GDB (xrefs)
scm-iterator.c
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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 
62 {
63  /* This always appears first. */
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 *
89 {
90  return iterator_smob_name;
91 }
92 
93 SCM
95 {
96  return i_smob->object;
97 }
98 
99 SCM
101 {
102  return i_smob->progress;
103 }
104 
105 void
107 {
108  i_smob->progress = progress;
109 }
110 
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
173 {
174  return SCM_SMOB_PREDICATE (iterator_smob_tag, scm);
175 }
176 
177 /* (iterator? object) -> boolean */
178 
179 static 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
190 {
191  return end_of_iteration;
192 }
193 
194 /* Return non-zero if OBJ is the end-of-iteration marker. */
195 
196 int
198 {
199  return scm_is_eq (obj, end_of_iteration);
200 }
201 
202 /* (end-of-iteration? obj) -> boolean */
203 
204 static SCM
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
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 
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,
235 
236  return self;
237 }
238 
239 /* (iterator-object <gdb:iterator>) -> object */
240 
241 static SCM
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
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
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
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 
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 
346 };
347 
348 void
350 {
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 }
static SCM scm_new_smob(scm_t_bits tc, scm_t_bits data)
void gdbscm_initialize_iterators(void)
Definition: scm-iterator.c:349
void gdbscm_define_functions(const scheme_function *, int is_public)
Definition: scm-utils.c:44
void itscm_set_iterator_smob_progress_x(iterator_smob *i_smob, SCM progress)
Definition: scm-iterator.c:106
SCM itscm_iterator_smob_progress(iterator_smob *i_smob)
Definition: scm-iterator.c:100
#define FUNC_NAME
static SCM gdbscm_iterator_object(SCM self)
Definition: scm-iterator.c:242
scm_t_bits gdbscm_make_smob_type(const char *name, size_t size)
Definition: scm-gsmob.c:102
const char * itscm_iterator_smob_name(void)
Definition: scm-iterator.c:88
#define _(String)
Definition: gdb_locale.h:40
static SCM gdbscm_iterator_progress(SCM self)
Definition: scm-iterator.c:256
SCM gdbscm_make_iterator(SCM object, SCM progress, SCM next)
Definition: scm-iterator.c:157
SCM itscm_safe_call_next_x(SCM iter, excp_matcher_func *ok_excps)
Definition: scm-iterator.c:215
int excp_matcher_func(SCM key)
static SCM end_of_iteration
Definition: scm-iterator.c:85
static SCM gdbscm_iterator_next_x(SCM self)
Definition: scm-iterator.c:288
static SCM gdbscm_iterator_p(SCM scm)
Definition: scm-iterator.c:180
void gdbscm_init_gsmob(gdb_smob *base)
Definition: scm-gsmob.c:113
static struct parser_state * pstate
Definition: ada-exp.c:149
static SCM gdbscm_end_of_iteration_p(SCM obj)
Definition: scm-iterator.c:205
#define gdb_assert(expr)
Definition: gdb_assert.h:33
void gdbscm_printf(SCM port, const char *format,...) ATTRIBUTE_PRINTF(2
Definition: value.c:172
int itscm_is_iterator(SCM scm)
Definition: scm-iterator.c:172
int itscm_is_end_of_iteration(SCM obj)
Definition: scm-iterator.c:197
SCM gdbscm_safe_call_1(SCM proc, SCM arg0, excp_matcher_func *ok_excps)
#define END_FUNCTIONS
static SCM itscm_make_iterator_smob(SCM object, SCM progress, SCM next)
Definition: scm-iterator.c:139
static SCM gdbscm_set_iterator_progress_x(SCM self, SCM value)
Definition: scm-iterator.c:270
SCM itscm_iterator_smob_object(iterator_smob *i_smob)
Definition: scm-iterator.c:94
static const char iterator_smob_name[]
Definition: scm-iterator.c:79
gdb_smob base
Definition: scm-iterator.c:64
SCM itscm_get_iterator_arg_unsafe(SCM self, int arg_pos, const char *func_name)
Definition: scm-iterator.c:231
int gdbscm_is_procedure(SCM proc)
Definition: scm-utils.c:579
SCM gdbscm_end_of_iteration(void)
Definition: scm-iterator.c:189
static int itscm_print_iterator_smob(SCM self, SCM port, scm_print_state *pstate)
Definition: scm-iterator.c:116
static scm_t_bits iterator_smob_tag
Definition: scm-iterator.c:82