-
-
Save eestrada/2f9ba8e3aa26a5ae075e to your computer and use it in GitHub Desktop.
A simple Python s-expression parser.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
from string import whitespace | |
atom_end = set('()"\'') | set(whitespace) | |
def parse(sexp): | |
stack, i, length = [[]], 0, len(sexp) | |
while i < length: | |
c = sexp[i] | |
print c, stack | |
reading = type(stack[-1]) | |
if reading == list: | |
if c == '(': stack.append([]) | |
elif c == ')': | |
stack[-2].append(stack.pop()) | |
if stack[-1][0] == ('quote',): stack[-2].append(stack.pop()) | |
elif c == '"': stack.append('') | |
elif c == "'": stack.append([('quote',)]) | |
elif c in whitespace: pass | |
else: stack.append((c,)) | |
elif reading == str: | |
if c == '"': | |
stack[-2].append(stack.pop()) | |
if stack[-1][0] == ('quote',): stack[-2].append(stack.pop()) | |
elif c == '\\': | |
i += 1 | |
stack[-1] += sexp[i] | |
else: stack[-1] += c | |
elif reading == tuple: | |
if c in atom_end: | |
atom = stack.pop() | |
if atom[0][0].isdigit(): stack[-1].append(eval(atom[0])) | |
else: stack[-1].append(atom) | |
if stack[-1][0] == ('quote',): stack[-2].append(stack.pop()) | |
continue | |
else: stack[-1] = ((stack[-1][0] + c),) | |
i += 1 | |
return stack.pop() |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment