Question: /* expr Parses strings in the language generated by the rule: -> {(+ | -) } */ void expr() { printf(Enter ); /* Parse the
/* expr
Parses strings in the language generated by the rule:
-> {(+ | -) }
*/
void expr() {
printf("Enter ");
/* Parse the first term */
term();
/* As long as the next token is + or -, get
the next token and parse the next term */
while (nextToken == ADD_OP || nextToken == SUB_OP) {
lex();
term();
}
printf("Exit ");
} /* End of function expr */
/* term
Parses strings in the language generated by the rule:
-> {(* | /) )
*/
void term() {
printf("Enter ");
/* Parse the first factor */
factor();
/* As long as the next token is * or /, get the
next token and parse the next factor */
while (nextToken == MULT_OP || nextToken == DIV_OP) {
lex();
factor();
}
printf("Exit ");
} /* End of function term */
/* factor
Parses strings in the language generated by the rule:
-> id | int_constant | (
*/
void factor() {
printf("Enter ");
/* Determine which RHS */
if (nextToken == IDENT || nextToken == INT_LIT)
/* Get the next token */
lex();
/* If the RHS is ( ), call lex to pass over the
left parenthesis, call expr, and check for the right
parenthesis */
else {
if (nextToken == LEFT_PAREN) {
lex();
expr();
if (nextToken == RIGHT_PAREN)
lex();
else
error();
} /* End of if (nextToken == ... */
/* It was not an id, an integer literal, or a left
parenthesis */
else
error();
} /* End of else */
printf("Exit ");;
} /* End of function factor */
***GIVEN THE CODE ABOVE FOR A LEXICAL ANALYZER in c++ Implement the Parser found below thats in C, to c++, with Input, EXP***
//expression(EXP) example:
// (sum + 47) /total
/*
the parse begins by calling lex and the start
symbol routine, in this case, expr .
Next token is: 25 Next lexeme is (
Enter
Enter
Enter
Next token is: 11 Next lexeme is sum
Enter
Enter
Enter
Next token is: 21 Next lexeme is +
Exit
Exit
Next token is: 10 Next lexeme is 47
Enter
Enter
Next token is: 26 Next lexeme is )
Exit
Exit
Exit
Next token is: 24 Next lexeme is /
Exit
Next token is: 11 Next lexeme is total
Enter
Next token is: -1 Next lexeme is EOF
Exit
Exit
Exit
*/
/* expr
Parses strings in the language generated by the rule:
-> {(+ | -) }
*/
void expr() {
printf("Enter ");
/* Parse the first term */
term();
/* As long as the next token is + or -, get
the next token and parse the next term */
while (nextToken == ADD_OP || nextToken == SUB_OP) {
lex();
term();
}
printf("Exit ");
} /* End of function expr */
/* term
Parses strings in the language generated by the rule:
-> {(* | /) )
*/
void term() {
printf("Enter ");
/* Parse the first factor */
factor();
/* As long as the next token is * or /, get the
next token and parse the next factor */
while (nextToken == MULT_OP || nextToken == DIV_OP) {
lex();
factor();
}
printf("Exit ");
} /* End of function term */
/* factor
Parses strings in the language generated by the rule:
-> id | int_constant | (
*/
void factor() {
printf("Enter ");
/* Determine which RHS */
if (nextToken == IDENT || nextToken == INT_LIT)
/* Get the next token */
lex();
/* If the RHS is ( ), call lex to pass over the
left parenthesis, call expr, and check for the right
parenthesis */
else {
if (nextToken == LEFT_PAREN) {
lex();
expr();
if (nextToken == RIGHT_PAREN)
lex();
else
error();
} /* End of if (nextToken == ... */
/* It was not an id, an integer literal, or a left
parenthesis */
else
error();
} /* End of else */
printf("Exit ");;
} /* End of function factor */
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