#!/usr/bin/env python3

import ply.lex as lex

# List of token names.   This is always required
tokens = (
    "OP",
    "JUMP",
    "COMMA",
    "COLON",
    "SYMBOL",
    "NUMBER",
    "HEXNUMBER",
    "DOT",
    "REG",
    "NL",
)

# Regular expression rules for simple tokens
t_COMMA = r","
t_COLON = r":"
t_DOT = r"\."


def t_OP(t):
    r"and|or|xor|not|mov|add|inc|sub|dec|cmp|neg|hlt|nop"
    return t


def t_REG(t):
    r"\b(AD?M?|DM?|M|_)\b"
    return t


def t_JUMP(t):
    r"jmp|jlt|jgt|jle|jge|jeq|jne"
    return t


def t_NUMBER(t):
    r"\#\d+"
    t.value = int(t.value[1:])
    return t


def t_HEXNUMBER(t):
    r"\#0x[0-9a-fA-F]+"
    t.value = int(t.value[1:], 16)
    return t


def t_SYMBOL(t):
    r"[a-z][A-Za-z0-9_]+"
    return t


# Define a rule so we can track line numbers
def t_NL(t):
    r"\n+"
    t.lexer.lineno += len(t.value)
    return t


# A string containing ignored characters (spaces and tabs)
t_ignore = " \t"
# t_ignore_COMMENT = r';.*'


def t_COMMENT(t):
    r";.*"
    pass


# Error handling rule
def t_error(t):
    print("!!! Illegal character '%s'" % t.value[0])
    t.lexer.skip(1)


# EOF handling rule
def t_eof(t):
    if not t.lexer.newline_added:
        t.lexer.input("\n")
        t.lexer.newline_added = True
        return t.lexer.token()
    return None


# Build the lexer
lexer = lex.lex()
lexer.newline_added = False