1 /* PSPP - a program for statistical analysis.
2 Copyright (C) 1997-9, 2000 Free Software Foundation, Inc.
4 This program is free software: you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation, either version 3 of the License, or
7 (at your option) any later version.
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program. If not, see <http://www.gnu.org/licenses/>. */
19 #include "control-stack.h"
21 #include <data/case.h>
22 #include <data/dictionary.h>
23 #include <data/procedure.h>
24 #include <data/settings.h>
25 #include <data/transformations.h>
26 #include <data/variable.h>
27 #include <language/command.h>
28 #include <language/expressions/public.h>
29 #include <language/lexer/lexer.h>
30 #include <libpspp/compiler.h>
31 #include <libpspp/message.h>
32 #include <libpspp/misc.h>
33 #include <libpspp/pool.h>
34 #include <libpspp/str.h>
39 #define _(msgid) gettext (msgid)
41 /* LOOP outputs a transformation that is executed only on the
42 first pass through the loop. On this trip, it initializes for
43 the first pass by resetting the pass number, setting up the
44 indexing clause, and testing the LOOP IF clause. If the loop
45 is not to be entered at all, it jumps forward just past the
46 END LOOP transformation; otherwise, it continues to the
47 transformation following LOOP.
49 END LOOP outputs a transformation that executes at the end of
50 each trip through the loop. It checks the END LOOP IF clause,
51 then updates the pass number, increments the indexing clause,
52 and tests the LOOP IF clause. If another pass through the
53 loop is due, it jumps backward to just after the LOOP
54 transformation; otherwise, it continues to the transformation
55 following END LOOP. */
62 /* Iteration limit. */
63 int max_pass_count; /* Maximum number of passes (-1=unlimited). */
64 int pass; /* Number of passes thru the loop so far. */
66 /* a=a TO b [BY c]. */
67 struct variable *index_var; /* Index variable. */
68 struct expression *first_expr; /* Starting index. */
69 struct expression *by_expr; /* Index increment (default 1.0 if null). */
70 struct expression *last_expr; /* Terminal index. */
71 double cur, by, last; /* Current value, increment, last value. */
73 /* IF condition for LOOP or END LOOP. */
74 struct expression *loop_condition;
75 struct expression *end_loop_condition;
77 /* Transformation indexes. */
78 int past_LOOP_index; /* Just past LOOP transformation. */
79 int past_END_LOOP_index; /* Just past END LOOP transformation. */
82 static const struct ctl_class loop_class;
84 static trns_finalize_func loop_trns_finalize;
85 static trns_proc_func loop_trns_proc, end_loop_trns_proc, break_trns_proc;
86 static trns_free_func loop_trns_free;
88 static struct loop_trns *create_loop_trns (struct dataset *);
89 static bool parse_if_clause (struct lexer *,
90 struct loop_trns *, struct expression **);
91 static bool parse_index_clause (struct dataset *, struct lexer *,
92 struct loop_trns *, bool *created_index_var);
93 static void close_loop (void *);
99 cmd_loop (struct lexer *lexer, struct dataset *ds)
101 struct loop_trns *loop;
102 bool created_index_var = false;
105 loop = create_loop_trns (ds);
106 while (lex_token (lexer) != '.' && ok)
108 if (lex_match_id (lexer, "IF"))
109 ok = parse_if_clause (lexer, loop, &loop->loop_condition);
111 ok = parse_index_clause (ds, lexer, loop, &created_index_var);
114 /* Clean up if necessary. */
117 loop->max_pass_count = 0;
118 if (loop->index_var != NULL && created_index_var)
120 dict_delete_var (dataset_dict (ds), loop->index_var);
121 loop->index_var = NULL;
125 return ok ? CMD_SUCCESS : CMD_CASCADING_FAILURE;
128 /* Parses END LOOP. */
130 cmd_end_loop (struct lexer *lexer, struct dataset *ds)
132 struct loop_trns *loop;
135 loop = ctl_stack_top (&loop_class);
137 return CMD_CASCADING_FAILURE;
139 assert (loop->ds == ds);
142 if (lex_match_id (lexer, "IF"))
143 ok = parse_if_clause (lexer, loop, &loop->end_loop_condition);
145 ok = lex_end_of_command (lexer) == CMD_SUCCESS;
148 loop->max_pass_count = 0;
150 ctl_stack_pop (loop);
152 return ok ? CMD_SUCCESS : CMD_FAILURE;
157 cmd_break (struct lexer *lexer, struct dataset *ds)
159 struct ctl_stmt *loop = ctl_stack_search (&loop_class);
161 return CMD_CASCADING_FAILURE;
163 add_transformation (ds, break_trns_proc, NULL, loop);
165 return lex_end_of_command (lexer);
168 /* Closes a LOOP construct by emitting the END LOOP
169 transformation and finalizing its members appropriately. */
171 close_loop (void *loop_)
173 struct loop_trns *loop = loop_;
175 add_transformation (loop->ds, end_loop_trns_proc, NULL, loop);
176 loop->past_END_LOOP_index = next_transformation (loop->ds);
178 /* If there's nothing else limiting the number of loops, use
179 MXLOOPS as a limit. */
180 if (loop->max_pass_count == -1
181 && loop->index_var == NULL
182 && loop->loop_condition == NULL
183 && loop->end_loop_condition == NULL)
184 loop->max_pass_count = settings_get_mxloops ();
187 /* Parses an IF clause for LOOP or END LOOP and stores the
188 resulting expression to *CONDITION.
189 Returns true if successful, false on failure. */
191 parse_if_clause (struct lexer *lexer,
192 struct loop_trns *loop, struct expression **condition)
194 if (*condition != NULL)
196 lex_sbc_only_once ("IF");
200 *condition = expr_parse_pool (lexer, loop->pool, loop->ds, EXPR_BOOLEAN);
201 return *condition != NULL;
204 /* Parses an indexing clause into LOOP.
205 Stores true in *CREATED_INDEX_VAR if the index clause created
206 a new variable, false otherwise.
207 Returns true if successful, false on failure. */
209 parse_index_clause (struct dataset *ds, struct lexer *lexer,
210 struct loop_trns *loop, bool *created_index_var)
212 if (loop->index_var != NULL)
214 msg (SE, _("Only one index clause may be specified."));
218 if (lex_token (lexer) != T_ID)
220 lex_error (lexer, NULL);
224 loop->index_var = dict_lookup_var (dataset_dict (ds), lex_tokid (lexer));
225 if (loop->index_var != NULL)
226 *created_index_var = false;
229 loop->index_var = dict_create_var_assert (dataset_dict (ds),
230 lex_tokid (lexer), 0);
231 *created_index_var = true;
235 if (!lex_force_match (lexer, '='))
238 loop->first_expr = expr_parse_pool (lexer, loop->pool,
239 loop->ds, EXPR_NUMBER);
240 if (loop->first_expr == NULL)
245 struct expression **e;
246 if (lex_match (lexer, T_TO))
247 e = &loop->last_expr;
248 else if (lex_match (lexer, T_BY))
255 lex_sbc_only_once (e == &loop->last_expr ? "TO" : "BY");
258 *e = expr_parse_pool (lexer, loop->pool, loop->ds, EXPR_NUMBER);
262 if (loop->last_expr == NULL)
264 lex_sbc_missing (lexer, "TO");
267 if (loop->by_expr == NULL)
273 /* Creates, initializes, and returns a new loop_trns. */
274 static struct loop_trns *
275 create_loop_trns (struct dataset *ds)
277 struct loop_trns *loop = pool_create_container (struct loop_trns, pool);
278 loop->max_pass_count = -1;
280 loop->index_var = NULL;
281 loop->first_expr = loop->by_expr = loop->last_expr = NULL;
282 loop->loop_condition = loop->end_loop_condition = NULL;
285 add_transformation_with_finalizer (ds, loop_trns_finalize,
286 loop_trns_proc, loop_trns_free, loop);
287 loop->past_LOOP_index = next_transformation (ds);
289 ctl_stack_push (&loop_class, loop);
294 /* Finalizes LOOP by clearing the control stack, thus ensuring
295 that all open LOOPs are closed. */
297 loop_trns_finalize (void *do_if_ UNUSED)
299 /* This will be called multiple times if multiple LOOPs were
300 executed, which is slightly unclean, but at least it's
305 /* Sets up LOOP for the first pass. */
307 loop_trns_proc (void *loop_, struct ccase *c, casenumber case_num)
309 struct loop_trns *loop = loop_;
311 if (loop->index_var != NULL)
313 /* Evaluate loop index expressions. */
314 loop->cur = expr_evaluate_num (loop->first_expr, c, case_num);
315 if (loop->by_expr != NULL)
316 loop->by = expr_evaluate_num (loop->by_expr, c, case_num);
317 loop->last = expr_evaluate_num (loop->last_expr, c, case_num);
319 /* Even if the loop is never entered, set the index
320 variable to the initial value. */
321 case_data_rw (c, loop->index_var)->f = loop->cur;
323 /* Throw out pathological cases. */
324 if (!isfinite (loop->cur) || !isfinite (loop->by)
325 || !isfinite (loop->last)
327 || (loop->by > 0.0 && loop->cur > loop->last)
328 || (loop->by < 0.0 && loop->cur < loop->last))
332 /* Initialize pass count. */
334 if (loop->max_pass_count >= 0 && loop->pass >= loop->max_pass_count)
337 /* Check condition. */
338 if (loop->loop_condition != NULL
339 && expr_evaluate_num (loop->loop_condition, c, case_num) != 1.0)
342 return loop->past_LOOP_index;
345 return loop->past_END_LOOP_index;
350 loop_trns_free (void *loop_)
352 struct loop_trns *loop = loop_;
354 pool_destroy (loop->pool);
358 /* Finishes a pass through the loop and starts the next. */
360 end_loop_trns_proc (void *loop_, struct ccase *c, casenumber case_num UNUSED)
362 struct loop_trns *loop = loop_;
364 if (loop->end_loop_condition != NULL
365 && expr_evaluate_num (loop->end_loop_condition, c, case_num) != 0.0)
368 /* MXLOOPS limiter. */
369 if (loop->max_pass_count >= 0)
371 if (loop->pass >= loop->max_pass_count)
376 /* Indexing clause limiter: counting downward. */
377 if (loop->index_var != NULL)
379 loop->cur += loop->by;
380 if ((loop->by > 0.0 && loop->cur > loop->last)
381 || (loop->by < 0.0 && loop->cur < loop->last))
383 case_data_rw (c, loop->index_var)->f = loop->cur;
386 if (loop->loop_condition != NULL
387 && expr_evaluate_num (loop->loop_condition, c, case_num) != 1.0)
390 return loop->past_LOOP_index;
393 return loop->past_END_LOOP_index;
396 /* Executes BREAK. */
398 break_trns_proc (void *loop_, struct ccase *c UNUSED, casenumber case_num UNUSED)
400 struct loop_trns *loop = loop_;
402 return loop->past_END_LOOP_index;
405 /* LOOP control structure class definition. */
406 static const struct ctl_class loop_class =