;;; lego-syntax.el --- Syntax of LEGO

;; This file is part of Proof General.

;; Portions © Copyright 1994-2012  David Aspinall and University of Edinburgh
;; Portions © Copyright 2003, 2012, 2014  Free Software Foundation, Inc.
;; Portions © Copyright 2001-2017  Pierre Courtieu
;; Portions © Copyright 2010, 2016  Erik Martin-Dorel
;; Portions © Copyright 2011-2013, 2016-2017  Hendrik Tews
;; Portions © Copyright 2015-2017  Clément Pit-Claudel

;; Author: Thomas Kleymann and Dilip Sequeira
;; Maintainer: Paul Callaghan <P.C.Callaghan@durham.ac.uk>

;; License:     GPL (GNU GENERAL PUBLIC LICENSE)

;;; Commentary:
;;

;;; Code:

(require 'proof-syntax)

;; ----- keywords for font-lock.

(defconst lego-keywords-goal '("$?Goal"))

(defconst lego-keywords-save '("$?Save" "SaveFrozen" "SaveUnfrozen"))

(defconst lego-commands
  (append lego-keywords-goal lego-keywords-save
	  '("allE" "allI" "andE" "andI" "Assumption" "Claim"
	    "Cut" "Discharge" "DischargeKeep"
	    "echo" "exE" "exI" "Expand" "ExpAll"
	    "ExportState" "Equiv" "For" "Freeze" "Hnf" "Immed"
	    "impE" "impI" "Induction" "Inductive"
	    "Invert" "Init" "intros" "Intros" "Module" "Next"
	    "Normal" "notE" "notI" "orE" "orIL" "orIR" "qnify" "Qnify"
	    "Qrepl" "Record" "Refine" "Repeat" "Try" "Unfreeze"))
  "Subset of LEGO keywords and tacticals which are terminated by a \?;")

(defconst lego-keywords
  (append lego-commands
	  '("Constructors" "Double" "ElimOver" "Fields" "Import" "Inversion"
	    "NoReductions" "Parameters" "Relation" "Theorems")))

(defconst lego-tacticals '("Then" "Else" "Try" "Repeat" "For"))

;; ----- regular expressions for font-lock
(defconst lego-error-regexp "^\\(cannot assume\\|Error\\|Lego parser\\)"
  "A regular expression indicating that the LEGO process has identified an error.")

(defvar lego-id proof-id)

(defvar lego-ids (concat lego-id "\\(\\s *,\\s *" lego-id "\\)*")
  "*For font-lock, we treat \",\" separated identifiers as one identifier
  and refontify commata using \\{lego-fixup-change}.")

(defconst lego-arg-list-regexp "\\s *\\(\\[[^]]+\\]\\s *\\)*"
  "Regular expression maching a list of arguments.")

(defun lego-decl-defn-regexp (char)
    (concat "\\[\\s *\\(" lego-ids "\\)" lego-arg-list-regexp char))
; Examples
;              ^        ^^^^        ^^^^^^^^^^^^^^^^^^^^^^^  ^^^^
;              [        sort                                 =
;              [        sort        [n:nat]                  =
;              [        sort        [abbrev=...][n:nat]      =

(defconst lego-definiendum-alternative-regexp
  (concat "\\(" lego-id "\\)" lego-arg-list-regexp "\\s * ==")
  "Regular expression where the first match identifies the definiendum.")

(defvar lego-font-lock-terms
  (list

   ; lambda binders
     (list (lego-decl-defn-regexp "[:|?]") 1
	   'proof-declaration-name-face)

     ; let binders
     (list lego-definiendum-alternative-regexp 1 'font-lock-function-name-face)
     (list (lego-decl-defn-regexp "=") 1 'font-lock-function-name-face)

     ; Pi and Sigma binders
     (list (concat "[{<]\\s *\\(" lego-ids "\\)") 1
	   'proof-declaration-name-face)

     ;; Kinds
     (cons (concat "\\<Prop\\>\\|\\<Type\\s *\\(("
		   lego-id ")\\)?") 'font-lock-type-face)

     ;; Special hacks!!
     (cons "Discharge.." 'font-lock-keyword-face)
     (cons "\\*\\*\\* QED \\*\\*\\*" 'font-lock-keyword-face))
  "*Font-lock table for LEGO terms (displayed in output buffers).")

;; Instead of "[^:]+", it may be better to use "lego-id". Furthermore,
;; it might be safer to append "\\s-*:".
(defconst lego-goal-with-hole-regexp
  (concat "\\(" (proof-ids-to-regexp lego-keywords-goal) "\\)\\s-+\\([^(){},:]+\\)")
  "Regular expression which matches an entry in `lego-keywords-goal'
  and the name of the goal.")

(defconst lego-save-with-hole-regexp
  (concat "\\(" (proof-ids-to-regexp lego-keywords-save) "\\)\\s-+\\([^;]+\\)")
  "Regular expression which matches an entry in
  `lego-keywords-save' and the name of the goal.")

(defvar lego-font-lock-keywords-1
   (append
    lego-font-lock-terms
    (list
     (cons (proof-ids-to-regexp lego-keywords) 'font-lock-keyword-face)
     (cons (proof-ids-to-regexp lego-tacticals) 'proof-tacticals-name-face)
     (list lego-goal-with-hole-regexp 2 'font-lock-function-name-face)
     (list lego-save-with-hole-regexp 2 'font-lock-function-name-face)
     ;; Remove spurious variable and function faces on commas.
     '(proof-zap-commas))))

(defun lego-init-syntax-table ()
  "Set appropriate values for syntax table in current buffer."

  (modify-syntax-entry ?_ "_")
  (modify-syntax-entry ?\' "_")
  (modify-syntax-entry ?\| ".")
  (modify-syntax-entry ?\* ". 23")
  (modify-syntax-entry ?\( "()1")
  (modify-syntax-entry ?\) ")(4"))

(provide 'lego-syntax)