1 /* Copyright (C) 1995,1996,2000,2001, 2004, 2005, 2006, 2008 Free Software Foundation, Inc.
2 *
3 * This library is free software; you can redistribute it and/or
4 * modify it under the terms of the GNU Lesser General Public
5 * License as published by the Free Software Foundation; either
6 * version 2.1 of the License, or (at your option) any later version.
7 *
8 * This library is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * Lesser General Public License for more details.
12 *
13 * You should have received a copy of the GNU Lesser General Public
14 * License along with this library; if not, write to the Free Software
15 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
16 */
17
18
19
20 #ifdef HAVE_CONFIG_H
21 # include <config.h>
22 #endif
23
24 #include "libguile/_scm.h"
25 #include "libguile/validate.h"
26
27 #include "libguile/pairs.h"
28
29
30
31 /* {Pairs}
32 */
33
34 #if (SCM_DEBUG_PAIR_ACCESSES == 1)
35
36 #include "libguile/ports.h"
37 #include "libguile/strings.h"
38
scm_error_pair_access(SCM non_pair)39 void scm_error_pair_access (SCM non_pair)
40 {
41 static unsigned int running = 0;
42 SCM message = scm_from_locale_string ("Non-pair accessed with SCM_C[AD]R: `~S'\n");
43
44 if (!running)
45 {
46 running = 1;
47 scm_simple_format (scm_current_error_port (),
48 message, scm_list_1 (non_pair));
49 abort ();
50 }
51 }
52
53 #endif
54
55 SCM_DEFINE (scm_cons, "cons", 2, 0, 0,
56 (SCM x, SCM y),
57 "Return a newly allocated pair whose car is @var{x} and whose\n"
58 "cdr is @var{y}. The pair is guaranteed to be different (in the\n"
59 "sense of @code{eq?}) from every previously existing object.")
60 #define FUNC_NAME s_scm_cons
61 {
62 return scm_cell (SCM_UNPACK (x), SCM_UNPACK (y));
63 }
64 #undef FUNC_NAME
65
66
67 SCM
scm_cons2(SCM w,SCM x,SCM y)68 scm_cons2 (SCM w, SCM x, SCM y)
69 {
70 return scm_cons (w, scm_cons (x, y));
71 }
72
73
74 SCM_DEFINE (scm_pair_p, "pair?", 1, 0, 0,
75 (SCM x),
76 "Return @code{#t} if @var{x} is a pair; otherwise return\n"
77 "@code{#f}.")
78 #define FUNC_NAME s_scm_pair_p
79 {
80 return scm_from_bool (scm_is_pair (x));
81 }
82 #undef FUNC_NAME
83
84 SCM
scm_car(SCM pair)85 scm_car (SCM pair)
86 {
87 if (!scm_is_pair (pair))
88 scm_wrong_type_arg_msg (NULL, 0, pair, "pair");
89 return SCM_CAR (pair);
90 }
91
92 SCM
scm_cdr(SCM pair)93 scm_cdr (SCM pair)
94 {
95 if (!scm_is_pair (pair))
96 scm_wrong_type_arg_msg (NULL, 0, pair, "pair");
97 return SCM_CDR (pair);
98 }
99
100 SCM
scm_i_chase_pairs(SCM tree,scm_t_uint32 pattern)101 scm_i_chase_pairs (SCM tree, scm_t_uint32 pattern)
102 {
103 do
104 {
105 if (!scm_is_pair (tree))
106 scm_wrong_type_arg_msg (NULL, 0, tree, "pair");
107 tree = (pattern & 1) ? SCM_CAR (tree) : SCM_CDR (tree);
108 pattern >>= 2;
109 }
110 while (pattern);
111 return tree;
112 }
113
114 SCM_DEFINE (scm_set_car_x, "set-car!", 2, 0, 0,
115 (SCM pair, SCM value),
116 "Stores @var{value} in the car field of @var{pair}. The value returned\n"
117 "by @code{set-car!} is unspecified.")
118 #define FUNC_NAME s_scm_set_car_x
119 {
120 SCM_VALIDATE_CONS (1, pair);
121 SCM_SETCAR (pair, value);
122 return SCM_UNSPECIFIED;
123 }
124 #undef FUNC_NAME
125
126
127 SCM_DEFINE (scm_set_cdr_x, "set-cdr!", 2, 0, 0,
128 (SCM pair, SCM value),
129 "Stores @var{value} in the cdr field of @var{pair}. The value returned\n"
130 "by @code{set-cdr!} is unspecified.")
131 #define FUNC_NAME s_scm_set_cdr_x
132 {
133 SCM_VALIDATE_CONS (1, pair);
134 SCM_SETCDR (pair, value);
135 return SCM_UNSPECIFIED;
136 }
137 #undef FUNC_NAME
138
139
140
141 /* Every cxr-pattern is made up of pairs of bits, starting with the two least
142 * significant bits. If in a pair of bits the least significant of the two
143 * bits is 0, this means CDR, otherwise CAR. The most significant bits of the
144 * two bits is only needed to indicate when cxr-ing is ready. This is the
145 * case, when all remaining pairs of bits equal 00. */
146
147 typedef struct {
148 const char *name;
149 unsigned char pattern;
150 } t_cxr;
151
152 static const t_cxr cxrs[] =
153 {
154 {"cdr", 0x02}, /* 00000010 */
155 {"car", 0x03}, /* 00000011 */
156 {"cddr", 0x0a}, /* 00001010 */
157 {"cdar", 0x0b}, /* 00001011 */
158 {"cadr", 0x0e}, /* 00001110 */
159 {"caar", 0x0f}, /* 00001111 */
160 {"cdddr", 0x2a}, /* 00101010 */
161 {"cddar", 0x2b}, /* 00101011 */
162 {"cdadr", 0x2e}, /* 00101110 */
163 {"cdaar", 0x2f}, /* 00101111 */
164 {"caddr", 0x3a}, /* 00111010 */
165 {"cadar", 0x3b}, /* 00111011 */
166 {"caadr", 0x3e}, /* 00111110 */
167 {"caaar", 0x3f}, /* 00111111 */
168 {"cddddr", 0xaa}, /* 10101010 */
169 {"cdddar", 0xab}, /* 10101011 */
170 {"cddadr", 0xae}, /* 10101110 */
171 {"cddaar", 0xaf}, /* 10101111 */
172 {"cdaddr", 0xba}, /* 10111010 */
173 {"cdadar", 0xbb}, /* 10111011 */
174 {"cdaadr", 0xbe}, /* 10111110 */
175 {"cdaaar", 0xbf}, /* 10111111 */
176 {"cadddr", 0xea}, /* 11101010 */
177 {"caddar", 0xeb}, /* 11101011 */
178 {"cadadr", 0xee}, /* 11101110 */
179 {"cadaar", 0xef}, /* 11101111 */
180 {"caaddr", 0xfa}, /* 11111010 */
181 {"caadar", 0xfb}, /* 11111011 */
182 {"caaadr", 0xfe}, /* 11111110 */
183 {"caaaar", 0xff}, /* 11111111 */
184 {0, 0}
185 };
186
187
188
189 void
scm_init_pairs()190 scm_init_pairs ()
191 {
192 unsigned int subnr = 0;
193
194 for (subnr = 0; cxrs[subnr].name; subnr++)
195 {
196 SCM (*pattern) () = (SCM (*) ()) (scm_t_bits) cxrs[subnr].pattern;
197 scm_c_define_subr (cxrs[subnr].name, scm_tc7_cxr, pattern);
198 }
199
200 #include "libguile/pairs.x"
201 }
202
203
204 /*
205 Local Variables:
206 c-file-style: "gnu"
207 End:
208 */
209