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+; "hashtab.scm", hash tables for Scheme.
+; Copyright (c) 1992, 1993 Aubrey Jaffer
+;
+;Permission to copy this software, to redistribute it, and to use it
+;for any purpose is granted, subject to the following restrictions and
+;understandings.
+;
+;1.  Any copy made of this software must include this copyright notice
+;in full.
+;
+;2.  I have made no warrantee or representation that the operation of
+;this software will be error-free, and I am under no obligation to
+;provide any services, by way of maintenance, update, or otherwise.
+;
+;3.  In conjunction with products arising from the use of this
+;material, there shall be no use of my name in any advertising,
+;promotional, or sales literature without prior written consent in
+;each case.
+
+(require 'hash)
+(require 'alist)
+
+(define (predicate->hash pred)
+  (cond ((eq? pred eq?) hashq)
+	((eq? pred eqv?) hashv)
+	((eq? pred equal?) hash)
+	((eq? pred =) hashv)
+	((eq? pred char=?) hashv)
+	((eq? pred char-ci=?) hashv)
+	((eq? pred string=?) hash)
+	((eq? pred string-ci=?) hash)
+	(else (slib:error "unknown predicate for hash" pred))))
+
+(define (make-hash-table k) (make-vector k '()))
+
+(define (predicate->hash-asso pred)
+  (let ((hashfun (predicate->hash pred))
+	(asso (predicate->asso pred)))
+    (lambda (key hashtab)
+      (asso key
+	    (vector-ref hashtab (hashfun key (vector-length hashtab)))))))
+
+(define (hash-inquirer pred)
+  (let ((hashfun (predicate->hash pred))
+	(ainq (alist-inquirer pred)))
+    (lambda (hashtab key)
+      (ainq (vector-ref hashtab (hashfun key (vector-length hashtab)))
+	    key))))
+
+(define (hash-associator pred)
+  (let ((hashfun (predicate->hash pred))
+	(asso (alist-associator pred)))
+    (lambda (hashtab key val)
+      (let* ((num (hashfun key (vector-length hashtab))))
+	(vector-set! hashtab num
+		     (asso (vector-ref hashtab num) key val)))
+      hashtab)))
+
+(define (hash-remover pred)
+  (let ((hashfun (predicate->hash pred))
+	(arem (alist-remover pred)))
+    (lambda (hashtab key)
+      (let* ((num (hashfun key (vector-length hashtab))))
+	(vector-set! hashtab num
+		     (arem (vector-ref hashtab num) key)))
+      hashtab)))
+
+(define (hash-map proc ht)
+  (define nht (make-vector (vector-length ht)))
+  (do ((i (+ -1 (vector-length ht)) (+ -1 i)))
+      ((negative? i) nht)
+    (vector-set!
+     nht i
+     (alist-map proc (vector-ref ht i)))))
+
+(define (hash-for-each proc ht)
+  (do ((i (+ -1 (vector-length ht)) (+ -1 i)))
+      ((negative? i))
+    (alist-for-each proc (vector-ref ht i))))