1 /* PSPP - a program for statistical analysis.
2 Copyright (C) 1997-9, 2000, 2009-2011 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 "language/control/control-stack.h"
21 #include "data/case.h"
22 #include "data/dataset.h"
23 #include "data/dictionary.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"
36 #include "gl/xalloc.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 through 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) != T_ENDCMD && 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 UNUSED, 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);
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 && loop->index_var == NULL)
181 loop->max_pass_count = settings_get_mxloops ();
184 /* Parses an IF clause for LOOP or END LOOP and stores the
185 resulting expression to *CONDITION.
186 Returns true if successful, false on failure. */
188 parse_if_clause (struct lexer *lexer,
189 struct loop_trns *loop, struct expression **condition)
191 if (*condition != NULL)
193 lex_sbc_only_once ("IF");
197 *condition = expr_parse_bool (lexer, loop->pool, loop->ds);
198 return *condition != NULL;
201 /* Parses an indexing clause into LOOP.
202 Stores true in *CREATED_INDEX_VAR if the index clause created
203 a new variable, false otherwise.
204 Returns true if successful, false on failure. */
206 parse_index_clause (struct dataset *ds, struct lexer *lexer,
207 struct loop_trns *loop, bool *created_index_var)
209 if (loop->index_var != NULL)
211 msg (SE, _("Only one index clause may be specified."));
215 if (lex_token (lexer) != T_ID)
217 lex_error (lexer, NULL);
221 loop->index_var = dict_lookup_var (dataset_dict (ds), lex_tokcstr (lexer));
222 if (loop->index_var != NULL)
223 *created_index_var = false;
226 loop->index_var = dict_create_var_assert (dataset_dict (ds),
227 lex_tokcstr (lexer), 0);
228 *created_index_var = true;
232 if (!lex_force_match (lexer, T_EQUALS))
235 loop->first_expr = expr_parse (lexer, loop->pool, loop->ds, VAL_NUMERIC);
236 if (loop->first_expr == NULL)
241 struct expression **e;
242 if (lex_match (lexer, T_TO))
243 e = &loop->last_expr;
244 else if (lex_match (lexer, T_BY))
251 lex_sbc_only_once (e == &loop->last_expr ? "TO" : "BY");
254 *e = expr_parse (lexer, loop->pool, loop->ds, VAL_NUMERIC);
258 if (loop->last_expr == NULL)
260 lex_sbc_missing ("TO");
263 if (loop->by_expr == NULL)
269 /* Creates, initializes, and returns a new loop_trns. */
270 static struct loop_trns *
271 create_loop_trns (struct dataset *ds)
273 struct loop_trns *loop = pool_create_container (struct loop_trns, pool);
274 loop->max_pass_count = -1;
276 loop->index_var = NULL;
277 loop->first_expr = loop->by_expr = loop->last_expr = NULL;
278 loop->loop_condition = loop->end_loop_condition = NULL;
281 add_transformation_with_finalizer (ds, loop_trns_finalize,
282 loop_trns_proc, loop_trns_free, loop);
283 loop->past_LOOP_index = next_transformation (ds);
285 ctl_stack_push (&loop_class, loop);
290 /* Finalizes LOOP by clearing the control stack, thus ensuring
291 that all open LOOPs are closed. */
293 loop_trns_finalize (void *do_if_ UNUSED)
295 /* This will be called multiple times if multiple LOOPs were
296 executed, which is slightly unclean, but at least it's
301 /* Sets up LOOP for the first pass. */
303 loop_trns_proc (void *loop_, struct ccase **c, casenumber case_num)
305 struct loop_trns *loop = loop_;
307 if (loop->index_var != NULL)
309 /* Evaluate loop index expressions. */
310 loop->cur = expr_evaluate_num (loop->first_expr, *c, case_num);
311 if (loop->by_expr != NULL)
312 loop->by = expr_evaluate_num (loop->by_expr, *c, case_num);
313 loop->last = expr_evaluate_num (loop->last_expr, *c, case_num);
315 /* Even if the loop is never entered, set the index
316 variable to the initial value. */
317 *c = case_unshare (*c);
318 *case_num_rw (*c, loop->index_var) = loop->cur;
320 /* Throw out pathological cases. */
321 if (!isfinite (loop->cur) || !isfinite (loop->by)
322 || !isfinite (loop->last)
324 || (loop->by > 0.0 && loop->cur > loop->last)
325 || (loop->by < 0.0 && loop->cur < loop->last))
329 /* Initialize pass count. */
331 if (loop->max_pass_count >= 0 && loop->pass >= loop->max_pass_count)
334 /* Check condition. */
335 if (loop->loop_condition != NULL
336 && expr_evaluate_num (loop->loop_condition, *c, case_num) != 1.0)
339 return loop->past_LOOP_index;
342 return loop->past_END_LOOP_index;
347 loop_trns_free (void *loop_)
349 struct loop_trns *loop = loop_;
351 pool_destroy (loop->pool);
355 /* Finishes a pass through the loop and starts the next. */
357 end_loop_trns_proc (void *loop_, struct ccase **c, casenumber case_num UNUSED)
359 struct loop_trns *loop = loop_;
361 if (loop->end_loop_condition != NULL
362 && expr_evaluate_num (loop->end_loop_condition, *c, case_num) != 0.0)
365 /* MXLOOPS limiter. */
366 if (loop->max_pass_count >= 0 && ++loop->pass >= loop->max_pass_count)
369 /* Indexing clause limiter: counting downward. */
370 if (loop->index_var != NULL)
372 loop->cur += loop->by;
373 if ((loop->by > 0.0 && loop->cur > loop->last)
374 || (loop->by < 0.0 && loop->cur < loop->last))
376 *c = case_unshare (*c);
377 *case_num_rw (*c, loop->index_var) = loop->cur;
380 if (loop->loop_condition != NULL
381 && expr_evaluate_num (loop->loop_condition, *c, case_num) != 1.0)
384 return loop->past_LOOP_index;
387 return loop->past_END_LOOP_index;
390 /* Executes BREAK. */
392 break_trns_proc (void *loop_, struct ccase **c UNUSED,
393 casenumber case_num UNUSED)
395 struct loop_trns *loop = loop_;
397 return loop->past_END_LOOP_index;
400 /* LOOP control structure class definition. */
401 static const struct ctl_class loop_class =