3759e1163f
Co-authored-by: aleksandr.vodyanov <aleksandr.vodyanov@avroid.tech> Reviewed-on: https://git.avroid.tech/Conan/conan_build/pulls/15
43 lines
857 B
Plaintext
43 lines
857 B
Plaintext
%{
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#include <iostream>
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#include <string>
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#include <map>
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#include <cstdlib> //-- I need this for atoi
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using namespace std;
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int yylex();
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int yyerror(const char *p) { cerr << "Error!" << endl; return 42; }
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%}
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%union {
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int val;
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char sym;
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};
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%token <val> NUM
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%token <sym> OPA OPM LP RP STOP
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%type <val> exp term sfactor factor res
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%%
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run: res run | res /* forces bison to process many stmts */
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res: exp STOP { cout << $1 << endl; }
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exp: exp OPA term { $$ = ($2 == '+' ? $1 + $3 : $1 - $3); }
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| term { $$ = $1; }
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term: term OPM factor { $$ = ($2 == '*' ? $1 * $3 : $1 / $3); }
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| sfactor { $$ = $1; }
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sfactor: OPA factor { $$ = ($1 == '+' ? $2 : -$2); }
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| factor { $$ = $1; }
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factor: NUM { $$ = $1; }
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| LP exp RP { $$ = $2; }
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%%
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int main()
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{
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yyparse();
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return 0;
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}
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