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e81d98ec | 1 | /* Copyright (C) 1995,1996,1998,1999,2000,2001 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 | 41 | |
1bbd0b84 | 42 | |
0f2d19dd JB |
43 | \f |
44 | ||
a0599745 MD |
45 | #include "libguile/_scm.h" |
46 | #include "libguile/eval.h" | |
47 | #include "libguile/alist.h" | |
48 | #include "libguile/fluids.h" | |
49 | #include "libguile/ports.h" | |
50 | #include "libguile/smob.h" | |
0f2d19dd | 51 | |
a0599745 | 52 | #include "libguile/dynwind.h" |
0f2d19dd JB |
53 | \f |
54 | ||
55 | /* {Dynamic wind} | |
b3460a50 MV |
56 | |
57 | Things that can be on the wind list: | |
58 | ||
59 | (enter-proc . leave-proc) dynamic-wind | |
60 | (tag . jmpbuf) catch | |
61 | (tag . lazy-catch) lazy-catch | |
62 | tag is either a symbol or a boolean | |
63 | ||
64 | ((fluid ...) . (value ...)) with-fluids | |
65 | ||
66 | */ | |
0f2d19dd JB |
67 | |
68 | ||
69 | ||
3b3b36dd | 70 | SCM_DEFINE (scm_dynamic_wind, "dynamic-wind", 3, 0, 0, |
1e6808ea MG |
71 | (SCM in_guard, SCM thunk, SCM out_guard), |
72 | "All three arguments must be 0-argument procedures.\n" | |
73 | "@var{in_guard} is called, then @var{thunk}, then\n" | |
74 | "@var{out_guard}.\n" | |
75 | "\n" | |
76 | "If, any time during the execution of @var{thunk}, the\n" | |
77 | "continuation of the @code{dynamic_wind} expression is escaped\n" | |
78 | "non-locally, @var{out_guard} is called. If the continuation of\n" | |
79 | "the dynamic-wind is re-entered, @var{in_guard} is called. Thus\n" | |
80 | "@var{in_guard} and @var{out_guard} may be called any number of\n" | |
81 | "times.\n" | |
82 | "@lisp\n" | |
b380b885 | 83 | "(define x 'normal-binding)\n" |
1e6808ea | 84 | "@result{} x\n" |
9401323e | 85 | "(define a-cont (call-with-current-continuation\n" |
b380b885 MD |
86 | " (lambda (escape)\n" |
87 | " (let ((old-x x))\n" | |
88 | " (dynamic-wind\n" | |
89 | " ;; in-guard:\n" | |
90 | " ;;\n" | |
1e6808ea MG |
91 | " (lambda () (set! x 'special-binding))\n" |
92 | "\n" | |
b380b885 MD |
93 | " ;; thunk\n" |
94 | " ;;\n" | |
95 | " (lambda () (display x) (newline)\n" | |
96 | " (call-with-current-continuation escape)\n" | |
97 | " (display x) (newline)\n" | |
1e6808ea MG |
98 | " x)\n" |
99 | "\n" | |
b380b885 MD |
100 | " ;; out-guard:\n" |
101 | " ;;\n" | |
1e6808ea MG |
102 | " (lambda () (set! x old-x)))))))\n" |
103 | "\n" | |
9401323e | 104 | ";; Prints:\n" |
b380b885 MD |
105 | "special-binding\n" |
106 | ";; Evaluates to:\n" | |
1e6808ea | 107 | "@result{} a-cont\n" |
b380b885 | 108 | "x\n" |
1e6808ea | 109 | "@result{} normal-binding\n" |
b380b885 MD |
110 | "(a-cont #f)\n" |
111 | ";; Prints:\n" | |
112 | "special-binding\n" | |
113 | ";; Evaluates to:\n" | |
1e6808ea | 114 | "@result{} a-cont ;; the value of the (define a-cont...)\n" |
b380b885 | 115 | "x\n" |
1e6808ea | 116 | "@result{} normal-binding\n" |
b380b885 MD |
117 | "a-cont\n" |
118 | "@result{} special-binding\n" | |
1e6808ea | 119 | "@end lisp") |
1bbd0b84 | 120 | #define FUNC_NAME s_scm_dynamic_wind |
0f2d19dd JB |
121 | { |
122 | SCM ans; | |
1e6808ea MG |
123 | SCM_ASSERT (SCM_NFALSEP (scm_thunk_p (out_guard)), |
124 | out_guard, | |
1bbd0b84 | 125 | SCM_ARG3, FUNC_NAME); |
fdc28395 | 126 | scm_call_0 (in_guard); |
1e6808ea | 127 | scm_dynwinds = scm_acons (in_guard, out_guard, scm_dynwinds); |
fdc28395 | 128 | ans = scm_call_0 (thunk); |
0f2d19dd | 129 | scm_dynwinds = SCM_CDR (scm_dynwinds); |
fdc28395 | 130 | scm_call_0 (out_guard); |
0f2d19dd JB |
131 | return ans; |
132 | } | |
1bbd0b84 | 133 | #undef FUNC_NAME |
0f2d19dd | 134 | |
3346a90f MD |
135 | /* The implementation of a C-callable dynamic-wind, |
136 | * scm_internal_dynamic_wind, requires packaging of C pointers in a | |
137 | * smob. Objects of this type are pushed onto the dynwind chain. | |
138 | */ | |
139 | ||
e841c3e0 | 140 | #define SCM_GUARDSP(obj) SCM_TYP16_PREDICATE (tc16_guards, obj) |
92c2555f MV |
141 | #define SCM_BEFORE_GUARD(obj) ((scm_t_guard) SCM_CELL_WORD (obj, 1)) |
142 | #define SCM_AFTER_GUARD(obj) ((scm_t_guard) SCM_CELL_WORD (obj, 2)) | |
bd47429e | 143 | #define SCM_GUARD_DATA(obj) ((void *) SCM_CELL_WORD (obj, 3)) |
3346a90f | 144 | |
92c2555f | 145 | static scm_t_bits tc16_guards; |
3346a90f | 146 | |
3346a90f | 147 | static int |
e81d98ec | 148 | guards_print (SCM exp, SCM port, scm_print_state *pstate SCM_UNUSED) |
3346a90f MD |
149 | { |
150 | scm_puts ("#<guards ", port); | |
f1267706 | 151 | scm_intprint (SCM_UNPACK (SCM_CDR (exp)), 16, port); |
3346a90f MD |
152 | scm_putc ('>', port); |
153 | return 1; | |
154 | } | |
155 | ||
3346a90f | 156 | SCM |
92c2555f MV |
157 | scm_internal_dynamic_wind (scm_t_guard before, |
158 | scm_t_inner inner, | |
159 | scm_t_guard after, | |
3346a90f MD |
160 | void *inner_data, |
161 | void *guard_data) | |
162 | { | |
163 | SCM guards, ans; | |
3346a90f | 164 | before (guard_data); |
92c2555f MV |
165 | SCM_NEWSMOB3 (guards, tc16_guards, (scm_t_bits) before, |
166 | (scm_t_bits) after, (scm_t_bits) guard_data); | |
3346a90f MD |
167 | scm_dynwinds = scm_acons (guards, SCM_BOOL_F, scm_dynwinds); |
168 | ans = inner (inner_data); | |
169 | scm_dynwinds = SCM_CDR (scm_dynwinds); | |
170 | after (guard_data); | |
171 | return ans; | |
172 | } | |
1cc91f1b | 173 | |
c2654ef0 | 174 | #ifdef GUILE_DEBUG |
a1ec6916 | 175 | SCM_DEFINE (scm_wind_chain, "wind-chain", 0, 0, 0, |
1bbd0b84 | 176 | (), |
156149ad MG |
177 | "Return the current wind chain. The wind chain contains all\n" |
178 | "information required by @code{dynamic-wind} to call its\n" | |
179 | "argument thunks when entering/exiting its scope.") | |
1bbd0b84 | 180 | #define FUNC_NAME s_scm_wind_chain |
c2654ef0 MD |
181 | { |
182 | return scm_dynwinds; | |
183 | } | |
1bbd0b84 | 184 | #undef FUNC_NAME |
c2654ef0 MD |
185 | #endif |
186 | ||
2e171178 | 187 | void |
904a077d | 188 | scm_swap_bindings (SCM vars, SCM vals) |
6778caf9 MD |
189 | { |
190 | SCM tmp; | |
191 | while (SCM_NIMP (vals)) | |
192 | { | |
904a077d MV |
193 | tmp = SCM_VARIABLE_REF (SCM_CAR (vars)); |
194 | SCM_VARIABLE_SET (SCM_CAR (vars), SCM_CAR (vals)); | |
6778caf9 | 195 | SCM_SETCAR (vals, tmp); |
904a077d | 196 | vars = SCM_CDR (vars); |
6778caf9 MD |
197 | vals = SCM_CDR (vals); |
198 | } | |
199 | } | |
c2654ef0 | 200 | |
0f2d19dd | 201 | void |
c014a02e | 202 | scm_dowinds (SCM to, long delta) |
0f2d19dd JB |
203 | { |
204 | tail: | |
843524cc | 205 | if (SCM_EQ_P (to, scm_dynwinds)); |
1be6b49c | 206 | else if (delta < 0) |
0f2d19dd JB |
207 | { |
208 | SCM wind_elt; | |
209 | SCM wind_key; | |
210 | ||
211 | scm_dowinds (SCM_CDR (to), 1 + delta); | |
212 | wind_elt = SCM_CAR (to); | |
213 | #if 0 | |
214 | if (SCM_INUMP (wind_elt)) | |
215 | { | |
216 | scm_cross_dynwind_binding_scope (wind_elt, 0); | |
217 | } | |
218 | else | |
219 | #endif | |
220 | { | |
221 | wind_key = SCM_CAR (wind_elt); | |
904a077d | 222 | /* key = #t | symbol | thunk | list of variables | list of fluids */ |
6778caf9 | 223 | if (SCM_NIMP (wind_key)) |
b3460a50 | 224 | { |
904a077d MV |
225 | if (SCM_CONSP (wind_key)) |
226 | { | |
227 | if (SCM_VARIABLEP (SCM_CAR (wind_key))) | |
228 | scm_swap_bindings (wind_key, SCM_CDR (wind_elt)); | |
229 | else if (SCM_FLUIDP (SCM_CAR (wind_key))) | |
230 | scm_swap_fluids (wind_key, SCM_CDR (wind_elt)); | |
231 | } | |
4725c298 MD |
232 | else if (SCM_GUARDSP (wind_key)) |
233 | SCM_BEFORE_GUARD (wind_key) (SCM_GUARD_DATA (wind_key)); | |
234 | else if (SCM_TYP3 (wind_key) == scm_tc3_closure) | |
fdc28395 | 235 | scm_call_0 (wind_key); |
b3460a50 | 236 | } |
0f2d19dd JB |
237 | } |
238 | scm_dynwinds = to; | |
239 | } | |
240 | else | |
241 | { | |
242 | SCM from; | |
243 | SCM wind_elt; | |
244 | SCM wind_key; | |
245 | ||
246 | from = SCM_CDR (SCM_CAR (scm_dynwinds)); | |
247 | wind_elt = SCM_CAR (scm_dynwinds); | |
248 | scm_dynwinds = SCM_CDR (scm_dynwinds); | |
249 | #if 0 | |
250 | if (SCM_INUMP (wind_elt)) | |
251 | { | |
252 | scm_cross_dynwind_binding_scope (wind_elt, 0); | |
253 | } | |
254 | else | |
255 | #endif | |
256 | { | |
257 | wind_key = SCM_CAR (wind_elt); | |
6778caf9 | 258 | if (SCM_NIMP (wind_key)) |
b3460a50 | 259 | { |
904a077d MV |
260 | if (SCM_CONSP (wind_key)) |
261 | { | |
262 | if (SCM_VARIABLEP (SCM_CAR (wind_key))) | |
263 | scm_swap_bindings (wind_key, SCM_CDR (wind_elt)); | |
264 | else if (SCM_FLUIDP (SCM_CAR (wind_key))) | |
265 | scm_swap_fluids_reverse (wind_key, SCM_CDR (wind_elt)); | |
266 | } | |
4725c298 MD |
267 | else if (SCM_GUARDSP (wind_key)) |
268 | SCM_AFTER_GUARD (wind_key) (SCM_GUARD_DATA (wind_key)); | |
269 | else if (SCM_TYP3 (wind_key) == scm_tc3_closure) | |
fdc28395 | 270 | scm_call_0 (from); |
b3460a50 | 271 | } |
0f2d19dd JB |
272 | } |
273 | delta--; | |
274 | goto tail; /* scm_dowinds(to, delta-1); */ | |
275 | } | |
276 | } | |
277 | ||
278 | ||
1cc91f1b | 279 | |
0f2d19dd JB |
280 | void |
281 | scm_init_dynwind () | |
0f2d19dd | 282 | { |
e841c3e0 KN |
283 | tc16_guards = scm_make_smob_type ("guards", 0); |
284 | scm_set_smob_print (tc16_guards, guards_print); | |
a0599745 | 285 | #include "libguile/dynwind.x" |
0f2d19dd | 286 | } |
89e00824 ML |
287 | |
288 | /* | |
289 | Local Variables: | |
290 | c-file-style: "gnu" | |
291 | End: | |
292 | */ |