From 5de9e31bdbc04d77ae6d854978e602a95873374f Mon Sep 17 00:00:00 2001
From: Tony Garnock-Jones <tonygarnockjones@gmail.com>
Date: Sat, 13 Apr 2019 23:51:00 +1200
Subject: [PATCH] preserves.el

---
 preserves.el | 141 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 141 insertions(+)
 create mode 100644 preserves.el

diff --git a/preserves.el b/preserves.el
new file mode 100644
index 0000000..071e2b3
--- /dev/null
+++ b/preserves.el
@@ -0,0 +1,141 @@
+;;; preserves.el --- Preserves editing commands for Emacs
+
+;; Add code like the following to your .emacs to install:
+;; (autoload 'preserves-mode "...path.to.wherever.you.put.this.file.../preserves.el" nil t)
+;; (setq auto-mode-alist (cons '("\\.mu\\'" . preserves-mode)
+;;                             auto-mode-alist))
+
+;; Copyright (C) 1988,94,96,2000  Free Software Foundation, Inc.
+;; Copyright (C) 2003, 2005, 2011, 2016, 2019 Tony Garnock-Jones <tonyg@leastfixedpoint.com>
+
+;; This 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 2, or (at your option)
+;; any later version.
+
+;; This 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 software; see the file COPYING.  If not, write to the
+;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+;; Boston, MA 02111-1307, USA.
+
+(require 'font-lock)
+(require 'smie)
+
+;;---------------------------------------------------------------------------
+;; Font-lock, Indentation, and Mode
+
+(defvar preserves-mode-syntax-table (make-syntax-table)
+  "Syntax table in use in preserves-mode buffers.")
+
+;; (modify-syntax-entry ?' "\"" preserves-mode-syntax-table)
+(modify-syntax-entry ?_ "_" preserves-mode-syntax-table)
+(modify-syntax-entry ?\n "> b" preserves-mode-syntax-table)
+(modify-syntax-entry ?\r "> b" preserves-mode-syntax-table)
+(modify-syntax-entry ?/ ". 12b" preserves-mode-syntax-table)
+(mapcar #'(lambda (x) (modify-syntax-entry x "w" preserves-mode-syntax-table))
+        '(?- ?_ ?$ ?! ?? ?* ?+ ?~))
+
+(defvar preserves-font-lock-keywords
+  (list
+   '("\\<\\(~\\|[A-Z]\\)[^[:space:].\n]*\\>" . font-lock-type-face)
+   '("\\\\[[:space:]]*?\n" . font-lock-warning-face)
+   (cons (regexp-opt '("->") 'symbols) 'font-lock-builtin-face)
+
+   ;; (cons (regexp-opt
+   ;;        '(
+   ;;          "float"
+   ;;          "double"
+   ;;          "word32"
+   ;;          "word64"
+   ;;          "integer"
+   ;;          "boolean"
+   ;;          "text"
+   ;;          "set"
+   ;;          "list"
+   ;;          "dict"
+   ;;          "not"
+   ;;          "ref"
+   ;;          )
+   ;;        'words)
+   ;;       'font-lock-builtin-face)
+
+   ))
+
+(defun preserves-mode-variables ()
+  (make-local-variable 'comment-use-syntax)
+  (make-local-variable 'comment-start)
+  (make-local-variable 'comment-end)
+  (make-local-variable 'comment-start-skip)
+  (setq comment-use-syntax t)
+  (setq comment-start "//")
+  (setq comment-end "")
+  (setq comment-start-skip "// *")
+  (make-local-variable 'font-lock-defaults)
+  (setq font-lock-defaults '(preserves-font-lock-keywords nil nil ()))
+  (make-local-variable 'indent-line-function)
+  (setq indent-line-function #'preserves-indent-line)
+  )
+
+(defvar preserves-indent-basic 2
+  "Basic indentation amount for Preserves.")
+
+(defun preserves-continuation-line-p ()
+  (save-excursion
+    (and (zerop (forward-line -1))
+         (progn (end-of-line)
+                (skip-syntax-backward " ")
+                (eq (char-before) ?\\)))))
+
+(defun preserves-hanging-paren-p ()
+  (save-excursion
+    (forward-char)
+    (while (and (not (eq (char-after) ?\n))
+                (eq (char-syntax (char-after)) ?\s))
+      (forward-char))
+    (eolp)))
+
+(defun preserves-indent-line ()
+  (let ((new-indentation
+         (save-excursion
+           (beginning-of-line)
+           (skip-syntax-forward " ")
+           (let* ((at-close-paren (eq (char-syntax (char-after)) ?\)))
+                  (ppss (syntax-ppss)))
+             (cond
+              ((cadddr ppss) nil) ;; when we are in a string, don't reindent
+              ((<= (car ppss) 0) 0) ;; not in any parentheses, outdent fully
+              (t (goto-char (cadr ppss))
+                 (cond
+                  ((preserves-hanging-paren-p)
+                   (beginning-of-line)
+                   (skip-syntax-forward " ")
+                   (if at-close-paren ;; close paren, no indent
+                       (current-column)
+                     (+ preserves-indent-basic (current-column))))
+                  (at-close-paren ;; close paren, treat it specially
+                   (current-column))
+                  (t ;; not a close paren, do the default thing
+                   (forward-char)
+                   (skip-syntax-forward " ")
+                   (current-column)))))))))
+    (when new-indentation
+      (indent-line-to (if (preserves-continuation-line-p)
+                          (+ new-indentation preserves-indent-basic)
+                        new-indentation)))))
+
+;;;###autoload
+(define-derived-mode preserves-mode prog-mode "Preserves"
+  "Major mode for editing Preserves structures."
+  (preserves-mode-variables))
+
+;;---------------------------------------------------------------------------
+;; Provides
+
+(provide 'preserves-mode)
+
+;;; preserves.el ends here