1 from __future__ import unicode_literals
11 class JSInterpreter(object):
12 def __init__(self, code):
17 def interpret_statement(self, stmt, local_vars, allow_recursion=20):
18 if allow_recursion < 0:
19 raise ExtractorError('Recursion limit reached')
21 if stmt.startswith('var '):
22 stmt = stmt[len('var '):]
23 ass_m = re.match(r'^(?P<out>[a-z]+)(?:\[(?P<index>[^\]]+)\])?' +
24 r'=(?P<expr>.*)$', stmt)
26 if ass_m.groupdict().get('index'):
28 lvar = local_vars[ass_m.group('out')]
29 idx = self.interpret_expression(
30 ass_m.group('index'), local_vars, allow_recursion)
31 assert isinstance(idx, int)
34 expr = ass_m.group('expr')
37 local_vars[ass_m.group('out')] = val
39 expr = ass_m.group('expr')
40 elif stmt.startswith('return '):
42 expr = stmt[len('return '):]
44 # Try interpreting it as an expression
48 v = self.interpret_expression(expr, local_vars, allow_recursion)
51 def interpret_expression(self, expr, local_vars, allow_recursion):
56 return local_vars[expr]
59 return json.loads(expr)
64 r'^(?P<var>[a-z]+)\.(?P<member>[^(]+)(?:\(+(?P<args>[^()]*)\))?$',
67 variable = m.group('var')
68 member = m.group('member')
69 arg_str = m.group('args')
71 if variable in local_vars:
72 obj = local_vars[variable]
74 if variable not in self._objects:
75 self._objects[variable] = self.extract_object(variable)
76 obj = self._objects[variable]
80 if member == 'length':
84 assert expr.endswith(')')
90 self.interpret_expression(v, local_vars, allow_recursion)
91 for v in arg_str.split(',')])
94 assert argvals == ('',)
97 assert len(argvals) == 1
98 return argvals[0].join(obj)
99 if member == 'reverse':
100 assert len(argvals) == 0
102 if member == 'slice':
103 assert len(argvals) == 1
104 return obj[argvals[0]:]
105 if member == 'splice':
106 assert isinstance(obj, list)
107 index, howMany = argvals
109 for i in range(index, min(index + howMany, len(obj))):
110 res.append(obj.pop(i))
113 return obj[member](argvals)
116 r'^(?P<in>[a-z]+)\[(?P<idx>.+)\]$', expr)
118 val = local_vars[m.group('in')]
119 idx = self.interpret_expression(
120 m.group('idx'), local_vars, allow_recursion - 1)
123 m = re.match(r'^(?P<a>.+?)(?P<op>[%])(?P<b>.+?)$', expr)
125 a = self.interpret_expression(
126 m.group('a'), local_vars, allow_recursion)
127 b = self.interpret_expression(
128 m.group('b'), local_vars, allow_recursion)
132 r'^(?P<func>[.a-zA-Z$]+)\((?P<args>[a-z0-9,]+)\)$', expr)
134 fname = m.group('func')
136 int(v) if v.isdigit() else local_vars[v]
137 for v in m.group('args').split(',')])
138 if fname not in self._functions:
139 self._functions[fname] = self.extract_function(fname)
140 return self._functions[fname](argvals)
141 raise ExtractorError('Unsupported JS expression %r' % expr)
143 def extract_object(self, objname):
146 (r'(?:var\s+)?%s\s*=\s*\{' % re.escape(objname)) +
147 r'\s*(?P<fields>([a-zA-Z$0-9]+\s*:\s*function\(.*?\)\s*\{.*?\})*)' +
150 fields = obj_m.group('fields')
151 # Currently, it only supports function definitions
152 fields_m = re.finditer(
153 r'(?P<key>[a-zA-Z$0-9]+)\s*:\s*function'
154 r'\((?P<args>[a-z,]+)\){(?P<code>[^}]+)}',
157 argnames = f.group('args').split(',')
158 obj[f.group('key')] = self.build_function(argnames, f.group('code'))
162 def extract_function(self, funcname):
164 (r'(?:function %s|[{;]%s\s*=\s*function)' % (
165 re.escape(funcname), re.escape(funcname))) +
166 r'\((?P<args>[a-z,]+)\){(?P<code>[^}]+)}',
169 raise ExtractorError('Could not find JS function %r' % funcname)
170 argnames = func_m.group('args').split(',')
172 return self.build_function(argnames, func_m.group('code'))
174 def build_function(self, argnames, code):
176 local_vars = dict(zip(argnames, args))
177 for stmt in code.split(';'):
178 res = self.interpret_statement(stmt, local_vars)