Added a simple binding (C-c C-l) to launch an inferior gosu process. …

…Made -> turn into arrows regardless of context, so you can have the pretty characters in map literals as well as lambdas. Added a bunch of keywords and made true, false, null and this be in the font lock constant face.

gosu-mode.el

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+;; The simplest approach to starting an Emacs major mode is to make it
+;; a "generic" mode.  Other options are to make it from scratch, or to
+;; derive it from another mode (such as java-mode, or cc-mode).
+;; Creating it from scratch confers more flexibility, while deriving
+;; it enjoys the benefits of code reuse.  On the other hand,
+;; overriding behavior from the parent mode can be awkward, so for the
+;; moment, I'm sticking with making a so-called generic mode.  (See
+;; the Emacs Info manuals on generic modes and on the
+;; define-generic-mode macro).
+(require 'generic-x)
+
+(defvar gosu-mode-syntax-table
+  (let ((gosu-mode-syntax-table (make-syntax-table)))
+    (modify-syntax-entry ?/ ". 124b" gosu-mode-syntax-table)
+    (modify-syntax-entry ?* ". 23" gosu-mode-syntax-table)
+    (modify-syntax-entry ?' "\"'" gosu-mode-syntax-table)
+    (modify-syntax-entry ?\n "> b" gosu-mode-syntax-table)
+    gosu-mode-syntax-table)
+  "`define-generic-defun' takes COMMENT-LIST, but its support for
+ending comments with the lint terminator seems not to work,
+so here we are setting up our own syntax table.")
+
+(defvar gosu-mode-map (make-keymap))
+(define-key gosu-mode-map (kbd "C-c C-l") 'run-gosu)
+
+(defun line-matchesp (regexp offset)
+  "Return t if line matches regular expression REGEXP.  The 
+selected line is chosen by applying OFFSET as a numeric 
+increment or decrement away from the current line number.
+This function modifies the match data that `match-beginning',
+`match-end' and `match-data' access; save and restore the match
+data if you want to preserve them."
+  (interactive)
+  (save-excursion
+    (forward-line offset)
+    (beginning-of-line)
+    (looking-at regexp)))
+
+(defun previous-line-matchesp (regexp)
+  "Return t if previous line matches regular expression REGEXP.
+This function modifies the match data that `match-beginning',
+`match-end' and `match-data' access; save and restore the match
+data if you want to preserve them."
+  (interactive)
+  (line-matchesp regexp -1))
+
+(defun current-line-matchesp (regexp)
+  "Return t if current line matches regular expression REGEXP.
+This function modifies the match data that `match-beginning',
+`match-end' and `match-data' access; save and restore the match
+data if you want to preserve them."
+  (interactive)
+  (line-matchesp regexp 0))
+
+(defun gosu-indent-line ()
+  (interactive)
+  "Establish a set of conditional cases for the types of lines that
+point currently is on, and the associated indentation rules."
+  (indent-line-to
+   (cond
+    ((and
+      (previous-line-matchesp "^[ \t]*\\*")
+      (current-line-matchesp "^[ \t]*\\*"))
+     (save-excursion
+       (forward-line -1)
+       (current-indentation)))
+    ((and
+      (previous-line-matchesp "^[ \t]*/\\*")
+      (current-line-matchesp "^[ \t]*\\*"))
+     (save-excursion
+       (forward-line -1)
+       (+ (current-indentation) 1)))
+    ((and
+      (previous-line-matchesp "^[ \t]*\\.")
+      (current-line-matchesp "^[ \t]**\\."))
+     (save-excursion
+       (forward-line -1)
+       (current-indentation)))
+    ((and
+      (not (previous-line-matchesp "^[ \t]*\\."))
+      (current-line-matchesp "^[ \t]*\\."))
+     (save-excursion
+       (forward-line -1)
+       (+ (current-indentation) default-tab-width)))
+    ((current-line-matchesp "^[ \t]*}")
+     (save-excursion
+       (beginning-of-line)
+       (backward-up-list)
+       (current-indentation)))
+    (t
+     (save-excursion
+       (condition-case nil
+           (progn
+             (beginning-of-line)
+             (backward-up-list)
+             (+ (current-indentation) default-tab-width))
+         (error 0)))))))
+
+;; Set up the actual generic mode
+(define-generic-mode 'gosu-mode
+  ;; comment-list
+  nil
+  ;; keyword-list
+  '(
+    "application"
+    "new"
+    "as"
+    "break"
+    "override"
+    "case"
+    "package"
+    "catch"
+    "private"
+    "class"
+    "property"
+    "continue"
+    "protected"
+    "default"
+    "public"
+    "do"
+    "readonly"
+    "else"
+    "request"
+    "eval"
+    "return"
+    "except"
+    "session"
+    "execution"
+    "set"
+    "extends"
+    "static"
+    "finally"
+    "super"
+    "final"
+    "switch"
+    "find"
+    "for"
+    "try"
+    "foreach"
+    "typeas"
+    "function"
+    "typeis"
+    "get"
+    "typeof"
+    "hide"
+    "unless"
+    "implements"
+    "uses"
+    "index"
+    "var"
+    "interface"
+    "void"
+    "internal"
+    "while"
+    "native"
+    "construct"
+    "if"
+    "using"
+    "in"
+    "block"
+    "and"
+    "or"
+    "not"
+    "property"
+    "writeable"
+    "throw"
+    "enhancement")
+  ;; font-lock-list
+  '(("\\b[0-9]+\\b\\|true\\|false\\|null\\|this" . font-lock-constant-face)
+    ("\\s-\\([A-Z][aA-zZ]*\\)\\." 1 'font-lock-type-face)
+    ("\\(uses\\|:\\|as\\).+\\.\\([A-Z][aA-zZ]*\\)" 2 'font-lock-type-face)
+    ("\\(:\\|\\bas\\b\\).+\\([A-Z][aA-zZ]*\\)" 2 'font-lock-type-face)
+    ("\\(\\\\\\).*\\(->\\)" 
+     (1 (prog1 ()
+          (compose-region (match-beginning 1) (match-end 1) ?λ)
+          (put-text-property (match-beginning 1) (match-end 1) 'font-lock-face 'font-lock-builtin-face)))
+     (2 (prog1 ()
+          (compose-region (match-beginning 2) (match-end 2) ?→)
+          (put-text-property (match-beginning 2) (match-end 2) 'font-lock-face 'font-lock-builtin-face))))
+    ("\\(->\\)" 
+     (1 (prog1 ()
+          (compose-region (match-beginning 1) (match-end 1) ?→)
+          (put-text-property (match-beginning 1) (match-end 1) 'font-lock-face 'font-lock-builtin-face)))))
+  ;; auto-mode-list
+  '(".gs\\'")
+  ;; function-list
+  '((lambda () 
+      (set-syntax-table gosu-mode-syntax-table)
+      (setq comment-start "//")
+      (setq comment-end "")
+      (set (make-local-variable 'indent-line-function) 'gosu-indent-line)
+      (use-local-map gosu-mode-map))))
+
+(provide 'gosu-mode)