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34 lines
750 B
Plaintext
34 lines
750 B
Plaintext
%{
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#define YYSTYPE double
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#include <stdio.h>
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// yylex() is generated by flex
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int yylex(void);
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// we have to define yyerror()
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int yyerror (char const *);
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%}
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%token NUMBER
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%left '+' '-'
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%left '*' '/'
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%right '('
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%%
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stmtlist: statement '\n' stmtlist {
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printf("done with statement equal to [%g]\n", $1);
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} | // EMPTY RULE i.e. stmtlist -> nil
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{ printf("DONE\n") ;};
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statement: expression { printf("VALUE=%g\n",$1); };
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expression: expression '+' expression { $$ = $1 + $3; } |
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expression '-' expression { $$ = $1 - $3; } |
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expression '*' expression { $$ = $1 * $3; } |
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expression '/' expression {
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if($3 !=0) { $$ = $1 / $3; } else
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{ printf("div by zero\n"); $$=0;} } |
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'(' expression ')' { $$ = $2; } |
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NUMBER { $$ = $1; } ;
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%%
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