File: expression-parser.y

package info (click to toggle)
fio 3.12-2
  • links: PTS, VCS
  • area: main
  • in suites: buster, sid
  • size: 4,488 kB
  • sloc: ansic: 65,165; sh: 3,284; python: 1,978; makefile: 657; yacc: 204; lex: 184
file content (247 lines) | stat: -rw-r--r-- 6,347 bytes parent folder | download
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
%{

/*
 * (C) Copyright 2014, Stephen M. Cameron.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2 as
 *  published by the Free Software Foundation.
 *
 *  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 <stdio.h>
#include <string.h>
#include <math.h>

struct parser_value_type {
	double dval;
	long long ival;
	int has_dval;
	int has_error;
};

typedef union valtype {
	struct parser_value_type v;
} PARSER_VALUE_TYPE;

#define YYSTYPE PARSER_VALUE_TYPE

int yyerror(__attribute__((unused)) long long *result,
		__attribute__((unused)) double *dresult,
		__attribute__((unused)) int *has_error,
		__attribute__((unused)) int *units_specified,
		__attribute__((unused)) const char *msg);

extern int yylex(void);
extern void yyrestart(FILE *file);
extern int lexer_value_is_time;

%}

%union valtype {
	struct parser_value_type {
		double dval;
		long long ival;
		int has_dval;
		int has_error;
	} v;
};

%token <v> NUMBER
%token <v> BYE
%token <v> SUFFIX 
%left '-' '+'
%right SUFFIX
%left '*' '/'
%right '^'
%left '%'
%nonassoc UMINUS
%parse-param { long long *result }
%parse-param { double *dresult }
%parse-param { int *has_error }
%parse-param { int *units_specified }

%type <v> expression
%%

top_level:	expression {
				*result = $1.ival;
				*dresult = $1.dval;
				*has_error = $1.has_error;
			}
		| expression error {
				*result = $1.ival;
				*dresult = $1.dval;
				*has_error = 1;
			}
expression:	expression '+' expression { 
			if (!$1.has_dval && !$3.has_dval)
				$$.ival = $1.ival + $3.ival;
			else
				$$.ival = (long long) ($1.dval + $3.dval);
			$$.dval = $1.dval + $3.dval;
			$$.has_error = $1.has_error || $3.has_error;
		}
	|	expression '-' expression {
			if (!$1.has_dval && !$3.has_dval)
				$$.ival = $1.ival - $3.ival; 
			else
				$$.ival = (long long) ($1.dval - $3.dval); 
			$$.dval = $1.dval - $3.dval; 
			$$.has_error = $1.has_error || $3.has_error;
		}
	|	expression '*' expression {
			if (!$1.has_dval && !$3.has_dval)
				$$.ival = $1.ival * $3.ival;
			else
				$$.ival = (long long) ($1.dval * $3.dval);
			$$.dval = $1.dval * $3.dval;
			$$.has_error = $1.has_error || $3.has_error;
		}
	|	expression '/' expression {
			if ($3.ival == 0)
				yyerror(0, 0, 0, 0, "divide by zero");
			else
				$$.ival = $1.ival / $3.ival;
			if ($3.dval < 1e-20 && $3.dval > -1e-20)
				yyerror(0, 0, 0, 0, "divide by zero");
			else
				$$.dval = $1.dval / $3.dval;
			if ($3.has_dval || $1.has_dval)
				$$.ival = (long long) $$.dval;
			$$.has_error = $1.has_error || $3.has_error;
		}
	|	'-' expression %prec UMINUS {
			$$.ival = -$2.ival;
			$$.dval = -$2.dval;
			$$.has_error = $2.has_error;
		}
	|	'(' expression ')' { $$ = $2; }
	|	expression SUFFIX {
			if (!$1.has_dval && !$2.has_dval)
				$$.ival = $1.ival * $2.ival;
			else
				$$.ival = (long long) $1.dval * $2.dval;
			if ($1.has_dval || $2.has_dval)
				$$.dval = $1.dval * $2.dval;
			else
				$$.dval = $1.ival * $2.ival;
			$$.has_error = $1.has_error || $2.has_error;
			*units_specified = 1;
		}
	|	expression '%' expression {
			if ($1.has_dval || $3.has_dval)
				yyerror(0, 0, 0, 0, "modulo on floats");
			if ($3.ival == 0)
				yyerror(0, 0, 0, 0, "divide by zero");
			else {
				$$.ival = $1.ival % $3.ival;
				$$.dval = $$.ival;
			}
			$$.has_error = $1.has_error || $3.has_error;
		}
	|	expression '^' expression {
			$$.has_error = $1.has_error || $3.has_error;
			if (!$1.has_dval && !$3.has_dval) {
				int i;

				if ($3.ival == 0) {
					$$.ival = 1;
				} else if ($3.ival > 0) {
					long long tmp = $1.ival;
					$$.ival = 1.0;
					for (i = 0; i < $3.ival; i++)
						$$.ival *= tmp;
				}  else {
					/* integers, 2^-3, ok, we now have doubles */
					double tmp;
					if ($1.ival == 0 && $3.ival == 0) {
						tmp = 1.0;
						$$.has_error = 1;
					} else {
						double x = (double) $1.ival;
						double y = (double) $3.ival;
						tmp = pow(x, y);
					}
					$$.ival = (long long) tmp;
				}
				$$.dval = pow($1.dval, $3.dval);
			} else {
				$$.dval = pow($1.dval, $3.dval);
				$$.ival = (long long) $$.dval;
			}
		}
	|	NUMBER { $$ = $1; };
%%
#include <stdio.h>

/* Urgh.  yacc and lex are kind of horrible.  This is not thread safe, obviously. */
static int lexer_read_offset = 0;
static char lexer_input_buffer[1000];

int lexer_input(char* buffer, unsigned int *bytes_read, int bytes_requested)
{
	int bytes_left = strlen(lexer_input_buffer) - lexer_read_offset;

	if (bytes_requested > bytes_left )
		bytes_requested = bytes_left;
	memcpy(buffer, &lexer_input_buffer[lexer_read_offset], bytes_requested);
	*bytes_read = bytes_requested;
	lexer_read_offset += bytes_requested;
	return 0;
}

static void setup_to_parse_string(const char *string)
{
	unsigned int len;

	len = strlen(string);
	if (len > sizeof(lexer_input_buffer) - 3)
		len = sizeof(lexer_input_buffer) - 3;

	strncpy(lexer_input_buffer, string, len);
	lexer_input_buffer[len] = '\0'; 
	lexer_input_buffer[len + 1] = '\0';  /* lex/yacc want string double null terminated! */
	lexer_read_offset = 0;
}

int evaluate_arithmetic_expression(const char *buffer, long long *ival, double *dval,
					double implied_units, int is_time)
{
	int rc, units_specified = 0, has_error = 0;

	lexer_value_is_time = is_time;
	setup_to_parse_string(buffer);
	rc = yyparse(ival, dval, &has_error, &units_specified);
	yyrestart(NULL);
	if (rc || has_error) {
		*ival = 0;
		*dval = 0;
		has_error = 1;
	}
	if (!units_specified) {
		*ival = (int) ((double) *ival * implied_units);
		*dval = *dval * implied_units;
	}
	return has_error;
}

int yyerror(__attribute__((unused)) long long *result,
		__attribute__((unused)) double *dresult,
		__attribute__((unused)) int *has_error,
		__attribute__((unused)) int *units_specified,
		__attribute__((unused)) const char *msg)
{
	/* We do not need to do anything here. */
	return 0;
}