1 /* PSPP - a program for statistical analysis.
2 Copyright (C) 1997-9, 2000, 2009-2013 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/>. */
21 #include "data/case.h"
22 #include "data/control-stack.h"
23 #include "data/dataset.h"
24 #include "data/transformations.h"
25 #include "data/value.h"
26 #include "language/command.h"
27 #include "language/expressions/public.h"
28 #include "language/lexer/lexer.h"
29 #include "libpspp/compiler.h"
30 #include "libpspp/message.h"
31 #include "libpspp/str.h"
33 #include "gl/xalloc.h"
36 #define _(msgid) gettext (msgid)
38 /* DO IF, ELSE IF, and ELSE are translated as a single
39 transformation that evaluates each condition and jumps to the
40 start of the appropriate block of transformations. Each block
41 of transformations (except for the last) ends with a
42 transformation that jumps past the remaining blocks.
44 So, the following code:
54 is effectively translated like this:
56 IF a GOTO 1, IF b GOTO 2, ELSE GOTO 3.
66 /* A conditional clause. */
69 struct expression *condition; /* Test expression; NULL for ELSE clause. */
70 int target_index; /* Transformation to jump to if true. */
73 /* DO IF transformation. */
76 struct dataset *ds; /* The dataset */
77 struct clause *clauses; /* Clauses. */
78 size_t clause_cnt; /* Number of clauses. */
79 int DO_IF_index; /* DO IF transformation. */
80 int past_END_IF_index; /* Transformation just past last clause. */
83 /* Jumps past the END IF. */
86 struct do_if_trns *do_if;
90 static const struct ctl_class do_if_class;
92 static int parse_clause (struct lexer *, struct do_if_trns *, struct dataset *ds);
93 static void add_clause (struct do_if_trns *, struct expression *condition);
94 static void add_else (struct do_if_trns *);
96 static bool has_else (struct do_if_trns *);
97 static bool must_not_have_else (struct do_if_trns *);
98 static void close_do_if (void *do_if);
100 static trns_proc_func do_if_trns_proc, end_if_trns_proc;
101 static trns_free_func do_if_trns_free, end_if_trns_free;
105 cmd_do_if (struct lexer *lexer, struct dataset *ds)
107 struct do_if_trns *do_if = xmalloc (sizeof *do_if);
108 do_if->clauses = NULL;
109 do_if->clause_cnt = 0;
111 do_if->DO_IF_index = next_transformation (ds);
113 ctl_stack_push (&do_if_class, do_if);
114 add_transformation (ds, do_if_trns_proc, do_if_trns_free, do_if);
116 return parse_clause (lexer, do_if, ds);
121 cmd_else_if (struct lexer *lexer, struct dataset *ds)
123 struct do_if_trns *do_if = ctl_stack_top (&do_if_class);
124 if (do_if == NULL || !must_not_have_else (do_if))
125 return CMD_CASCADING_FAILURE;
126 return parse_clause (lexer, do_if, ds);
131 cmd_else (struct lexer *lexer UNUSED, struct dataset *ds)
133 struct do_if_trns *do_if = ctl_stack_top (&do_if_class);
134 assert (ds == do_if->ds);
135 if (do_if == NULL || !must_not_have_else (do_if))
136 return CMD_CASCADING_FAILURE;
143 cmd_end_if (struct lexer *lexer UNUSED, struct dataset *ds)
145 struct do_if_trns *do_if = ctl_stack_top (&do_if_class);
148 return CMD_CASCADING_FAILURE;
150 assert (ds == do_if->ds);
151 ctl_stack_pop (do_if);
156 /* Closes out DO_IF, by adding a sentinel ELSE clause if
157 necessary and setting past_END_IF_index. */
159 close_do_if (void *do_if_)
161 struct do_if_trns *do_if = do_if_;
163 if (!has_else (do_if))
165 do_if->past_END_IF_index = next_transformation (do_if->ds);
168 /* Adds an ELSE clause to DO_IF pointing to the next
171 add_else (struct do_if_trns *do_if)
173 assert (!has_else (do_if));
174 add_clause (do_if, NULL);
177 /* Returns true if DO_IF does not yet have an ELSE clause.
178 Reports an error and returns false if it does already. */
180 must_not_have_else (struct do_if_trns *do_if)
182 if (has_else (do_if))
184 msg (SE, _("This command may not follow %s in %s ... %s."), "ELSE", "DO IF", "END IF");
191 /* Returns true if DO_IF already has an ELSE clause,
194 has_else (struct do_if_trns *do_if)
196 return (do_if->clause_cnt != 0
197 && do_if->clauses[do_if->clause_cnt - 1].condition == NULL);
200 /* Parses a DO IF or ELSE IF expression and appends the
201 corresponding clause to DO_IF. Checks for end of command and
202 returns a command return code. */
204 parse_clause (struct lexer *lexer, struct do_if_trns *do_if, struct dataset *ds)
206 struct expression *condition;
208 condition = expr_parse (lexer, ds, EXPR_BOOLEAN);
209 if (condition == NULL)
210 return CMD_CASCADING_FAILURE;
212 add_clause (do_if, condition);
217 /* Adds a clause to DO_IF that tests for the given CONDITION and,
218 if true, jumps to the set of transformations produced by
219 following commands. */
221 add_clause (struct do_if_trns *do_if, struct expression *condition)
223 struct clause *clause;
225 if (do_if->clause_cnt > 0)
227 struct end_if_trns *end_if;
229 end_if = xmalloc (sizeof *end_if);
230 end_if->do_if = do_if;
231 end_if->index = next_transformation (do_if->ds);
232 add_transformation (do_if->ds,
233 end_if_trns_proc, end_if_trns_free, end_if);
236 do_if->clauses = xnrealloc (do_if->clauses,
237 do_if->clause_cnt + 1, sizeof *do_if->clauses);
238 clause = &do_if->clauses[do_if->clause_cnt++];
239 clause->condition = condition;
240 clause->target_index = next_transformation (do_if->ds);
243 /* DO IF transformation procedure.
244 Checks each clause and jumps to the appropriate
247 do_if_trns_proc (void *do_if_, struct ccase **c, casenumber case_num UNUSED)
249 struct do_if_trns *do_if = do_if_;
250 struct clause *clause;
252 for (clause = do_if->clauses; clause < do_if->clauses + do_if->clause_cnt;
255 if (clause->condition != NULL)
257 double boolean = expr_evaluate_num (clause->condition, *c, case_num);
259 return clause->target_index - do_if->DO_IF_index;
260 else if (boolean == SYSMIS)
261 return do_if->past_END_IF_index - do_if->DO_IF_index;
264 return clause->target_index - do_if->DO_IF_index;
266 return do_if->past_END_IF_index;
269 /* Frees a DO IF transformation. */
271 do_if_trns_free (void *do_if_)
273 struct do_if_trns *do_if = do_if_;
274 struct clause *clause;
276 for (clause = do_if->clauses; clause < do_if->clauses + do_if->clause_cnt;
278 expr_free (clause->condition);
279 free (do_if->clauses);
284 /* Breaks out of a DO IF construct. */
286 end_if_trns_proc (void *end_if_, struct ccase **c UNUSED,
287 casenumber case_num UNUSED)
289 struct end_if_trns *end_if = end_if_;
291 return end_if->do_if->past_END_IF_index - end_if->index;
294 /* Frees an END IF transformation. */
296 end_if_trns_free (void *end_if_)
298 struct end_if_trns *end_if = end_if_;
303 /* DO IF control structure class definition. */
304 static const struct ctl_class do_if_class =