mirror of
https://github.com/golang/go
synced 2024-11-24 16:40:15 -07:00
545 lines
20 KiB
EmacsLisp
545 lines
20 KiB
EmacsLisp
;;; go-mode.el --- Major mode for the Go programming language
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;;; Commentary:
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;; For installation instructions, see go-mode-load.el
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;;; To do:
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;; * Indentation is *almost* identical to gofmt
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;; ** We think struct literal keys are labels and outdent them
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;; ** We disagree on the indentation of function literals in arguments
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;; ** There are bugs with the close brace of struct literals
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;; * Highlight identifiers according to their syntactic context: type,
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;; variable, function call, or tag
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;; * Command for adding an import
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;; ** Check if it's already there
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;; ** Factor/unfactor the import line
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;; ** Alphabetize
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;; * Remove unused imports
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;; ** This is hard, since I have to be aware of shadowing to do it
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;; right
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;; * Format region using gofmt
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;;; Code:
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(eval-when-compile (require 'cl))
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(defvar go-mode-syntax-table
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(let ((st (make-syntax-table)))
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;; Add _ to :word: character class
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(modify-syntax-entry ?_ "w" st)
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;; Operators (punctuation)
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(modify-syntax-entry ?+ "." st)
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(modify-syntax-entry ?- "." st)
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(modify-syntax-entry ?* "." st)
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(modify-syntax-entry ?/ "." st)
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(modify-syntax-entry ?% "." st)
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(modify-syntax-entry ?& "." st)
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(modify-syntax-entry ?| "." st)
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(modify-syntax-entry ?^ "." st)
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(modify-syntax-entry ?! "." st)
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(modify-syntax-entry ?= "." st)
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(modify-syntax-entry ?< "." st)
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(modify-syntax-entry ?> "." st)
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;; Strings
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(modify-syntax-entry ?\" "\"" st)
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(modify-syntax-entry ?\' "\"" st)
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(modify-syntax-entry ?` "\"" st)
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(modify-syntax-entry ?\\ "\\" st)
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;; Comments
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(modify-syntax-entry ?/ ". 124b" st)
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(modify-syntax-entry ?* ". 23" st)
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(modify-syntax-entry ?\n "> b" st)
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(modify-syntax-entry ?\^m "> b" st)
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st)
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"Syntax table for Go mode.")
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(defvar go-mode-keywords
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'("break" "default" "func" "interface" "select"
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"case" "defer" "go" "map" "struct"
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"chan" "else" "goto" "package" "switch"
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"const" "fallthrough" "if" "range" "type"
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"continue" "for" "import" "return" "var")
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"All keywords in the Go language. Used for font locking and
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some syntax analysis.")
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(defvar go-mode-font-lock-keywords
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(let ((builtins '("append" "cap" "close" "complex" "copy" "imag" "len"
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"make" "new" "panic" "print" "println" "real" "recover"))
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(constants '("nil" "true" "false" "iota"))
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(type-name "\\s *\\(?:[*(]\\s *\\)*\\(?:\\w+\\s *\\.\\s *\\)?\\(\\w+\\)")
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)
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`((,(regexp-opt go-mode-keywords 'words) . font-lock-keyword-face)
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(,(regexp-opt builtins 'words) . font-lock-builtin-face)
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(,(regexp-opt constants 'words) . font-lock-constant-face)
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;; Function names in declarations
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("\\<func\\>\\s *\\(\\w+\\)" 1 font-lock-function-name-face)
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;; Function names in methods are handled by function call pattern
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;; Function names in calls
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;; XXX Doesn't match if function name is surrounded by parens
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("\\(\\w+\\)\\s *(" 1 font-lock-function-name-face)
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;; Type names
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("\\<type\\>\\s *\\(\\w+\\)" 1 font-lock-type-face)
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(,(concat "\\<type\\>\\s *\\w+\\s *" type-name) 1 font-lock-type-face)
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;; Arrays/slices/map value type
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;; XXX Wrong. Marks 0 in expression "foo[0] * x"
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;; (,(concat "]" type-name) 1 font-lock-type-face)
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;; Map key type
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(,(concat "\\<map\\s *\\[" type-name) 1 font-lock-type-face)
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;; Channel value type
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(,(concat "\\<chan\\>\\s *\\(?:<-\\)?" type-name) 1 font-lock-type-face)
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;; new/make type
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(,(concat "\\<\\(?:new\\|make\\)\\>\\(?:\\s \\|)\\)*(" type-name) 1 font-lock-type-face)
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;; Type conversion
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(,(concat "\\.\\s *(" type-name) 1 font-lock-type-face)
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;; Method receiver type
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(,(concat "\\<func\\>\\s *(\\w+\\s +" type-name) 1 font-lock-type-face)
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;; Labels
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;; XXX Not quite right. Also marks compound literal fields.
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("^\\s *\\(\\w+\\)\\s *:\\(\\S.\\|$\\)" 1 font-lock-constant-face)
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("\\<\\(goto\\|break\\|continue\\)\\>\\s *\\(\\w+\\)" 2 font-lock-constant-face)))
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"Basic font lock keywords for Go mode. Highlights keywords,
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built-ins, functions, and some types.")
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; Key map
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;;
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(defvar go-mode-map
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(let ((m (make-sparse-keymap)))
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(define-key m "}" #'go-mode-insert-and-indent)
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(define-key m ")" #'go-mode-insert-and-indent)
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(define-key m ":" #'go-mode-delayed-electric)
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;; In case we get : indentation wrong, correct ourselves
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(define-key m "=" #'go-mode-insert-and-indent)
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m)
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"Keymap used by Go mode to implement electric keys.")
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(defun go-mode-insert-and-indent (key)
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"Invoke the global binding of KEY, then reindent the line."
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(interactive (list (this-command-keys)))
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(call-interactively (lookup-key (current-global-map) key))
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(indent-according-to-mode))
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(defvar go-mode-delayed-point nil
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"The point following the previous insertion if the insertion
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was a delayed electric key. Used to communicate between
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`go-mode-delayed-electric' and `go-mode-delayed-electric-hook'.")
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(make-variable-buffer-local 'go-mode-delayed-point)
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(defun go-mode-delayed-electric (p)
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"Perform electric insertion, but delayed by one event.
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This inserts P into the buffer, as usual, then waits for another key.
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If that second key causes a buffer modification starting at the
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point after the insertion of P, reindents the line containing P."
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(interactive "p")
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(self-insert-command p)
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(setq go-mode-delayed-point (point)))
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(defun go-mode-delayed-electric-hook (b e l)
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"An after-change-function that implements `go-mode-delayed-electric'."
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(when (and go-mode-delayed-point
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(= go-mode-delayed-point b))
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(save-excursion
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(save-match-data
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(goto-char go-mode-delayed-point)
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(indent-according-to-mode))))
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(setq go-mode-delayed-point nil))
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; Parser
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;;
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(defvar go-mode-mark-cs-end 1
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"The point at which the comment/string cache ends. The buffer
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will be marked from the beginning up to this point (that is, up
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to and including character (1- go-mode-mark-cs-end)).")
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(make-variable-buffer-local 'go-mode-mark-cs-end)
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(defvar go-mode-mark-cs-state nil
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"The `parse-partial-sexp' state of the comment/string parser as
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of the point `go-mode-mark-cs-end'.")
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(make-variable-buffer-local 'go-mode-mark-cs-state)
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(defvar go-mode-mark-nesting-end 1
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"The point at which the nesting cache ends. The buffer will be
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marked from the beginning up to this point.")
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(make-variable-buffer-local 'go-mode-mark-nesting-end)
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(defun go-mode-mark-clear-cache (b e l)
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"An after-change-function that clears the comment/string and
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nesting caches from the modified point on."
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(save-restriction
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(widen)
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(when (< b go-mode-mark-cs-end)
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(remove-text-properties b (min go-mode-mark-cs-end (point-max)) '(go-mode-cs nil))
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(setq go-mode-mark-cs-end b
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go-mode-mark-cs-state nil))
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(when (< b go-mode-mark-nesting-end)
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(remove-text-properties b (min go-mode-mark-nesting-end (point-max)) '(go-mode-nesting nil))
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(setq go-mode-mark-nesting-end b))))
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(defmacro go-mode-parser (&rest body)
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"Evaluate BODY in an environment set up for parsers that use
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text properties to mark text. This inhibits changes to the undo
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list or the buffer's modification status and inhibits calls to
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the modification hooks. It also saves the excursion and
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restriction and widens the buffer, since most parsers are
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context-sensitive."
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(let ((modified-var (make-symbol "modified")))
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`(let ((buffer-undo-list t)
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(,modified-var (buffer-modified-p))
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(inhibit-modification-hooks t)
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(inhibit-read-only t))
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(save-excursion
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(save-restriction
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(widen)
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(unwind-protect
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(progn ,@body)
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(set-buffer-modified-p ,modified-var)))))))
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(defsubst go-mode-cs (&optional pos)
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"Return the comment/string state at point POS. If point is
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inside a comment or string (including the delimiters), this
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returns a pair (START . END) indicating the extents of the
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comment or string."
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(unless pos
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(setq pos (point)))
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(if (= pos 1)
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nil
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(when (> pos go-mode-mark-cs-end)
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(go-mode-mark-cs pos))
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(get-text-property (- pos 1) 'go-mode-cs)))
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(defun go-mode-mark-cs (end)
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"Mark comments and strings up to point END. Don't call this
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directly; use `go-mode-cs'."
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(setq end (min end (point-max)))
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(go-mode-parser
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(let* ((pos go-mode-mark-cs-end)
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(state (or go-mode-mark-cs-state (syntax-ppss pos))))
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;; Mark comments and strings
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(when (nth 8 state)
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;; Get to the beginning of the comment/string
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(setq pos (nth 8 state)
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state nil))
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(while (> end pos)
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;; Find beginning of comment/string
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(while (and (> end pos)
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(progn
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(setq state (parse-partial-sexp pos end nil nil state 'syntax-table)
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pos (point))
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(not (nth 8 state)))))
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;; Find end of comment/string
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(let ((start (nth 8 state)))
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(when start
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(setq state (parse-partial-sexp pos (point-max) nil nil state 'syntax-table)
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pos (point))
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;; Mark comment
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(put-text-property start (- pos 1) 'go-mode-cs (cons start pos))
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(when nil
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(put-text-property start (- pos 1) 'face
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`((:background "midnight blue")))))))
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;; Update state
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(setq go-mode-mark-cs-end pos
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go-mode-mark-cs-state state))))
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(defsubst go-mode-nesting (&optional pos)
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"Return the nesting at point POS. The nesting is a list
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of (START . END) pairs for all braces, parens, and brackets
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surrounding POS, starting at the inner-most nesting. START is
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the location of the open character. END is the location of the
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close character or nil if the nesting scanner has not yet
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encountered the close character."
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(unless pos
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(setq pos (point)))
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(if (= pos 1)
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'()
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(when (> pos go-mode-mark-nesting-end)
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(go-mode-mark-nesting pos))
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(get-text-property (- pos 1) 'go-mode-nesting)))
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(defun go-mode-mark-nesting (pos)
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"Mark nesting up to point END. Don't call this directly; use
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`go-mode-nesting'."
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(go-mode-cs pos)
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(go-mode-parser
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;; Mark depth
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(goto-char go-mode-mark-nesting-end)
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(let ((nesting (go-mode-nesting))
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(last (point)))
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(while (< last pos)
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;; Find the next depth-changing character
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(skip-chars-forward "^(){}[]" pos)
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;; Mark everything up to this character with the current
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;; nesting
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(put-text-property last (point) 'go-mode-nesting nesting)
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(when nil
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(let ((depth (length nesting)))
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(put-text-property last (point) 'face
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`((:background
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,(format "gray%d" (* depth 10)))))))
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(setq last (point))
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;; Update nesting
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(unless (eobp)
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(let ((ch (unless (go-mode-cs) (char-after))))
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(forward-char 1)
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(case ch
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((?\( ?\{ ?\[)
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(setq nesting (cons (cons (- (point) 1) nil)
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nesting)))
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((?\) ?\} ?\])
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(when nesting
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(setcdr (car nesting) (- (point) 1))
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(setq nesting (cdr nesting))))))))
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;; Update state
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(setq go-mode-mark-nesting-end last))))
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; Indentation
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;;
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(defvar go-mode-non-terminating-keywords-regexp
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(let* ((kws go-mode-keywords)
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(kws (remove "break" kws))
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(kws (remove "continue" kws))
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(kws (remove "fallthrough" kws))
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(kws (remove "return" kws)))
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(regexp-opt kws 'words))
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"Regular expression matching all Go keywords that *do not*
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implicitly terminate a statement.")
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(defun go-mode-semicolon-p ()
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"True iff point immediately follows either an explicit or
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implicit semicolon. Point should immediately follow the last
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token on the line."
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;; #Semicolons
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(case (char-before)
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((?\;) t)
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;; String literal
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((?' ?\" ?`) t)
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;; One of the operators and delimiters ++, --, ), ], or }
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((?+) (eq (char-before (1- (point))) ?+))
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((?-) (eq (char-before (1- (point))) ?-))
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((?\) ?\] ?\}) t)
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;; An identifier or one of the keywords break, continue,
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;; fallthrough, or return or a numeric literal
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(otherwise
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(save-excursion
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(when (/= (skip-chars-backward "[:word:]_") 0)
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(not (looking-at go-mode-non-terminating-keywords-regexp)))))))
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(defun go-mode-indentation ()
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"Compute the ideal indentation level of the current line.
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To the first order, this is the brace depth of the current line,
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plus parens that follow certain keywords. case, default, and
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labels are outdented one level, and continuation lines are
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indented one level."
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(save-excursion
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(back-to-indentation)
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(let ((cs (go-mode-cs)))
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;; Treat comments and strings differently only if the beginning
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;; of the line is contained within them
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(when (and cs (= (point) (car cs)))
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(setq cs nil))
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;; What type of context am I in?
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(cond
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((and cs (save-excursion
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(goto-char (car cs))
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(looking-at "\\s\"")))
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;; Inside a multi-line string. Don't mess with indentation.
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nil)
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(cs
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;; Inside a general comment
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(goto-char (car cs))
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(forward-char 1)
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(current-column))
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(t
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;; Not in a multi-line string or comment
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(let ((indent 0)
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(inside-indenting-paren nil))
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;; Count every enclosing brace, plus parens that follow
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;; import, const, var, or type and indent according to
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;; depth. This simple rule does quite well, but also has a
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;; very large extent. It would be better if we could mimic
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;; some nearby indentation.
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(save-excursion
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(skip-chars-forward "})")
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(let ((first t))
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(dolist (nest (go-mode-nesting))
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(case (char-after (car nest))
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((?\{)
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(incf indent tab-width))
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((?\()
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(goto-char (car nest))
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(forward-comment (- (buffer-size)))
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;; Really just want the token before
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(when (looking-back "\\<import\\|const\\|var\\|type"
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(max (- (point) 7) (point-min)))
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(incf indent tab-width)
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(when first
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(setq inside-indenting-paren t)))))
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(setq first nil))))
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;; case, default, and labels are outdented 1 level
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(when (looking-at "\\<case\\>\\|\\<default\\>\\|\\w+\\s *:\\(\\S.\\|$\\)")
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(decf indent tab-width))
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;; Continuation lines are indented 1 level
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(forward-comment (- (buffer-size)))
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(when (case (char-before)
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((nil ?\{ ?:)
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;; At the beginning of a block or the statement
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;; following a label.
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nil)
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((?\()
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;; Usually a continuation line in an expression,
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;; unless this paren is part of a factored
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;; declaration.
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(not inside-indenting-paren))
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((?,)
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;; Could be inside a literal. We're a little
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;; conservative here and consider any comma within
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;; curly braces (as opposed to parens) to be a
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;; literal separator. This will fail to recognize
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;; line-breaks in parallel assignments as
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;; continuation lines.
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(let ((depth (go-mode-nesting)))
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(and depth
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(not (eq (char-after (caar depth)) ?\{)))))
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(t
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;; We're in the middle of a block. Did the
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;; previous line end with an implicit or explicit
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;; semicolon?
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(not (go-mode-semicolon-p))))
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(incf indent tab-width))
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(max indent 0)))))))
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(defun go-mode-indent-line ()
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"Indent the current line according to `go-mode-indentation'."
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(interactive)
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(let ((col (go-mode-indentation)))
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(when col
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(let ((offset (- (current-column) (current-indentation))))
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(indent-line-to col)
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(when (> offset 0)
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(forward-char offset))))))
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; Go mode
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;;
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;;;###autoload
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(define-derived-mode go-mode nil "Go"
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"Major mode for editing Go source text.
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This provides basic syntax highlighting for keywords, built-ins,
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functions, and some types. It also provides indentation that is
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\(almost) identical to gofmt."
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;; Font lock
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(set (make-local-variable 'font-lock-defaults)
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'(go-mode-font-lock-keywords nil nil nil nil))
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;; Remove stale text properties
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(save-restriction
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(widen)
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(remove-text-properties 1 (point-max)
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|
'(go-mode-cs nil go-mode-nesting nil)))
|
|
|
|
;; Reset the syntax mark caches
|
|
(setq go-mode-mark-cs-end 1
|
|
go-mode-mark-cs-state nil
|
|
go-mode-mark-nesting-end 1)
|
|
(add-hook 'after-change-functions #'go-mode-mark-clear-cache nil t)
|
|
|
|
;; Indentation
|
|
(set (make-local-variable 'indent-line-function)
|
|
#'go-mode-indent-line)
|
|
(add-hook 'after-change-functions #'go-mode-delayed-electric-hook nil t)
|
|
|
|
;; Comments
|
|
(set (make-local-variable 'comment-start) "// ")
|
|
(set (make-local-variable 'comment-end) "")
|
|
|
|
;; Go style
|
|
(setq indent-tabs-mode t))
|
|
|
|
;;;###autoload
|
|
(add-to-list 'auto-mode-alist (cons "\\.go$" #'go-mode))
|
|
|
|
(defun go-mode-reload ()
|
|
"Reload go-mode.el and put the current buffer into Go mode.
|
|
Useful for development work."
|
|
|
|
(interactive)
|
|
(unload-feature 'go-mode)
|
|
(require 'go-mode)
|
|
(go-mode))
|
|
|
|
;;;###autoload
|
|
(defun gofmt ()
|
|
"Pipe the current buffer through the external tool `gofmt`.
|
|
Replace the current buffer on success; display errors on failure."
|
|
|
|
(interactive)
|
|
(let ((srcbuf (current-buffer)))
|
|
(with-temp-buffer
|
|
(let ((outbuf (current-buffer))
|
|
(errbuf (get-buffer-create "*Gofmt Errors*"))
|
|
(coding-system-for-read 'utf-8) ;; use utf-8 with subprocesses
|
|
(coding-system-for-write 'utf-8))
|
|
(with-current-buffer errbuf (erase-buffer))
|
|
(with-current-buffer srcbuf
|
|
(save-restriction
|
|
(let (deactivate-mark)
|
|
(widen)
|
|
(if (= 0 (shell-command-on-region (point-min) (point-max) "gofmt"
|
|
outbuf nil errbuf))
|
|
;; gofmt succeeded: replace the current buffer with outbuf,
|
|
;; restore the mark and point, and discard errbuf.
|
|
(let ((old-mark (mark t)) (old-point (point)))
|
|
(erase-buffer)
|
|
(insert-buffer-substring outbuf)
|
|
(goto-char (min old-point (point-max)))
|
|
(if old-mark (push-mark (min old-mark (point-max)) t))
|
|
(kill-buffer errbuf))
|
|
|
|
;; gofmt failed: display the errors
|
|
(display-buffer errbuf)))))
|
|
|
|
;; Collapse any window opened on outbuf if shell-command-on-region
|
|
;; displayed it.
|
|
(delete-windows-on outbuf)))))
|
|
|
|
;;;###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)"
|
|
|
|
(interactive)
|
|
(when (eq major-mode 'go-mode) (gofmt)))
|
|
|
|
(provide 'go-mode)
|