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b8608812 | 1 | ;;; -*-lisp-*- |
2 | ;;; | |
b8608812 | 3 | ;;; Anaphoric extensions |
4 | ;;; | |
5 | ;;; (c) 2005 Straylight/Edgeware | |
6 | ;;; | |
7 | ||
8 | ;;;----- Licensing notice --------------------------------------------------- | |
9 | ;;; | |
10 | ;;; This program is free software; you can redistribute it and/or modify | |
11 | ;;; it under the terms of the GNU General Public License as published by | |
12 | ;;; the Free Software Foundation; either version 2 of the License, or | |
13 | ;;; (at your option) any later version. | |
b2c12b4e | 14 | ;;; |
b8608812 | 15 | ;;; This program is distributed in the hope that it will be useful, |
16 | ;;; but WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | ;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
18 | ;;; GNU General Public License for more details. | |
b2c12b4e | 19 | ;;; |
b8608812 | 20 | ;;; You should have received a copy of the GNU General Public License |
21 | ;;; along with this program; if not, write to the Free Software Foundation, | |
22 | ;;; Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
23 | ||
1dc0d275 | 24 | (defpackage #:anaphora |
0eed4749 | 25 | (:use #:common-lisp #:mdw.base)) |
1dc0d275 | 26 | (in-package #:anaphora) |
b8608812 | 27 | |
e8567770 MW |
28 | (export 'it) |
29 | ||
30 | (export 'aif) | |
b8608812 | 31 | (defmacro aif (cond then &optional else) |
32 | "Bind `it' to result of COND when evaluating THEN or ELSE." | |
33 | `(let ((it ,cond)) | |
34 | (if it ,then ,@(and else (list else))))) | |
0ff9df03 | 35 | |
e8567770 | 36 | (export 'aif2) |
b8608812 | 37 | (defmacro aif2 (cond then &optional else) |
38 | "Bind `it' to first value of COND; switch on second." | |
39 | (let ((tmp (gensym))) | |
40 | `(multiple-value-bind (it ,tmp) ,cond | |
41 | (declare (ignorable it)) | |
42 | (if ,tmp ,then ,@(and else (list else)))))) | |
43 | ||
e8567770 | 44 | (export 'awhen) |
b8608812 | 45 | (defmacro awhen (cond &body body) |
46 | "Bind `it' to result of COND when evaluating BODY." | |
47 | `(let ((it ,cond)) | |
48 | (when it ,@body))) | |
0ff9df03 | 49 | |
e8567770 | 50 | (export 'awhen2) |
b8608812 | 51 | (defmacro awhen2 (cond &body body) |
52 | "Bind `it' to first value of COND; switch on second." | |
53 | (let ((tmp (gensym))) | |
54 | `(multiple-value-bind (it ,tmp) ,cond | |
55 | (declare (ignorable it)) | |
56 | (when ,tmp ,@body)))) | |
57 | ||
e8567770 | 58 | (export 'aand) |
b8608812 | 59 | (defmacro aand (&rest things) |
60 | "Like `and', with `it' bound to previous value." | |
61 | (labels ((foo (things) | |
62 | (if (cdr things) | |
63 | `(let ((it ,(car things))) | |
64 | (if it ,(foo (cdr things)))) | |
65 | (car things)))) | |
66 | (if things | |
67 | (foo things) | |
68 | t))) | |
69 | ||
e8567770 | 70 | (export 'awhile) |
b8608812 | 71 | (defmacro awhile (cond &body body) |
72 | "Like `while', with `it' bound to value of COND in BODY." | |
73 | `(loop | |
74 | (let ((it ,cond)) | |
75 | (unless it (return)) | |
76 | ,@body))) | |
77 | ||
e8567770 | 78 | (export 'asetf) |
0eed4749 | 79 | (defmacro asetf (&rest pairs) |
b8608812 | 80 | "Set PLACE to value of FORM; in FORM, `it' is bound to current value of |
0ff9df03 | 81 | PLACE." |
0eed4749 MW |
82 | `(progn ,@(do ((list nil) |
83 | (pairs pairs (cddr pairs))) | |
84 | ((endp pairs) (nreverse list)) | |
85 | (unless (cdr pairs) | |
86 | (error "Odd number of arguments to `asetf'.")) | |
87 | (push (with-places/gensyms ((place (car pairs))) | |
88 | `(let ((it ,place)) | |
89 | (declare (ignorable it)) | |
90 | (setf ,place ,(cadr pairs)))) | |
91 | list)))) | |
b2c12b4e | 92 | |
e8567770 | 93 | (export 'acond) |
b8608812 | 94 | (defmacro acond (&rest clauses) |
95 | "Like `cond', but in each clause the consequent has `it' bound to the value | |
0ff9df03 | 96 | of its guard." |
b8608812 | 97 | (labels ((foo (clauses) |
98 | (when clauses | |
99 | (let ((tmp (gensym)) | |
100 | (clause (car clauses))) | |
101 | `(let ((,tmp ,(car clause))) | |
102 | (if ,tmp | |
103 | (let ((it ,tmp)) | |
104 | (declare (ignorable it)) | |
105 | ,@(cdr clause)) | |
106 | ,(foo (cdr clauses)))))))) | |
107 | (foo clauses))) | |
108 | ||
109 | ;;;----- That's all, folks -------------------------------------------------- |