| 1 | /* Simple iterators for GDB/Scheme. |
| 2 | |
| 3 | Copyright (C) 2014-2015 Free Software Foundation, Inc. |
| 4 | |
| 5 | This file is part of GDB. |
| 6 | |
| 7 | This program is free software; you can redistribute it and/or modify |
| 8 | it under the terms of the GNU General Public License as published by |
| 9 | the Free Software Foundation; either version 3 of the License, or |
| 10 | (at your option) any later version. |
| 11 | |
| 12 | This program is distributed in the hope that it will be useful, |
| 13 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 15 | GNU General Public License for more details. |
| 16 | |
| 17 | You should have received a copy of the GNU General Public License |
| 18 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| 19 | |
| 20 | /* See README file in this directory for implementation notes, coding |
| 21 | conventions, et.al. */ |
| 22 | |
| 23 | /* These are *simple* iterators, used to implement iterating over a collection |
| 24 | of objects. They are implemented as a smob containing three objects: |
| 25 | |
| 26 | 1) the object being iterated over, |
| 27 | 2) an object to record the progress of the iteration, |
| 28 | 3) a procedure of one argument (the iterator object) that returns the next |
| 29 | object in the iteration or a pre-determined end marker. |
| 30 | |
| 31 | Simple example: |
| 32 | |
| 33 | (define-public (make-list-iterator l end-marker) |
| 34 | "Return a <gdb:iterator> object for a list." |
| 35 | (let ((next! (lambda (iter) |
| 36 | (let ((l (iterator-progress iter))) |
| 37 | (if (eq? l '()) |
| 38 | end-marker |
| 39 | (begin |
| 40 | (set-iterator-progress! iter (cdr l)) |
| 41 | (car l))))))) |
| 42 | (make-iterator l l next!))) |
| 43 | |
| 44 | (define l '(1 2)) |
| 45 | (define i (make-list-iterator l #:eoi)) |
| 46 | (iterator-next! i) -> 1 |
| 47 | (iterator-next! i) -> 2 |
| 48 | (iterator-next! i) -> #:eoi |
| 49 | |
| 50 | There is SRFI 41, Streams. We might support that too eventually (not with |
| 51 | this interface of course). */ |
| 52 | |
| 53 | #include "defs.h" |
| 54 | #include "guile-internal.h" |
| 55 | |
| 56 | /* A smob for iterating over something. |
| 57 | Typically this is used when computing a list of everything is |
| 58 | too expensive. |
| 59 | The typedef for this struct is in guile-internal.h. */ |
| 60 | |
| 61 | struct _iterator_smob |
| 62 | { |
| 63 | /* This always appears first. */ |
| 64 | gdb_smob base; |
| 65 | |
| 66 | /* The object being iterated over. */ |
| 67 | SCM object; |
| 68 | |
| 69 | /* An arbitrary object describing the progress of the iteration. |
| 70 | This is used by next_x to track progress. */ |
| 71 | SCM progress; |
| 72 | |
| 73 | /* A procedure of one argument, the iterator. |
| 74 | It returns the next object in the iteration. |
| 75 | How to signal "end of iteration" is up to next_x. */ |
| 76 | SCM next_x; |
| 77 | }; |
| 78 | |
| 79 | static const char iterator_smob_name[] = "gdb:iterator"; |
| 80 | |
| 81 | /* The tag Guile knows the iterator smob by. */ |
| 82 | static scm_t_bits iterator_smob_tag; |
| 83 | |
| 84 | /* A unique-enough marker to denote "end of iteration". */ |
| 85 | static SCM end_of_iteration; |
| 86 | |
| 87 | const char * |
| 88 | itscm_iterator_smob_name (void) |
| 89 | { |
| 90 | return iterator_smob_name; |
| 91 | } |
| 92 | |
| 93 | SCM |
| 94 | itscm_iterator_smob_object (iterator_smob *i_smob) |
| 95 | { |
| 96 | return i_smob->object; |
| 97 | } |
| 98 | |
| 99 | SCM |
| 100 | itscm_iterator_smob_progress (iterator_smob *i_smob) |
| 101 | { |
| 102 | return i_smob->progress; |
| 103 | } |
| 104 | |
| 105 | void |
| 106 | itscm_set_iterator_smob_progress_x (iterator_smob *i_smob, SCM progress) |
| 107 | { |
| 108 | i_smob->progress = progress; |
| 109 | } |
| 110 | \f |
| 111 | /* Administrivia for iterator smobs. */ |
| 112 | |
| 113 | /* The smob "print" function for <gdb:iterator>. */ |
| 114 | |
| 115 | static int |
| 116 | itscm_print_iterator_smob (SCM self, SCM port, scm_print_state *pstate) |
| 117 | { |
| 118 | iterator_smob *i_smob = (iterator_smob *) SCM_SMOB_DATA (self); |
| 119 | |
| 120 | gdbscm_printf (port, "#<%s ", iterator_smob_name); |
| 121 | scm_write (i_smob->object, port); |
| 122 | scm_puts (" ", port); |
| 123 | scm_write (i_smob->progress, port); |
| 124 | scm_puts (" ", port); |
| 125 | scm_write (i_smob->next_x, port); |
| 126 | scm_puts (">", port); |
| 127 | |
| 128 | scm_remember_upto_here_1 (self); |
| 129 | |
| 130 | /* Non-zero means success. */ |
| 131 | return 1; |
| 132 | } |
| 133 | |
| 134 | /* Low level routine to make a <gdb:iterator> object. |
| 135 | Caller must verify correctness of arguments. |
| 136 | No exceptions are thrown. */ |
| 137 | |
| 138 | static SCM |
| 139 | itscm_make_iterator_smob (SCM object, SCM progress, SCM next) |
| 140 | { |
| 141 | iterator_smob *i_smob = (iterator_smob *) |
| 142 | scm_gc_malloc (sizeof (iterator_smob), iterator_smob_name); |
| 143 | SCM i_scm; |
| 144 | |
| 145 | i_smob->object = object; |
| 146 | i_smob->progress = progress; |
| 147 | i_smob->next_x = next; |
| 148 | i_scm = scm_new_smob (iterator_smob_tag, (scm_t_bits) i_smob); |
| 149 | gdbscm_init_gsmob (&i_smob->base); |
| 150 | |
| 151 | return i_scm; |
| 152 | } |
| 153 | |
| 154 | /* (make-iterator object object procedure) -> <gdb:iterator> */ |
| 155 | |
| 156 | SCM |
| 157 | gdbscm_make_iterator (SCM object, SCM progress, SCM next) |
| 158 | { |
| 159 | SCM i_scm; |
| 160 | |
| 161 | SCM_ASSERT_TYPE (gdbscm_is_procedure (next), next, SCM_ARG3, FUNC_NAME, |
| 162 | _("procedure")); |
| 163 | |
| 164 | i_scm = itscm_make_iterator_smob (object, progress, next); |
| 165 | |
| 166 | return i_scm; |
| 167 | } |
| 168 | |
| 169 | /* Return non-zero if SCM is a <gdb:iterator> object. */ |
| 170 | |
| 171 | int |
| 172 | itscm_is_iterator (SCM scm) |
| 173 | { |
| 174 | return SCM_SMOB_PREDICATE (iterator_smob_tag, scm); |
| 175 | } |
| 176 | |
| 177 | /* (iterator? object) -> boolean */ |
| 178 | |
| 179 | static SCM |
| 180 | gdbscm_iterator_p (SCM scm) |
| 181 | { |
| 182 | return scm_from_bool (itscm_is_iterator (scm)); |
| 183 | } |
| 184 | |
| 185 | /* (end-of-iteration) -> an "end-of-iteration" marker |
| 186 | We rely on this not being used as a data result of an iterator. */ |
| 187 | |
| 188 | SCM |
| 189 | gdbscm_end_of_iteration (void) |
| 190 | { |
| 191 | return end_of_iteration; |
| 192 | } |
| 193 | |
| 194 | /* Return non-zero if OBJ is the end-of-iteration marker. */ |
| 195 | |
| 196 | int |
| 197 | itscm_is_end_of_iteration (SCM obj) |
| 198 | { |
| 199 | return scm_is_eq (obj, end_of_iteration); |
| 200 | } |
| 201 | |
| 202 | /* (end-of-iteration? obj) -> boolean */ |
| 203 | |
| 204 | static SCM |
| 205 | gdbscm_end_of_iteration_p (SCM obj) |
| 206 | { |
| 207 | return scm_from_bool (itscm_is_end_of_iteration (obj)); |
| 208 | } |
| 209 | |
| 210 | /* Call the next! method on ITER, which must be a <gdb:iterator> object. |
| 211 | Returns a <gdb:exception> object if an exception is thrown. |
| 212 | OK_EXCPS is passed to gdbscm_safe_call_1. */ |
| 213 | |
| 214 | SCM |
| 215 | itscm_safe_call_next_x (SCM iter, excp_matcher_func *ok_excps) |
| 216 | { |
| 217 | iterator_smob *i_smob; |
| 218 | |
| 219 | gdb_assert (itscm_is_iterator (iter)); |
| 220 | |
| 221 | i_smob = (iterator_smob *) SCM_SMOB_DATA (iter); |
| 222 | return gdbscm_safe_call_1 (i_smob->next_x, iter, ok_excps); |
| 223 | } |
| 224 | \f |
| 225 | /* Iterator methods. */ |
| 226 | |
| 227 | /* Returns the <gdb:iterator> smob in SELF. |
| 228 | Throws an exception if SELF is not an iterator smob. */ |
| 229 | |
| 230 | SCM |
| 231 | itscm_get_iterator_arg_unsafe (SCM self, int arg_pos, const char *func_name) |
| 232 | { |
| 233 | SCM_ASSERT_TYPE (itscm_is_iterator (self), self, arg_pos, func_name, |
| 234 | iterator_smob_name); |
| 235 | |
| 236 | return self; |
| 237 | } |
| 238 | |
| 239 | /* (iterator-object <gdb:iterator>) -> object */ |
| 240 | |
| 241 | static SCM |
| 242 | gdbscm_iterator_object (SCM self) |
| 243 | { |
| 244 | SCM i_scm; |
| 245 | iterator_smob *i_smob; |
| 246 | |
| 247 | i_scm = itscm_get_iterator_arg_unsafe (self, SCM_ARG1, FUNC_NAME); |
| 248 | i_smob = (iterator_smob *) SCM_SMOB_DATA (i_scm); |
| 249 | |
| 250 | return i_smob->object; |
| 251 | } |
| 252 | |
| 253 | /* (iterator-progress <gdb:iterator>) -> object */ |
| 254 | |
| 255 | static SCM |
| 256 | gdbscm_iterator_progress (SCM self) |
| 257 | { |
| 258 | SCM i_scm; |
| 259 | iterator_smob *i_smob; |
| 260 | |
| 261 | i_scm = itscm_get_iterator_arg_unsafe (self, SCM_ARG1, FUNC_NAME); |
| 262 | i_smob = (iterator_smob *) SCM_SMOB_DATA (i_scm); |
| 263 | |
| 264 | return i_smob->progress; |
| 265 | } |
| 266 | |
| 267 | /* (set-iterator-progress! <gdb:iterator> object) -> unspecified */ |
| 268 | |
| 269 | static SCM |
| 270 | gdbscm_set_iterator_progress_x (SCM self, SCM value) |
| 271 | { |
| 272 | SCM i_scm; |
| 273 | iterator_smob *i_smob; |
| 274 | |
| 275 | i_scm = itscm_get_iterator_arg_unsafe (self, SCM_ARG1, FUNC_NAME); |
| 276 | i_smob = (iterator_smob *) SCM_SMOB_DATA (i_scm); |
| 277 | |
| 278 | i_smob->progress = value; |
| 279 | return SCM_UNSPECIFIED; |
| 280 | } |
| 281 | |
| 282 | /* (iterator-next! <gdb:iterator>) -> object |
| 283 | The result is the next value in the iteration or some "end" marker. |
| 284 | It is up to each iterator's next! function to specify what its end |
| 285 | marker is. */ |
| 286 | |
| 287 | static SCM |
| 288 | gdbscm_iterator_next_x (SCM self) |
| 289 | { |
| 290 | SCM i_scm; |
| 291 | iterator_smob *i_smob; |
| 292 | |
| 293 | i_scm = itscm_get_iterator_arg_unsafe (self, SCM_ARG1, FUNC_NAME); |
| 294 | i_smob = (iterator_smob *) SCM_SMOB_DATA (i_scm); |
| 295 | /* We leave type-checking of the procedure to gdbscm_safe_call_1. */ |
| 296 | |
| 297 | return gdbscm_safe_call_1 (i_smob->next_x, self, NULL); |
| 298 | } |
| 299 | \f |
| 300 | /* Initialize the Scheme iterator code. */ |
| 301 | |
| 302 | static const scheme_function iterator_functions[] = |
| 303 | { |
| 304 | { "make-iterator", 3, 0, 0, gdbscm_make_iterator, |
| 305 | "\ |
| 306 | Create a <gdb:iterator> object.\n\ |
| 307 | \n\ |
| 308 | Arguments: object progress next!\n\ |
| 309 | object: The object to iterate over.\n\ |
| 310 | progress: An object to use to track progress of the iteration.\n\ |
| 311 | next!: A procedure of one argument, the iterator.\n\ |
| 312 | Returns the next element in the iteration or an implementation-chosen\n\ |
| 313 | value to signify iteration is complete.\n\ |
| 314 | By convention end-of-iteration should be marked with (end-of-iteration)\n\ |
| 315 | from module (gdb iterator)." }, |
| 316 | |
| 317 | { "iterator?", 1, 0, 0, gdbscm_iterator_p, |
| 318 | "\ |
| 319 | Return #t if the object is a <gdb:iterator> object." }, |
| 320 | |
| 321 | { "iterator-object", 1, 0, 0, gdbscm_iterator_object, |
| 322 | "\ |
| 323 | Return the object being iterated over." }, |
| 324 | |
| 325 | { "iterator-progress", 1, 0, 0, gdbscm_iterator_progress, |
| 326 | "\ |
| 327 | Return the progress object of the iterator." }, |
| 328 | |
| 329 | { "set-iterator-progress!", 2, 0, 0, gdbscm_set_iterator_progress_x, |
| 330 | "\ |
| 331 | Set the progress object of the iterator." }, |
| 332 | |
| 333 | { "iterator-next!", 1, 0, 0, gdbscm_iterator_next_x, |
| 334 | "\ |
| 335 | Invoke the next! procedure of the iterator and return its result." }, |
| 336 | |
| 337 | { "end-of-iteration", 0, 0, 0, gdbscm_end_of_iteration, |
| 338 | "\ |
| 339 | Return the end-of-iteration marker." }, |
| 340 | |
| 341 | { "end-of-iteration?", 1, 0, 0, gdbscm_end_of_iteration_p, |
| 342 | "\ |
| 343 | Return #t if the object is the end-of-iteration marker." }, |
| 344 | |
| 345 | END_FUNCTIONS |
| 346 | }; |
| 347 | |
| 348 | void |
| 349 | gdbscm_initialize_iterators (void) |
| 350 | { |
| 351 | iterator_smob_tag = gdbscm_make_smob_type (iterator_smob_name, |
| 352 | sizeof (iterator_smob)); |
| 353 | scm_set_smob_print (iterator_smob_tag, itscm_print_iterator_smob); |
| 354 | |
| 355 | gdbscm_define_functions (iterator_functions, 1); |
| 356 | |
| 357 | /* We can make this more unique if it's necessary, |
| 358 | but this is good enough for now. */ |
| 359 | end_of_iteration = scm_from_latin1_keyword ("end-of-iteration"); |
| 360 | } |