[jsinterp] Some optimizations and refactoring

Motivated by: https://github.com/ytdl-org/youtube-dl/issues/30641#issuecomment-1041904912

Authored by: dirkf, pukkandan
This commit is contained in:
pukkandan 2022-06-21 21:46:35 +05:30
parent e4afcfde08
commit 230d5c8239
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@ -6,22 +6,19 @@ import re
from .utils import ExtractorError, remove_quotes
_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_$0-9]*'
_NAME_RE = r'[a-zA-Z_$][\w$]*'
_OPERATORS = {
'|': operator.or_,
'^': operator.xor,
'&': operator.and_,
'>>': operator.rshift,
'<<': operator.lshift,
'-': operator.sub,
'+': operator.add,
'%': operator.mod,
'/': operator.truediv,
'*': operator.mul,
}
_MATCHING_PARENS = dict(zip('({[', ')}]'))
_QUOTES = '\'"'
@ -50,13 +47,11 @@ class LocalNameSpace(collections.ChainMap):
class JSInterpreter:
__named_object_counter = 0
def __init__(self, code, objects=None):
if objects is None:
objects = {}
self.code = code
self._functions = {}
self._objects = objects
self.__named_object_counter = 0
self.code, self._functions = code, {}
self._objects = {} if objects is None else objects
def _named_object(self, namespace, obj):
self.__named_object_counter += 1
@ -93,9 +88,9 @@ class JSInterpreter:
break
yield expr[start:]
@staticmethod
def _separate_at_paren(expr, delim):
separated = list(JSInterpreter._separate(expr, delim, 1))
@classmethod
def _separate_at_paren(cls, expr, delim):
separated = list(cls._separate(expr, delim, 1))
if len(separated) < 2:
raise ExtractorError(f'No terminating paren {delim} in {expr}')
return separated[0][1:].strip(), separated[1].strip()
@ -104,33 +99,29 @@ class JSInterpreter:
if allow_recursion < 0:
raise ExtractorError('Recursion limit reached')
sub_statements = list(self._separate(stmt, ';'))
stmt = (sub_statements or ['']).pop()
should_abort = False
sub_statements = list(self._separate(stmt, ';')) or ['']
stmt = sub_statements.pop().lstrip()
for sub_stmt in sub_statements:
ret, should_abort = self.interpret_statement(sub_stmt, local_vars, allow_recursion - 1)
if should_abort:
return ret
return ret, should_abort
should_abort = False
stmt = stmt.lstrip()
stmt_m = re.match(r'var\s', stmt)
if stmt_m:
expr = stmt[len(stmt_m.group(0)):]
m = re.match(r'(?P<var>var\s)|return(?:\s+|$)', stmt)
if not m: # Try interpreting it as an expression
expr = stmt
elif m.group('var'):
expr = stmt[len(m.group(0)):]
else:
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
expr = stmt[len(m.group(0)):]
should_abort = True
v = self.interpret_expression(expr, local_vars, allow_recursion)
return v, should_abort
return self.interpret_expression(expr, local_vars, allow_recursion), should_abort
def interpret_expression(self, expr, local_vars, allow_recursion):
expr = expr.strip()
if expr == '': # Empty expression
if not expr:
return None
if expr.startswith('{'):
@ -156,8 +147,8 @@ class JSInterpreter:
for item in self._separate(inner)])
expr = name + outer
m = re.match(r'try\s*', expr)
if m:
m = re.match(r'(?P<try>try)\s*|(?:(?P<catch>catch)|(?P<for>for)|(?P<switch>switch))\s*\(', expr)
if m and m.group('try'):
if expr[m.end()] == '{':
try_expr, expr = self._separate_at_paren(expr[m.end():], '}')
else:
@ -167,21 +158,19 @@ class JSInterpreter:
return ret
return self.interpret_statement(expr, local_vars, allow_recursion - 1)[0]
m = re.match(r'catch\s*\(', expr)
if m:
elif m and m.group('catch'):
# We ignore the catch block
_, expr = self._separate_at_paren(expr, '}')
return self.interpret_statement(expr, local_vars, allow_recursion - 1)[0]
m = re.match(r'for\s*\(', expr)
if m:
elif m and m.group('for'):
constructor, remaining = self._separate_at_paren(expr[m.end() - 1:], ')')
if remaining.startswith('{'):
body, expr = self._separate_at_paren(remaining, '}')
else:
m = re.match(r'switch\s*\(', remaining) # FIXME
if m:
switch_val, remaining = self._separate_at_paren(remaining[m.end() - 1:], ')')
switch_m = re.match(r'switch\s*\(', remaining) # FIXME
if switch_m:
switch_val, remaining = self._separate_at_paren(remaining[switch_m.end() - 1:], ')')
body, expr = self._separate_at_paren(remaining, '}')
body = 'switch(%s){%s}' % (switch_val, body)
else:
@ -206,8 +195,7 @@ class JSInterpreter:
f'Premature return in the initialization of a for loop in {constructor!r}')
return self.interpret_statement(expr, local_vars, allow_recursion - 1)[0]
m = re.match(r'switch\s*\(', expr)
if m:
elif m and m.group('switch'):
switch_val, remaining = self._separate_at_paren(expr[m.end() - 1:], ')')
switch_val = self.interpret_expression(switch_val, local_vars, allow_recursion)
body, expr = self._separate_at_paren(remaining, '}')
@ -250,55 +238,63 @@ class JSInterpreter:
ret = local_vars[var]
expr = expr[:start] + json.dumps(ret) + expr[end:]
for op, opfunc in _ASSIGN_OPERATORS:
m = re.match(rf'''(?x)
(?P<out>{_NAME_RE})(?:\[(?P<index>[^\]]+?)\])?
\s*{re.escape(op)}
(?P<expr>.*)$''', expr)
if not m:
continue
right_val = self.interpret_expression(m.group('expr'), local_vars, allow_recursion)
if not expr:
return None
if m.groupdict().get('index'):
lvar = local_vars[m.group('out')]
idx = self.interpret_expression(m.group('index'), local_vars, allow_recursion)
if not isinstance(idx, int):
raise ExtractorError(f'List indices must be integers: {idx}')
cur = lvar[idx]
val = opfunc(cur, right_val)
lvar[idx] = val
return val
m = re.match(fr'''(?x)
(?P<assign>
(?P<out>{_NAME_RE})(?:\[(?P<index>[^\]]+?)\])?\s*
(?P<op>{"|".join(map(re.escape, _OPERATORS))})?
=(?P<expr>.*)$
)|(?P<return>
(?!if|return|true|false|null)(?P<name>{_NAME_RE})$
)|(?P<indexing>
(?P<in>{_NAME_RE})\[(?P<idx>.+)\]$
)|(?P<attribute>
(?P<var>{_NAME_RE})(?:\.(?P<member>[^(]+)|\[(?P<member2>[^\]]+)\])\s*
)|(?P<function>
(?P<fname>{_NAME_RE})\((?P<args>[\w$,]*)\)$
)''', expr)
if m and m.group('assign'):
if not m.group('op'):
opfunc = lambda curr, right: right
else:
cur = local_vars.get(m.group('out'))
val = opfunc(cur, right_val)
local_vars[m.group('out')] = val
return val
opfunc = _OPERATORS[m.group('op')]
right_val = self.interpret_expression(m.group('expr'), local_vars, allow_recursion)
left_val = local_vars.get(m.group('out'))
if expr.isdigit():
if not m.group('index'):
local_vars[m.group('out')] = opfunc(left_val, right_val)
return local_vars[m.group('out')]
elif left_val is None:
raise ExtractorError(f'Cannot index undefined variable: {m.group("out")}')
idx = self.interpret_expression(m.group('index'), local_vars, allow_recursion)
if not isinstance(idx, int):
raise ExtractorError(f'List indices must be integers: {idx}')
left_val[idx] = opfunc(left_val[idx], right_val)
return left_val[idx]
elif expr.isdigit():
return int(expr)
if expr == 'break':
elif expr == 'break':
raise JS_Break()
elif expr == 'continue':
raise JS_Continue()
var_m = re.match(
r'(?!if|return|true|false|null)(?P<name>%s)$' % _NAME_RE,
expr)
if var_m:
return local_vars[var_m.group('name')]
elif m and m.group('return'):
return local_vars[m.group('name')]
with contextlib.suppress(ValueError):
return json.loads(expr)
m = re.match(
r'(?P<in>%s)\[(?P<idx>.+)\]$' % _NAME_RE, expr)
if m:
if m and m.group('indexing'):
val = local_vars[m.group('in')]
idx = self.interpret_expression(m.group('idx'), local_vars, allow_recursion)
return val[idx]
for op, opfunc in _OPERATORS:
for op, opfunc in _OPERATORS.items():
separated = list(self._separate(expr, op))
if len(separated) < 2:
continue
@ -314,10 +310,7 @@ class JSInterpreter:
raise ExtractorError(f'Premature right-side return of {op} in {expr!r}')
return opfunc(left_val or 0, right_val)
m = re.match(
r'(?P<var>%s)(?:\.(?P<member>[^(]+)|\[(?P<member2>[^]]+)\])\s*' % _NAME_RE,
expr)
if m:
if m and m.group('attribute'):
variable = m.group('var')
member = remove_quotes(m.group('member') or m.group('member2'))
arg_str = expr[m.end():]
@ -332,7 +325,6 @@ class JSInterpreter:
raise ExtractorError(f'{member} {msg}: {expr}')
def eval_method():
nonlocal member
if variable == 'String':
obj = str
elif variable in local_vars:
@ -342,8 +334,8 @@ class JSInterpreter:
self._objects[variable] = self.extract_object(variable)
obj = self._objects[variable]
# Member access
if arg_str is None:
# Member access
if member == 'length':
return len(obj)
return obj[member]
@ -418,9 +410,7 @@ class JSInterpreter:
except ValueError:
return -1
if isinstance(obj, list):
member = int(member)
return obj[member](argvals)
return obj[int(member) if isinstance(obj, list) else member](argvals)
if remaining:
return self.interpret_expression(
@ -429,9 +419,8 @@ class JSInterpreter:
else:
return eval_method()
m = re.match(r'^(?P<func>%s)\((?P<args>[a-zA-Z0-9_$,]*)\)$' % _NAME_RE, expr)
if m:
fname = m.group('func')
elif m and m.group('function'):
fname = m.group('fname')
argvals = tuple(
int(v) if v.isdigit() else local_vars[v]
for v in self._separate(m.group('args')))
@ -441,8 +430,7 @@ class JSInterpreter:
self._functions[fname] = self.extract_function(fname)
return self._functions[fname](argvals)
if expr:
raise ExtractorError('Unsupported JS expression %r' % expr)
raise ExtractorError(f'Unsupported JS expression {expr!r}')
def extract_object(self, objname):
_FUNC_NAME_RE = r'''(?:[a-zA-Z$0-9]+|"[a-zA-Z$0-9]+"|'[a-zA-Z$0-9]+')'''
@ -471,14 +459,17 @@ class JSInterpreter:
""" @returns argnames, code """
func_m = re.search(
r'''(?x)
(?:function\s+%s|[{;,]\s*%s\s*=\s*function|var\s+%s\s*=\s*function)\s*
(?:
function\s+%(name)s|
[{;,]\s*%(name)s\s*=\s*function|
var\s+%(name)s\s*=\s*function
)\s*
\((?P<args>[^)]*)\)\s*
(?P<code>\{(?:(?!};)[^"]|"([^"]|\\")*")+\})''' % (
re.escape(funcname), re.escape(funcname), re.escape(funcname)),
(?P<code>{(?:(?!};)[^"]|"([^"]|\\")*")+})''' % {'name': re.escape(funcname)},
self.code)
code, _ = self._separate_at_paren(func_m.group('code'), '}') # refine the match
if func_m is None:
raise ExtractorError('Could not find JS function %r' % funcname)
raise ExtractorError(f'Could not find JS function "{funcname}"')
return func_m.group('args').split(','), code
def extract_function(self, funcname):
@ -492,11 +483,9 @@ class JSInterpreter:
break
start, body_start = mobj.span()
body, remaining = self._separate_at_paren(code[body_start - 1:], '}')
name = self._named_object(
local_vars,
self.extract_function_from_code(
[str.strip(x) for x in mobj.group('args').split(',')],
body, local_vars, *global_stack))
name = self._named_object(local_vars, self.extract_function_from_code(
[x.strip() for x in mobj.group('args').split(',')],
body, local_vars, *global_stack))
code = code[:start] + name + remaining
return self.build_function(argnames, code, local_vars, *global_stack)