#lang scheme/base
 (all-from-out syntax/stx))

(define (format-stx fmt . args)
  (apply format fmt (->sexp args)))
(define (map-stx fn . stxs)
  (apply map fn (map syntax->list stxs)))

;; FIXME: doesn't handle all cases (i.e. vectors..)
(define (->sexp x)
   ((syntax? x) (syntax->datum x))
   ((list? x)   (map ->sexp x))
   ((pair? x)   (cons (->sexp (car x)) (->sexp (cdr x))))
   ((null? x)   '())
   (else x)))

; (define ->syntax datum->syntax)
; (define ->datum  syntax->datum)

(define (prefix-id . names)
  (let ((orig-stx (car (reverse names)))) ;; use original name info
    (datum->syntax orig-stx   ;; lexical context
                    (apply string-append
                            (lambda (x)
                              (format "~a"
                                      (if (syntax? x)
                                          (syntax->datum x)
                   orig-stx   ;; source info
                   orig-stx   ;; properties

(define (stx-reverse stx)
  #`(#,@(reverse (syntax->list stx))))

(define (lexical-binding? stx)
  (eq? 'lexical (identifier-binding stx)))

(define (stx-uncons stx)
  (values (stx-car stx) (stx-cdr stx)))

(define (stx-length s)
  (length (syntax->datum s)))

;; re-interpret lexical interpretation, keeping source location. can
;; be used for 'include' semantics.
(define (lexical-context-from stx-lex)
  (lambda (stx)
    (let ((new-stx
           (datum->syntax stx-lex
                          (syntax->datum stx)
      ;; (printf "~a ~a ~a\n" (syntax->datum stx) (syntax-source stx) (syntax-source new-stx))

;; Expand all sub-expressions in a tree.
(define-syntax-rule (syntax-case/r tree-stx literals clause ...)
  (let down ((stx tree-stx))
    (syntax-case stx literals
      clause ...
      ((el (... ...))
       (map down (syntax->list #'(el (... ...)))))
      (el #'el))))

;; Structs

(define (struct->struct-info name [context name])
  (let ([v (syntax-local-value name (lambda () #f))])
    (unless (struct-info? v)
      (raise-syntax-error #f "identifier is not bound to a structure type" context name))
    (let ((v (extract-struct-info v)))
      (printf "~a\n" v)

(define (struct->constructor . a) (cadr (apply struct->struct-info a)))
(define (struct->members . a)     (cadddr (apply struct->struct-info a)))

(define (in-stx stx) (in-list (syntax->list stx)))

;; Non-higienically introduce a collection of identifiers.
(define (datum->syntax-list stx lst)
  (map (lambda (x) (datum->syntax stx x)) lst))

(define-syntax-rule (syntax-introduce-identifiers stx lst body)
  (syntax-case (datum->syntax-list stx 'lst) ()
    (lst body)))

;; Hash tables of identifiers represented as symbols.  Useful for code
;; analysis.

(define-syntax-rule (define-hashes name ...)
  (begin (define name (make-hash)) ...))

(define (datum id) (if (syntax? id) (syntax->datum id) id))
(define (id-reg! hash id [val #t]) (hash-set! hash (datum id) val))
(define (id-find hash id) (hash-ref hash (datum id) false))
(define (ids hash) (for/list (((k v) hash)) k))

(require (for-template scheme/base))

;; Staged macros: safe syntax evaluation at compile time.
;; (require (for-syntax scheme/base))
(define-syntax-rule (let-staged ((n v) ...) body ...)
        ((m (lambda (stx)
              (let ((n v) ...) body ...))))

;; (provide (for-template (all-from-out scheme/base)))