parser.c

#include <stdio.h>
#include "lexer.h"

// Token types
#define NUMBER 1
#define IDENTIFIER 2
#define BEGIN_TOKEN 3
#define END_TOKEN 4
#define WHITESPACE 5
#define UNKNOWN 6
#define SEMICOLON 7
#define FOR_TOKEN 8
#define IF_TOKEN 9
#define WHILE_TOKEN 10
#define DO_TOKEN 11
#define THEN_TOKEN 12
#define ELSE_TOKEN 13
#define TO 14
#define LEQ 15
#define NEQ 16
#define LT 17
#define GEQ 18
#define GT 19
#define ASSIGN 20
#define OF 21
#define PLUST 22
#define MINUS 23
#define MULT 24
#define EQUAL 25
#define ARRAY 26
#define HAT 27
#define REAL 28
#define CHAR 29
#define INT 30
#define DOTDOT 31
#define CLOSE_BRACKET 32
#define OPEN_BRACKET 33

const char *token_names[] = {
    "INVALID",
    "NUMBER",
    "IDENTIFIER",
    "BEGIN",
    "END",
    "WHITESPACE",
    "UNKNOWN",
    "SEMICOLON",
    "FOR",
    "IF",
    "WHILE",
    "DO",
    "THEN",
    "ELSE",
    "TO",
    "LEQ",
    "NEQ",
    "LT",
    "GEQ",
    "GT",
    "ASSIGN",
    "OF",
    "PLUST",
    "MINUS",
    "MULT",
    "EQUAL",
    "ARRAY",
    "HAT",
    "REAL",
    "CHAR",
    "INT",
    "DOTDOT",
    "CLOSE_BRACKET",
    "OPEN_BRACKET"
};
int parse_type();
int parse_simple();

int match(int expected_token) {
    int token = yylex();
    if (token == expected_token) {
        printf("%s: %s\n", yytext, token_names[token]);
        return 1;  // Matched successfully
    } else {
        printf("Error: Expected %s but got %s\n", token_names[expected_token], yytext);
        return 0;  // Match failed
    }
}

// Function for the 'type' non-terminal
int parse_type() {
    int token = yylex();
    
    if (token == REAL || token == INT || token == CHAR || token == NUMBER) {
        printf("%s: %s\n", yytext, token_names[token]);
        return 1;  // Successfully parsed
    } else if (token == HAT) {
        printf("%s: %s\n", yytext, token_names[token]);
        return match(IDENTIFIER);  // Parse ^id
    } else if (token == ARRAY) {
        printf("%s: %s\n", yytext, token_names[token]);
        if (match(OPEN_BRACKET) && match(NUMBER) && match(DOTDOT) && match(NUMBER) && match(CLOSE_BRACKET) && match(OF)) {
            return parse_type();  // Parse array [num doddot num] of type
        } else {
            return 0;  // Error in parsing array declaration
        }
    } else {
        printf("Error: Unexpected token %s\n", yytext);
        return 0;  // Parsing failed
    }
}

// Function for the 'simple' non-terminal
int parse_simple() {
    int token = yylex();

    if (token == REAL || token == INT || token == CHAR || token == NUMBER) {
        printf("%s: %s\n", yytext, token_names[token]);
        return 1;  // Successfully parsed
    } else {
        printf("Error: Unexpected token %s\n", yytext);
        return 0;  // Parsing failed
    }
}

int main() {
    int success = parse_type();

    if (success) {
        printf("Parsing successful!\n");
    } else {
        printf("Parsing failed.\n");
    }

    return 0;
}