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bd47429e | 1 | /* Copyright (C) 1995, 1996, 1998, 1999, 2000 Free Software Foundation, Inc. |
0f2d19dd JB |
2 | * |
3 | * This program is free software; you can redistribute it and/or modify | |
4 | * it under the terms of the GNU General Public License as published by | |
5 | * the Free Software Foundation; either version 2, or (at your option) | |
6 | * any later version. | |
7 | * | |
8 | * This program 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 | |
11 | * GNU General Public License for more details. | |
12 | * | |
13 | * You should have received a copy of the GNU General Public License | |
14 | * along with this software; see the file COPYING. If not, write to | |
82892bed JB |
15 | * the Free Software Foundation, Inc., 59 Temple Place, Suite 330, |
16 | * Boston, MA 02111-1307 USA | |
0f2d19dd JB |
17 | * |
18 | * As a special exception, the Free Software Foundation gives permission | |
19 | * for additional uses of the text contained in its release of GUILE. | |
20 | * | |
21 | * The exception is that, if you link the GUILE library with other files | |
22 | * to produce an executable, this does not by itself cause the | |
23 | * resulting executable to be covered by the GNU General Public License. | |
24 | * Your use of that executable is in no way restricted on account of | |
25 | * linking the GUILE library code into it. | |
26 | * | |
27 | * This exception does not however invalidate any other reasons why | |
28 | * the executable file might be covered by the GNU General Public License. | |
29 | * | |
30 | * This exception applies only to the code released by the | |
31 | * Free Software Foundation under the name GUILE. If you copy | |
32 | * code from other Free Software Foundation releases into a copy of | |
33 | * GUILE, as the General Public License permits, the exception does | |
34 | * not apply to the code that you add in this way. To avoid misleading | |
35 | * anyone as to the status of such modified files, you must delete | |
36 | * this exception notice from them. | |
37 | * | |
38 | * If you write modifications of your own for GUILE, it is your choice | |
39 | * whether to permit this exception to apply to your modifications. | |
82892bed | 40 | * If you do not wish that, delete this exception notice. */ |
1bbd0b84 GB |
41 | |
42 | /* Software engineering face-lift by Greg J. Badros, 11-Dec-1999, | |
43 | gjb@cs.washington.edu, http://www.cs.washington.edu/homes/gjb */ | |
44 | ||
0f2d19dd JB |
45 | \f |
46 | ||
47 | #include <stdio.h> | |
48 | #include "_scm.h" | |
20e6290e JB |
49 | #include "eval.h" |
50 | #include "alist.h" | |
b3460a50 | 51 | #include "fluids.h" |
f04d8caf | 52 | #include "ports.h" |
3346a90f | 53 | #include "smob.h" |
0f2d19dd | 54 | |
20e6290e | 55 | #include "dynwind.h" |
0f2d19dd JB |
56 | \f |
57 | ||
58 | /* {Dynamic wind} | |
b3460a50 MV |
59 | |
60 | Things that can be on the wind list: | |
61 | ||
62 | (enter-proc . leave-proc) dynamic-wind | |
63 | (tag . jmpbuf) catch | |
64 | (tag . lazy-catch) lazy-catch | |
65 | tag is either a symbol or a boolean | |
66 | ||
67 | ((fluid ...) . (value ...)) with-fluids | |
68 | ||
69 | */ | |
0f2d19dd JB |
70 | |
71 | ||
72 | ||
3b3b36dd | 73 | SCM_DEFINE (scm_dynamic_wind, "dynamic-wind", 3, 0, 0, |
1bbd0b84 | 74 | (SCM thunk1, SCM thunk2, SCM thunk3), |
b380b885 MD |
75 | "All three arguments must be 0-argument procedures.\n\n" |
76 | "@var{in-guard} is called, then @var{thunk}, then @var{out-guard}.\n\n" | |
77 | "If, any time during the execution of @var{thunk}, the continuation\n" | |
78 | "of the @code{dynamic-wind} expression is escaped non-locally, @var{out-guard}\n" | |
79 | "is called. If the continuation of the dynamic-wind is re-entered,\n" | |
80 | "@var{in-guard} is called. Thus @var{in-guard} and @var{out-guard} may\n" | |
81 | "be called any number of times.\n\n" | |
82 | "@example\n" | |
83 | "(define x 'normal-binding)\n" | |
84 | "@result{} x\n\n" | |
85 | "(define a-cont (call-with-current-continuation \n" | |
86 | " (lambda (escape)\n" | |
87 | " (let ((old-x x))\n" | |
88 | " (dynamic-wind\n" | |
89 | " ;; in-guard:\n" | |
90 | " ;;\n" | |
91 | " (lambda () (set! x 'special-binding))\n\n" | |
92 | " ;; thunk\n" | |
93 | " ;;\n" | |
94 | " (lambda () (display x) (newline)\n" | |
95 | " (call-with-current-continuation escape)\n" | |
96 | " (display x) (newline)\n" | |
97 | " x)\n\n" | |
98 | " ;; out-guard:\n" | |
99 | " ;;\n" | |
100 | " (lambda () (set! x old-x)))))))\n\n" | |
101 | ";; Prints: \n" | |
102 | "special-binding\n" | |
103 | ";; Evaluates to:\n" | |
104 | "@result{} a-cont\n\n" | |
105 | "x\n" | |
106 | "@result{} normal-binding\n\n" | |
107 | "(a-cont #f)\n" | |
108 | ";; Prints:\n" | |
109 | "special-binding\n" | |
110 | ";; Evaluates to:\n" | |
111 | "@result{} a-cont ;; the value of the (define a-cont...)\n\n" | |
112 | "x\n" | |
113 | "@result{} normal-binding\n\n" | |
114 | "a-cont\n" | |
115 | "@result{} special-binding\n" | |
116 | "@end example\n" | |
117 | "") | |
1bbd0b84 | 118 | #define FUNC_NAME s_scm_dynamic_wind |
0f2d19dd JB |
119 | { |
120 | SCM ans; | |
6778caf9 MD |
121 | SCM_ASSERT (SCM_NFALSEP (scm_thunk_p (thunk3)), |
122 | thunk3, | |
1bbd0b84 | 123 | SCM_ARG3, FUNC_NAME); |
0f2d19dd JB |
124 | scm_apply (thunk1, SCM_EOL, SCM_EOL); |
125 | scm_dynwinds = scm_acons (thunk1, thunk3, scm_dynwinds); | |
126 | ans = scm_apply (thunk2, SCM_EOL, SCM_EOL); | |
127 | scm_dynwinds = SCM_CDR (scm_dynwinds); | |
128 | scm_apply (thunk3, SCM_EOL, SCM_EOL); | |
129 | return ans; | |
130 | } | |
1bbd0b84 | 131 | #undef FUNC_NAME |
0f2d19dd | 132 | |
3346a90f MD |
133 | /* The implementation of a C-callable dynamic-wind, |
134 | * scm_internal_dynamic_wind, requires packaging of C pointers in a | |
135 | * smob. Objects of this type are pushed onto the dynwind chain. | |
136 | */ | |
137 | ||
bd47429e MD |
138 | #define SCM_GUARDSP(obj) SCM_SMOB_PREDICATE (tc16_guards, obj) |
139 | #define SCM_BEFORE_GUARD(obj) ((scm_guard_t) SCM_CELL_WORD (obj, 1)) | |
140 | #define SCM_AFTER_GUARD(obj) ((scm_guard_t) SCM_CELL_WORD (obj, 2)) | |
141 | #define SCM_GUARD_DATA(obj) ((void *) SCM_CELL_WORD (obj, 3)) | |
3346a90f MD |
142 | |
143 | static long tc16_guards; | |
144 | ||
3346a90f MD |
145 | static int |
146 | printguards (SCM exp, SCM port, scm_print_state *pstate) | |
147 | { | |
148 | scm_puts ("#<guards ", port); | |
f1267706 | 149 | scm_intprint (SCM_UNPACK (SCM_CDR (exp)), 16, port); |
3346a90f MD |
150 | scm_putc ('>', port); |
151 | return 1; | |
152 | } | |
153 | ||
3346a90f MD |
154 | SCM |
155 | scm_internal_dynamic_wind (scm_guard_t before, | |
156 | scm_inner_t inner, | |
157 | scm_guard_t after, | |
158 | void *inner_data, | |
159 | void *guard_data) | |
160 | { | |
161 | SCM guards, ans; | |
3346a90f | 162 | before (guard_data); |
843524cc DH |
163 | SCM_NEWSMOB3 (guards, tc16_guards, (scm_bits_t) before, |
164 | (scm_bits_t) after, (scm_bits_t) guard_data); | |
3346a90f MD |
165 | scm_dynwinds = scm_acons (guards, SCM_BOOL_F, scm_dynwinds); |
166 | ans = inner (inner_data); | |
167 | scm_dynwinds = SCM_CDR (scm_dynwinds); | |
168 | after (guard_data); | |
169 | return ans; | |
170 | } | |
1cc91f1b | 171 | |
c2654ef0 | 172 | #ifdef GUILE_DEBUG |
a1ec6916 | 173 | SCM_DEFINE (scm_wind_chain, "wind-chain", 0, 0, 0, |
1bbd0b84 | 174 | (), |
b380b885 | 175 | "") |
1bbd0b84 | 176 | #define FUNC_NAME s_scm_wind_chain |
c2654ef0 MD |
177 | { |
178 | return scm_dynwinds; | |
179 | } | |
1bbd0b84 | 180 | #undef FUNC_NAME |
c2654ef0 MD |
181 | #endif |
182 | ||
6778caf9 MD |
183 | static void |
184 | scm_swap_bindings (SCM glocs, SCM vals) | |
185 | { | |
186 | SCM tmp; | |
187 | while (SCM_NIMP (vals)) | |
188 | { | |
189 | tmp = SCM_GLOC_VAL (SCM_CAR (glocs)); | |
15237f30 MD |
190 | SCM_SETCDR (SCM_PACK (SCM_UNPACK (SCM_CAR (glocs)) - 1L), |
191 | SCM_CAR (vals)); | |
6778caf9 MD |
192 | SCM_SETCAR (vals, tmp); |
193 | glocs = SCM_CDR (glocs); | |
194 | vals = SCM_CDR (vals); | |
195 | } | |
196 | } | |
c2654ef0 | 197 | |
0f2d19dd | 198 | void |
6e8d25a6 | 199 | scm_dowinds (SCM to, long delta) |
0f2d19dd JB |
200 | { |
201 | tail: | |
843524cc | 202 | if (SCM_EQ_P (to, scm_dynwinds)); |
0f2d19dd JB |
203 | else if (0 > delta) |
204 | { | |
205 | SCM wind_elt; | |
206 | SCM wind_key; | |
207 | ||
208 | scm_dowinds (SCM_CDR (to), 1 + delta); | |
209 | wind_elt = SCM_CAR (to); | |
210 | #if 0 | |
211 | if (SCM_INUMP (wind_elt)) | |
212 | { | |
213 | scm_cross_dynwind_binding_scope (wind_elt, 0); | |
214 | } | |
215 | else | |
216 | #endif | |
217 | { | |
218 | wind_key = SCM_CAR (wind_elt); | |
6778caf9 MD |
219 | /* key = #t | symbol | thunk | list of glocs | list of fluids */ |
220 | if (SCM_NIMP (wind_key)) | |
b3460a50 | 221 | { |
6778caf9 MD |
222 | if (SCM_TYP3 (wind_key) == scm_tc3_cons_gloc) |
223 | scm_swap_bindings (wind_key, SCM_CDR (wind_elt)); | |
4725c298 MD |
224 | else if (SCM_TYP3 (wind_key) == scm_tc3_cons) |
225 | scm_swap_fluids (wind_key, SCM_CDR (wind_elt)); | |
226 | else if (SCM_GUARDSP (wind_key)) | |
227 | SCM_BEFORE_GUARD (wind_key) (SCM_GUARD_DATA (wind_key)); | |
228 | else if (SCM_TYP3 (wind_key) == scm_tc3_closure) | |
229 | scm_apply (wind_key, SCM_EOL, SCM_EOL); | |
b3460a50 | 230 | } |
0f2d19dd JB |
231 | } |
232 | scm_dynwinds = to; | |
233 | } | |
234 | else | |
235 | { | |
236 | SCM from; | |
237 | SCM wind_elt; | |
238 | SCM wind_key; | |
239 | ||
240 | from = SCM_CDR (SCM_CAR (scm_dynwinds)); | |
241 | wind_elt = SCM_CAR (scm_dynwinds); | |
242 | scm_dynwinds = SCM_CDR (scm_dynwinds); | |
243 | #if 0 | |
244 | if (SCM_INUMP (wind_elt)) | |
245 | { | |
246 | scm_cross_dynwind_binding_scope (wind_elt, 0); | |
247 | } | |
248 | else | |
249 | #endif | |
250 | { | |
251 | wind_key = SCM_CAR (wind_elt); | |
6778caf9 | 252 | if (SCM_NIMP (wind_key)) |
b3460a50 | 253 | { |
6778caf9 MD |
254 | if (SCM_TYP3 (wind_key) == scm_tc3_cons_gloc) |
255 | scm_swap_bindings (wind_key, from); | |
4725c298 MD |
256 | else if (SCM_TYP3 (wind_key) == scm_tc3_cons) |
257 | scm_swap_fluids_reverse (wind_key, from); | |
258 | else if (SCM_GUARDSP (wind_key)) | |
259 | SCM_AFTER_GUARD (wind_key) (SCM_GUARD_DATA (wind_key)); | |
260 | else if (SCM_TYP3 (wind_key) == scm_tc3_closure) | |
261 | scm_apply (from, SCM_EOL, SCM_EOL); | |
b3460a50 | 262 | } |
0f2d19dd JB |
263 | } |
264 | delta--; | |
265 | goto tail; /* scm_dowinds(to, delta-1); */ | |
266 | } | |
267 | } | |
268 | ||
269 | ||
1cc91f1b | 270 | |
0f2d19dd JB |
271 | void |
272 | scm_init_dynwind () | |
0f2d19dd | 273 | { |
bd47429e MD |
274 | tc16_guards = scm_make_smob_type_mfpe ("guards", 0, |
275 | NULL, scm_free0, printguards, NULL); | |
0f2d19dd JB |
276 | #include "dynwind.x" |
277 | } | |
89e00824 ML |
278 | |
279 | /* | |
280 | Local Variables: | |
281 | c-file-style: "gnu" | |
282 | End: | |
283 | */ |