1 /* Simple iterators for GDB/Scheme.
3 Copyright (C) 2014-2017 Free Software Foundation, Inc.
5 This file is part of GDB.
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.
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.
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/>. */
20 /* See README file in this directory for implementation notes, coding
21 conventions, et.al. */
23 /* These are *simple* iterators, used to implement iterating over a collection
24 of objects. They are implemented as a smob containing three objects:
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.
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)))
40 (set-iterator-progress! iter (cdr l))
42 (make-iterator l l next!)))
45 (define i (make-list-iterator l #:eoi))
46 (iterator-next! i) -> 1
47 (iterator-next! i) -> 2
48 (iterator-next! i) -> #:eoi
50 There is SRFI 41, Streams. We might support that too eventually (not with
51 this interface of course). */
54 #include "guile-internal.h"
56 /* A smob for iterating over something.
57 Typically this is used when computing a list of everything is
59 The typedef for this struct is in guile-internal.h. */
63 /* This always appears first. */
66 /* The object being iterated over. */
69 /* An arbitrary object describing the progress of the iteration.
70 This is used by next_x to track progress. */
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. */
79 static const char iterator_smob_name[] = "gdb:iterator";
81 /* The tag Guile knows the iterator smob by. */
82 static scm_t_bits iterator_smob_tag;
84 /* A unique-enough marker to denote "end of iteration". */
85 static SCM end_of_iteration;
88 itscm_iterator_smob_name (void)
90 return iterator_smob_name;
94 itscm_iterator_smob_object (iterator_smob *i_smob)
96 return i_smob->object;
100 itscm_iterator_smob_progress (iterator_smob *i_smob)
102 return i_smob->progress;
106 itscm_set_iterator_smob_progress_x (iterator_smob *i_smob, SCM progress)
108 i_smob->progress = progress;
111 /* Administrivia for iterator smobs. */
113 /* The smob "print" function for <gdb:iterator>. */
116 itscm_print_iterator_smob (SCM self, SCM port, scm_print_state *pstate)
118 iterator_smob *i_smob = (iterator_smob *) SCM_SMOB_DATA (self);
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);
128 scm_remember_upto_here_1 (self);
130 /* Non-zero means success. */
134 /* Low level routine to make a <gdb:iterator> object.
135 Caller must verify correctness of arguments.
136 No exceptions are thrown. */
139 itscm_make_iterator_smob (SCM object, SCM progress, SCM next)
141 iterator_smob *i_smob = (iterator_smob *)
142 scm_gc_malloc (sizeof (iterator_smob), iterator_smob_name);
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);
154 /* (make-iterator object object procedure) -> <gdb:iterator> */
157 gdbscm_make_iterator (SCM object, SCM progress, SCM next)
161 SCM_ASSERT_TYPE (gdbscm_is_procedure (next), next, SCM_ARG3, FUNC_NAME,
164 i_scm = itscm_make_iterator_smob (object, progress, next);
169 /* Return non-zero if SCM is a <gdb:iterator> object. */
172 itscm_is_iterator (SCM scm)
174 return SCM_SMOB_PREDICATE (iterator_smob_tag, scm);
177 /* (iterator? object) -> boolean */
180 gdbscm_iterator_p (SCM scm)
182 return scm_from_bool (itscm_is_iterator (scm));
185 /* (end-of-iteration) -> an "end-of-iteration" marker
186 We rely on this not being used as a data result of an iterator. */
189 gdbscm_end_of_iteration (void)
191 return end_of_iteration;
194 /* Return non-zero if OBJ is the end-of-iteration marker. */
197 itscm_is_end_of_iteration (SCM obj)
199 return scm_is_eq (obj, end_of_iteration);
202 /* (end-of-iteration? obj) -> boolean */
205 gdbscm_end_of_iteration_p (SCM obj)
207 return scm_from_bool (itscm_is_end_of_iteration (obj));
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. */
215 itscm_safe_call_next_x (SCM iter, excp_matcher_func *ok_excps)
217 iterator_smob *i_smob;
219 gdb_assert (itscm_is_iterator (iter));
221 i_smob = (iterator_smob *) SCM_SMOB_DATA (iter);
222 return gdbscm_safe_call_1 (i_smob->next_x, iter, ok_excps);
225 /* Iterator methods. */
227 /* Returns the <gdb:iterator> smob in SELF.
228 Throws an exception if SELF is not an iterator smob. */
231 itscm_get_iterator_arg_unsafe (SCM self, int arg_pos, const char *func_name)
233 SCM_ASSERT_TYPE (itscm_is_iterator (self), self, arg_pos, func_name,
239 /* (iterator-object <gdb:iterator>) -> object */
242 gdbscm_iterator_object (SCM self)
245 iterator_smob *i_smob;
247 i_scm = itscm_get_iterator_arg_unsafe (self, SCM_ARG1, FUNC_NAME);
248 i_smob = (iterator_smob *) SCM_SMOB_DATA (i_scm);
250 return i_smob->object;
253 /* (iterator-progress <gdb:iterator>) -> object */
256 gdbscm_iterator_progress (SCM self)
259 iterator_smob *i_smob;
261 i_scm = itscm_get_iterator_arg_unsafe (self, SCM_ARG1, FUNC_NAME);
262 i_smob = (iterator_smob *) SCM_SMOB_DATA (i_scm);
264 return i_smob->progress;
267 /* (set-iterator-progress! <gdb:iterator> object) -> unspecified */
270 gdbscm_set_iterator_progress_x (SCM self, SCM value)
273 iterator_smob *i_smob;
275 i_scm = itscm_get_iterator_arg_unsafe (self, SCM_ARG1, FUNC_NAME);
276 i_smob = (iterator_smob *) SCM_SMOB_DATA (i_scm);
278 i_smob->progress = value;
279 return SCM_UNSPECIFIED;
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
288 gdbscm_iterator_next_x (SCM self)
291 iterator_smob *i_smob;
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. */
297 return gdbscm_safe_call_1 (i_smob->next_x, self, NULL);
300 /* Initialize the Scheme iterator code. */
302 static const scheme_function iterator_functions[] =
304 { "make-iterator", 3, 0, 0, as_a_scm_t_subr (gdbscm_make_iterator),
306 Create a <gdb:iterator> object.\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)." },
317 { "iterator?", 1, 0, 0, as_a_scm_t_subr (gdbscm_iterator_p),
319 Return #t if the object is a <gdb:iterator> object." },
321 { "iterator-object", 1, 0, 0, as_a_scm_t_subr (gdbscm_iterator_object),
323 Return the object being iterated over." },
325 { "iterator-progress", 1, 0, 0, as_a_scm_t_subr (gdbscm_iterator_progress),
327 Return the progress object of the iterator." },
329 { "set-iterator-progress!", 2, 0, 0,
330 as_a_scm_t_subr (gdbscm_set_iterator_progress_x),
332 Set the progress object of the iterator." },
334 { "iterator-next!", 1, 0, 0, as_a_scm_t_subr (gdbscm_iterator_next_x),
336 Invoke the next! procedure of the iterator and return its result." },
338 { "end-of-iteration", 0, 0, 0, as_a_scm_t_subr (gdbscm_end_of_iteration),
340 Return the end-of-iteration marker." },
342 { "end-of-iteration?", 1, 0, 0, as_a_scm_t_subr (gdbscm_end_of_iteration_p),
344 Return #t if the object is the end-of-iteration marker." },
350 gdbscm_initialize_iterators (void)
352 iterator_smob_tag = gdbscm_make_smob_type (iterator_smob_name,
353 sizeof (iterator_smob));
354 scm_set_smob_print (iterator_smob_tag, itscm_print_iterator_smob);
356 gdbscm_define_functions (iterator_functions, 1);
358 /* We can make this more unique if it's necessary,
359 but this is good enough for now. */
360 end_of_iteration = scm_from_latin1_keyword ("end-of-iteration");