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b470a02c SC |
1 | %{ |
2 | ||
3 | /* | |
4 | * (C) Copyright 2014, Stephen M. Cameron. | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License version 2 as | |
8 | * published by the Free Software Foundation. | |
9 | * | |
10 | * This program is distributed in the hope that it will be useful, | |
11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
13 | * GNU General Public License for more details. | |
14 | * | |
15 | * You should have received a copy of the GNU General Public License | |
16 | * along with this program; if not, write to the Free Software | |
17 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
18 | * | |
19 | */ | |
20 | ||
21 | #include <stdio.h> | |
22 | #include <string.h> | |
23 | ||
24 | struct parser_value_type { | |
25 | double dval; | |
26 | long long ival; | |
27 | int has_dval; | |
28 | int has_error; | |
29 | }; | |
30 | ||
31 | typedef union valtype { | |
32 | struct parser_value_type v; | |
33 | } PARSER_VALUE_TYPE; | |
34 | ||
35 | #define YYSTYPE PARSER_VALUE_TYPE | |
36 | ||
37 | int yyerror(__attribute__((unused)) long long *result, | |
38 | __attribute__((unused)) double *dresult, | |
39 | __attribute__((unused)) int *has_error, | |
40 | __attribute__((unused)) int *bye, const char *msg); | |
41 | ||
42 | extern int yylex(void); | |
43 | extern void yyrestart(FILE *file); | |
44 | ||
45 | %} | |
46 | ||
47 | %union valtype { | |
48 | struct parser_value_type { | |
49 | double dval; | |
50 | long long ival; | |
51 | int has_dval; | |
52 | int has_error; | |
53 | } v; | |
54 | }; | |
55 | ||
56 | %token <v> NUMBER | |
57 | %token <v> BYE | |
58 | %left '-' '+' | |
59 | %left '*' '/' | |
60 | %nonassoc UMINUS | |
61 | %parse-param { long long *result } | |
62 | %parse-param { double *dresult } | |
63 | %parse-param { int *has_error } | |
64 | %parse-param { int *bye } | |
65 | ||
66 | %type <v> expression | |
67 | %% | |
68 | ||
69 | top_level: expression { | |
70 | *result = $1.ival; | |
71 | *dresult = $1.dval; | |
72 | *has_error = $1.has_error; | |
73 | } | |
74 | | expression error { | |
75 | *result = $1.ival; | |
76 | *dresult = $1.dval; | |
77 | *has_error = 1; | |
78 | } | |
79 | expression: expression '+' expression { | |
80 | if (!$1.has_dval && !$3.has_dval) | |
81 | $$.ival = $1.ival + $3.ival; | |
82 | else | |
83 | $$.ival = (long long) ($1.dval + $3.dval); | |
84 | $$.dval = $1.dval + $3.dval; | |
85 | $$.has_error = $1.has_error || $3.has_error; | |
86 | } | |
87 | | expression '-' expression { | |
88 | if (!$1.has_dval && !$3.has_dval) | |
89 | $$.ival = $1.ival - $3.ival; | |
90 | else | |
91 | $$.ival = (long long) ($1.dval - $3.dval); | |
92 | $$.dval = $1.dval - $3.dval; | |
93 | $$.has_error = $1.has_error || $3.has_error; | |
94 | } | |
95 | | expression '*' expression { | |
96 | if (!$1.has_dval && !$3.has_dval) | |
97 | $$.ival = $1.ival * $3.ival; | |
98 | else | |
99 | $$.ival = (long long) ($1.dval * $3.dval); | |
100 | $$.dval = $1.dval * $3.dval; | |
101 | $$.has_error = $1.has_error || $3.has_error; | |
102 | } | |
103 | | expression '/' expression { | |
104 | if ($3.ival == 0) | |
105 | yyerror(0, 0, 0, 0, "divide by zero"); | |
106 | else | |
107 | $$.ival = $1.ival / $3.ival; | |
108 | if ($3.dval < 1e-20 && $3.dval > -1e-20) | |
109 | yyerror(0, 0, 0, 0, "divide by zero"); | |
110 | else | |
111 | $$.dval = $1.dval / $3.dval; | |
112 | if ($3.has_dval || $1.has_dval) | |
113 | $$.ival = (long long) $$.dval; | |
114 | $$.has_error = $1.has_error || $3.has_error; | |
115 | } | |
116 | | '-' expression %prec UMINUS { | |
117 | $$.ival = -$2.ival; | |
118 | $$.dval = -$2.dval; | |
119 | $$.has_error = $2.has_error; | |
120 | } | |
121 | | '(' expression ')' { $$ = $2; } | |
122 | | NUMBER { $$ = $1; } | |
123 | | BYE { $$ = $1; *bye = 1; }; | |
124 | %% | |
125 | #include <stdio.h> | |
126 | ||
127 | /* Urgh. yacc and lex are kind of horrible. This is not thread safe, obviously. */ | |
128 | static int lexer_read_offset = 0; | |
129 | static char lexer_input_buffer[1000]; | |
130 | ||
131 | int lexer_input(char* buffer, int *bytes_read, int bytes_requested) | |
132 | { | |
133 | int bytes_left = strlen(lexer_input_buffer) - lexer_read_offset; | |
134 | ||
135 | if (bytes_requested > bytes_left ) | |
136 | bytes_requested = bytes_left; | |
137 | memcpy(buffer, &lexer_input_buffer[lexer_read_offset], bytes_requested); | |
138 | *bytes_read = bytes_requested; | |
139 | lexer_read_offset += bytes_requested; | |
140 | return 0; | |
141 | } | |
142 | ||
143 | static void setup_to_parse_string(const char *string) | |
144 | { | |
145 | unsigned int len; | |
146 | ||
147 | len = strlen(string); | |
148 | if (len > sizeof(lexer_input_buffer) - 3) | |
149 | len = sizeof(lexer_input_buffer) - 3; | |
150 | ||
151 | strncpy(lexer_input_buffer, string, len); | |
152 | lexer_input_buffer[len] = '\0'; | |
153 | lexer_input_buffer[len + 1] = '\0'; /* lex/yacc want string double null terminated! */ | |
154 | lexer_read_offset = 0; | |
155 | } | |
156 | ||
157 | int evaluate_arithmetic_expression(const char *buffer, long long *ival, double *dval) | |
158 | { | |
159 | int rc, bye = 0, has_error = 0; | |
160 | ||
161 | setup_to_parse_string(buffer); | |
162 | rc = yyparse(ival, dval, &has_error, &bye); | |
163 | yyrestart(NULL); | |
164 | if (rc || bye || has_error) { | |
165 | *ival = 0; | |
166 | *dval = 0; | |
167 | has_error = 1; | |
168 | } | |
169 | return has_error; | |
170 | } | |
171 | ||
172 | int yyerror(__attribute__((unused)) long long *result, | |
173 | __attribute__((unused)) double *dresult, | |
174 | __attribute__((unused)) int *has_error, | |
175 | __attribute__((unused)) int *bye, const char *msg) | |
176 | { | |
177 | fprintf(stderr, "%s\n", msg); | |
178 | return 0; | |
179 | } | |
180 |