bandcamp-dl/bandcamp_dl/jsobj.py

82 lines
3.1 KiB
Python

"""
Simple JavaScript/ECMAScript object literal reader
Only supports object literals wrapped in `var x = ...;` statements, so you
might want to do read_js_object('var x = %s;' % literal) if it's in another format.
Requires the slimit <https://github.com/rspivak/slimit> library for parsing.
Basic constand folding on strings and numbers is done, e.g. "hi " + "there!" reduces to "hi there!",
and 1+1 reduces to 2.
Copyright (c) 2013 darkf
Licensed under the terms of the WTFPL:
DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
Version 2, December 2004
Everyone is permitted to copy and distribute verbatim or modified
copies of this license document, and changing it is allowed as long
as the name is changed.
DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
0. You just DO WHAT THE FUCK YOU WANT TO.
"""
from slimit.parser import Parser
import slimit.ast as ast
def read_js_object(code):
parser = Parser()
def visit(node):
if isinstance(node, ast.Program):
d = {}
for child in node:
if not isinstance(child, ast.VarStatement):
raise ValueError("All statements should be var statements")
key, val = visit(child)
d[key] = val
return d
elif isinstance(node, ast.VarStatement):
return visit(node.children()[0])
elif isinstance(node, ast.VarDecl):
return visit(node.identifier), visit(node.initializer)
elif isinstance(node, ast.Object):
d = {}
for property in node:
key = visit(property.left)
value = visit(property.right)
d[key] = value
return d
elif isinstance(node, ast.BinOp):
# simple constant folding
if node.op == '+':
if isinstance(node.left, ast.String) and isinstance(node.right, ast.String):
return visit(node.left) + visit(node.right)
elif isinstance(node.left, ast.Number) and isinstance(node.right, ast.Number):
return visit(node.left) + visit(node.right)
else:
raise ValueError("Cannot + on anything other than two literals")
else:
raise ValueError("Cannot do operator '{}'".format(node.op))
elif isinstance(node, ast.String):
return node.value.strip('"').strip("'")
elif isinstance(node, ast.Array):
return [visit(x) for x in node]
elif isinstance(node, ast.Number) or isinstance(node, ast.Identifier)\
or isinstance(node, ast.Boolean) or isinstance(node, ast.Null):
return node.value
else:
raise Exception("Unhandled node: {}".format(node))
return visit(parser.parse(code))
if __name__ == "__main__":
print(read_js_object("""var foo = {x: 10, y: "hi " + "there!"};
var bar = {derp: ["herp", "it", "up", "forever"]};"""))