type-name-regexp) 2 font-lock-type-face) ;; Arrays/slices
(,(concat "\\(" go-type-name-regexp "\\)" "{") 1 font-lock-type-face)
(,(concat (go--regexp-enclose-in-symbol "map") "\\[[^]]+\\]" go-type-name-regexp) 1 font-lock-type-face) ;; map value type
(,(concat (go--regexp-enclose-in-symbol "map") "\\[" go-type-name-regexp) 1 font-lock-type-face) ;; map key type
(,(concat (go--regexp-enclose-in-symbol "chan") "[[:space:]]*\\(?:<-[[:space:]]*\\)?" go-type-name-regexp) 1 font-lock-type-face) ;; channel type
(,(concat (go--regexp-enclose-in-symbol "\\(?:new\\|make\\)") "\\(?:[[:space:]]\\|)\\)*(" go-type-name-regexp) 1 font-lock-type-face) ;; new/make type
;; TODO do we actually need this one or isn't it just a function call?
(,(concat "\\.\\s *(" go-type-name-regexp) 1 font-lock-type-face) ;; Type conversion
;; Like the original go-mode this also marks compound literal
;; fields. There, it was marked as to fix, but I grew quite
;; accustomed to it, so it'll stay for now.
(,(concat "^[[:space:]]*\\(" go-label-regexp "\\)[[:space:]]*:\\(\\S.\\|$\\)") 1 font-lock-constant-face) ;; Labels and compound literal fields
(,(concat (go--regexp-enclose-in-symbol "\\(goto\\|break\\|continue\\)") "[[:space:]]*\\(" go-label-regexp "\\)") 2 font-lock-constant-face)))) ;; labels in goto/break/continue
(defconst go--font-lock-syntactic-keywords
;; Override syntax property of raw string literal contents, so that
;; backslashes have no special meaning in ``. Used in Emacs 23 or older.
'((go--match-raw-string-literal
(1 (7 . ?`))
(2 (15 . nil)) ;; 15 = "generic string"
(3 (7 . ?`)))))
(defvar go-mode-map
(let ((m (make-sparse-keymap)))
(define-key m "}" #'go-mode-insert-and-indent)
(define-key m ")" #'go-mode-insert-and-indent)
(define-key m "," #'go-mode-insert-and-indent)
(define-key m ":" #'go-mode-insert-and-indent)
(define-key m "=" #'go-mode-insert-and-indent)
(define-key m (kbd "C-c C-a") #'go-import-add)
(define-key m (kbd "C-c C-j") #'godef-jump)
(define-key m (kbd "C-x 4 C-c C-j") #'godef-jump-other-window)
(define-key m (kbd "C-c C-d") #'godef-describe)
m)
"Keymap used by Go mode to implement electric keys.")
(defun go-mode-insert-and-indent (key)
"Invoke the global binding of KEY, then reindent the line."
(interactive (list (this-command-keys)))
(call-interactively (lookup-key (current-global-map) key))
(indent-according-to-mode))
(defmacro go-paren-level ()
`(car (syntax-ppss)))
(defmacro go-in-string-or-comment-p ()
`(nth 8 (syntax-ppss)))
(defmacro go-in-string-p ()
`(nth 3 (syntax-ppss)))
(defmacro go-in-comment-p ()
`(nth 4 (syntax-ppss)))
(defmacro go-goto-beginning-of-string-or-comment ()
`(goto-char (nth 8 (syntax-ppss))))
(defun go--backward-irrelevant (&optional stop-at-string)
"Skips backwards over any characters that are irrelevant for
indentation and related tasks.
It skips over whitespace, comments, cases and labels and, if
STOP-AT-STRING is not true, over strings."
(let (pos (start-pos (point)))
(skip-chars-backward "\n\s\t")
(if (and (save-excursion (beginning-of-line) (go-in-string-p)) (looking-back "`") (not stop-at-string))
(backward-char))
(if (and (go-in-string-p) (not stop-at-string))
(go-goto-beginning-of-string-or-comment))
(if (looking-back "\\*/")
(backward-char))
(if (go-in-comment-p)
(go-goto-beginning-of-string-or-comment))
(setq pos (point))
(beginning-of-line)
(if (or (looking-at (concat "^" go-label-regexp ":")) (looking-at "^[[:space:]]*\\(case .+\\|default\\):"))
(end-of-line 0)
(goto-char pos))
(if (/= start-pos (point))
(go--backward-irrelevant stop-at-string))
(/= start-pos (point))))
(defun go--buffer-narrowed-p ()
"Return non-nil if the current buffer is narrowed."
(/= (buffer-size)
(- (point-max)
(point-min))))
(defun go--match-raw-string-literal (end)
"Search for a raw string literal. Set point to the end of the
occurence found on success. Returns nil on failure."
(unless (go-in-string-or-comment-p)
(when (search-forward "`" end t)
(goto-char (match-beginning 0))
(if (go-in-string-or-comment-p)
(progn (goto-char (match-end 0))
(go--match-raw-string-literal end))
(when (looking-at "\\(`\\)\\([^`]*\\)\\(`\\)")
(goto-char (match-end 0))
t)))))
(defun go-previous-line-has-dangling-op-p ()
"Returns non-nil if the current line is a continuation line."
(let* ((cur-line (line-number-at-pos))
(val (gethash cur-line go-dangling-cache 'nope)))
(if (or (go--buffer-narrowed-p) (equal val 'nope))
(save-excursion
(beginning-of-line)
(go--backward-irrelevant t)
(setq val (looking-back go-dangling-operators-regexp))
(if (not (go--buffer-narrowed-p))
(puthash cur-line val go-dangling-cache))))
val))
(defun go--at-function-definition ()
"Return non-nil if point is on the opening curly brace of a
function definition.
We do this by first calling (beginning-of-defun), which will take
us to the start of *some* function. We then look for the opening
curly brace of that function and compare its position against the
curly brace we are checking. If they match, we return non-nil."
(if (= (char-after) ?\{)
(save-excursion
(let ((old-point (point))
start-nesting)
(beginning-of-defun)
(when (looking-at "func ")
(setq start-nesting (go-paren-level))
(skip-chars-forward "^{")
(while (> (go-paren-level) start-nesting)
(forward-char)
(skip-chars-forward "^{") 0)
(if (and (= (go-paren-level) start-nesting) (= old-point (point)))
t))))))
(defun go--indentation-for-opening-parenthesis ()
"Return the semantic indentation for the current opening parenthesis.
If point is on an opening curly brace and said curly brace
belongs to a function declaration, the indentation of the func
keyword will be returned. Otherwise the indentation of the
current line will be returned."
(save-excursion
(if (go--at-function-definition)
(progn
(beginning-of-defun)
(current-indentation))
(current-indentation))))
(defun go-indentation-at-point ()
(save-excursion
(let (start-nesting)
(back-to-indentation)
(setq start-nesting (go-paren-level))
(cond
((go-in-string-p)
(current-indentation))
((looking-at "[])}]")
(go-goto-opening-parenthesis)
(if (go-previous-line-has-dangling-op-p)
(- (current-indentation) tab-width)
(go--indentation-for-opening-parenthesis)))
((progn (go--backward-irrelevant t) (looking-back go-dangling-operators-regexp))
;; only one nesting for all dangling operators in one operation
(if (go-previous-line-has-dangling-op-p)
(current-indentation)
(+ (current-indentation) tab-width)))
((zerop (go-paren-level))
0)
((progn (go-goto-opening-parenthesis) (< (go-paren-level) start-nesting))
(if (go-previous-line-has-dangling-op-p)
(current-indentation)
(+ (go--indentation-for-opening-parenthesis) tab-width)))
(t
(current-indentation))))))
(defun go-mode-indent-line ()
(interactive)
(let (indent
shift-amt
(pos (- (point-max) (point)))
(point (point))
(beg (line-beginning-position)))
(back-to-indentation)
(if (go-in-string-or-comment-p)
(goto-char point)
(setq indent (go-indentation-at-point))
(if (looking-at (concat go-label-regexp ":\\([[:space:]]*/.+\\)?$\\|case .+:\\|default:"))
(decf indent tab-width))
(setq shift-amt (- indent (current-column)))
(if (zerop shift-amt)
nil
(delete-region beg (point))
(indent-to indent))
;; If initial point was within line's indentation,
;; position after the indentation. Else stay at same point in text.
(if (> (- (point-max) pos) (point))
(goto-char (- (point-max) pos))))))
(defun go-beginning-of-defun (&optional count)
(unless (bolp)
(end-of-line))
(setq count (or count 1))
(let (first failure)
(dotimes (i (abs count))
(setq first t)
(while (and (not failure)
(or first (go-in-string-or-comment-p)))
(if (>= count 0)
(progn
(go--backward-irrelevant)
(if (not (re-search-backward go-func-meth-regexp nil t))
(setq failure t)))
(if (looking-at go-func-meth-regexp)
(forward-char))
(if (not (re-search-forward go-func-meth-regexp nil t))
(setq failure t)))
(setq first nil)))
(if (< count 0)
(beginning-of-line))
(not failure)))
(defun go-end-of-defun ()
(let (orig-level)
;; It can happen that we're not placed before a function by emacs
(if (not (looking-at "func"))
(go-beginning-of-defun -1))
;; Find the { that starts the function, i.e., the next { that isn't
;; preceded by struct or interface, or a comment or struct tag. BUG:
;; breaks if there's a comment between the struct/interface keyword and
;; bracket, like this:
;;
;; struct /* why? */ {
(while (progn
(skip-chars-forward "^{")
(forward-char)
(or (go-in-string-or-comment-p)
(looking-back "\\(struct\\|interface\\)\\s-*{"))))
(setq orig-level (go-paren-level))
(while (>= (go-paren-level) orig-level)
(skip-chars-forward "^}")
(forward-char))))
(defun go--find-enclosing-parentheses (position)
"Return points of outermost '(' and ')' surrounding POSITION if
such parentheses exist.
If outermost '(' exists but ')' does not, it returns the next blank
line or end-of-buffer position instead of the position of the closing
parenthesis.
If the starting parenthesis is not found, it returns (POSITION
POSITION).
"
(save-excursion
(let (beg end)
(goto-char position)
(while (> (go-paren-level) 0)
(re-search-backward "[(\\[{]" nil t)
(when (looking-at "(")
(setq beg (point))))
(if (null beg)
(list position position)
(goto-char position)
(while (and (> (go-paren-level) 0)
(search-forward ")" nil t)))
(when (> (go-paren-level) 0)
(unless (re-search-forward "^[[:space:]]*$" nil t)
(goto-char (point-max))))
(list beg (point))))))
(defun go--search-next-comma (end)
"Search forward from point for a comma whose nesting level is
the same as point. If it reaches the end of line or a closing
parenthesis before a comma, it stops at it."
(let ((orig-level (go-paren-level)))
(while (and (< (point) end)
(or (looking-at "[^,)\n]")
(> (go-paren-level) orig-level)))
(forward-char))
(when (and (looking-at ",")
(< (point) (1- end)))
(forward-char))))
(defun go--looking-at-keyword ()
(and (looking-at (concat "\\(" go-identifier-regexp "\\)"))
(member (match-string 1) go-mode-keywords)))
(defun go--match-func (end)
"Search for identifiers used as type names from a function
parameter list, and set the identifier positions as the results
of last search. Return t if search succeeded."
(when (re-search-forward (go--regexp-enclose-in-symbol "func") end t)
(let ((regions (go--match-func-type-names end)))
(if (null regions)
;; Nothing to highlight. This can happen if the current func
;; is "func()". Try next one.
(go--match-func end)
;; There are something to highlight. Set those positions as
;; last search results.
(setq regions (go--filter-match-data regions end))
(when regions
(set-match-data (go--make-match-data regions))
t)))))
(defun go--match-func-type-names (end)
(cond
;; Function declaration (e.g. "func foo(")
((looking-at (concat "[[:space:]\n]*" go-identifier-regexp "[[:space:]\n]*("))
(goto-char (match-end 0))
(nconc (go--match-parameter-list end)
(go--match-function-result end)))
;; Method declaration, function literal, or function type
((looking-at "[[:space:]]*(")
(goto-char (match-end 0))
(let ((regions (go--match-parameter-list end)))
;; Method declaration (e.g. "func (x y) foo(")
(when (looking-at (concat "[[:space:]]*" go-identifier-regexp "[[:space:]\n]*("))
(goto-char (match-end 0))
(setq regions (nconc regions (go--match-parameter-list end))))
(nconc regions (go--match-function-result end))))))
(defun go--parameter-list-type (end)
"Return 'present if the parameter list has names, or 'absent if
not, assuming point is at the beginning of a parameter list, just
after '('."
(save-excursion
(skip-chars-forward "[:space:]\n" end)
(cond ((> (point) end)
nil)
((looking-at (concat go-identifier-regexp "[[:space:]\n]*,"))
(goto-char (match-end 0))
(go--parameter-list-type end))
((or (looking-at go-qualified-identifier-regexp)
(looking-at (concat go-type-name-no-prefix-regexp "[[:space:]\n]*\\(?:)\\|\\'\\)"))
(go--looking-at-keyword)
(looking-at "[*\\[]\\|\\.\\.\\.\\|\\'"))
'absent)
(t 'present))))
(defconst go--opt-dotdotdot-regexp "\\(?:\\.\\.\\.\\)?")
(defconst go--parameter-type-regexp
(concat go--opt-dotdotdot-regexp "[[:space:]*\n]*\\(" go-type-name-no-prefix-regexp "\\)[[:space:]\n]*\\([,)]\\|\\'\\)"))
(defconst go--func-type-in-parameter-list-regexp
(concat go--opt-dotdotdot-regexp "[[:space:]*\n]*\\(" (go--regexp-enclose-in-symbol "func") "\\)"))
(defun go--match-parameters-common (identifier-regexp end)
(let ((acc ())
(start -1))
(while (progn (skip-chars-forward "[:space:]\n" end)
(and (not (looking-at "\\(?:)\\|\\'\\)"))
(< start (point))
(<= (point) end)))
(setq start (point))
(cond
((looking-at (concat identifier-regexp go--parameter-type-regexp))
(setq acc (nconc acc (list (match-beginning 1) (match-end 1))))
(goto-char (match-beginning 2)))
((looking-at (concat identifier-regexp go--func-type-in-parameter-list-regexp))
(goto-char (match-beginning 1))
(setq acc (nconc acc (go--match-func-type-names end)))
(go--search-next-comma end))
(t
(go--search-next-comma end))))
(when (and (looking-at ")")
(< (point) end))
(forward-char))
acc))
(defun go--match-parameters-with-identifier-list (end)
(go--match-parameters-common
(concat go-identifier-regexp "[[:space:]\n]+")
end))
(defun go--match-parameters-without-identifier-list (end)
(go--match-parameters-common "" end))
(defun go--filter-match-data (regions end)
"Remove points from regions if they are beyond end. Regions are
a list whose size is multiple of 2. Element 2n is beginning of a
region and 2n+1 is end of it.
This function is used to make sure we don't override end point
that font-lock-mode gave to us."
(when regions
(let* ((vec (vconcat regions))
(i 0)
(len (length vec)))
(while (and (< i len)
(<= (nth i regions) end)
(<= (nth (1+ i) regions) end))
(setq i (+ i 2)))
(cond ((= i len)
regions)
((zerop i)
nil)
(t
(setcdr (nth i regions) nil)
regions)))))
(defun go--make-match-data (regions)
(let ((deficit (- (* 2 go--font-lock-func-param-num-groups)
(length regions))))
(when (> deficit 0)
(let ((last (car (last regions))))
(setq regions (nconc regions (make-list deficit last))))))
`(,(car regions) ,@(last regions) ,@regions))
(defun go--match-parameter-list (end)
"Returns a list of identifier positions that are used as type
names in a function parameter list, assuming point is at the
beginning of a parameter list. Returns nil if the text after
point does not look like a parameter list.
Set point to end of closing parenthesis on success.
In Go, the names must either all be present or all be absent
within a list of parameters.
Parsing a parameter list is a little bit complicated because we
have to scan through the parameter list to determine whether or
not the list has names. Until a type name is found or reaching
end of a parameter list, we are not sure which form the parameter
list is.
For example, X and Y are type names in a parameter list \"(X,
Y)\" but are parameter names in \"(X, Y int)\". We cannot say if
X is a type name until we see int after Y.
Note that even \"(int, float T)\" is a valid parameter
list. Builtin type names are not reserved words. In this example,
int and float are parameter names and only T is a type name.
In this function, we first scan the parameter list to see if the
list has names, and then handle it accordingly."
(let ((name (go--parameter-list-type end)))
(cond ((eq name 'present)
(go--match-parameters-with-identifier-list end))
((eq name 'absent)
(go--match-parameters-without-identifier-list end))
(t nil))))
(defun go--match-function-result (end)
"Returns a list of identifier positions that are used as type
names in a function result, assuming point is at the beginning of
a result.
Function result is a unparenthesized type or a parameter list."
(cond ((and (looking-at (concat "[[:space:]*]*\\(" go-type-name-no-prefix-regexp "\\)"))
(not (member (match-string 1) go-mode-keywords)))
(list (match-beginning 1) (match-end 1)))
((looking-at "[[:space:]]*(")
(goto-char (match-end 0))
(go--match-parameter-list end))
(t nil)))
;;;###autoload
(define-derived-mode go-mode prog-mode "Go"
"Major mode for editing Go source text.
This mode provides (not just) basic editing capabilities for
working with Go code. It offers almost complete syntax
highlighting, indentation that is almost identical to gofmt and
proper parsing of the buffer content to allow features such as
navigation by function, manipulation of comments or detection of
strings.
In addition to these core features, it offers various features to
help with writing Go code. You can directly run buffer content
through gofmt, read godoc documentation from within Emacs, modify
and clean up the list of package imports or interact with the
Playground (uploading and downloading pastes).
The following extra functions are defined:
- `gofmt'
- `godoc'
- `go-import-add'
- `go-remove-unused-imports'
- `go-goto-imports'
- `go-play-buffer' and `go-play-region'
- `go-download-play'
- `godef-describe' and `godef-jump'
- `go-coverage'
If you want to automatically run `gofmt' before saving a file,
add the following hook to your emacs configuration:
\(add-hook 'before-save-hook #'gofmt-before-save)
If you want to use `godef-jump' instead of etags (or similar),
consider binding godef-jump to `M-.', which is the default key
for `find-tag':
\(add-hook 'go-mode-hook (lambda ()
(local-set-key (kbd \"M-.\") #'godef-jump)))
Please note that godef is an external dependency. You can install
it with
go get code.google.com/p/rog-go/exp/cmd/godef
If you're looking for even more integration with Go, namely
on-the-fly syntax checking, auto-completion and snippets, it is
recommended that you look at flycheck
\(see URL `https://github.com/flycheck/flycheck') or flymake in combination
with goflymake \(see URL `https://github.com/dougm/goflymake'), gocode
\(see URL `https://github.com/nsf/gocode'), go-eldoc
\(see URL `github.com/syohex/emacs-go-eldoc') and yasnippet-go
\(see URL `https://github.com/dominikh/yasnippet-go')"
;; Font lock
(set (make-local-variable 'font-lock-defaults)
'(go--build-font-lock-keywords))
;; Indentation
(set (make-local-variable 'indent-line-function) #'go-mode-indent-line)
;; Comments
(set (make-local-variable 'comment-start) "// ")
(set (make-local-variable 'comment-end) "")
(set (make-local-variable 'comment-use-syntax) t)
(set (make-local-variable 'comment-start-skip) "\\(//+\\|/\\*+\\)\\s *")
(set (make-local-variable 'beginning-of-defun-function) #'go-beginning-of-defun)
(set (make-local-variable 'end-of-defun-function) #'go-end-of-defun)
(set (make-local-variable 'parse-sexp-lookup-properties) t)
(if (boundp 'syntax-propertize-function)
(set (make-local-variable 'syntax-propertize-function) #'go-propertize-syntax)
(set (make-local-variable 'font-lock-syntactic-keywords)
go--font-lock-syntactic-keywords)
(set (make-local-variable 'font-lock-multiline) t))
(set (make-local-variable 'go-dangling-cache) (make-hash-table :test 'eql))
(add-hook 'before-change-functions (lambda (x y) (setq go-dangling-cache (make-hash-table :test 'eql))) t t)
;; ff-find-other-file
(setq ff-other-file-alist 'go-other-file-alist)
(setq imenu-generic-expression
'(("type" "^type *\\([^ \t\n\r\f]*\\)" 1)
("func" "^func *\\(.*\\) {" 1)))
(imenu-add-to-menubar "Index")
;; Go style
(setq indent-tabs-mode t)
;; Handle unit test failure output in compilation-mode
;;
;; Note the final t argument to add-to-list for append, ie put these at the
;; *ends* of compilation-error-regexp-alist[-alist]. We want go-test to be
;; handled first, otherwise other elements will match that don't work, and
;; those alists are traversed in *reverse* order:
;; http://lists.gnu.org/archive/html/bug-gnu-emacs/2001-12/msg00674.html
(when (and (boundp 'compilation-error-regexp-alist)
(boundp 'compilation-error-regexp-alist-alist))
(add-to-list 'compilation-error-regexp-alist 'go-test t)
(add-to-list 'compilation-error-regexp-alist-alist
'(go-test . ("^\t+\\([^()\t\n]+\\):\\([0-9]+\\):? .*$" 1 2)) t)))
;;;###autoload
(add-to-list 'auto-mode-alist (cons "\\.go\\'" 'go-mode))
(defun go--apply-rcs-patch (patch-buffer)
"Apply an RCS-formatted diff from PATCH-BUFFER to the current
buffer."
(let ((target-buffer (current-buffer))
;; Relative offset between buffer line numbers and line numbers
;; in patch.
;;
;; Line numbers in the patch are based on the source file, so
;; we have to keep an offset when making changes to the
;; buffer.
;;
;; Appending lines decrements the offset (possibly making it
;; negative), deleting lines increments it. This order
;; simplifies the forward-line invocations.
(line-offset 0))
(save-excursion
(with-current-buffer patch-buffer
(goto-char (point-min))
(while (not (eobp))
(unless (looking-at "^\\([ad]\\)\\([0-9]+\\) \\([0-9]+\\)")
(error "invalid rcs patch or internal error in go--apply-rcs-patch"))
(forward-line)
(let ((action (match-string 1))
(from (string-to-number (match-string 2)))
(len (string-to-number (match-string 3))))
(cond
((equal action "a")
(let ((start (point)))
(forward-line len)
(let ((text (buffer-substring start (point))))
(with-current-buffer target-buffer
(decf line-offset len)
(goto-char (point-min))
(forward-line (- from len line-offset))
(insert text)))))
((equal action "d")
(with-current-buffer target-buffer
(go--goto-line (- from line-offset))
(incf line-offset len)
(go--delete-whole-line len)))
(t
(error "invalid rcs patch or internal error in go--apply-rcs-patch")))))))))
(defun gofmt ()
"Formats the current buffer according to the gofmt tool."
(interactive)
(let ((tmpfile (make-temp-file "gofmt" nil ".go"))
(patchbuf (get-buffer-create "*Gofmt patch*"))
(errbuf (if gofmt-show-errors (get-buffer-create "*Gofmt Errors*")))
(coding-system-for-read 'utf-8)
(coding-system-for-write 'utf-8))
(save-restriction
(widen)
(if errbuf
(with-current-buffer errbuf
(setq buffer-read-only nil)
(erase-buffer)))
(with-current-buffer patchbuf
(erase-buffer))
(write-region nil nil tmpfile)
;; We're using errbuf for the mixed stdout and stderr output. This
;; is not an issue because gofmt -w does not produce any stdout
;; output in case of success.
(if (zerop (call-process gofmt-command nil errbuf nil "-w" tmpfile))
(progn
(if (zerop (call-process-region (point-min) (point-max) "diff" nil patchbuf nil "-n" "-" tmpfile))
(message "Buffer is already gofmted")
(go--apply-rcs-patch patchbuf)
(message "Applied gofmt"))
(if errbuf (gofmt--kill-error-buffer errbuf)))
(message "Could not apply gofmt")
(if errbuf (gofmt--process-errors (buffer-file-name) tmpfile errbuf)))
(kill-buffer patchbuf)
(delete-file tmpfile))))
(defun gofmt--process-errors (filename tmpfile errbuf)
(with-current-buffer errbuf
(if (eq gofmt-show-errors 'echo)
(progn
(message "%s" (buffer-string))
(gofmt--kill-error-buffer errbuf))
;; Convert the gofmt stderr to something understood by the compilation mode.
(goto-char (point-min))
(insert "gofmt errors:\n")
(while (search-forward-regexp (concat "^\\(" (regexp-quote tmpfile) "\\):") nil t)
(replace-match (file-name-nondirectory filename) t t nil 1))
(compilation-mode)
(display-buffer errbuf))))
(defun gofmt--kill-error-buffer (errbuf)
(let ((win (get-buffer-window errbuf)))
(if win
(quit-window t win)
(kill-buffer errbuf))))
;;;###autoload
(defun gofmt-before-save ()
"Add this to .emacs to run gofmt on the current buffer when saving:
(add-hook 'before-save-hook 'gofmt-before-save).