brightscript-mode.el

;;; brightscript-mode.el --- Major mode for editing Brightscript files -*- lexical-binding: t; -*-

;; Copyright (c) 2020 Daniel Mircea, Free Software Foundation, Inc.

;; Author: Daniel Mircea <daniel@viseztrance.com>
;; URL: https://github.com/viseztrance/brightscript-mode
;; Version: 1.1.0
;; Package-Requires: ((emacs "26.3"))
;; Maintainer: daniel@viseztrance.com
;; Created: Mar 2020
;; Keywords: languages

;; This program is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.

;; This program is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with this program.  If not, see <https://www.gnu.org/licenses/>.

;;; Commentary:

;; Adds support for the BrightScript programming language from BrightSign and
;; Roku devices.  This language is used by digital signage and media players.

;;; Code:

(defgroup brightscript nil
  "Major mode for editing BrightScript code."
  :prefix "brightscript-"
  :group 'languages
  :link '(url-link :tag "Github" "https://github.com/viseztrance/brightscript-mode")
  :link '(emacs-commentary-link :tag "Commentary" "brightscript-mode"))

(defcustom brightscript-mode-indent-offset 2
  "Specifies the indentation offset for `brightscript-mode-indent-line'."
  :type 'integer
  :group 'brightscript)

(defun brightscript-mode-indent-perform (indentation)
  "Set the line indent to the provided INDENTATION."
  (let ((adjusted-indentation (max indentation 0)))
    (indent-line-to adjusted-indentation)))

(defun brightscript-mode-indent-start-of-block-p ()
  "Check if current line is the start of a block such as function or loop construct."
  (or
   (looking-at-p "^[ \t]*\\_<\\(sub\\|function\\|if\\|else\\|elseif\\|while\\|for\\)\\_>")
   (looking-at-p ".*?\{[ \t]*$")))

(defun brightscript-mode-indent-end-of-block-p ()
  "Check if current line is the end of a block such as function or loop construct."
  (or
   (looking-at-p "^[ \t]*\\_<\\(end\\|endif\\|endfor\\|endwhile\\|else\\|elseif\\)\\_>")
   (looking-at-p "^[ \t]*\}\,?")))

(defun brightscript-mode-indent-go-to-previous-non-blank-line ()
  "Jumps the previous non blank line."
  (let ((found))
    (while (not (or found (bobp)))
      (forward-line -1)
      (unless (looking-at "^[ \t]*$")
        (setq found t)))))

(defun brightscript-mode-indent-line-function ()
  "Indent current line as Brightscript code."
  (interactive)
  (beginning-of-line)
  (let ((new-indentation 0)
        (main-line-ends-block (brightscript-mode-indent-end-of-block-p))
        (offset 0))
    (unless (bobp)
      (save-excursion
        (brightscript-mode-indent-go-to-previous-non-blank-line)
        (when (brightscript-mode-indent-start-of-block-p)
          (setq offset brightscript-mode-indent-offset))
        (when main-line-ends-block
          (setq offset (- brightscript-mode-indent-offset)))
        (setq new-indentation (+ (current-indentation) offset))))
    (brightscript-mode-indent-perform new-indentation)))

(defconst brightscript-mode-reserved-keywords
  '("and" "as" "dim" "each" "else" "elseif" "end" "end for" "end function" "endif"
    "end sub" "endwhile" "end if" "end while" "exit" "false" "for" "function" "goto" "if"
    "in" "library" "line_num" "m*" "next" "objfun" "or" "pos" "print" "rem" "return" "rnd"
    "step" "stop" "sub" "tab" "then" "to" "true" "type" "while")
  "BrightScript keywords.")

(defconst brightscript-mode-primitives
  '("void" "dynamic" "boolean" "integer" "longinteger" "float" "double" "string"
    "object" "interface")
  "BrightScript variable types.")

(defconst brightscript-mode-global-functions
  '("CopyFile" "CreateObject" "CreateDirectory" "DeleteFile" "DeleteDirectory"
    "EjectDrive" "EnableZoneSupport" "EnableAudioMixer" "FormatDrive" "GetInterface"
    "GetDefaultDrive" "LCase" "Left" "ListDir" "MatchFiles" "Mid" "MoveFile" "Pi"
    "ReadAsciiFile" "RebootSystem" "Right" "RunGarbageCollector" "SetDefaultDrive"
    "ShutdownSystem" "Sleep" "StringI" "String" "UCase" "UpTime" "Wait" "WriteAsciiFile"
    "abs" "asc" "atn" "cdbl" "chr" "cint" "cos" "csng" "exp" "fix" "instr" "int"
    "len" "log" "rnd" "sgn" "sgnI" "sin" "sqr" "str" "strI" "strtoi" "tan" "val")
  "BrightScript global functions.")

(defconst brightscript-mode-objects
  '("roArray" "roAssociativeArray" "roBoolean" "roByteArray" "roDouble"
    "roIntrinsicDouble" "roFunction" "roGlobal" "roInt" "roFloat" "roString"
    "roList" "roRegex" "roXMLElement" "roXMLList" "roAudioEventMx" "roAudioOutput"
    "roAudioPlayer" "roAudioPlayerMx" "roCanvasWidget" "roClockWidget" "roHtmlWidget"
    "roImageBuffer" "roImagePlayer" "roImageWidget" "roRectangle" "roShoutcastStream"
    "roShoutcastStreamEvent" "roIRRemotePress" "roTextField" "roTextWidget"
    "roVideoEvent" "roAudioEvent" "roVideoInput" "roVideoMode" "roVideoPlayer"
    "roSqliteStatement" "roTouchCalibrationEvent" "roTouchEvent" "roTouchScreen"
    "roBrightPackage" "roHashGenerator" "roReadFile" "roCreateFile" "roReadWriteFile"
    "roAppendFile" "roRegistry" "roRegistrySection" "roSqliteDatabase" "roSqliteEvent"
    "roStorageAttached" "roStorageDetached" "roStorageHotplug" "roStorageInfo"
    "roAssetCollection" "roAssetFetcher" "roAssetFetcherEvent"
    "roAssetFetcherProgressEvent" "roAssetPool" "roAssetPoolFiles" "roAssetRealizer"
    "roAssetRealizerEvent" "roDatagramSender" "roDatagramReceiver" "roDatagramSocket"
    "roDatagramEvent" "roHttpEvent" "roHttpServer" "roMimeStream" "roMimeStreamEvent"
    "roNetworkAdvertisement" "roNetworkAttached" "roNetworkDetached"
    "roNetworkConfiguration" "roNetworkHotplug" "roRssParser" "roRssArticle"
    "roRtspStream" "roRtspStreamEvent" "roShoutcastStream" "roShoutcastStreamEvent"
    "roSnmpAgent" "roSnmpEvent" "roStreamByteEvent" "roStreamConnectResultEvent"
    "roStreamEndEvent" "roStreamLineEvent" "roSyncSpec" "roTCPConnectEvent"
    "roTCPServer" "roTCPStream" "roUrlEvent" "roUrlStream" "roUrlTransfer"
    "roCecInterface" "roCecRxFrameEvent" "roCecTxCompleteEvent" "roChannelManager"
    "roControlPort" "roControlUp" "roControlDown" "roGpioControlPort" "roGpioButton"
    "roIRRemote" "roKeyboard" "roKeyboardPress" "roMessagePort" "roSequenceMatcher"
    "roSequenceMatchEvent" "roSerialPort" "roDeviceInfo" "roResourceManager"
    "roSystemLog" "roDateTime" "roSystemTime" "roTimer" "roTimerEvent" "roTimeSpan"
    "roSyncPool" "roSyncPoolEvent" "roSyncPoolFiles" "roSyncPoolProgressEvent")
  "BrightScript objects that can be constructed by the `CreateObject' function.")

(defface brightscript-mode-objects-face
  '((t :weight bold))
  "Face for highlight substrings in a text"
  :group 'brightscript-mode)

(defvar brightscript-mode-font-lock
  (let
      ((reserved-keywords-regexp
        (regexp-opt brightscript-mode-reserved-keywords 'symbols))
       (primitives-regexp
        (regexp-opt brightscript-mode-primitives 'symbols))
       (global-functions-regexp
        (regexp-opt brightscript-mode-global-functions 'symbols))
       (objects-regexp
        (regexp-opt brightscript-mode-objects 'words)))
    `(
                                        ; Matches function or sub definition
      ("^[ \t]*\\(?:sub\\|function\\)\\(?:[ \t]*\\)?\\([a-z0-9_]+\\)[^( \t\n]*"
       (1 font-lock-function-name-face)
       ;; Matches function arguments
       ("\\([a-z0-9_\$%!#]+\\).*?\\(?:,\\|)\\)"
        (save-excursion
          (goto-char (match-end 0))
          (backward-char)
          (ignore-errors
            (forward-sexp))
          (point))
        (goto-char (match-end 0))
        (1 font-lock-variable-name-face)))
      ;; Matches object function calls
      ("\\.\\([a-z0-9_]*\\)\(" 1 font-lock-function-name-face)
      ;; Matches the `invalid' keyword and `==' which is not legal syntax
      ("\\(==\\|invalid\\)" 1 font-lock-warning-face)
      ;; Matches `goto' calls
      ("goto[ \t]*\\([a-z0-9_]*\\)" 1 font-lock-warning-face)
      ;; Matches the global `m' var
      ("\\_<\\(m\\)\\." 1 font-lock-variable-name-face)
      ;; Matches comments in the `REM' format
      ("^REM.*$" 0 font-lock-comment-face prepend)
      (,objects-regexp 0 'brightscript-mode-objects-face append)
      (,primitives-regexp . font-lock-type-face)
      (,reserved-keywords-regexp . font-lock-builtin-face)
      (,global-functions-regexp . font-lock-constant-face))))

(defvar brightscript-mode-syntax-table
  (let ((table (make-syntax-table)))
    (modify-syntax-entry ?' "<" table)
    (modify-syntax-entry ?\n ">" table)
    table))

(defvar brightscript-imenu-generic-expression
  '(("Function" "^[Ff]unction +\\([a-zA-Z_]+\\)" 1)
    ("Function" "^[Ss]ub +\\([a-zA-Z_]+\\)" 1)))

;;;###autoload
(define-derived-mode brightscript-mode prog-mode "BrightScript"
  "Major mode for editing BrightScript code."
  (setq-local indent-line-function 'brightscript-mode-indent-line-function)
  (setq-local font-lock-defaults '(brightscript-mode-font-lock nil t))

  (setq-local comment-start "'")
  (setq-local comment-end "")
  (set-syntax-table brightscript-mode-syntax-table)

  (setq-local imenu-generic-expression brightscript-imenu-generic-expression))

(provide 'brightscript-mode)

;;; brightscript-mode.el ends here