module/ice-9/hash-table.scm

   1 ;;;; hash-table.scm --- Additional hash table procedures
   2 ;;;; Copyright (C) 2013 Free Software Foundation, Inc.
   3 ;;;;
   4 ;;;; This library is free software; you can redistribute it and/or
   5 ;;;; modify it under the terms of the GNU Lesser General Public
   6 ;;;; License as published by the Free Software Foundation; either
   7 ;;;; version 3 of the License, or (at your option) any later version.
   8 ;;;;
   9 ;;;; This library is distributed in the hope that it will be useful,
  10 ;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 ;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12 ;;;; Lesser General Public License for more details.
  13 ;;;;
  14 ;;;; You should have received a copy of the GNU Lesser General Public
  15 ;;;; License along with this library; if not, write to the Free Software
  16 ;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  17 ;;;;
  18
  19 (define-module (ice-9 hash-table)
  20   #:export (alist->hash-table
  21             alist->hashq-table
  22             alist->hashv-table
  23             alist->hashx-table))
  24
  25 (define-syntax-rule (define-alist-converter name hash-set-proc)
  26   (define (name alist)
  27     "Convert ALIST into a hash table."
  28     (let ((table (make-hash-table)))
  29       (for-each (lambda (pair)
  30                   (hash-set-proc table (car pair) (cdr pair)))
  31                 (reverse alist))
  32       table)))
  33
  34 (define-alist-converter alist->hash-table hash-set!)
  35 (define-alist-converter alist->hashq-table hashq-set!)
  36 (define-alist-converter alist->hashv-table hashv-set!)
  37
  38 (define (alist->hashx-table hash assoc alist)
  39   "Convert ALIST into a hash table with custom HASH and ASSOC
  40 procedures."
  41   (let ((table (make-hash-table)))
  42     (for-each (lambda (pair)
  43                 (hashx-set! hash assoc table (car pair) (cdr pair)))
  44               (reverse alist))
  45     table))