[jsinterp] Some optimizations and refactoring
Motivated by: https://github.com/ytdl-org/youtube-dl/issues/30641#issuecomment-1041904912 Authored by: dirkf, pukkandan
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pukkandan
parent
e4afcfde08
commit
230d5c8239
1 changed files with 98 additions and 109 deletions
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@ -6,22 +6,19 @@ import re
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from .utils import ExtractorError, remove_quotes
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_OPERATORS = [
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('|', operator.or_),
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('^', operator.xor),
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('&', operator.and_),
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('>>', operator.rshift),
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('<<', operator.lshift),
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('-', operator.sub),
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('+', operator.add),
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('%', operator.mod),
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('/', operator.truediv),
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('*', operator.mul),
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]
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_ASSIGN_OPERATORS = [(op + '=', opfunc) for op, opfunc in _OPERATORS]
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_ASSIGN_OPERATORS.append(('=', (lambda cur, right: right)))
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_NAME_RE = r'[a-zA-Z_$][a-zA-Z_$0-9]*'
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_NAME_RE = r'[a-zA-Z_$][\w$]*'
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_OPERATORS = {
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'|': operator.or_,
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'^': operator.xor,
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'&': operator.and_,
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'>>': operator.rshift,
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'<<': operator.lshift,
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'-': operator.sub,
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'+': operator.add,
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'%': operator.mod,
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'/': operator.truediv,
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'*': operator.mul,
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}
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_MATCHING_PARENS = dict(zip('({[', ')}]'))
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_QUOTES = '\'"'
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@ -50,13 +47,11 @@ class LocalNameSpace(collections.ChainMap):
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class JSInterpreter:
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__named_object_counter = 0
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def __init__(self, code, objects=None):
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if objects is None:
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objects = {}
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self.code = code
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self._functions = {}
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self._objects = objects
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self.__named_object_counter = 0
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self.code, self._functions = code, {}
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self._objects = {} if objects is None else objects
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def _named_object(self, namespace, obj):
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self.__named_object_counter += 1
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@ -93,9 +88,9 @@ class JSInterpreter:
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break
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yield expr[start:]
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@staticmethod
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def _separate_at_paren(expr, delim):
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separated = list(JSInterpreter._separate(expr, delim, 1))
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@classmethod
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def _separate_at_paren(cls, expr, delim):
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separated = list(cls._separate(expr, delim, 1))
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if len(separated) < 2:
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raise ExtractorError(f'No terminating paren {delim} in {expr}')
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return separated[0][1:].strip(), separated[1].strip()
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@ -104,33 +99,29 @@ class JSInterpreter:
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if allow_recursion < 0:
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raise ExtractorError('Recursion limit reached')
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sub_statements = list(self._separate(stmt, ';'))
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stmt = (sub_statements or ['']).pop()
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should_abort = False
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sub_statements = list(self._separate(stmt, ';')) or ['']
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stmt = sub_statements.pop().lstrip()
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for sub_stmt in sub_statements:
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ret, should_abort = self.interpret_statement(sub_stmt, local_vars, allow_recursion - 1)
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if should_abort:
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return ret
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return ret, should_abort
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should_abort = False
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stmt = stmt.lstrip()
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stmt_m = re.match(r'var\s', stmt)
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if stmt_m:
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expr = stmt[len(stmt_m.group(0)):]
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m = re.match(r'(?P<var>var\s)|return(?:\s+|$)', stmt)
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if not m: # Try interpreting it as an expression
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expr = stmt
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elif m.group('var'):
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expr = stmt[len(m.group(0)):]
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else:
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return_m = re.match(r'return(?:\s+|$)', stmt)
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if return_m:
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expr = stmt[len(return_m.group(0)):]
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should_abort = True
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else:
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# Try interpreting it as an expression
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expr = stmt
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expr = stmt[len(m.group(0)):]
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should_abort = True
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v = self.interpret_expression(expr, local_vars, allow_recursion)
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return v, should_abort
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return self.interpret_expression(expr, local_vars, allow_recursion), should_abort
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def interpret_expression(self, expr, local_vars, allow_recursion):
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expr = expr.strip()
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if expr == '': # Empty expression
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if not expr:
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return None
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if expr.startswith('{'):
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@ -156,8 +147,8 @@ class JSInterpreter:
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for item in self._separate(inner)])
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expr = name + outer
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m = re.match(r'try\s*', expr)
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if m:
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m = re.match(r'(?P<try>try)\s*|(?:(?P<catch>catch)|(?P<for>for)|(?P<switch>switch))\s*\(', expr)
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if m and m.group('try'):
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if expr[m.end()] == '{':
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try_expr, expr = self._separate_at_paren(expr[m.end():], '}')
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else:
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@ -167,21 +158,19 @@ class JSInterpreter:
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return ret
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return self.interpret_statement(expr, local_vars, allow_recursion - 1)[0]
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m = re.match(r'catch\s*\(', expr)
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if m:
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elif m and m.group('catch'):
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# We ignore the catch block
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_, expr = self._separate_at_paren(expr, '}')
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return self.interpret_statement(expr, local_vars, allow_recursion - 1)[0]
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m = re.match(r'for\s*\(', expr)
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if m:
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elif m and m.group('for'):
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constructor, remaining = self._separate_at_paren(expr[m.end() - 1:], ')')
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if remaining.startswith('{'):
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body, expr = self._separate_at_paren(remaining, '}')
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else:
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m = re.match(r'switch\s*\(', remaining) # FIXME
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if m:
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switch_val, remaining = self._separate_at_paren(remaining[m.end() - 1:], ')')
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switch_m = re.match(r'switch\s*\(', remaining) # FIXME
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if switch_m:
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switch_val, remaining = self._separate_at_paren(remaining[switch_m.end() - 1:], ')')
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body, expr = self._separate_at_paren(remaining, '}')
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body = 'switch(%s){%s}' % (switch_val, body)
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else:
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@ -206,8 +195,7 @@ class JSInterpreter:
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f'Premature return in the initialization of a for loop in {constructor!r}')
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return self.interpret_statement(expr, local_vars, allow_recursion - 1)[0]
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m = re.match(r'switch\s*\(', expr)
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if m:
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elif m and m.group('switch'):
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switch_val, remaining = self._separate_at_paren(expr[m.end() - 1:], ')')
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switch_val = self.interpret_expression(switch_val, local_vars, allow_recursion)
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body, expr = self._separate_at_paren(remaining, '}')
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@ -250,55 +238,63 @@ class JSInterpreter:
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ret = local_vars[var]
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expr = expr[:start] + json.dumps(ret) + expr[end:]
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for op, opfunc in _ASSIGN_OPERATORS:
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m = re.match(rf'''(?x)
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(?P<out>{_NAME_RE})(?:\[(?P<index>[^\]]+?)\])?
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\s*{re.escape(op)}
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(?P<expr>.*)$''', expr)
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if not m:
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continue
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right_val = self.interpret_expression(m.group('expr'), local_vars, allow_recursion)
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if not expr:
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return None
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if m.groupdict().get('index'):
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lvar = local_vars[m.group('out')]
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idx = self.interpret_expression(m.group('index'), local_vars, allow_recursion)
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if not isinstance(idx, int):
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raise ExtractorError(f'List indices must be integers: {idx}')
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cur = lvar[idx]
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val = opfunc(cur, right_val)
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lvar[idx] = val
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return val
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m = re.match(fr'''(?x)
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(?P<assign>
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(?P<out>{_NAME_RE})(?:\[(?P<index>[^\]]+?)\])?\s*
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(?P<op>{"|".join(map(re.escape, _OPERATORS))})?
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=(?P<expr>.*)$
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)|(?P<return>
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(?!if|return|true|false|null)(?P<name>{_NAME_RE})$
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)|(?P<indexing>
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(?P<in>{_NAME_RE})\[(?P<idx>.+)\]$
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)|(?P<attribute>
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(?P<var>{_NAME_RE})(?:\.(?P<member>[^(]+)|\[(?P<member2>[^\]]+)\])\s*
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)|(?P<function>
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(?P<fname>{_NAME_RE})\((?P<args>[\w$,]*)\)$
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)''', expr)
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if m and m.group('assign'):
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if not m.group('op'):
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opfunc = lambda curr, right: right
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else:
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cur = local_vars.get(m.group('out'))
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val = opfunc(cur, right_val)
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local_vars[m.group('out')] = val
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return val
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opfunc = _OPERATORS[m.group('op')]
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right_val = self.interpret_expression(m.group('expr'), local_vars, allow_recursion)
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left_val = local_vars.get(m.group('out'))
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if expr.isdigit():
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if not m.group('index'):
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local_vars[m.group('out')] = opfunc(left_val, right_val)
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return local_vars[m.group('out')]
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elif left_val is None:
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raise ExtractorError(f'Cannot index undefined variable: {m.group("out")}')
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idx = self.interpret_expression(m.group('index'), local_vars, allow_recursion)
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if not isinstance(idx, int):
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raise ExtractorError(f'List indices must be integers: {idx}')
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left_val[idx] = opfunc(left_val[idx], right_val)
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return left_val[idx]
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elif expr.isdigit():
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return int(expr)
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if expr == 'break':
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elif expr == 'break':
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raise JS_Break()
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elif expr == 'continue':
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raise JS_Continue()
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var_m = re.match(
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r'(?!if|return|true|false|null)(?P<name>%s)$' % _NAME_RE,
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expr)
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if var_m:
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return local_vars[var_m.group('name')]
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elif m and m.group('return'):
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return local_vars[m.group('name')]
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with contextlib.suppress(ValueError):
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return json.loads(expr)
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m = re.match(
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r'(?P<in>%s)\[(?P<idx>.+)\]$' % _NAME_RE, expr)
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if m:
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if m and m.group('indexing'):
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val = local_vars[m.group('in')]
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idx = self.interpret_expression(m.group('idx'), local_vars, allow_recursion)
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return val[idx]
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for op, opfunc in _OPERATORS:
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for op, opfunc in _OPERATORS.items():
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separated = list(self._separate(expr, op))
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if len(separated) < 2:
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continue
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@ -314,10 +310,7 @@ class JSInterpreter:
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raise ExtractorError(f'Premature right-side return of {op} in {expr!r}')
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return opfunc(left_val or 0, right_val)
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m = re.match(
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r'(?P<var>%s)(?:\.(?P<member>[^(]+)|\[(?P<member2>[^]]+)\])\s*' % _NAME_RE,
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expr)
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if m:
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if m and m.group('attribute'):
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variable = m.group('var')
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member = remove_quotes(m.group('member') or m.group('member2'))
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arg_str = expr[m.end():]
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@ -332,7 +325,6 @@ class JSInterpreter:
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raise ExtractorError(f'{member} {msg}: {expr}')
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def eval_method():
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nonlocal member
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if variable == 'String':
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obj = str
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elif variable in local_vars:
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@ -342,8 +334,8 @@ class JSInterpreter:
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self._objects[variable] = self.extract_object(variable)
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obj = self._objects[variable]
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# Member access
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if arg_str is None:
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# Member access
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if member == 'length':
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return len(obj)
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return obj[member]
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@ -418,9 +410,7 @@ class JSInterpreter:
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except ValueError:
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return -1
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if isinstance(obj, list):
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member = int(member)
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return obj[member](argvals)
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return obj[int(member) if isinstance(obj, list) else member](argvals)
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if remaining:
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return self.interpret_expression(
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@ -429,9 +419,8 @@ class JSInterpreter:
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else:
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return eval_method()
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m = re.match(r'^(?P<func>%s)\((?P<args>[a-zA-Z0-9_$,]*)\)$' % _NAME_RE, expr)
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if m:
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fname = m.group('func')
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elif m and m.group('function'):
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fname = m.group('fname')
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argvals = tuple(
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int(v) if v.isdigit() else local_vars[v]
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for v in self._separate(m.group('args')))
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@ -441,8 +430,7 @@ class JSInterpreter:
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self._functions[fname] = self.extract_function(fname)
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return self._functions[fname](argvals)
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if expr:
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raise ExtractorError('Unsupported JS expression %r' % expr)
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raise ExtractorError(f'Unsupported JS expression {expr!r}')
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def extract_object(self, objname):
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_FUNC_NAME_RE = r'''(?:[a-zA-Z$0-9]+|"[a-zA-Z$0-9]+"|'[a-zA-Z$0-9]+')'''
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@ -471,14 +459,17 @@ class JSInterpreter:
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""" @returns argnames, code """
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func_m = re.search(
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r'''(?x)
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(?:function\s+%s|[{;,]\s*%s\s*=\s*function|var\s+%s\s*=\s*function)\s*
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(?:
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function\s+%(name)s|
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[{;,]\s*%(name)s\s*=\s*function|
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var\s+%(name)s\s*=\s*function
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)\s*
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\((?P<args>[^)]*)\)\s*
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(?P<code>\{(?:(?!};)[^"]|"([^"]|\\")*")+\})''' % (
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re.escape(funcname), re.escape(funcname), re.escape(funcname)),
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(?P<code>{(?:(?!};)[^"]|"([^"]|\\")*")+})''' % {'name': re.escape(funcname)},
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self.code)
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code, _ = self._separate_at_paren(func_m.group('code'), '}') # refine the match
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if func_m is None:
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raise ExtractorError('Could not find JS function %r' % funcname)
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raise ExtractorError(f'Could not find JS function "{funcname}"')
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return func_m.group('args').split(','), code
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def extract_function(self, funcname):
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@ -492,11 +483,9 @@ class JSInterpreter:
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break
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start, body_start = mobj.span()
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body, remaining = self._separate_at_paren(code[body_start - 1:], '}')
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name = self._named_object(
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local_vars,
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self.extract_function_from_code(
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[str.strip(x) for x in mobj.group('args').split(',')],
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body, local_vars, *global_stack))
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name = self._named_object(local_vars, self.extract_function_from_code(
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[x.strip() for x in mobj.group('args').split(',')],
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body, local_vars, *global_stack))
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code = code[:start] + name + remaining
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return self.build_function(argnames, code, local_vars, *global_stack)
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