--- /dev/null
+/* PSPP - computes sample statistics.
+ Copyright (C) 1997-9, 2000 Free Software Foundation, Inc.
+ Written by Ben Pfaff <blp@gnu.org>.
+
+ 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 2 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, write to the Free Software
+ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ 02110-1301, USA. */
+
+#include <config.h>
+#include "control-stack.h"
+#include "message.h"
+#include <stdlib.h>
+#include "alloc.h"
+#include "command.h"
+#include "message.h"
+#include "expressions/public.h"
+#include "lexer.h"
+#include "str.h"
+#include "variable.h"
+
+#include "gettext.h"
+#define _(msgid) gettext (msgid)
+
+/* DO IF, ELSE IF, and ELSE are translated as a single
+ transformation that evaluates each condition and jumps to the
+ start of the appropriate block of transformations. Each block
+ of transformations (except for the last) ends with a
+ transformation that jumps past the remaining blocks.
+
+ So, the following code:
+
+ DO IF a.
+ ...block 1...
+ ELSE IF b.
+ ...block 2...
+ ELSE.
+ ...block 3...
+ END IF.
+
+ is effectively translated like this:
+
+ IF a GOTO 1, IF b GOTO 2, ELSE GOTO 3.
+ 1: ...block 1...
+ GOTO 4
+ 2: ...block 2...
+ GOTO 4
+ 3: ...block 3...
+ 4:
+
+*/
+
+/* A conditional clause. */
+struct clause
+ {
+ struct expression *condition; /* Test expression; NULL for ELSE clause. */
+ int target_index; /* Transformation to jump to if true. */
+ };
+
+/* DO IF transformation. */
+struct do_if_trns
+ {
+ struct clause *clauses; /* Clauses. */
+ size_t clause_cnt; /* Number of clauses. */
+ int past_END_IF_index; /* Transformation just past last clause. */
+ };
+
+static struct ctl_class do_if_class;
+
+static int parse_clause (struct do_if_trns *);
+static void add_clause (struct do_if_trns *,
+ struct expression *condition, int target_index);
+static void add_else (struct do_if_trns *);
+
+static bool has_else (struct do_if_trns *);
+static bool must_not_have_else (struct do_if_trns *);
+static void close_do_if (void *do_if);
+
+static trns_proc_func do_if_trns_proc, break_trns_proc;
+static trns_free_func do_if_trns_free;
+
+/* Parse DO IF. */
+int
+cmd_do_if (void)
+{
+ struct do_if_trns *do_if = xmalloc (sizeof *do_if);
+ do_if->clauses = NULL;
+ do_if->clause_cnt = 0;
+
+ ctl_stack_push (&do_if_class, do_if);
+ add_transformation (do_if_trns_proc, do_if_trns_free, do_if);
+
+ return parse_clause (do_if);
+}
+
+/* Parse ELSE IF. */
+int
+cmd_else_if (void)
+{
+ struct do_if_trns *do_if = ctl_stack_top (&do_if_class);
+ if (do_if == NULL || !must_not_have_else (do_if))
+ return CMD_CASCADING_FAILURE;
+ return parse_clause (do_if);
+}
+
+/* Parse ELSE. */
+int
+cmd_else (void)
+{
+ struct do_if_trns *do_if = ctl_stack_top (&do_if_class);
+ if (do_if == NULL || !must_not_have_else (do_if))
+ return CMD_CASCADING_FAILURE;
+ add_else (do_if);
+ return lex_end_of_command ();
+}
+
+/* Parse END IF. */
+int
+cmd_end_if (void)
+{
+ struct do_if_trns *do_if = ctl_stack_top (&do_if_class);
+ if (do_if == NULL)
+ return CMD_CASCADING_FAILURE;
+
+ ctl_stack_pop (do_if);
+
+ return lex_end_of_command ();
+}
+
+/* Closes out DO_IF, by adding a sentinel ELSE clause if
+ necessary and setting past_END_IF_index. */
+static void
+close_do_if (void *do_if_)
+{
+ struct do_if_trns *do_if = do_if_;
+
+ if (!has_else (do_if))
+ add_else (do_if);
+ do_if->past_END_IF_index = next_transformation ();
+}
+
+/* Adds an ELSE clause to DO_IF pointing to the next
+ transformation. */
+static void
+add_else (struct do_if_trns *do_if)
+{
+ assert (!has_else (do_if));
+ add_clause (do_if, NULL, next_transformation ());
+}
+
+/* Returns true if DO_IF does not yet have an ELSE clause.
+ Reports an error and returns false if it does already. */
+static bool
+must_not_have_else (struct do_if_trns *do_if)
+{
+ if (has_else (do_if))
+ {
+ msg (SE, _("This command may not follow ELSE in DO IF...END IF."));
+ return false;
+ }
+ else
+ return true;
+}
+
+/* Returns true if DO_IF already has an ELSE clause,
+ false otherwise. */
+static bool
+has_else (struct do_if_trns *do_if)
+{
+ return (do_if->clause_cnt != 0
+ && do_if->clauses[do_if->clause_cnt - 1].condition == NULL);
+}
+
+/* Parses a DO IF or ELSE IF expression and appends the
+ corresponding clause to DO_IF. Checks for end of command and
+ returns a command return code. */
+static int
+parse_clause (struct do_if_trns *do_if)
+{
+ struct expression *condition;
+
+ condition = expr_parse (default_dict, EXPR_BOOLEAN);
+ if (condition == NULL)
+ return CMD_CASCADING_FAILURE;
+
+ add_clause (do_if, condition, next_transformation ());
+
+ return lex_end_of_command ();
+}
+
+/* Adds a clause to DO_IF that tests for the given CONDITION and,
+ if true, jumps to TARGET_INDEX. */
+static void
+add_clause (struct do_if_trns *do_if,
+ struct expression *condition, int target_index)
+{
+ struct clause *clause;
+
+ if (do_if->clause_cnt > 0)
+ add_transformation (break_trns_proc, NULL, do_if);
+
+ do_if->clauses = xnrealloc (do_if->clauses,
+ do_if->clause_cnt + 1, sizeof *do_if->clauses);
+ clause = &do_if->clauses[do_if->clause_cnt++];
+ clause->condition = condition;
+ clause->target_index = target_index;
+}
+
+/* DO IF transformation procedure.
+ Checks each clause and jumps to the appropriate
+ transformation. */
+static int
+do_if_trns_proc (void *do_if_, struct ccase *c, int case_num UNUSED)
+{
+ struct do_if_trns *do_if = do_if_;
+ struct clause *clause;
+
+ for (clause = do_if->clauses; clause < do_if->clauses + do_if->clause_cnt;
+ clause++)
+ {
+ if (clause->condition != NULL)
+ {
+ double boolean = expr_evaluate_num (clause->condition, c, case_num);
+ if (boolean == 1.0)
+ return clause->target_index;
+ else if (boolean == SYSMIS)
+ return do_if->past_END_IF_index;
+ }
+ else
+ return clause->target_index;
+ }
+ return do_if->past_END_IF_index;
+}
+
+/* Frees a DO IF transformation. */
+static bool
+do_if_trns_free (void *do_if_)
+{
+ struct do_if_trns *do_if = do_if_;
+ struct clause *clause;
+
+ for (clause = do_if->clauses; clause < do_if->clauses + do_if->clause_cnt;
+ clause++)
+ expr_free (clause->condition);
+ free (do_if->clauses);
+ free (do_if);
+ return true;
+}
+
+/* Breaks out of a DO IF construct. */
+static int
+break_trns_proc (void *do_if_, struct ccase *c UNUSED, int case_num UNUSED)
+{
+ struct do_if_trns *do_if = do_if_;
+
+ return do_if->past_END_IF_index;
+}
+
+/* DO IF control structure class definition. */
+static struct ctl_class do_if_class =
+ {
+ "DO IF",
+ "END IF",
+ close_do_if,
+ };
projects / pspp-builds.git / blobdiff