aboutsummaryrefslogtreecommitdiff
path: root/gdb/guile/scm-iterator.c
blob: ce9c323e82526328f9849f8c9b967796af29bb18 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
/* Simple iterators for GDB/Scheme.

   Copyright (C) 2014-2016 Free Software Foundation, Inc.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

/* See README file in this directory for implementation notes, coding
   conventions, et.al.  */

/* These are *simple* iterators, used to implement iterating over a collection
   of objects.  They are implemented as a smob containing three objects:

   1) the object being iterated over,
   2) an object to record the progress of the iteration,
   3) a procedure of one argument (the iterator object) that returns the next
      object in the iteration or a pre-determined end marker.

   Simple example:

   (define-public (make-list-iterator l end-marker)
     "Return a <gdb:iterator> object for a list."
     (let ((next! (lambda (iter)
		    (let ((l (iterator-progress iter)))
		      (if (eq? l '())
		          end-marker
		          (begin
			    (set-iterator-progress! iter (cdr l))
			    (car l)))))))
       (make-iterator l l next!)))

   (define l '(1 2))
   (define i (make-list-iterator l #:eoi))
   (iterator-next! i) -> 1
   (iterator-next! i) -> 2
   (iterator-next! i) -> #:eoi

   There is SRFI 41, Streams.  We might support that too eventually (not with
   this interface of course).  */

#include "defs.h"
#include "guile-internal.h"

/* A smob for iterating over something.
   Typically this is used when computing a list of everything is
   too expensive.
   The typedef for this struct is in guile-internal.h.  */

struct _iterator_smob
{
  /* This always appears first.  */
  gdb_smob base;

  /* The object being iterated over.  */
  SCM object;

  /* An arbitrary object describing the progress of the iteration.
     This is used by next_x to track progress.  */
  SCM progress;

  /* A procedure of one argument, the iterator.
     It returns the next object in the iteration.
     How to signal "end of iteration" is up to next_x.  */
  SCM next_x;
};

static const char iterator_smob_name[] = "gdb:iterator";

/* The tag Guile knows the iterator smob by.  */
static scm_t_bits iterator_smob_tag;

/* A unique-enough marker to denote "end of iteration".  */
static SCM end_of_iteration;

const char *
itscm_iterator_smob_name (void)
{
  return iterator_smob_name;
}

SCM
itscm_iterator_smob_object (iterator_smob *i_smob)
{
  return i_smob->object;
}

SCM
itscm_iterator_smob_progress (iterator_smob *i_smob)
{
  return i_smob->progress;
}

void
itscm_set_iterator_smob_progress_x (iterator_smob *i_smob, SCM progress)
{
  i_smob->progress = progress;
}

/* Administrivia for iterator smobs.  */

/* The smob "print" function for <gdb:iterator>.  */

static int
itscm_print_iterator_smob (SCM self, SCM port, scm_print_state *pstate)
{
  iterator_smob *i_smob = (iterator_smob *) SCM_SMOB_DATA (self);

  gdbscm_printf (port, "#<%s ", iterator_smob_name);
  scm_write (i_smob->object, port);
  scm_puts (" ", port);
  scm_write (i_smob->progress, port);
  scm_puts (" ", port);
  scm_write (i_smob->next_x, port);
  scm_puts (">", port);

  scm_remember_upto_here_1 (self);

  /* Non-zero means success.  */
  return 1;
}

/* Low level routine to make a <gdb:iterator> object.
   Caller must verify correctness of arguments.
   No exceptions are thrown.  */

static SCM
itscm_make_iterator_smob (SCM object, SCM progress, SCM next)
{
  iterator_smob *i_smob = (iterator_smob *)
    scm_gc_malloc (sizeof (iterator_smob), iterator_smob_name);
  SCM i_scm;

  i_smob->object = object;
  i_smob->progress = progress;
  i_smob->next_x = next;
  i_scm = scm_new_smob (iterator_smob_tag, (scm_t_bits) i_smob);
  gdbscm_init_gsmob (&i_smob->base);

  return i_scm;
}

/* (make-iterator object object procedure) -> <gdb:iterator> */

SCM
gdbscm_make_iterator (SCM object, SCM progress, SCM next)
{
  SCM i_scm;

  SCM_ASSERT_TYPE (gdbscm_is_procedure (next), next, SCM_ARG3, FUNC_NAME,
		   _("procedure"));

  i_scm = itscm_make_iterator_smob (object, progress, next);

  return i_scm;
}

/* Return non-zero if SCM is a <gdb:iterator> object.  */

int
itscm_is_iterator (SCM scm)
{
  return SCM_SMOB_PREDICATE (iterator_smob_tag, scm);
}

/* (iterator? object) -> boolean */

static SCM
gdbscm_iterator_p (SCM scm)
{
  return scm_from_bool (itscm_is_iterator (scm));
}

/* (end-of-iteration) -> an "end-of-iteration" marker
   We rely on this not being used as a data result of an iterator.  */

SCM
gdbscm_end_of_iteration (void)
{
  return end_of_iteration;
}

/* Return non-zero if OBJ is the end-of-iteration marker.  */

int
itscm_is_end_of_iteration (SCM obj)
{
  return scm_is_eq (obj, end_of_iteration);
}

/* (end-of-iteration? obj) -> boolean */

static SCM
gdbscm_end_of_iteration_p (SCM obj)
{
  return scm_from_bool (itscm_is_end_of_iteration (obj));
}

/* Call the next! method on ITER, which must be a <gdb:iterator> object.
   Returns a <gdb:exception> object if an exception is thrown.
   OK_EXCPS is passed to gdbscm_safe_call_1.  */

SCM
itscm_safe_call_next_x (SCM iter, excp_matcher_func *ok_excps)
{
  iterator_smob *i_smob;

  gdb_assert (itscm_is_iterator (iter));

  i_smob = (iterator_smob *) SCM_SMOB_DATA (iter);
  return gdbscm_safe_call_1 (i_smob->next_x, iter, ok_excps);
}

/* Iterator methods.  */

/* Returns the <gdb:iterator> smob in SELF.
   Throws an exception if SELF is not an iterator smob.  */

SCM
itscm_get_iterator_arg_unsafe (SCM self, int arg_pos, const char *func_name)
{
  SCM_ASSERT_TYPE (itscm_is_iterator (self), self, arg_pos, func_name,
		   iterator_smob_name);

  return self;
}

/* (iterator-object <gdb:iterator>) -> object */

static SCM
gdbscm_iterator_object (SCM self)
{
  SCM i_scm;
  iterator_smob *i_smob;

  i_scm = itscm_get_iterator_arg_unsafe (self, SCM_ARG1, FUNC_NAME);
  i_smob = (iterator_smob *) SCM_SMOB_DATA (i_scm);

  return i_smob->object;
}

/* (iterator-progress <gdb:iterator>) -> object */

static SCM
gdbscm_iterator_progress (SCM self)
{
  SCM i_scm;
  iterator_smob *i_smob;

  i_scm = itscm_get_iterator_arg_unsafe (self, SCM_ARG1, FUNC_NAME);
  i_smob = (iterator_smob *) SCM_SMOB_DATA (i_scm);

  return i_smob->progress;
}

/* (set-iterator-progress! <gdb:iterator> object) -> unspecified */

static SCM
gdbscm_set_iterator_progress_x (SCM self, SCM value)
{
  SCM i_scm;
  iterator_smob *i_smob;

  i_scm = itscm_get_iterator_arg_unsafe (self, SCM_ARG1, FUNC_NAME);
  i_smob = (iterator_smob *) SCM_SMOB_DATA (i_scm);

  i_smob->progress = value;
  return SCM_UNSPECIFIED;
}

/* (iterator-next! <gdb:iterator>) -> object
   The result is the next value in the iteration or some "end" marker.
   It is up to each iterator's next! function to specify what its end
   marker is.  */

static SCM
gdbscm_iterator_next_x (SCM self)
{
  SCM i_scm;
  iterator_smob *i_smob;

  i_scm = itscm_get_iterator_arg_unsafe (self, SCM_ARG1, FUNC_NAME);
  i_smob = (iterator_smob *) SCM_SMOB_DATA (i_scm);
  /* We leave type-checking of the procedure to gdbscm_safe_call_1.  */

  return gdbscm_safe_call_1 (i_smob->next_x, self, NULL);
}

/* Initialize the Scheme iterator code.  */

static const scheme_function iterator_functions[] =
{
  { "make-iterator", 3, 0, 0, as_a_scm_t_subr (gdbscm_make_iterator),
    "\
Create a <gdb:iterator> object.\n\
\n\
  Arguments: object progress next!\n\
    object:   The object to iterate over.\n\
    progress: An object to use to track progress of the iteration.\n\
    next!:    A procedure of one argument, the iterator.\n\
      Returns the next element in the iteration or an implementation-chosen\n\
      value to signify iteration is complete.\n\
      By convention end-of-iteration should be marked with (end-of-iteration)\n\
      from module (gdb iterator)." },

  { "iterator?", 1, 0, 0, as_a_scm_t_subr (gdbscm_iterator_p),
    "\
Return #t if the object is a <gdb:iterator> object." },

  { "iterator-object", 1, 0, 0, as_a_scm_t_subr (gdbscm_iterator_object),
    "\
Return the object being iterated over." },

  { "iterator-progress", 1, 0, 0, as_a_scm_t_subr (gdbscm_iterator_progress),
    "\
Return the progress object of the iterator." },

  { "set-iterator-progress!", 2, 0, 0,
    as_a_scm_t_subr (gdbscm_set_iterator_progress_x),
    "\
Set the progress object of the iterator." },

  { "iterator-next!", 1, 0, 0, as_a_scm_t_subr (gdbscm_iterator_next_x),
    "\
Invoke the next! procedure of the iterator and return its result." },

  { "end-of-iteration", 0, 0, 0, as_a_scm_t_subr (gdbscm_end_of_iteration),
    "\
Return the end-of-iteration marker." },

  { "end-of-iteration?", 1, 0, 0, as_a_scm_t_subr (gdbscm_end_of_iteration_p),
    "\
Return #t if the object is the end-of-iteration marker." },

  END_FUNCTIONS
};

void
gdbscm_initialize_iterators (void)
{
  iterator_smob_tag = gdbscm_make_smob_type (iterator_smob_name,
					     sizeof (iterator_smob));
  scm_set_smob_print (iterator_smob_tag, itscm_print_iterator_smob);

  gdbscm_define_functions (iterator_functions, 1);

  /* We can make this more unique if it's necessary,
     but this is good enough for now.  */
  end_of_iteration = scm_from_latin1_keyword ("end-of-iteration");
}