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# TODO Logging is interesting for debugging purposes, decide what to do with it
from logger import newlogger
logger = newlogger(__name__)
#import logging
#logger.setLevel(logging.WARN)
######
from enum import Enum
from reader import Reader
binChars = set("01")
octChars = set("01234567")
decChars = set("0123456789")
hexChars = set("0123456789ABCDEFabcdef")
class TokenType(Enum):
"""
These are the possible tokens that the lexer knows, they are converted to
their most accurate representation in python.
"""
identifier = 0 # Represented as strings
label = 1 # Represented as strings or integer if they are numeric
instruction = 2 # Represented as strings
directive = 3 # Represented as strings
integer = 4 # Represented as int
character = 5 # Represented as strings of length 1
string = 6 # Represented as strings
float = 7 # Represented as ??
# (we need correct conversions to the binary value)
# TODO
end = 8
argsep = 9
openparens = 10
closeparens = 11
class Lexer:
def __init__(self, reader):
self.reader = reader
self.tokenstart = 0
def __iter__(self):
return self
def __next__(self):
if self.reader.char is None:
self.reader.advance()
while True:
try:
# Instruction end
if self.reader.char == "\n" or self.reader.char == ";":
self.reader.advance()
return (TokenType.end, None)
# Argument separator
elif self.reader.char == ",":
self.reader.advance()
return (TokenType.argsep, None)
# String
elif self.reader.char == '"':
return self.string()
# Character
elif self.reader.char == "'":
return self.character()
# Comment
elif self.reader.char == "#":
self.comment()
# Parenthesis
# Load a register as an address + an offset
elif self.reader.char == '(':
self.reader.advance()
return (TokenType.openparens, None)
elif self.reader.char == ')':
self.reader.advance()
return (TokenType.closeparens, None)
# Starts with digit:
# - Numbers (any kind)
# - Numeric Labels
# - Numeric Label references
# - Load register as address: ld a1, 4(a0)
# ^^^^^
# offset + reg
elif self.reader.char.isdigit() or self.reader.char == "-":
return self.number()
# Identifiers
elif self.reader.char.isalpha():
return self.identifier()
elif self.reader.char == "":
break # FILE END
else:
# TODO: Remove this, it's just for testing
self.reader.advance()
except Exception as e:
# Handle exceptions
# raise StopIteration
raise e
raise StopIteration
def string (self):
logger.info("Found string")
self.reader.advance() # Ignore opening quotes
string = ""
escaped = False # Set if previous character was a backslash
while self.reader.char != '"' or escaped:
if self.reader.char == "":
# TODO: Check how to do this
raise ValueError("Error: string not closed, found EOF")
if self.reader.char == "\n":
# TODO: Consider the string as closed and continue but report
# the error?
raise ValueError("Error: string not closed, found newline")
if escaped:
string += self.escaped_char(self.reader.char)
logger.debug("Escape sequence processed %s",
string[-1].__repr__())
escaped = False
continue
if self.reader.char == "\\":
escaped = True
self.reader.advance()
continue
escaped = False
string += self.reader.char
self.reader.advance()
logger.info("Lexed string %s", string.__repr__())
self.reader.advance() # Discard closing "
return (TokenType.string, string)
def character (self):
logger.info("Found character")
self.reader.advance() # Ignore the opening quote
character = self.reader.char
if character == "":
# TODO: Check how to do this
raise ValueError("Error: found EOF")
if not character.isprintable() :
raise ValueError("Error: Non printable character")
if character == "\\":
self.reader.advance()
character = self.escaped_char(self.reader.char)
logger.debug("Escape sequence processed: %s", character.__repr__())
# Make sure it's correctly closed
self.reader.advance()
if self.reader.char != "'":
raise ValueError("Parse error: expected `'`, found " + self.reader.char)
self.reader.advance() # Discard closing '
logger.info("Lexed char %s", character.__repr__())
return (TokenType.character, character)
def comment(self):
while self.reader != "\n":
self.reader.advance()
def escaped_char(self, ch):
if ch == '"':
return '"'
elif ch == 'n':
return '\n'
elif ch == 't':
return '\t'
elif ch == '\\':
return '\\'
else:
# TODO: implement more escape sequences
return ""
def number(self):
"""
Process anything that starts with a number. Could be:
- An actual number in hex, octal, binary or decimal
- Numeric labels or numeric label references
- floating point (not implemented yet)
"""
numbstr = self.reader.char
self.reader.advance()
logger.info("Found number: %s", numbstr)
# Hex, Bin, Oct and the 0
if numbstr == "0":
reprid = self.reader.peek()
if reprid == "x":
self.reader.advance()
return self.hex()
elif reprid == "b":
self.reader.advance()
return self.bin()
elif reprid.isdigit():
return self.oct()
else:
return (TokenType.integer, 0)
# TODO: floating point numbers
# Decimal number
# consume a decimal number
while self.reader.char in decChars:
numbstr += self.reader.char
self.reader.advance()
# Numeric label reference
if self.reader.char in set("bf"):
numbstr += self.reader.char
self.reader.advance()
return (TokenType.identifier, numbstr)
# TODO: Return identifier or label?
# It's a label-ref not a label!
# Numeric label
if self.reader.char in ":":
self.reader.advance()
return (TokenType.label, numbstr)
return (TokenType.integer, int(numbstr))
def hex(self):
# TODO: Handle possible errors
numbstr = ""
while self.reader.char in hexChars:
numbstr += self.reader.char
self.reader.advance()
return (TokenType.integer, int(numbstr, 16))
def oct(self):
# TODO: Handle possible errors
numbstr = ""
while self.reader.char in octChars:
numbstr += self.reader.char
self.reader.advance()
return (TokenType.integer, int(numbstr, 8))
def bin(self):
# TODO: Handle possible errors
numbstr = ""
while self.reader.char in binChars:
numbstr += self.reader.char
self.reader.advance()
return (TokenType.integer, int(numbstr, 2))
def identifier(self):
s = ""
while self.reader.char.isalnum() or self.reader.char == "_":
s += self.reader.char
self.reader.advance()
return (TokenType.identifier, s)
if __name__ == "__main__":
import sys
with Reader(sys.argv[1]) as src:
lexer = Lexer(src)
for token in lexer:
print(token)
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