lexer.h

#ifndef LEXER_H
#define LEXER_H

// operation order : https://www.cs.uic.edu/~i109/Notes/COperatorPrecedenceTable.pdf

typedef enum TokenType {
    UNDEFINED, BEGIN,
    P0,
    ADD, MIN,
    P1,
    MUL, DIV, MOD,
    PRIORITY_END,
    NUMBER, DECIMAL,
    PAREN, THESE,
    NOT,
    EQ, GE, GT, LE, LT, NE,
    AND, OR,
    EQ_ASS, ADD_ASS, MIN_ASS, MUL_ASS, DIV_ASS, MOD_ASS,
    AND_ASS, OR_ASS, XOR_ASS, NOT_ASS,
    LEFT_SHIFT_ASS, RIGHT_SHIFT_ASS,
    BIT_AND, BIT_OR, BIT_XOR, BIT_NOT,
    LEFT_SHIFT, RIGHT_SHIFT,
    TEXT,
    END,
} TokenType;

extern char *lookup_TokenType[]; // in lexer.c

typedef double Decimal;

typedef struct Token {
    TokenType type;
    union {
        struct {
            char *text;
            int len;
        };
        int number;
        Decimal decimal;
    };
} Token;

static Token token_null = {
    .type = UNDEFINED,
    .number = 0,
};

int next_token(char *prog, Token *tok);
void print_tok(Token tok);
int token_equals(Token tok1, Token tok2);

#endif // LEXER_H