Files
lisp-interpreter/reader.py
T
2026-04-27 00:43:43 -06:00

82 lines
2.3 KiB
Python

import re
import lisp
from lisp import prettyprint
class Reader:
tokens: list[str]
def __init__(self, outputfile: str):
self.tokens = []
self.interpreter = lisp.Lisp()
self.outputfile = outputfile
def run(self):
if len(self.tokens) == 0:
return
try:
with open(self.outputfile, "a") as file:
while self.peek() != "":
result = prettyprint(self.interpreter.evaluate(self.read_expression()))
print(">> " + result)
file.write(result+"\n")
except Exception as e:
print("ERROR: " + str(e))
self.tokens = []
return
self.flush()
def tokenize(self, expression: str):
self.tokens += re.findall(r"""(?:;.*|[\s,]*)([()']|"(?:\\.|[^\\"])*"?|[^\s()'",;]*)""", expression)
def peek(self):
return self.tokens[0]
def flush(self):
while len(self.tokens) > 0:
if self.peek() == "":
self.consume()
def consume(self):
token = self.tokens[0]
self.tokens = self.tokens[1:]
return token
def read_expression(self):
if len(self.tokens) == 0:
return None
if self.peek() == "(":
self.consume()
atomlist = []
token = self.peek()
while token != ")":
atomlist.append(self.read_expression())
while self.peek() == "":
self.flush()
expression: str = input("... ").upper()
self.tokenize(expression)
token = self.peek()
self.consume()
return atomlist
elif self.peek() == "'":
# Expand the quote macro!
self.consume()
return ["QUOTE", self.read_expression()]
elif self.peek() == ")":
raise SyntaxError("Unexpected ')'")
else:
return self.read_atom()
def read_atom(self):
token = self.consume()
if token.upper() == "T":
return True
elif token.upper() == "NIL":
return False
try:
return int(token)
except ValueError:
try:
return float(token)
except ValueError:
return token