guile-prescheme/ps-compiler/util/util.scm

;;; Ported from Scheme 48 1.9.  See file COPYING for notices and license.
;;;
;;; Port Author: Andrew Whatson
;;;
;;; Original Authors: Richard Kelsey, Mike Sperber
;;;
;;;   scheme48-1.9.2/ps-compiler/util/util.scm

(define-module (ps-compiler util util)
  #:use-module (prescheme scheme48)
  #:replace (or-map string-hash)
  #:export (bug
            user-error
            user-warning
            true false
            remove-similar-elts
            select-from-table
            table->list table->entry-list
            table-push table-pop
            merge-lists
            vector-every?
            make-ignorable
            sub-vector->list
            flag-assq

            enforce
            writec
            mem?
            walk-vector
            vector-replace
            copy-list
            copy-vector
            object-hash
            union intersection set-difference))

;; Messages
;;==========================================================================

(define (bug format-string . args)
  (apply error (list "~?~%  (compiler error)" format-string args)))

(define (user-error format-string . args)
  (apply error (list "~?~%  (source error)" format-string args)))

(define (user-warning format-string . args)
  (apply error (list "~?~%  (source error)" format-string args)))

;; Little utilities.
;;========================================================================

(define (true  x) #t)
(define (false x) #f)

(define (or-map proc list)
  (do ((list list (cdr list))
       (r '#f (or (proc (car list)) r)))
      ((null? list) r)))

(define (remove-similar-elts pred list)
  (do ((list list (cdr list))
       (res  '()  (if (mem? pred (car list) res)
                      res
                      (cons (car list) res))))
      ((null-list? list)
       res)))

(define (select-from-table pred table)
  (let ((res '()))
    (table-walk (lambda (key entry)
                  (if (pred key entry)
                      (set! res `((,key . ,entry) . ,res))))
                table)
    res))

(define (table->list table)
  (select-from-table (lambda (x y) #t) table))

;; this is exported from `tables', but that's a fairly recent development
(define (table->entry-list table)
  (let ((res '()))
    (table-walk (lambda  (key entry)
                  (set! res (cons entry res)))
                table)
    res))

(define (table-push table key val)
  (let ((old (table-ref table key)))
    (table-set! table key (if old
                              (cons val old)
                              (list val)))
    val))

(define (table-pop table key)
  (let ((old (table-ref table key)))
    (table-set! table key (cdr old))
    (car old)))

(define (merge-lists x y)
  (cond ((null? y) x)
        (else (do ((z x (cdr z))
                   (u y (let ((w (car z)))
                          (if (memq? w u) u (cons w u)))))
                  ((null? z) u)))))

(define (vector-every? pred vec)
  (let loop ((i (- (vector-length vec) '1)))
    (cond ((< i '0)
           '#t)
          ((not (pred (vector-ref vec i)))
           '#f)
          (else
           (loop (- i '1))))))

(define (make-ignorable vars)
  (let loop ((vars vars) (res '()))
    (cond ((null? vars)
           `(ignorable . ,res))
          ((atom? vars)
           `(ignorable ,vars . ,res))
          (else
           (loop (cdr vars) (cons (car vars) res))))))

(define (sub-vector->list vec start)
  (do ((i (- (vector-length vec) '1) (- i '1))
       (r '() (cons (vector-ref vec i) r)))
      ((< i start)
       r)))

;; A version of ASSQ that works on lists containing atoms.

(define (flag-assq obj list)
  (let loop ((l list))
    (if (null-list? l)
        #f
        (let ((z (car l)))
          (if (and (pair? z)
                   (eq? obj (car z)))
              z
              (loop (cdr l)))))))

;; T system stuff

(define (enforce predicate value)
  (if (predicate value)
      value
      (error "enforce ~A failed on ~A" predicate value)))

(define (writec port char)
  (write-char char port))

(define (mem? predicate object list)
  (let loop ((list list))
    (cond ((null? list)
           #f)
          ((predicate object (car list))
           #t)
          (else
           (loop (cdr list))))))

(define (walk-vector procedure vector)
  (do ((i 0 (+ i 1)))
      ((>= i (vector-length vector))
       (values))
    (procedure (vector-ref vector i))))

(define (vector-replace to from count)
  (do ((i 0 (+ i 1)))
      ((>= i count))
    (vector-set! to i (vector-ref from i)))
  (values))

(define (copy-vector vector)
  (let ((new (make-vector (vector-length vector))))
    (do ((i 0 (+ i 1)))
        ((= i (vector-length vector)))
      (vector-set! new i (vector-ref vector i)))
    new))

(define (copy-list list)
  (if (null-list? list)
      list
      (let ((copy (cons (car list) '())))
        (let loop ((list (cdr list)) (result copy))
          (cond ((not (null-list? list))
                 (let ((next (cons (car list) '())))
                   (set-cdr! result next)
                   (loop (cdr list) next)))))
        copy)))

(define (object-hash x)
  0)           ; wah!

(define (union l1 l2)
  (if (null? l2)
      l1
      (do ((l1 l1 (cdr l1))
           (res l2 (if (memq? (car l1) res) res (cons (car l1) res))))
          ((null? l1)
           res))))

(define (intersection l1 l2)
  (if (null? l2)
      '()
      (do ((l1 l1 (cdr l1))
           (res '() (if (memq? (car l1) l2) (cons (car l1) res) res)))
          ((null? l1)
           res))))

(define (set-difference l1 l2)
  (if (null? l2)
      l1
      (do ((l1 l1 (cdr l1))
           (res '() (if (memq? (car l1) l2) res (cons (car l1) res))))
          ((null? l1)
           res))))