ydl.ast.py

import ast
import urllib
import unparse

YDL_YOUTUBE_IE_SOURCE="https://raw.github.com/rg3/youtube-dl/master/youtube_dl/extractor/youtube.py"

class TargetFinder(ast.NodeVisitor):
    def __init__(self):
        self.target = None

    def visit_FunctionDef(self, node):
        if node.name == "_decrypt_signature":
            self.target = node
        super(TargetFinder, self).generic_visit(node)

    def visit_arguments(self, node):
        if node.args:
            node.args = [ arg for arg in node.args if arg.id != 'self']
        super(TargetFinder, self).generic_visit(node)

    def visit_If(self, node):
        if node.orelse and isinstance(node.orelse[0], ast.Raise):
            # don't raise Exception. it will return None
            node.orelse=[]
        super(TargetFinder, self).generic_visit(node)


    def find(self, node):
        self.visit(node)
        return self.target


source=urllib.urlopen(YDL_YOUTUBE_IE_SOURCE).read()
tree=ast.parse(source)

function = TargetFinder().find(tree)
unparse.Unparser(function)