#ifndef _lex_h_
#define _lex_h_
#include <stdio.h>

#include "pre.h"
#include "location.h"
#include "state.h"
#include "libs/stb_ds.h"

enum LexTokenId {
	T_INVALID = 0,
	/* Unary and binary operators */
	T_PLUS, T_MINUS, T_STAR, T_BAR,
	T_LESSTHAN, T_GREATTHAN, T_LOGNOT, T_LOGAND, T_LOGOR, T_LOGICEQUAL, T_NOTEQUAL,
	T_HASH,
	/* Others */
	T_EQUAL, T_EXCLAMATION, T_LPAREN, T_RPAREN, T_COMMA,
	T_COLON, T_SEMICOLON, T_LBRACKET, T_RBRACKET, T_LBRACE, T_RBRACE,
	/* Atoms */
	T_IDENT, T_STRING, T_NUMBER, T_DECNUMBER,
	/* Keywords */
	T_CONST,
	T_ELSE,
	T_END,
	T_ELIF,
	T_IF,
	T_LET,
	T_PROC,
	T_RETURN,
	T_VAR,
	T_DISCARD,
	T_WHILE,
	T_STRUCT,
	T_USE,
	T_BREAK,
	T_NEXT,
	/* Control */
	T_EOF, T_ERROR,
	T_TOKEN_COUNT, /* does not represent an actual token */
};

/* Table mapping a `LexTokenId` to a string name of the token */
extern const char *TokenIdStr[];

typedef struct {
	enum LexTokenId id;
	union {
		Str ident, str, keyword;
		/* XXX: Defer number parsing until it is actually needed?
		 * So we can move number parsing out of the lexer. */
		/* Integer literal, it's the parser problem to tell
		 * whether the literal is negative or not.
		 */
		u64 inumber;
		/* Floating point literal */
		double floatn;
	};
	isize len; /* Size in bytes of this token */
	Location loc; /* Start position of this token in the file or stream */
} LexToken;

typedef HashMapStr(i8) IdentsBucket;

typedef struct {
	FILE *input_fp;
	/* Lexing buffer. This is actually split into two buffers, providing
	 * a double-buffering scheme */
	u8 *buf;
	/* Actual length of each buffer (fread may read less than LEX_BUFFER_SIZE) */
	isize buflen, buflen2;

	u8 *lbegin; /* marks the begin of the current lexeme */
	u8 *fwd; /* this pointer is the scanner */
   	Vec(LexToken) backlist; /* stack of backed up tokens */

	int tabsize;
	bool eof;
	Location cur_loc;
	Compiler *cm;
	IdentsBucket *idents;
} LexState;

LexToken
lex_scan(LexState *ls);
void
lex_backup(LexState *ls, LexToken token);
bool
lex_match(LexState *ls, LexToken *t, enum LexTokenId exp_tok);
LexState *
lex_new(Compiler *cm, FILE *input_fp, Str file_name, usize tabsize);
void
lex_destroy(LexState *l);

#endif