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/**
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* test/demos/parser/parser.yy
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* Copyright (C) 2008 Markus Broeker
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*/
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%{
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#include <stdio.h>
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#include <ctype.h>
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int regs[26];
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int base;
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int yyerror();
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int yylex();
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%}
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%start list
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%token DIGIT LETTER
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%left MINUS PLUS MUL DIV
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%left UMINUS
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%%
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list : /* empty */
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| list stat '\n'
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| list error '\n' { yyerrok; };
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stat :
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expr { (void) printf( "RESULT: %d\n", $1 ); }
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| LETTER '=' expr { regs[$1] = $3; }
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;
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expr : '(' expr ')'
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{
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$$ = $2;
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}
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| expr PLUS expr
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{
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$$ = $1 + $3;
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}
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| expr MINUS expr
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{
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$$ = $1 - $3;
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}
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| expr MUL expr
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{
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$$ = $1 * $3;
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}
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| expr DIV expr
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{
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$$ = $1 / $3;
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}
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| MINUS expr %prec UMINUS
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{
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$$ = -$2;
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}
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| LETTER
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{
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$$ = regs[$1];
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}
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| number
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;
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number : DIGIT
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{
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$$ = $1; base = ($1==0) ? 8 : 10;
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}
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| number DIGIT
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{
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$$ = base * $1 + $2;
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}
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;
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%%
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int yyerror()
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{
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printf("ERROR\n");
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return 0;
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}
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int yywrap()
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{
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return 1;
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}
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