Commit | Line | Data |
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e81d98ec | 1 | /* Copyright (C) 1995,1996,1998,1999,2000,2001 Free Software Foundation, Inc. |
0f2d19dd | 2 | * |
73be1d9e MV |
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. | |
0f2d19dd | 7 | * |
73be1d9e MV |
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. | |
0f2d19dd | 12 | * |
73be1d9e MV |
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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
16 | */ | |
1bbd0b84 | 17 | |
1bbd0b84 | 18 | |
0f2d19dd JB |
19 | \f |
20 | ||
a0599745 MD |
21 | #include "libguile/_scm.h" |
22 | #include "libguile/eval.h" | |
23 | #include "libguile/alist.h" | |
24 | #include "libguile/fluids.h" | |
25 | #include "libguile/ports.h" | |
26 | #include "libguile/smob.h" | |
0f2d19dd | 27 | |
a0599745 | 28 | #include "libguile/dynwind.h" |
0f2d19dd JB |
29 | \f |
30 | ||
31 | /* {Dynamic wind} | |
b3460a50 MV |
32 | |
33 | Things that can be on the wind list: | |
34 | ||
35 | (enter-proc . leave-proc) dynamic-wind | |
36 | (tag . jmpbuf) catch | |
37 | (tag . lazy-catch) lazy-catch | |
38 | tag is either a symbol or a boolean | |
39 | ||
40 | ((fluid ...) . (value ...)) with-fluids | |
41 | ||
42 | */ | |
0f2d19dd JB |
43 | |
44 | ||
45 | ||
3b3b36dd | 46 | SCM_DEFINE (scm_dynamic_wind, "dynamic-wind", 3, 0, 0, |
1e6808ea MG |
47 | (SCM in_guard, SCM thunk, SCM out_guard), |
48 | "All three arguments must be 0-argument procedures.\n" | |
49 | "@var{in_guard} is called, then @var{thunk}, then\n" | |
50 | "@var{out_guard}.\n" | |
51 | "\n" | |
52 | "If, any time during the execution of @var{thunk}, the\n" | |
53 | "continuation of the @code{dynamic_wind} expression is escaped\n" | |
54 | "non-locally, @var{out_guard} is called. If the continuation of\n" | |
55 | "the dynamic-wind is re-entered, @var{in_guard} is called. Thus\n" | |
56 | "@var{in_guard} and @var{out_guard} may be called any number of\n" | |
57 | "times.\n" | |
58 | "@lisp\n" | |
b380b885 | 59 | "(define x 'normal-binding)\n" |
1e6808ea | 60 | "@result{} x\n" |
9401323e | 61 | "(define a-cont (call-with-current-continuation\n" |
b380b885 MD |
62 | " (lambda (escape)\n" |
63 | " (let ((old-x x))\n" | |
64 | " (dynamic-wind\n" | |
65 | " ;; in-guard:\n" | |
66 | " ;;\n" | |
1e6808ea MG |
67 | " (lambda () (set! x 'special-binding))\n" |
68 | "\n" | |
b380b885 MD |
69 | " ;; thunk\n" |
70 | " ;;\n" | |
71 | " (lambda () (display x) (newline)\n" | |
72 | " (call-with-current-continuation escape)\n" | |
73 | " (display x) (newline)\n" | |
1e6808ea MG |
74 | " x)\n" |
75 | "\n" | |
b380b885 MD |
76 | " ;; out-guard:\n" |
77 | " ;;\n" | |
1e6808ea MG |
78 | " (lambda () (set! x old-x)))))))\n" |
79 | "\n" | |
9401323e | 80 | ";; Prints:\n" |
b380b885 MD |
81 | "special-binding\n" |
82 | ";; Evaluates to:\n" | |
1e6808ea | 83 | "@result{} a-cont\n" |
b380b885 | 84 | "x\n" |
1e6808ea | 85 | "@result{} normal-binding\n" |
b380b885 MD |
86 | "(a-cont #f)\n" |
87 | ";; Prints:\n" | |
88 | "special-binding\n" | |
89 | ";; Evaluates to:\n" | |
1e6808ea | 90 | "@result{} a-cont ;; the value of the (define a-cont...)\n" |
b380b885 | 91 | "x\n" |
1e6808ea | 92 | "@result{} normal-binding\n" |
b380b885 MD |
93 | "a-cont\n" |
94 | "@result{} special-binding\n" | |
1e6808ea | 95 | "@end lisp") |
1bbd0b84 | 96 | #define FUNC_NAME s_scm_dynamic_wind |
0f2d19dd JB |
97 | { |
98 | SCM ans; | |
1e6808ea MG |
99 | SCM_ASSERT (SCM_NFALSEP (scm_thunk_p (out_guard)), |
100 | out_guard, | |
1bbd0b84 | 101 | SCM_ARG3, FUNC_NAME); |
fdc28395 | 102 | scm_call_0 (in_guard); |
1e6808ea | 103 | scm_dynwinds = scm_acons (in_guard, out_guard, scm_dynwinds); |
fdc28395 | 104 | ans = scm_call_0 (thunk); |
0f2d19dd | 105 | scm_dynwinds = SCM_CDR (scm_dynwinds); |
fdc28395 | 106 | scm_call_0 (out_guard); |
0f2d19dd JB |
107 | return ans; |
108 | } | |
1bbd0b84 | 109 | #undef FUNC_NAME |
0f2d19dd | 110 | |
3346a90f MD |
111 | /* The implementation of a C-callable dynamic-wind, |
112 | * scm_internal_dynamic_wind, requires packaging of C pointers in a | |
113 | * smob. Objects of this type are pushed onto the dynwind chain. | |
114 | */ | |
115 | ||
e841c3e0 | 116 | #define SCM_GUARDSP(obj) SCM_TYP16_PREDICATE (tc16_guards, obj) |
92c2555f MV |
117 | #define SCM_BEFORE_GUARD(obj) ((scm_t_guard) SCM_CELL_WORD (obj, 1)) |
118 | #define SCM_AFTER_GUARD(obj) ((scm_t_guard) SCM_CELL_WORD (obj, 2)) | |
bd47429e | 119 | #define SCM_GUARD_DATA(obj) ((void *) SCM_CELL_WORD (obj, 3)) |
3346a90f | 120 | |
92c2555f | 121 | static scm_t_bits tc16_guards; |
3346a90f | 122 | |
3346a90f | 123 | static int |
e81d98ec | 124 | guards_print (SCM exp, SCM port, scm_print_state *pstate SCM_UNUSED) |
3346a90f MD |
125 | { |
126 | scm_puts ("#<guards ", port); | |
f1267706 | 127 | scm_intprint (SCM_UNPACK (SCM_CDR (exp)), 16, port); |
3346a90f MD |
128 | scm_putc ('>', port); |
129 | return 1; | |
130 | } | |
131 | ||
3346a90f | 132 | SCM |
92c2555f MV |
133 | scm_internal_dynamic_wind (scm_t_guard before, |
134 | scm_t_inner inner, | |
135 | scm_t_guard after, | |
3346a90f MD |
136 | void *inner_data, |
137 | void *guard_data) | |
138 | { | |
139 | SCM guards, ans; | |
3346a90f | 140 | before (guard_data); |
92c2555f MV |
141 | SCM_NEWSMOB3 (guards, tc16_guards, (scm_t_bits) before, |
142 | (scm_t_bits) after, (scm_t_bits) guard_data); | |
3346a90f MD |
143 | scm_dynwinds = scm_acons (guards, SCM_BOOL_F, scm_dynwinds); |
144 | ans = inner (inner_data); | |
145 | scm_dynwinds = SCM_CDR (scm_dynwinds); | |
146 | after (guard_data); | |
147 | return ans; | |
148 | } | |
1cc91f1b | 149 | |
c2654ef0 | 150 | #ifdef GUILE_DEBUG |
a1ec6916 | 151 | SCM_DEFINE (scm_wind_chain, "wind-chain", 0, 0, 0, |
1bbd0b84 | 152 | (), |
156149ad MG |
153 | "Return the current wind chain. The wind chain contains all\n" |
154 | "information required by @code{dynamic-wind} to call its\n" | |
155 | "argument thunks when entering/exiting its scope.") | |
1bbd0b84 | 156 | #define FUNC_NAME s_scm_wind_chain |
c2654ef0 MD |
157 | { |
158 | return scm_dynwinds; | |
159 | } | |
1bbd0b84 | 160 | #undef FUNC_NAME |
c2654ef0 MD |
161 | #endif |
162 | ||
2e171178 | 163 | void |
904a077d | 164 | scm_swap_bindings (SCM vars, SCM vals) |
6778caf9 MD |
165 | { |
166 | SCM tmp; | |
167 | while (SCM_NIMP (vals)) | |
168 | { | |
904a077d MV |
169 | tmp = SCM_VARIABLE_REF (SCM_CAR (vars)); |
170 | SCM_VARIABLE_SET (SCM_CAR (vars), SCM_CAR (vals)); | |
6778caf9 | 171 | SCM_SETCAR (vals, tmp); |
904a077d | 172 | vars = SCM_CDR (vars); |
6778caf9 MD |
173 | vals = SCM_CDR (vals); |
174 | } | |
175 | } | |
c2654ef0 | 176 | |
0f2d19dd | 177 | void |
c014a02e | 178 | scm_dowinds (SCM to, long delta) |
0f2d19dd JB |
179 | { |
180 | tail: | |
843524cc | 181 | if (SCM_EQ_P (to, scm_dynwinds)); |
1be6b49c | 182 | else if (delta < 0) |
0f2d19dd JB |
183 | { |
184 | SCM wind_elt; | |
185 | SCM wind_key; | |
186 | ||
187 | scm_dowinds (SCM_CDR (to), 1 + delta); | |
188 | wind_elt = SCM_CAR (to); | |
189 | #if 0 | |
190 | if (SCM_INUMP (wind_elt)) | |
191 | { | |
192 | scm_cross_dynwind_binding_scope (wind_elt, 0); | |
193 | } | |
194 | else | |
195 | #endif | |
196 | { | |
197 | wind_key = SCM_CAR (wind_elt); | |
904a077d | 198 | /* key = #t | symbol | thunk | list of variables | list of fluids */ |
6778caf9 | 199 | if (SCM_NIMP (wind_key)) |
b3460a50 | 200 | { |
904a077d MV |
201 | if (SCM_CONSP (wind_key)) |
202 | { | |
203 | if (SCM_VARIABLEP (SCM_CAR (wind_key))) | |
204 | scm_swap_bindings (wind_key, SCM_CDR (wind_elt)); | |
205 | else if (SCM_FLUIDP (SCM_CAR (wind_key))) | |
206 | scm_swap_fluids (wind_key, SCM_CDR (wind_elt)); | |
207 | } | |
4725c298 MD |
208 | else if (SCM_GUARDSP (wind_key)) |
209 | SCM_BEFORE_GUARD (wind_key) (SCM_GUARD_DATA (wind_key)); | |
210 | else if (SCM_TYP3 (wind_key) == scm_tc3_closure) | |
fdc28395 | 211 | scm_call_0 (wind_key); |
b3460a50 | 212 | } |
0f2d19dd JB |
213 | } |
214 | scm_dynwinds = to; | |
215 | } | |
216 | else | |
217 | { | |
218 | SCM from; | |
219 | SCM wind_elt; | |
220 | SCM wind_key; | |
221 | ||
222 | from = SCM_CDR (SCM_CAR (scm_dynwinds)); | |
223 | wind_elt = SCM_CAR (scm_dynwinds); | |
224 | scm_dynwinds = SCM_CDR (scm_dynwinds); | |
225 | #if 0 | |
226 | if (SCM_INUMP (wind_elt)) | |
227 | { | |
228 | scm_cross_dynwind_binding_scope (wind_elt, 0); | |
229 | } | |
230 | else | |
231 | #endif | |
232 | { | |
233 | wind_key = SCM_CAR (wind_elt); | |
6778caf9 | 234 | if (SCM_NIMP (wind_key)) |
b3460a50 | 235 | { |
904a077d MV |
236 | if (SCM_CONSP (wind_key)) |
237 | { | |
238 | if (SCM_VARIABLEP (SCM_CAR (wind_key))) | |
239 | scm_swap_bindings (wind_key, SCM_CDR (wind_elt)); | |
240 | else if (SCM_FLUIDP (SCM_CAR (wind_key))) | |
241 | scm_swap_fluids_reverse (wind_key, SCM_CDR (wind_elt)); | |
242 | } | |
4725c298 MD |
243 | else if (SCM_GUARDSP (wind_key)) |
244 | SCM_AFTER_GUARD (wind_key) (SCM_GUARD_DATA (wind_key)); | |
245 | else if (SCM_TYP3 (wind_key) == scm_tc3_closure) | |
fdc28395 | 246 | scm_call_0 (from); |
b3460a50 | 247 | } |
0f2d19dd JB |
248 | } |
249 | delta--; | |
250 | goto tail; /* scm_dowinds(to, delta-1); */ | |
251 | } | |
252 | } | |
253 | ||
254 | ||
1cc91f1b | 255 | |
0f2d19dd JB |
256 | void |
257 | scm_init_dynwind () | |
0f2d19dd | 258 | { |
e841c3e0 KN |
259 | tc16_guards = scm_make_smob_type ("guards", 0); |
260 | scm_set_smob_print (tc16_guards, guards_print); | |
a0599745 | 261 | #include "libguile/dynwind.x" |
0f2d19dd | 262 | } |
89e00824 ML |
263 | |
264 | /* | |
265 | Local Variables: | |
266 | c-file-style: "gnu" | |
267 | End: | |
268 | */ |