from __future__ import unicode_literals
import json
+import operator
import re
from .utils import (
ExtractorError,
)
+_OPERATORS = [
+ ('|', operator.or_),
+ ('^', operator.xor),
+ ('&', operator.and_),
+ ('>>', operator.rshift),
+ ('<<', operator.lshift),
+ ('-', operator.sub),
+ ('+', operator.add),
+ ('%', operator.mod),
+ ('/', operator.truediv),
+ ('*', operator.mul),
+]
+_ASSIGN_OPERATORS = [(op + '=', opfunc) for op, opfunc in _OPERATORS]
+_ASSIGN_OPERATORS.append(('=', lambda cur, right: right))
+
+_NAME_RE = r'[a-zA-Z_$][a-zA-Z_$0-9]*'
+
class JSInterpreter(object):
- def __init__(self, code):
+ def __init__(self, code, objects=None):
+ if objects is None:
+ objects = {}
self.code = code
self._functions = {}
- self._objects = {}
+ self._objects = objects
- def interpret_statement(self, stmt, local_vars, allow_recursion=20):
+ def interpret_statement(self, stmt, local_vars, allow_recursion=100):
if allow_recursion < 0:
raise ExtractorError('Recursion limit reached')
- if stmt.startswith('var '):
- stmt = stmt[len('var '):]
- ass_m = re.match(r'^(?P<out>[a-z]+)(?:\[(?P<index>[^\]]+)\])?' +
- r'=(?P<expr>.*)$', stmt)
- if ass_m:
- if ass_m.groupdict().get('index'):
- def assign(val):
- lvar = local_vars[ass_m.group('out')]
- idx = self.interpret_expression(
- ass_m.group('index'), local_vars, allow_recursion)
- assert isinstance(idx, int)
- lvar[idx] = val
- return val
- expr = ass_m.group('expr')
- else:
- def assign(val):
- local_vars[ass_m.group('out')] = val
- return val
- expr = ass_m.group('expr')
- elif stmt.startswith('return '):
- assign = lambda v: v
- expr = stmt[len('return '):]
+ should_abort = False
+ stmt = stmt.lstrip()
+ stmt_m = re.match(r'var\s', stmt)
+ if stmt_m:
+ expr = stmt[len(stmt_m.group(0)):]
else:
- # Try interpreting it as an expression
- expr = stmt
- assign = lambda v: v
+ return_m = re.match(r'return(?:\s+|$)', stmt)
+ if return_m:
+ expr = stmt[len(return_m.group(0)):]
+ should_abort = True
+ else:
+ # Try interpreting it as an expression
+ expr = stmt
v = self.interpret_expression(expr, local_vars, allow_recursion)
- return assign(v)
+ return v, should_abort
def interpret_expression(self, expr, local_vars, allow_recursion):
+ expr = expr.strip()
+
+ if expr == '': # Empty expression
+ return None
+
+ if expr.startswith('('):
+ parens_count = 0
+ for m in re.finditer(r'[()]', expr):
+ if m.group(0) == '(':
+ parens_count += 1
+ else:
+ parens_count -= 1
+ if parens_count == 0:
+ sub_expr = expr[1:m.start()]
+ sub_result = self.interpret_expression(
+ sub_expr, local_vars, allow_recursion)
+ remaining_expr = expr[m.end():].strip()
+ if not remaining_expr:
+ return sub_result
+ else:
+ expr = json.dumps(sub_result) + remaining_expr
+ break
+ else:
+ raise ExtractorError('Premature end of parens in %r' % expr)
+
+ for op, opfunc in _ASSIGN_OPERATORS:
+ m = re.match(r'''(?x)
+ (?P<out>%s)(?:\[(?P<index>[^\]]+?)\])?
+ \s*%s
+ (?P<expr>.*)$''' % (_NAME_RE, re.escape(op)), expr)
+ if not m:
+ continue
+ right_val = self.interpret_expression(
+ m.group('expr'), local_vars, allow_recursion - 1)
+
+ if m.groupdict().get('index'):
+ lvar = local_vars[m.group('out')]
+ idx = self.interpret_expression(
+ m.group('index'), local_vars, allow_recursion)
+ assert isinstance(idx, int)
+ cur = lvar[idx]
+ val = opfunc(cur, right_val)
+ lvar[idx] = val
+ return val
+ else:
+ cur = local_vars.get(m.group('out'))
+ val = opfunc(cur, right_val)
+ local_vars[m.group('out')] = val
+ return val
+
if expr.isdigit():
return int(expr)
- if expr.isalpha():
- return local_vars[expr]
+ var_m = re.match(
+ r'(?!if|return|true|false)(?P<name>%s)$' % _NAME_RE,
+ expr)
+ if var_m:
+ return local_vars[var_m.group('name')]
try:
return json.loads(expr)
pass
m = re.match(
- r'^(?P<var>[$a-zA-Z0-9_]+)\.(?P<member>[^(]+)(?:\(+(?P<args>[^()]*)\))?$',
+ r'(?P<var>%s)\.(?P<member>[^(]+)(?:\(+(?P<args>[^()]*)\))?$' % _NAME_RE,
expr)
if m:
variable = m.group('var')
return obj[member](argvals)
m = re.match(
- r'^(?P<in>[a-z]+)\[(?P<idx>.+)\]$', expr)
+ r'(?P<in>%s)\[(?P<idx>.+)\]$' % _NAME_RE, expr)
if m:
val = local_vars[m.group('in')]
idx = self.interpret_expression(
m.group('idx'), local_vars, allow_recursion - 1)
return val[idx]
- m = re.match(r'^(?P<a>.+?)(?P<op>[%])(?P<b>.+?)$', expr)
- if m:
- a = self.interpret_expression(
- m.group('a'), local_vars, allow_recursion)
- b = self.interpret_expression(
- m.group('b'), local_vars, allow_recursion)
- return a % b
+ for op, opfunc in _OPERATORS:
+ m = re.match(r'(?P<x>.+?)%s(?P<y>.+)' % re.escape(op), expr)
+ if not m:
+ continue
+ x, abort = self.interpret_statement(
+ m.group('x'), local_vars, allow_recursion - 1)
+ if abort:
+ raise ExtractorError(
+ 'Premature left-side return of %s in %r' % (op, expr))
+ y, abort = self.interpret_statement(
+ m.group('y'), local_vars, allow_recursion - 1)
+ if abort:
+ raise ExtractorError(
+ 'Premature right-side return of %s in %r' % (op, expr))
+ return opfunc(x, y)
m = re.match(
- r'^(?P<func>[a-zA-Z$]+)\((?P<args>[a-z0-9,]+)\)$', expr)
+ r'^(?P<func>%s)\((?P<args>[a-zA-Z0-9_$,]+)\)$' % _NAME_RE, expr)
if m:
fname = m.group('func')
argvals = tuple([
if fname not in self._functions:
self._functions[fname] = self.extract_function(fname)
return self._functions[fname](argvals)
+
raise ExtractorError('Unsupported JS expression %r' % expr)
def extract_object(self, objname):
def extract_function(self, funcname):
func_m = re.search(
- (r'(?:function %s|[{;]%s\s*=\s*function)' % (
- re.escape(funcname), re.escape(funcname))) +
- r'\((?P<args>[a-z,]+)\){(?P<code>[^}]+)}',
+ r'''(?x)
+ (?:function\s+%s|[{;]%s\s*=\s*function)\s*
+ \((?P<args>[^)]*)\)\s*
+ \{(?P<code>[^}]+)\}''' % (
+ re.escape(funcname), re.escape(funcname)),
self.code)
if func_m is None:
raise ExtractorError('Could not find JS function %r' % funcname)
return self.build_function(argnames, func_m.group('code'))
+ def call_function(self, funcname, *args):
+ f = self.extract_function(funcname)
+ return f(args)
+
def build_function(self, argnames, code):
def resf(args):
local_vars = dict(zip(argnames, args))
for stmt in code.split(';'):
- res = self.interpret_statement(stmt, local_vars)
+ res, abort = self.interpret_statement(stmt, local_vars)
+ if abort:
+ break
return res
return resf
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