From 230d5c8239d6b6e211f413de26979398c1cabb04 Mon Sep 17 00:00:00 2001 From: pukkandan Date: Tue, 21 Jun 2022 21:46:35 +0530 Subject: [PATCH] [jsinterp] Some optimizations and refactoring Motivated by: https://github.com/ytdl-org/youtube-dl/issues/30641#issuecomment-1041904912 Authored by: dirkf, pukkandan --- yt_dlp/jsinterp.py | 207 +++++++++++++++++++++------------------------ 1 file changed, 98 insertions(+), 109 deletions(-) diff --git a/yt_dlp/jsinterp.py b/yt_dlp/jsinterp.py index 56229cd99..c95a0ff57 100644 --- a/yt_dlp/jsinterp.py +++ b/yt_dlp/jsinterp.py @@ -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$]*' +_OPERATORS = { + '|': operator.or_, + '^': operator.xor, + '&': operator.and_, + '>>': operator.rshift, + '<<': operator.lshift, + '-': operator.sub, + '+': operator.add, + '%': operator.mod, + '/': operator.truediv, + '*': operator.mul, +} _MATCHING_PARENS = dict(zip('({[', ')}]')) _QUOTES = '\'"' @@ -50,13 +47,11 @@ class LocalNameSpace(collections.ChainMap): class JSInterpreter: + __named_object_counter = 0 + def __init__(self, code, objects=None): - if objects is None: - objects = {} - self.code = code - self._functions = {} - self._objects = objects - self.__named_object_counter = 0 + self.code, self._functions = code, {} + self._objects = {} if objects is None else objects def _named_object(self, namespace, obj): self.__named_object_counter += 1 @@ -93,9 +88,9 @@ class JSInterpreter: break yield expr[start:] - @staticmethod - def _separate_at_paren(expr, delim): - separated = list(JSInterpreter._separate(expr, delim, 1)) + @classmethod + def _separate_at_paren(cls, expr, delim): + separated = list(cls._separate(expr, delim, 1)) if len(separated) < 2: raise ExtractorError(f'No terminating paren {delim} in {expr}') return separated[0][1:].strip(), separated[1].strip() @@ -104,33 +99,29 @@ class JSInterpreter: if allow_recursion < 0: raise ExtractorError('Recursion limit reached') - sub_statements = list(self._separate(stmt, ';')) - stmt = (sub_statements or ['']).pop() + should_abort = False + sub_statements = list(self._separate(stmt, ';')) or [''] + stmt = sub_statements.pop().lstrip() + for sub_stmt in sub_statements: ret, should_abort = self.interpret_statement(sub_stmt, local_vars, allow_recursion - 1) if should_abort: - return ret + return ret, should_abort - should_abort = False - stmt = stmt.lstrip() - stmt_m = re.match(r'var\s', stmt) - if stmt_m: - expr = stmt[len(stmt_m.group(0)):] + m = re.match(r'(?Pvar\s)|return(?:\s+|$)', 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'(?Ptry)\s*|(?:(?Pcatch)|(?Pfor)|(?Pswitch))\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{_NAME_RE})(?:\[(?P[^\]]+?)\])? - \s*{re.escape(op)} - (?P.*)$''', 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 + (?P{_NAME_RE})(?:\[(?P[^\]]+?)\])?\s* + (?P{"|".join(map(re.escape, _OPERATORS))})? + =(?P.*)$ + )|(?P + (?!if|return|true|false|null)(?P{_NAME_RE})$ + )|(?P + (?P{_NAME_RE})\[(?P.+)\]$ + )|(?P + (?P{_NAME_RE})(?:\.(?P[^(]+)|\[(?P[^\]]+)\])\s* + )|(?P + (?P{_NAME_RE})\((?P[\w$,]*)\)$ + )''', 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%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%s)\[(?P.+)\]$' % _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%s)(?:\.(?P[^(]+)|\[(?P[^]]+)\])\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%s)\((?P[a-zA-Z0-9_$,]*)\)$' % _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* \((?P[^)]*)\)\s* - (?P\{(?:(?!};)[^"]|"([^"]|\\")*")+\})''' % ( - re.escape(funcname), re.escape(funcname), re.escape(funcname)), + (?P{(?:(?!};)[^"]|"([^"]|\\")*")+})''' % {'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)