Mercurial > jwe > qt-gui-with-push-parser
annotate parser.yy @ 12:894be158b32d
define parser as a class and eliminate some global variables
| author | John W. Eaton <jwe@octave.org> |
|---|---|
| date | Thu, 23 May 2019 17:57:20 -0400 |
| parents | b652a5528fb1 |
| children | d179b0bb85e4 |
| rev | line source |
|---|---|
| 0 | 1 // Infix notation calculator. |
| 2 | |
| 3 %{ | |
| 4 | |
| 5 #define YYSTYPE double | |
| 6 | |
| 7 #include <iostream> | |
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8 #include <string> |
| 0 | 9 |
| 10 #include <cctype> | |
| 11 #include <cmath> | |
| 12 #include <cstdio> | |
| 13 | |
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14 #include "interpreter.h" |
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15 #include "parser.h" |
| 0 | 16 |
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17 namespace calc |
| 0 | 18 { |
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19 static void *create_parser_state (void); |
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20 static void delete_parser_state (void *); |
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21 |
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22 parser::parser (interpreter& interp) |
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23 : m_interpreter (interp), |
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24 m_parser_state (create_parser_state ()), |
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25 m_beg_of_stmt (true) |
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26 { } |
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27 |
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28 parser::~parser (void) |
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29 { |
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30 delete_parser_state (m_parser_state); |
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31 } |
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32 |
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33 void parser::emit_error (const char *msg) const |
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34 { |
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35 m_interpreter.emit_error (msg); |
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36 } |
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37 |
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38 void parser::emit_result (double value) const |
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39 { |
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40 m_interpreter.emit_result (value); |
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41 } |
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42 |
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43 // For communication between the lexer and parser. |
| 0 | 44 size_t bufptr = 0; |
| 45 size_t chunk_size = 0; | |
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46 const char *buf; |
| 0 | 47 |
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48 static int yylex (YYSTYPE& token_value); |
| 0 | 49 } |
| 50 | |
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51 static void yyerror (calc::parser&, char const *); |
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52 |
| 0 | 53 %} |
| 54 | |
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55 %define api.pure full |
| 0 | 56 %define api.push-pull push |
| 57 | |
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58 %parse-param {calc::parser& parser} |
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59 |
| 0 | 60 // Bison declarations. |
| 61 %token NUM | |
| 62 %left '-' '+' | |
| 63 %left '*' '/' | |
| 64 %left NEG // negation--unary minus | |
| 65 %right '^' // exponentiation | |
| 66 | |
| 67 %% | |
| 68 | |
| 69 input : // empty | |
| 70 { } | |
| 71 | input line | |
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72 | error |
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73 { |
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74 YYABORT; |
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75 } |
| 0 | 76 ; |
| 77 | |
| 78 line : ';' | |
| 79 { } | |
| 80 | exp ';' | |
| 81 { | |
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82 parser.emit_result ($1); |
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83 parser.beg_of_stmt (true); |
| 0 | 84 } |
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85 ; |
| 0 | 86 |
| 87 exp : NUM | |
| 88 { | |
| 89 $$ = $1; | |
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90 parser.beg_of_stmt (false); |
| 0 | 91 } |
| 92 | exp '+' exp | |
| 93 { | |
| 94 $$ = $1 + $3; | |
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95 parser.beg_of_stmt (false); |
| 0 | 96 } |
| 97 | exp '-' exp | |
| 98 { | |
| 99 $$ = $1 - $3; | |
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100 parser.beg_of_stmt (false); |
| 0 | 101 } |
| 102 | exp '*' exp | |
| 103 { | |
| 104 $$ = $1 * $3; | |
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105 parser.beg_of_stmt (false); |
| 0 | 106 } |
| 107 | exp '/' exp | |
| 108 { | |
| 109 $$ = $1 / $3; | |
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110 parser.beg_of_stmt (false); |
| 0 | 111 } |
| 112 | '-' exp %prec NEG | |
| 113 { | |
| 114 $$ = -$2; | |
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115 parser.beg_of_stmt (false); |
| 0 | 116 } |
| 117 | exp '^' exp | |
| 118 { | |
| 119 $$ = std::pow ($1, $3); | |
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120 parser.beg_of_stmt (false); |
| 0 | 121 } |
| 122 | '(' exp ')' | |
| 123 { | |
| 124 $$ = $2; | |
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125 parser.beg_of_stmt (false); |
| 0 | 126 } |
| 127 ; | |
| 128 | |
| 129 %% | |
| 130 | |
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131 namespace calc |
| 0 | 132 { |
| 133 // The lexical analyzer returns a double floating point number on the | |
| 134 // stack and the token NUM, or the numeric code of the character read | |
| 135 // if not a number. It skips all blanks and tabs, and returns -1 for | |
| 136 // end-of-input. | |
| 137 | |
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138 static int yylex (YYSTYPE& token_value) |
| 0 | 139 { |
| 140 int c; | |
| 141 | |
| 142 if (bufptr >= chunk_size) | |
| 143 return -1; | |
| 144 | |
| 145 // Skip white space. | |
| 146 while ((c = buf[bufptr++]) == ' ' || c == '\t' || c == '\n') | |
| 147 ; | |
| 148 | |
| 149 // Process numbers. | |
| 150 if (c == '.' || isdigit (c)) | |
| 151 { | |
| 152 int chars_read = 0; | |
| 153 bufptr--; | |
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154 sscanf (&buf[bufptr], "%lf%n", &token_value, &chars_read); |
| 0 | 155 bufptr += chars_read; |
| 156 return NUM; | |
| 157 } | |
| 158 | |
| 159 // Return a single char. | |
| 160 return c; | |
| 161 } | |
| 162 | |
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163 int parser::parse_and_execute (const std::string& line) |
| 0 | 164 { |
| 165 bufptr = 0; | |
| 166 chunk_size = line.length (); | |
| 167 buf = line.c_str (); | |
| 168 | |
| 169 int status; | |
| 170 | |
| 171 do | |
| 172 { | |
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173 YYSTYPE token_value; |
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174 int input_char = yylex (token_value); |
| 0 | 175 |
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176 if (input_char < 0) |
| 0 | 177 return -1; |
| 178 | |
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179 status = yypush_parse (static_cast<yypstate *> (m_parser_state), |
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180 input_char, &token_value, *this); |
| 0 | 181 } |
| 182 while (status == YYPUSH_MORE); | |
| 183 | |
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184 return -2; |
| 0 | 185 } |
| 186 | |
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187 static void *create_parser_state (void) |
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188 { |
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189 return yypstate_new (); |
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190 } |
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191 |
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192 static void delete_parser_state (void *parser_state) |
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193 { |
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194 return yypstate_delete (static_cast<yypstate *> (parser_state)); |
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195 } |
| 0 | 196 } |
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197 |
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198 static void yyerror (calc::parser& parser, char const *msg) |
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199 { |
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200 parser.emit_error (msg); |
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201 } |