259 lines
6.4 KiB
C
259 lines
6.4 KiB
C
/* -*- mode: c; style: linux -*- */
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/* expr.c
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* Copyright (C) 2000 Helix Code, Inc.
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*
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* Written by Bradford Hovinen (hovinen@helixcode.com)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
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* 02111-1307, USA.
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*/
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#ifdef HAVE_CONFIG_H
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# include <config.h>
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#endif
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#include "expr.h"
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static gdouble int_parse_sentence (GScanner *scanner);
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static gdouble int_parse_unary (GScanner *scanner);
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static gdouble int_parse_atom (GScanner *scanner);
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static gdouble int_parse_expr (GScanner *scanner, gboolean expr,
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gboolean neg);
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static gdouble int_parse_term (GScanner *scanner, gboolean expr,
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gboolean inv);
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static gdouble int_parse_factor (GScanner *scanner, gboolean expr);
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gboolean
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parse_sentence (gchar *sentence, GScanner *scanner)
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{
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g_scanner_input_text (scanner, sentence, strlen (sentence));
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g_scanner_get_next_token (scanner);
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return int_parse_sentence (scanner) != 0.0;
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}
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gdouble
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parse_expr (gchar *expr, gdouble var)
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{
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static GScannerConfig config;
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GScanner *scanner;
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gchar *var_string;
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gfloat ret;
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config.cset_skip_characters = " \t\n";
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config.cset_identifier_first = "abcdefghijklmnopqrstuvwxyz";
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config.cset_identifier_nth = "abcdefghijklmnopqrstuvwxyz_";
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config.scan_symbols = TRUE;
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config.scan_identifier = TRUE;
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scanner = g_scanner_new (&config);
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g_scanner_input_text (scanner, expr, strlen (expr));
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g_scanner_get_next_token (scanner);
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g_scanner_set_scope (scanner, 0);
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var_string = g_strdup_printf ("%f", var);
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g_scanner_scope_add_symbol (scanner, 0, "var", var_string);
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ret = int_parse_expr (scanner, TRUE, FALSE);
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g_free (var_string);
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g_scanner_destroy (scanner);
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return ret;
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}
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static gdouble
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int_parse_sentence (GScanner *scanner)
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{
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GTokenType token_type;
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GTokenValue value;
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gdouble left;
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left = int_parse_unary (scanner);
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token_type = g_scanner_cur_token (scanner);
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value = g_scanner_cur_value (scanner);
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if ((token_type == G_TOKEN_CHAR && value.v_char == '&') ||
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(token_type == G_TOKEN_SYMBOL && value.v_symbol == SYMBOL_AND))
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{
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g_scanner_get_next_token (scanner);
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return (int_parse_sentence (scanner) != 0.0 &&
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left != 0.0) ? 1.0 : 0.0;
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}
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else if ((token_type == G_TOKEN_CHAR && value.v_char == '|') ||
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(token_type == G_TOKEN_SYMBOL &&
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value.v_symbol == SYMBOL_OR))
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{
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g_scanner_get_next_token (scanner);
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return (int_parse_sentence (scanner) != 0.0 ||
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left != 0.0) ? 1.0 : 0.0;
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}
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return left;
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}
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static gdouble
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int_parse_unary (GScanner *scanner)
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{
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GTokenType token_type;
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GTokenValue value;
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token_type = g_scanner_cur_token (scanner);
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value = g_scanner_cur_value (scanner);
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if ((token_type == G_TOKEN_CHAR && value.v_char == '!') ||
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(token_type == G_TOKEN_SYMBOL && value.v_symbol == SYMBOL_NOT))
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{
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g_scanner_get_next_token (scanner);
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return (int_parse_unary (scanner) != 0.0) ? 0.0 : 1.0;
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} else {
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return (int_parse_atom (scanner) != 0.0) ? 1.0 : 0.0;
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}
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}
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static gdouble
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int_parse_atom (GScanner *scanner)
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{
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GTokenType token_type;
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GTokenValue value;
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gdouble left;
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left = int_parse_expr (scanner, FALSE, FALSE);
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token_type = g_scanner_cur_token (scanner);
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if (token_type == G_TOKEN_CHAR) {
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value = g_scanner_cur_value (scanner);
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if (value.v_char == '=') {
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g_scanner_get_next_token (scanner);
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return (int_parse_expr (scanner, FALSE, FALSE)
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== left) ? 1.0 : 0.0;
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}
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else if (value.v_char == '<') {
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g_scanner_get_next_token (scanner);
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return (int_parse_expr (scanner, FALSE, FALSE)
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> left) ? 1.0 : 0.0;
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}
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else if (value.v_char == '>') {
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g_scanner_get_next_token (scanner);
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return (int_parse_expr (scanner, FALSE, FALSE)
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< left) ? 1.0 : 0.0;
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}
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}
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return left;
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}
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static gdouble
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int_parse_expr (GScanner *scanner, gboolean expr, gboolean neg)
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{
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GTokenType token_type;
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GTokenValue value;
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gdouble left;
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gdouble ret;
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left = int_parse_term (scanner, expr, FALSE);
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token_type = g_scanner_cur_token (scanner);
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if (token_type == G_TOKEN_CHAR) {
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value = g_scanner_cur_value (scanner);
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if (value.v_char == '+') {
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g_scanner_get_next_token (scanner);
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return left + int_parse_expr (scanner, expr, FALSE);
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}
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else if (value.v_char == '-') {
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g_scanner_get_next_token (scanner);
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ret = int_parse_expr (scanner, expr, TRUE);
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if (neg)
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return left + ret;
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else
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return left - ret;
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}
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}
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return left;
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}
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static gdouble
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int_parse_term (GScanner *scanner, gboolean expr, gboolean inv)
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{
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GTokenType token_type;
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GTokenValue value;
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gdouble left;
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gdouble ret;
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left = int_parse_factor (scanner, expr);
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token_type = g_scanner_cur_token (scanner);
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if (token_type == G_TOKEN_CHAR) {
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value = g_scanner_cur_value (scanner);
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if (token_type == '*') {
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g_scanner_get_next_token (scanner);
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return left * int_parse_term (scanner, expr, FALSE);
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}
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else if (token_type == '/') {
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g_scanner_get_next_token (scanner);
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ret = int_parse_term (scanner, expr, TRUE);
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if (inv)
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return left * ret;
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else
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return left / ret;
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}
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}
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return left;
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}
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static gdouble
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int_parse_factor (GScanner *scanner, gboolean expr)
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{
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GTokenType token_type;
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GTokenValue value;
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gdouble ret;
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token_type = g_scanner_cur_token (scanner);
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value = g_scanner_cur_value (scanner);
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g_scanner_get_next_token (scanner);
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if (token_type == G_TOKEN_CHAR && value.v_char == '(') {
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if (expr)
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ret = int_parse_expr (scanner, TRUE, FALSE);
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else
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ret = int_parse_sentence (scanner);
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g_scanner_get_next_token (scanner);
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return ret;
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}
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else if (token_type == G_TOKEN_INT) {
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return value.v_int;
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}
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else if (token_type == G_TOKEN_FLOAT) {
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return value.v_float;
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}
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else if (token_type == G_TOKEN_SYMBOL) {
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if (value.v_symbol == (gpointer) 1)
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return (gint) value.v_symbol;
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else
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return g_strtod (value.v_symbol, NULL);
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}
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else if (token_type == G_TOKEN_IDENTIFIER) {
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return 0.0;
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} else {
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g_scanner_error (scanner, "Parse error in expression");
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}
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return 0;
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}
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