def scan_token(self):
c = self.advance()
if c == "(":
self.add_token(TokenType.LEFT_PAREN)
elif c == ")":
self.add_token(TokenType.RIGHT_PAREN)
elif c == "{":
self.add_token(TokenType.LEFT_BRACE)
elif c == "}":
self.add_token(TokenType.RIGHT_BRACE)
elif c == ",":
self.add_token(TokenType.COMMA)
elif c == ".":
self.add_token(TokenType.DOT)
elif c == "-":
self.add_token(TokenType.MINUS)
elif c == "+":
self.add_token(TokenType.PLUS)
elif c == ";":
self.add_token(TokenType.SEMICOLON)
elif c == "*":
self.add_token(TokenType.STAR)
elif c == "!":
self.add_token(TokenType.BANG_EQUAL if self.match("=") else TokenType.BANG)
elif c == "=":
self.add_token(
TokenType.EQUAL_EQUAL if self.match("=") else TokenType.EQUAL
)
elif c == "<":
self.add_token(TokenType.LESS_EQUAL if self.match("=") else TokenType.LESS)
elif c == ">":
self.add_token(
TokenType.GREATER_EQUAL if self.match("=") else TokenType.GREATER
)
elif c == "/":
if self.match("/"): # a comment, consume till \n
while not self.at_end() and self.peek() != "\n":
self.advance()
else:
self.add_token(TokenType.SLASH)
elif c == " ":
pass
elif c == "\r":
pass
elif c == "\t":
pass
elif c == "\n":
self.line += 1
elif c == '"':
self.string()
elif c.isdigit():
self.number()
elif self.isalpha(c):
self.identifier()
else:
Lox.error(self.line, f"Unexpected character '{c}'.")
def string(self):
while not self.at_end() and self.peek() != '"':
if self.peek() == "\n": # multi line comments
self.line += 1
self.advance()
if self.at_end():
Lox.error(line, "Unterminated string.")
return
self.advance() # final "
literal = self.source[self.start + 1 : self.current - 1]
self.add_token(TokenType.STRING, literal)
def run_prompt(iptr: lox.Lox, parser: argparse.ArgumentParser):
"""Creates a prompt (REPL) for executing code.
Args:
iptr (lox.Lox): Interpreter to pass code into.
parser (ArgumentParser): ArgumentParser of the executable, used to output
exec-level errors (e.g. file not found).
"""
print("pylox version alpha")
while True:
try:
line = input(">>> ")
iptr.run(line)
except KeyboardInterrupt:
sys.exit(0)
def run_file(filename: str, iptr: lox.Lox, parser: argparse.ArgumentParser):
"""Executes code from a file.
Args:
filename (str): Filename of code to execute.
iptr (Lox): Interpreter to pass code into.
parser (ArgumentParser): ArgumentParser of the executable, used to output
exec-level errors (e.g. file not found).
"""
try:
with open(filename) as source:
iptr.run(source.read())
if iptr.error:
sys.exit(2)
except FileNotFoundError:
parser.error("File not found: {0}".format(filename))
def run_test(test, verbose=True):
with open(test, "r", encoding="utf-8") as f:
source = f.read()
# get expected output if exists
expected = "\n".join([
line.split("// expect: ")[1] for line in source.split("\n")
if "// expect:" in line
])
# use this to change acceptance conditions
expected_type = OUTPUT
# get token error if exists
if not expected:
for line in source.split("\n"):
search = TOKEN_REGEX.search(line)
if search:
expected_type = TOKEN_ERROR
expected += search.group(0).strip() + "\n"
# get runtime error
if not expected:
for line in source.split("\n"):
search = RUNTIME_REGEX.search(line)
if search:
expected_type = RUNTIME_ERROR
expected += search.group(0).strip() + "\n"
# actually run the thing
captured_stdout = io.StringIO()
with redirect_stdout(captured_stdout):
Lox(test=True).run(source=source)
# process + compare output to expected
actual = captured_stdout.getvalue()[:-1]
if expected_type == TOKEN_ERROR:
actual = "\n".join([
TOKEN_REGEX.search(line).group(0).strip()
for line in actual.split("\n")
])
if expected_type == RUNTIME_ERROR:
actual = "\n".join(
[actual.split("[")[0].strip() for line in actual.split("\n")])
if actual.strip() == expected.strip():
return 1
else:
print(f"{test} failed")
if verbose:
print(f"Expected:\n{expected}\n")
print(f"Actual:\n{actual}\n\n")
return 0
"""Run the interpreter"""
from lox import Lox
if __name__ == "__main__":
Lox()
def _error(self, token, msg):
from lox import Lox
Lox.error_token(token, msg)
return ParseError()
import argparse
from lox import Lox
parser = argparse.ArgumentParser()
parser.add_argument('path', nargs='?', default=None)
args = parser.parse_args()
lox = Lox()
if args.path is not None:
lox.run_file(args.path)
else:
lox.run_prompt()
def error(self, token, msg):
Lox.parsing_error(token, msg)
return ParseError()
def interpret(self, statements):
try:
for statement in statements:
self.execute(statement)
except RunTimeError as ex:
Lox.runtime_error(ex)
def _Lox_error(self, message):
from lox import Lox
Lox.error_line(self.line, message)