#ifndef LEXER_H
#define LEXER_H

#include <lexer/token.h>
#include <stddef.h>
#include <utils/libstring.h>

// True if C could be used as a word
#define ISWORD(C)                                                              \
    C == TOKEN_WORD || C == TOKEN_THEN || C == TOKEN_ELIF || C == TOKEN_ELSE   \
        || C == TOKEN_IF || C == TOKEN_WHILE || C == TOKEN_UNTIL               \
        || C == TOKEN_DO || C == TOKEN_DONE || C == TOKEN_FOR || C == TOKEN_IN \
        || C == TOKEN_NEG || C == TOKEN_FI || C == TOKEN_CURLY_LEFT            \
        || C == TOKEN_CURLY_RIGHT

struct lexer
{
    struct string *input; // input data
    size_t pos; // the current offset inside the input data
    char processed;
    struct token current_tok; // next (if processed) token
};

// Creates a new lexer given an input string
struct lexer *lexer_new(struct string *input);

// Frees the given lexer, not its input
void lexer_free(struct lexer *lexer);

// Returns a token from the input string
// If the token is a WORD, copies the word to the current_tok.value field
struct token lexer_next_token(struct lexer *lexer);

/*
** Processes the next token if necessary
** (previous call to lexer_pop or first call)
*/
// Returns the next token
struct token lexer_peek(struct lexer *lexer);

/*
** Processes the next token if necessary
** (previous call to lexer_pop or first call)
*/
// Returns the next token and moves the cursor forward
struct token lexer_pop(struct lexer *lexer);

#endif /* ! LEXER_H */