lisp/obarray.el

   1 ;;; obarray.el --- obarray functions -*- lexical-binding: t -*-
   2
   3 ;; Copyright (C) 2015-2017 Free Software Foundation, Inc.
   4
   5 ;; Maintainer: emacs-devel@gnu.org
   6 ;; Keywords: obarray functions
   7 ;; Package: emacs
   8
   9 ;; This file is part of GNU Emacs.
  10
  11 ;; GNU Emacs is free software: you can redistribute it and/or modify
  12 ;; it under the terms of the GNU General Public License as published by
  13 ;; the Free Software Foundation, either version 3 of the License, or
  14 ;; (at your option) any later version.
  15
  16 ;; GNU Emacs is distributed in the hope that it will be useful,
  17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 ;; GNU General Public License for more details.
  20
  21 ;; You should have received a copy of the GNU General Public License
  22 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  23
  24 ;;; Commentary:
  25
  26 ;; This file provides function for working with obarrays.
  27
  28 ;;; Code:
  29
  30 (defconst obarray-default-size 59
  31   "The value 59 is an arbitrary prime number that gives a good hash.")
  32
  33 (defun obarray-make (&optional size)
  34   "Return a new obarray of size SIZE or `obarray-default-size'."
  35   (let ((size (or size obarray-default-size)))
  36     (if (< 0 size)
  37         (make-vector size 0)
  38       (signal 'wrong-type-argument '(size 0)))))
  39
  40 (defun obarrayp (object)
  41   "Return t if OBJECT is an obarray."
  42   (and (vectorp object)
  43        (< 0 (length object))))
  44
  45 ;; Don’t use obarray as a variable name to avoid shadowing.
  46 (defun obarray-get (ob name)
  47   "Return symbol named NAME if it is contained in obarray OB.
  48 Return nil otherwise."
  49   (intern-soft name ob))
  50
  51 (defun obarray-put (ob name)
  52   "Return symbol named NAME from obarray OB.
  53 Creates and adds the symbol if doesn't exist."
  54   (intern name ob))
  55
  56 (defun obarray-remove (ob name)
  57   "Remove symbol named NAME if it is contained in obarray OB.
  58 Return t on success, nil otherwise."
  59   (unintern name ob))
  60
  61 (defun obarray-map (fn ob)
  62   "Call function FN on every symbol in obarray OB and return nil."
  63   (mapatoms fn ob))
  64
  65 (provide 'obarray)
  66 ;;; obarray.el ends here