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/>. */
21 #include "control-stack.h"
22 #include <data/case.h>
23 #include <data/procedure.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/alloc.h>
30 #include <libpspp/compiler.h>
31 #include <libpspp/message.h>
32 #include <libpspp/message.h>
33 #include <libpspp/str.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 past_END_IF_index; /* Transformation just past last clause. */
82 static const struct ctl_class do_if_class;
84 static int parse_clause (struct lexer *, struct do_if_trns *, struct dataset *ds);
85 static void add_clause (struct do_if_trns *,
86 struct expression *condition, int target_index);
87 static void add_else (struct do_if_trns *);
89 static bool has_else (struct do_if_trns *);
90 static bool must_not_have_else (struct do_if_trns *);
91 static void close_do_if (void *do_if);
93 static trns_finalize_func do_if_finalize_func;
94 static trns_proc_func do_if_trns_proc, break_trns_proc;
95 static trns_free_func do_if_trns_free;
99 cmd_do_if (struct lexer *lexer, struct dataset *ds)
101 struct do_if_trns *do_if = xmalloc (sizeof *do_if);
102 do_if->clauses = NULL;
103 do_if->clause_cnt = 0;
106 ctl_stack_push (&do_if_class, do_if);
107 add_transformation_with_finalizer (ds, do_if_finalize_func,
108 do_if_trns_proc, do_if_trns_free, do_if);
110 return parse_clause (lexer, do_if, ds);
115 cmd_else_if (struct lexer *lexer, struct dataset *ds)
117 struct do_if_trns *do_if = ctl_stack_top (&do_if_class);
118 if (do_if == NULL || !must_not_have_else (do_if))
119 return CMD_CASCADING_FAILURE;
120 return parse_clause (lexer, do_if, ds);
125 cmd_else (struct lexer *lexer, struct dataset *ds)
127 struct do_if_trns *do_if = ctl_stack_top (&do_if_class);
128 assert (ds == do_if->ds);
129 if (do_if == NULL || !must_not_have_else (do_if))
130 return CMD_CASCADING_FAILURE;
132 return lex_end_of_command (lexer);
137 cmd_end_if (struct lexer *lexer, struct dataset *ds)
139 struct do_if_trns *do_if = ctl_stack_top (&do_if_class);
140 assert (ds == do_if->ds);
143 return CMD_CASCADING_FAILURE;
145 ctl_stack_pop (do_if);
147 return lex_end_of_command (lexer);
150 /* Closes out DO_IF, by adding a sentinel ELSE clause if
151 necessary and setting past_END_IF_index. */
153 close_do_if (void *do_if_)
155 struct do_if_trns *do_if = do_if_;
157 if (!has_else (do_if))
159 do_if->past_END_IF_index = next_transformation (do_if->ds);
162 /* Adds an ELSE clause to DO_IF pointing to the next
165 add_else (struct do_if_trns *do_if)
167 assert (!has_else (do_if));
168 add_clause (do_if, NULL, next_transformation (do_if->ds));
171 /* Returns true if DO_IF does not yet have an ELSE clause.
172 Reports an error and returns false if it does already. */
174 must_not_have_else (struct do_if_trns *do_if)
176 if (has_else (do_if))
178 msg (SE, _("This command may not follow ELSE in DO IF...END IF."));
185 /* Returns true if DO_IF already has an ELSE clause,
188 has_else (struct do_if_trns *do_if)
190 return (do_if->clause_cnt != 0
191 && do_if->clauses[do_if->clause_cnt - 1].condition == NULL);
194 /* Parses a DO IF or ELSE IF expression and appends the
195 corresponding clause to DO_IF. Checks for end of command and
196 returns a command return code. */
198 parse_clause (struct lexer *lexer, struct do_if_trns *do_if, struct dataset *ds)
200 struct expression *condition;
202 condition = expr_parse (lexer, ds, EXPR_BOOLEAN);
203 if (condition == NULL)
204 return CMD_CASCADING_FAILURE;
206 add_clause (do_if, condition, next_transformation (ds));
208 return lex_end_of_command (lexer);
211 /* Adds a clause to DO_IF that tests for the given CONDITION and,
212 if true, jumps to TARGET_INDEX. */
214 add_clause (struct do_if_trns *do_if,
215 struct expression *condition, int target_index)
217 struct clause *clause;
219 if (do_if->clause_cnt > 0)
220 add_transformation (do_if->ds, break_trns_proc, NULL, do_if);
222 do_if->clauses = xnrealloc (do_if->clauses,
223 do_if->clause_cnt + 1, sizeof *do_if->clauses);
224 clause = &do_if->clauses[do_if->clause_cnt++];
225 clause->condition = condition;
226 clause->target_index = target_index;
229 /* Finalizes DO IF by clearing the control stack, thus ensuring
230 that all open DO IFs are closed. */
232 do_if_finalize_func (void *do_if_ UNUSED)
234 /* This will be called multiple times if multiple DO IFs were
235 executed, which is slightly unclean, but at least it's
240 /* DO IF transformation procedure.
241 Checks each clause and jumps to the appropriate
244 do_if_trns_proc (void *do_if_, struct ccase *c, casenumber case_num UNUSED)
246 struct do_if_trns *do_if = do_if_;
247 struct clause *clause;
249 for (clause = do_if->clauses; clause < do_if->clauses + do_if->clause_cnt;
252 if (clause->condition != NULL)
254 double boolean = expr_evaluate_num (clause->condition, c, case_num);
256 return clause->target_index;
257 else if (boolean == SYSMIS)
258 return do_if->past_END_IF_index;
261 return clause->target_index;
263 return do_if->past_END_IF_index;
266 /* Frees a DO IF transformation. */
268 do_if_trns_free (void *do_if_)
270 struct do_if_trns *do_if = do_if_;
271 struct clause *clause;
273 for (clause = do_if->clauses; clause < do_if->clauses + do_if->clause_cnt;
275 expr_free (clause->condition);
276 free (do_if->clauses);
281 /* Breaks out of a DO IF construct. */
283 break_trns_proc (void *do_if_, struct ccase *c UNUSED, casenumber case_num UNUSED)
285 struct do_if_trns *do_if = do_if_;
287 return do_if->past_END_IF_index;
290 /* DO IF control structure class definition. */
291 static const struct ctl_class do_if_class =