yalk/lexer.c at master · yahiaelidev/yalk · GitHub

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#include "ds.h"

static const t_rules	g_precedence[UCHAR_MAX] = {
	[TOK_DIV] = 3,
	[TOK_MULT] = 3,
	[TOK_PLUS] = 2,
	[TOK_MINUS] = 2,
	[TOK_LPAREN] = 1,
	[TOK_RPAREN] = 1,
};

void	lexer_init(const char *input, t_lexer *lex) {
	lex->input = input;
	lex->len = ft_strlen(input);
	lexer_read(lex);
}

void	lexer_read(t_lexer *lex) {
	if (!(lex->cursor >= lex->len)) {
		lex->ch = lex->input[lex->cursor++];
		return;
	}

	lex->ch = TOK_NUL;
}

void	lexer_skip(t_lexer *lex) {
	while (lex->ch == TOK_SPACE || lex->ch == TOK_TAB)
		lexer_read(lex);
}

void token_create(t_token *tok,t_tok_type type, long data) {
	tok->type = type;
	tok->data = data;
	if (type == TOK_NUM){
		tok->pre = -1;
		return;
	}
	tok->pre = g_precedence[data];
}

long lexer_atoi(t_lexer *lex) {
	long data;
	data = 0;
	while (ft_isdigit(lex->ch)) {
		data = data * 10 + (lex->ch - ZERO);
		lexer_read(lex);
	}
	return (data);
}

void	lexer_next(t_lexer *lex, t_token *token) {
	long data = 0;
	unsigned char c = 0;

	lexer_skip(lex);

	if (lex->ch == TOK_NUL)
		return token_create(token ,TOK_NUL, 0);

	if (ft_isdigit(lex->ch)) {
		data = lexer_atoi(lex);
		return token_create(token, TOK_NUM, data);
	}

	if (tok_issign(lex->ch)) {
		c = lex->ch;
		lexer_read(lex);
		return token_create(token, (t_tok_type)c, c);
	}

	if (tok_isparen(lex->ch)) {
		c = lex->ch;
		lexer_read(lex);
		return token_create(token, (t_tok_type)c, c);
	}

	lexer_read(lex);
}