Program to recognize and count the number of identifiers in a given input file. | Compiler Design Lab Programs

Program to recognize and count the number of identifiers in a given input file. | Compiler Design Lab Programs

Compiler Design Lap Program : %{  #include<stdio.h>  int id=0; %} %% [a-zA-Z][a-zA-Z0-9_]* { id++ ; ECHO; printf(“...

Compiler Design Lap Program :

%{

 #include<stdio.h>

 int id=0;

%}

%%

[a-zA-Z][a-zA-Z0-9_]* { id++ ; ECHO; printf(“\n”);}

.+ { ;}

\n { ;}

%%

int yywrap()

{

return 1;

}

main (int argc, char *argv[])

{

 if(argc!=2)

 {

 printf(“Usage: <./a.out> <sourcefile>\n”);

 exit(0);

 }

 yyin=fopen(argv[1],”r”);

 printf(“Valid identifires are\n”);

 yylex();

 printf(“No of identifiers = %d\n”,id);

} 

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February 23, 2019

Program to test the validity of a simple expression involving operators +, -, * and / | Compiler Design Lab Programs | Yacc Programs

Program to test the validity of a simple expression involving operators +, -, * and / | Compiler Design Lab Programs | Yacc Programs

Yacc Part : %token NUMBER ID NL %left ‘+’ ‘-‘ %left ‘*’ ‘/’ %% stmt : exp NL { printf(“Valid Expression”); exit(0);}  ; ...

Yacc Part :

%token NUMBER ID NL

%left ‘+’ ‘-‘

%left ‘*’ ‘/’

%%

stmt : exp NL { printf(“Valid Expression”); exit(0);}

 ;

exp : exp ‘+’ exp

 | exp ‘-‘ exp

 | exp ‘*’ exp

 | exp ‘/’ exp

 | ‘(‘ exp ‘)’

 | ID

 | NUMBER

 ;

%%

int yyerror(char *msg)

{

 printf(“Invalid Expression\n”);

 exit(0);

}

main ()

{

 printf(“Enter the expression\n”);

 yyparse();

} 

Lex Part :

%{

 #include “y.tab.h”

%}

%%

[0-9]+ { return DIGIT; }

[a-zA-Z][a-zA-Z0-9_]* { return ID; }

\n { return NL ;}

. { return yytext[0]; }

%%

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February 23, 2019

Program to recognize nested IF control statements and display the levels of nesting . | Compiler Design Lab Programs | Yacc Programs

Program to recognize nested IF control statements and display the levels of nesting . | Compiler Design Lab Programs | Yacc Programs

Yacc Part : %token IF RELOP S NUMBER ID %{  int count=0; %} %% stmt : if_stmt { printf(“No of nested if statements=%d\n”...

Yacc Part :

%token IF RELOP S NUMBER ID

%{

 int count=0;

%}

%%

stmt : if_stmt { printf(“No of nested if statements=%d\n”,count); exit(0);}

 ;

if_stmt : IF ‘(‘ cond ‘)’ if_stmt {count++;}

 | S;

 ;

cond : x RELOP x

 ;

x : ID

 | NUMBER

 ;

%%

int yyerror(char *msg)

{

 printf(“Invalid Expression\n”);

 exit(0);

}

main ()

{

 printf(“Enter the statement”);

 yyparse();

} 

Lex Part :

%{

 #include “y.tab.h”

%}

%%

“if” { return IF; }

[sS][0-9]* {return S;}

“<”|”>”|”==”|”!=”|”<=”|”>=” { return RELOP; }

[0-9]+ { return NUMBER; }

[a-zA-Z][a-zA-Z0-9_]* { return ID; }

\n { ; }

. { return yytext[0]; }

%%

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February 23, 2019

Program to check the syntax of a simple expression involving operators +, -, * and / . | Compiler Lab Programs | Yacc Programs

Program to check the syntax of a simple expression involving operators +, -, * and / . | Compiler Lab Programs | Yacc Programs

Yacc Part : %token NUMBER ID NL %left ‘+’ ‘-‘ %left ‘*’ ‘/’ %% stmt : exp NL { printf(“Valid Expression”); exit(0);}  ; ...

Yacc Part :

%token NUMBER ID NL

%left ‘+’ ‘-‘

%left ‘*’ ‘/’

%%

stmt : exp NL { printf(“Valid Expression”); exit(0);}

 ;

exp : exp ‘+’ exp

 | exp ‘-‘ exp

 | exp ‘*’ exp

 | exp ‘/’ exp

 | ‘(‘ exp ‘)’

 | ID

 | NUMBER

 ;

%%

int yyerror(char *msg)

{

 printf(“Invalid Expression\n”);

 exit(0);

}

main ()

{

 printf(“Enter the expression\n”);

 yyparse();

} 

Lex Part :

%{

 #include “y.tab.h”

%}

%%

[0-9]+ { return NUMBER; }

[a-zA-Z][a-zA-Z0-9_]* { return ID; }

\n { return NL ;}

. { return yytext[0]; }

%% 

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February 23, 2019

Program to recognize a valid variable, which starts with a letter, followed by any number of letters or digits. | Compiler Design Lab Programs | Yacc Programs

Program to recognize a valid variable, which starts with a letter, followed by any number of letters or digits. | Compiler Design Lab Programs | Yacc Programs

Yacc Part : %token DIGIT LETTER NL UND %% stmt : variable NL { printf(“Valid Identifiers\n”); exit(0);}  ; variable : LE...

Yacc Part :

%token DIGIT LETTER NL UND

%%

stmt : variable NL { printf(“Valid Identifiers\n”); exit(0);}

 ;

variable : LETTER alphanumeric

 ;

alphanumeric: LETTER alphanumeric

 | DIGIT alphanumeric

 | UND alphanumeric

 | LETTER

 | DIGIT

 | UND

 ;

%%

int yyerror(char *msg)

{

 printf(“Invalid Expression\n”);

 exit(0);

}

main ()

{

 printf(“Enter the variable name\n”);

 yyparse();

} 

Lex Part :

%{

 #include “y.tab.h”

%}

%%

[a-zA-Z] { return LETTER ;}

[0-9] { return DIGIT ; }

[\n] { return NL ;}

[_] { return UND; }

. { return yytext[0]; }

%%

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February 23, 2019

Program to evaluate an arithmetic expression involving operating +, -, * and /. | Compiler Design Lab Programs | Yacc Programs

Program to evaluate an arithmetic expression involving operating +, -, * and /. | Compiler Design Lab Programs | Yacc Programs

Yacc Part : %token NUMBER ID NL %left ‘+’ ‘-‘ %left ‘*’ ‘/’ %% stmt : exp NL { printf(“Value = %d\n”,$1); exit(0);}  ; ...

Yacc Part :

%token NUMBER ID NL

%left ‘+’ ‘-‘

%left ‘*’ ‘/’

%%

stmt : exp NL { printf(“Value = %d\n”,$1); exit(0);}

 ;

exp : exp ‘+’ exp { $$=$1+$3; }

 | exp ‘-‘ exp { $$=$1-$3; }

 | exp ‘*’ exp { $$=$1*$3; }

 | exp ‘/’ exp { if($3==0)

 {

printf(“Cannot divide by 0”);

exit(0);

 }

 else

 $$=$1/$3;

}

 | ‘(‘ exp ‘)’ { $$=$2; }

 | ID { $$=$1; }

 | NUMBER { $$=$1; }

 ;

%%

int yyerror(char *msg)

{

 printf(“Invalid Expression\n”);

 exit(0);

}

main ()

{

 printf(“Enter the expression\n”);

 yyparse();

} 

Lex Part :

%{

 #include “y.tab.h”

 extern int yylval;

%}

%%

[0-9]+ { yylval=atoi(yytext); return NUMBER; }

\n { return NL ;}

. { return yytext[0]; }

%%

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February 23, 2019

Program to recognize strings ‘aaab’, ‘abbb’, ‘ab’ and ‘a’ using grammar (an b n , n>=0) . | Compiler Design Lab Programs | Yacc Programs

Program to recognize strings ‘aaab’, ‘abbb’, ‘ab’ and ‘a’ using grammar (an b n , n>=0) . | Compiler Design Lab Programs | Yacc Programs

Yacc Part : %token A B NL %% stmt : s NL { printf(“Valid String\n”); exit(0) ;}  ; s : A s B  |  ; %% int yyerror(...

Yacc Part :

%token A B NL

%%

stmt : s NL { printf(“Valid String\n”); exit(0) ;}

 ;

s : A s B

 |

 ;

%%

int yyerror(char *msg)

{

 printf(“Invalid String\n”);

 exit(0);

}

main ()

{

 printf(“Enter the String\n”);

 yyparse();

}

Lex Part :

%{

 #include “y.tab.h”

%}

%%

[aA] { return A; }

[bB] { return B; }

\n { return NL ;}

. { return yytext[0]; }

%%

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February 23, 2019