;;; MAKEFILE:
;;; =========

;;; (define-syntax makefile
;;;   (syntax-rules () 
;;;     ((makefile ?rule0 ...)
;;;      (let ((rule-candidates '()))
;;;        (let* ((rule-candidates (?rule0 rule-candidates))
;;; 	      ...)
;;; 	 rule-candidates)))))

;;; 
;;; <makefile> ::= '(' + "makefile" + <makerule-clause>* + ')'
;;; <makerule-clause> ::= <rule-clause> 
;;;                       | <md5-clause> 
;;; 		          | <always-clause> 
;;; 		          | <once-clause>
;;; 
;;;
(define-syntax makefile
  (syntax-rules () 
    ((makefile) (list))
    ((makefile ?rule0 ?rule1 ...) (?rule0 (makefile ?rule1 ...)))))

;;; 
;;; <rule-clause>
;;; 
;;; to achieve consistency only rule will use the rule-tmpvars 
;;; macro directly and all other macros use this clause
;;; 
(define-syntax makefile-rule
  (syntax-rules ()
    ((makefile-rule ?target ?prereqs ?thunk) (rule ?target ?prereqs ?thunk))))

(define-syntax is-out-of-date?
  (syntax-rules ()
    ((is-out-of-date? ?target ?prereqs ?thunk) (rule ?target ?prereqs ?thunk))))

(define-syntax rule
  (syntax-rules ()
    ((rule ?target (?prereq0 ...) ?thunk)
     (rule-tmpvars () ?target (?prereq0 ...) ?thunk))))

(define-syntax rule-tmpvars
  (syntax-rules ()
    ((rule-tmpvars (tmp1 ...) ?target () ?thunk)
     (let ((target ?target)
	   (prereqs (list tmp1 ...)))
       (lambda (rule-candidates)
	 (cons (list target
		     prereqs
		     (make-is-out-of-date? target tmp1 ...)
		     (make-rule-build-func target prereqs ?thunk))
	       rule-candidates))))
    ((rule-tmpvars (tmp1 ...) ?target (?prereq0 ?prereq1 ...) ?thunk)
     (let ((tmp2 ?prereq0))
       (rule-tmpvars (tmp1 ... tmp2) ?target (?prereq1 ...) ?thunk)))))

;;; 
;;; <md5-clause>
;;; 
;;; to achieve consistency only rule-md5 will use the rule-md5-tmpvars 
;;; macro directly and all other macros use this clause
;;; 
(define-syntax md5
  (syntax-rules ()
    ((md5 ?target ?prereqs ?thunk) (rule-md5 ?target ?prereqs ?thunk))))

(define-syntax rule-md5
  (syntax-rules ()
    ((rule-md5 ?target (?prereq0 ...) ?thunk) 
     (rule-md5-tmpvars () ?target (?prereq0 ...) ?thunk))))

(define-syntax rule-md5-tmpvars
  (syntax-rules ()
    ((rule-md5-tmpvars (tmp1 ...) ?target () ?thunk)
     (let ((target ?target)
	   (prereqs (list tmp1 ...)))
       (lambda (rule-candidates)
	 (cons (list target
		     prereqs
		     (make-md5-sum-changed? target tmp1 ...)
		     (make-md5-build-func target prereqs ?thunk))
	       rule-candidates))))
    ((rule-md5-tmpvars (tmp1 ...) ?target (?prereq0 ?prereq1 ...) ?thunk)
     (let ((tmp2 ?prereq0))
       (rule-md5-tmpvars (tmp1 ... tmp2) ?target (?prereq1 ...) ?thunk)))))

;;; 
;;; <always-clause>
;;; 
;;; to achieve consistency only rule-always will use the rule-always-tmpvars 
;;; macro directly and all other macros use this clause
;;; 
(define-syntax phony
  (syntax-rules ()
    ((phony ?target ?prereqs ?thunk) (rule-always ?target ?prereqs ?thunk))))

(define-syntax always
  (syntax-rules ()
    ((always ?target ?prereqs ?thunk) (rule-always ?target ?prereqs ?thunk))))

(define-syntax is-out-of-date!
  (syntax-rules ()
    ((is-out-of-date! ?target ?prereqs ?thunk) 
     (rule-always ?target ?prereqs ?thunk))))

(define-syntax rule-always
  (syntax-rules ()
    ((rule-always ?target (?prereq0 ...) ?thunk)
     (rule-always-tmpvars () ?target (?prereq0 ...) ?thunk))))

(define-syntax rule-always-tmpvars
  (syntax-rules ()
    ((rule-always-tmpvars (tmp1 ...) ?target () ?thunk)
     (let ((target ?target)
	   (prereqs (list tmp1 ...)))
       (lambda (rule-candidates)
	 (cons (list target
		     prereqs
		     (make-is-out-of-date! target tmp1 ...)
		     (make-always-build-func target prereqs ?thunk))
	       rule-candidates))))
    ((rule-always-tmpvars (tmp1 ...) ?target (?prereq0 ?prereq1 ...) ?thunk)
     (let ((tmp2 ?prereq0))
       (rule-always-tmpvars (tmp1 ... tmp2) ?target (?prereq1 ...) ?thunk)))))

;;; 
;;; <once-clause>
;;; 
;;; to achieve consistency only rule-once will use the rule-once-tmpvars 
;;; macro directly and all other macros use this clause
;;; 
(define-syntax once
  (syntax-rules ()
    ((once ?target ?prereqs ?thunk)
     (rule-once ?target ?prereqs ?thunk))))

(define-syntax rule-once
  (syntax-rules ()
    ((rule-once ?target (?prereq0 ...) ?thunk)
     (rule-once-tmpvars () ?target (?prereq0 ...) ?thunk))))

(define-syntax rule-once-tmpvars
  (syntax-rules ()
    ((rule-once-tmpvars (tmp1 ...) ?target () ?thunk)
     (let ((target ?target)
	   (prereqs (list tmp1 ...)))
       (lambda (rule-candidates)
	 (cons (list target
		     prereqs
		     (make-once target tmp1 ...)
		     (make-once-build-func target prereqs ?thunk))
	       rule-candidates))))
    ((rule-once-tmpvars (tmp1 ...) ?target (?prereq0 ?prereq1 ...) ?thunk)
     (let ((tmp2 ?prereq0))
       (rule-once-tmpvars (tmp1 ... tmp2) ?target (?prereq1 ...) ?thunk)))))