import sly

class Lexer(sly.Lexer):
    # define token types
    tokens = { 
        # Keyworkds
        BREAK, CASE, DEFAULT, ELSE, FLOAT,
        IF, INPUT, INT, OUTPUT, SWITCH, WHILE,
        # Operators
        RELOP, ADDOP, MULOP, OR, AND, NOT, CAST, 
        # misc
        ID, NUM 
    }
    ignore = ' \t'
    literals = { '(', ')', '{', '}', ',', ':', ';', '=' }

    # define each token
    RELOP = r'(==|!=|<|>|>=|<=)'
    ADDOP = r'(\+|-)'
    MULOP = r'(\*|/)'
    OR = '\|\|'
    AND = '&&'
    NOT = '!'
    CAST = r'static_cast<(int|float)>'

    ID = r'[a-zA-Z][a-zA-Z0-9]*'
    NUM = r'[0-9]+(\.[0-9]*)?'

    # define keywords on ID
    ID['break'] = BREAK
    ID['case'] = CASE
    ID['default'] = DEFAULT
    ID['else'] = ELSE
    ID['float'] = FLOAT
    ID['if'] = IF
    ID['input'] = INPUT
    ID['int'] = INT
    ID['output'] = OUTPUT
    ID['switch'] = SWITCH
    ID['while'] = WHILE    

    @_(r'\n+')
    def newline(self, t):
        self.lineno += t.value.count('\n')
    
    def error(self, t):
        print(f"Error at line {self.lineno}: unexpect character {t.value[0]}")
        self.index += 1