source: trunk/abcl/src/org/armedbear/lisp/case.lisp @ 14207

Last change on this file since 14207 was 11391, checked in by vvoutilainen, 12 years ago

ABCL license is GPL + Classpath exception. This was intended
by Peter Graves, the original author. For reference, see
http://sourceforge.net/mailarchive/forum.php?thread_name=20040721115302.839%40prufrock&forum_name=armedbear-j-announce

  • Property svn:eol-style set to native
  • Property svn:keywords set to Id
File size: 7.3 KB
Line 
1;;; case.lisp
2;;;
3;;; Copyright (C) 2003-2005 Peter Graves
4;;; $Id: case.lisp 11391 2008-11-15 22:38:34Z vvoutilainen $
5;;;
6;;; This program is free software; you can redistribute it and/or
7;;; modify it under the terms of the GNU General Public License
8;;; as published by the Free Software Foundation; either version 2
9;;; of the License, or (at your option) any later version.
10;;;
11;;; This program is distributed in the hope that it will be useful,
12;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
13;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14;;; GNU General Public License for more details.
15;;;
16;;; You should have received a copy of the GNU General Public License
17;;; along with this program; if not, write to the Free Software
18;;; Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
19;;;
20;;; As a special exception, the copyright holders of this library give you
21;;; permission to link this library with independent modules to produce an
22;;; executable, regardless of the license terms of these independent
23;;; modules, and to copy and distribute the resulting executable under
24;;; terms of your choice, provided that you also meet, for each linked
25;;; independent module, the terms and conditions of the license of that
26;;; module.  An independent module is a module which is not derived from
27;;; or based on this library.  If you modify this library, you may extend
28;;; this exception to your version of the library, but you are not
29;;; obligated to do so.  If you do not wish to do so, delete this
30;;; exception statement from your version.
31
32;;; Adapted from SBCL.
33
34(in-package #:system)
35
36;;; Is X a (possibly-improper) list of at least N elements?
37(defun list-of-length-at-least-p (x n)
38  (or (zerop n) ; since anything can be considered an improper list of length 0
39      (and (consp x)
40     (list-of-length-at-least-p (cdr x) (1- n)))))
41
42(defun case-body-error (name keyform keyform-value expected-type keys)
43  (declare (ignore name keys))
44  (restart-case
45   (error 'type-error
46          :datum keyform-value
47          :expected-type expected-type)
48   (store-value (value)
49                :report (lambda (stream)
50                          (format stream "Supply a new value for ~S." keyform))
51                :interactive read-evaluated-form
52                value)))
53
54;;; CASE-BODY-AUX provides the expansion once CASE-BODY has groveled
55;;; all the cases. Note: it is not necessary that the resulting code
56;;; signal case-failure conditions, but that's what KMP's prototype
57;;; code did. We call CASE-BODY-ERROR, because of how closures are
58;;; compiled. RESTART-CASE has forms with closures that the compiler
59;;; causes to be generated at the top of any function using the case
60;;; macros, regardless of whether they are needed.
61;;;
62;;; The CASE-BODY-ERROR function is defined later, when the
63;;; RESTART-CASE macro has been defined.
64(defun case-body-aux (name keyform keyform-value clauses keys
65                           errorp proceedp expected-type)
66  (if proceedp
67      (let ((block (gensym))
68      (again (gensym)))
69  `(let ((,keyform-value ,keyform))
70     (block ,block
71       (tagbody
72        ,again
73        (return-from
74         ,block
75         (cond ,@(nreverse clauses)
76         (t
77          (setf ,keyform-value
78          (setf ,keyform
79          (case-body-error
80           ',name ',keyform ,keyform-value
81           ',expected-type ',keys)))
82          (go ,again))))))))
83      `(let ((,keyform-value ,keyform))
84   (cond
85    ,@(nreverse clauses)
86    ,@(if errorp
87;;    `((t (error 'case-failure
88;;          :name ',name
89;;          :datum ,keyform-value
90;;          :expected-type ',expected-type
91;;          :possibilities ',keys))))))))
92    `((t (error 'type-error
93          :datum ,keyform-value
94          :expected-type ',expected-type))))))))
95
96;;; CASE-BODY returns code for all the standard "case" macros. NAME is
97;;; the macro name, and KEYFORM is the thing to case on. MULTI-P
98;;; indicates whether a branch may fire off a list of keys; otherwise,
99;;; a key that is a list is interpreted in some way as a single key.
100;;; When MULTI-P, TEST is applied to the value of KEYFORM and each key
101;;; for a given branch; otherwise, TEST is applied to the value of
102;;; KEYFORM and the entire first element, instead of each part, of the
103;;; case branch. When ERRORP, no T or OTHERWISE branch is permitted,
104;;; and an ERROR form is generated. When PROCEEDP, it is an error to
105;;; omit ERRORP, and the ERROR form generated is executed within a
106;;; RESTART-CASE allowing KEYFORM to be set and retested.
107(defun case-body (name keyform cases multi-p test errorp proceedp needcasesp)
108  (unless (or cases (not needcasesp))
109    (warn "no clauses in ~S" name))
110  (let ((keyform-value (gensym))
111  (clauses ())
112  (keys ()))
113    (do* ((cases cases (cdr cases))
114    (case (car cases) (car cases)))
115   ((null cases) nil)
116      (unless (list-of-length-at-least-p case 1)
117  (error "~S -- bad clause in ~S" case name))
118      (destructuring-bind (keyoid &rest forms) case
119  (cond ((and (memq keyoid '(t otherwise))
120        (null (cdr cases)))
121         (if errorp
122       (progn
123         (style-warn "~@<Treating bare ~A in ~A as introducing a ~
124                                  normal-clause, not an otherwise-clause~@:>"
125         keyoid name)
126         (push keyoid keys)
127         (push `((,test ,keyform-value ',keyoid) nil ,@forms)
128         clauses))
129       (push `(t nil ,@forms) clauses)))
130        ((and multi-p (listp keyoid))
131         (setf keys (append keyoid keys))
132         (push `((or ,@(mapcar (lambda (key)
133               `(,test ,keyform-value ',key))
134             keyoid))
135           nil
136           ,@forms)
137         clauses))
138        (t
139         (push keyoid keys)
140         (push `((,test ,keyform-value ',keyoid)
141           nil
142           ,@forms)
143         clauses)))))
144    (case-body-aux name keyform keyform-value clauses keys errorp proceedp
145       `(,(if multi-p 'member 'or) ,@keys))))
146
147(defmacro case (keyform &body cases)
148  "CASE Keyform {({(Key*) | Key} Form*)}*
149  Evaluates the Forms in the first clause with a Key EQL to the value of
150  Keyform. If a singleton key is T then the clause is a default clause."
151  (case-body 'case keyform cases t 'eql nil nil nil))
152
153(defmacro ccase (keyform &body cases)
154  "CCASE Keyform {({(Key*) | Key} Form*)}*
155  Evaluates the Forms in the first clause with a Key EQL to the value of
156  Keyform. If none of the keys matches then a correctable error is
157  signalled."
158  (case-body 'ccase keyform cases t 'eql t t t))
159
160(defmacro ecase (keyform &body cases)
161  "ECASE Keyform {({(Key*) | Key} Form*)}*
162  Evaluates the Forms in the first clause with a Key EQL to the value of
163  Keyform. If none of the keys matches then an error is signalled."
164  (case-body 'ecase keyform cases t 'eql t nil t))
165
166(defmacro typecase (keyform &body cases)
167  "TYPECASE Keyform {(Type Form*)}*
168  Evaluates the Forms in the first clause for which TYPEP of Keyform and Type
169  is true."
170  (case-body 'typecase keyform cases nil 'typep nil nil nil))
171
172(defmacro ctypecase (keyform &body cases)
173  "CTYPECASE Keyform {(Type Form*)}*
174  Evaluates the Forms in the first clause for which TYPEP of Keyform and Type
175  is true. If no form is satisfied then a correctable error is signalled."
176  (case-body 'ctypecase keyform cases nil 'typep t t t))
177
178(defmacro etypecase (keyform &body cases)
179  "ETYPECASE Keyform {(Type Form*)}*
180  Evaluates the Forms in the first clause for which TYPEP of Keyform and Type
181  is true. If no form is satisfied then an error is signalled."
182  (case-body 'etypecase keyform cases nil 'typep t nil t))
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