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1 ;;; alist.el --- utility functions about assoc-list
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2
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3 ;; Copyright (C) 1993,1994,1995,1996 Free Software Foundation, Inc.
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4
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5 ;; Author: MORIOKA Tomohiko <morioka@jaist.ac.jp>
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6 ;; Version:
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7 ;; $Id: alist.el,v 1.1 1997/11/29 20:37:43 steve Exp $
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8 ;; Keywords: alist
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9
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10 ;; This file is part of SEMI (SEMI is Emacs MIME Interfaces).
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11
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12 ;; This program is free software; you can redistribute it and/or
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13 ;; modify it under the terms of the GNU General Public License as
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14 ;; published by the Free Software Foundation; either version 2, or (at
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15 ;; your option) any later version.
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16
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17 ;; This program is distributed in the hope that it will be useful, but
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18 ;; WITHOUT ANY WARRANTY; without even the implied warranty of
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19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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20 ;; General Public License for more details.
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21
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22 ;; You should have received a copy of the GNU General Public License
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23 ;; along with GNU Emacs; see the file COPYING. If not, write to the
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24 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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25 ;; Boston, MA 02111-1307, USA.
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26
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27 ;;; Code:
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28
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29 (defun put-alist (item value alist)
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30 "Modify ALIST to set VALUE to ITEM.
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31 If there is a pair whose car is ITEM, replace its cdr by VALUE.
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32 If there is not such pair, create new pair (ITEM . VALUE) and
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33 return new alist whose car is the new pair and cdr is ALIST.
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34 \[tomo's ELIS like function]"
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35 (let ((pair (assoc item alist)))
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36 (if pair
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37 (progn
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38 (setcdr pair value)
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39 alist)
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40 (cons (cons item value) alist)
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41 )))
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42
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43 (defun del-alist (item alist)
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44 "If there is a pair whose key is ITEM, delete it from ALIST.
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45 \[tomo's ELIS emulating function]"
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46 (if (equal item (car (car alist)))
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47 (cdr alist)
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48 (let ((pr alist)
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49 (r (cdr alist))
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50 )
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51 (catch 'tag
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52 (while (not (null r))
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53 (if (equal item (car (car r)))
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54 (progn
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55 (rplacd pr (cdr r))
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56 (throw 'tag alist)))
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57 (setq pr r)
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58 (setq r (cdr r))
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59 )
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60 alist))))
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61
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62 (defun set-alist (symbol item value)
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63 "Modify a alist indicated by SYMBOL to set VALUE to ITEM."
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64 (or (boundp symbol)
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65 (set symbol nil)
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66 )
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67 (set symbol (put-alist item value (symbol-value symbol)))
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68 )
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69
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70 (defun remove-alist (symbol item)
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71 "Remove ITEM from the alist indicated by SYMBOL."
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72 (and (boundp symbol)
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73 (set symbol (del-alist item (symbol-value symbol)))
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74 ))
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75
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76 (defun modify-alist (modifier default)
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77 "Modify alist DEFAULT into alist MODIFIER."
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78 (mapcar (function
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79 (lambda (as)
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80 (setq default (put-alist (car as)(cdr as) default))
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81 ))
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82 modifier)
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83 default)
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84
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85 (defun set-modified-alist (sym modifier)
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86 "Modify a value of a symbol SYM into alist MODIFIER.
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87 The symbol SYM should be alist. If it is not bound,
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88 its value regard as nil."
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89 (if (not (boundp sym))
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90 (set sym nil)
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91 )
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92 (set sym (modify-alist modifier (eval sym)))
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93 )
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94
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95
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96 ;;; @ end
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97 ;;;
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98
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99 (provide 'alist)
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100
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101 ;;; alist.el ends here
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