"""Parse tree transformation module.  Transforms Python source code into an abstract syntax tree (AST) defined in the ast module.  The simplest ways to invoke this module are via parse and parseFile. parse(buf) -> AST parseFile(path) -> AST """  # Original version written by Greg Stein (gstein@lyra.org) #                         and Bill Tutt (rassilon@lima.mudlib.org) # February 1997. # # Modifications and improvements for Python 2.0 by Jeremy Hylton and # Mark Hammond # # Some fixes to try to have correct line number on almost all nodes # (except Module, Discard and Stmt) added by Sylvain Thenault # # Portions of this file are: # Copyright (C) 1997-1998 Greg Stein. All Rights Reserved. # # This module is provided under a BSD-ish license. See #   http://www.opensource.org/licenses/bsd-license.html # and replace OWNER, ORGANIZATION, and YEAR as appropriate.  from compiler.ast import * from pyparser.pygram import syms as symbol, sym_name, tokens as token, tok_name import pyparser.pyparse as parser  class WalkerError(StandardError):     pass  from compiler.consts import CO_VARARGS, CO_VARKEYWORDS from compiler.consts import OP_ASSIGN, OP_DELETE, OP_APPLY  def parseFile(path):     f = open(path, "U")     # XXX The parser API tolerates files without a trailing newline,     # but not strings without a trailing newline.  Always add an extra     # newline to the file contents, since we're going through the string     # version of the API.     src = f.read() + "\n"     f.close()     return parse(src)  def parse(buf, mode="exec"):     if mode == "exec" or mode == "single":         return Transformer().parsesuite(buf)     elif mode == "eval":         return Transformer().parseexpr(buf)     else:         raise ValueError("compile() arg 3 must be"                          " 'exec' or 'eval' or 'single'")  def extractLineNo(ast):     if not isinstance(ast[1], tuple):         # get a terminal node         return ast[2]     for child in ast[1:]:         if isinstance(child, tuple):             lineno = extractLineNo(child)             if lineno is not None:                 return lineno  def Node(*args):     kind = args[0]     if kind in nodes:         try:             return nodes[kind](*args[1:])         except TypeError:             print nodes[kind], len(args), args             raise     else:         raise WalkerError, "Can't find appropriate Node type: %s" % str(args)         #return apply(ast.Node, args)  class Transformer:     """Utility object for transforming Python parse trees.      Exposes the following methods:         tree = transform(ast_tree)         tree = parsesuite(text)         tree = parseexpr(text)         tree = parsefile(fileob | filename)     """      def __init__(self):         self._dispatch = {}         for value, name in sym_name.items():             if hasattr(self, name):                 self._dispatch[value] = getattr(self, name)         self._dispatch[token["NEWLINE"]] = self.com_NEWLINE         self._atom_dispatch = {token["LPAR"]: self.atom_lpar,                                token["LSQB"]: self.atom_lsqb,                                token["LBRACE"]: self.atom_lbrace,                                token["BACKQUOTE"]: self.atom_backquote,                                token["NUMBER"]: self.atom_number,                                token["STRING"]: self.atom_string,                                token["NAME"]: self.atom_name,                                }         self.encoding = None      def transform(self, tree):         """Transform an AST into a modified parse tree."""         if not (isinstance(tree, tuple) or isinstance(tree, list)):             tree = parser.st2tuple(tree, line_info=1)         return self.compile_node(tree)      def parsesuite(self, text):         """Return a modified parse tree for the given suite text."""         return self.transform(parser.suite(text))      def parseexpr(self, text):         """Return a modified parse tree for the given expression text."""         return self.transform(parser.expr(text))      def parsefile(self, file):         """Return a modified parse tree for the contents of the given file."""         if type(file) == type(''):             file = open(file)         return self.parsesuite(file.read())      # --------------------------------------------------------------     #     # PRIVATE METHODS     #      def compile_node(self, node):         ### emit a line-number node?         n = node[0]          if n == symbol["encoding_decl"]:             self.encoding = node[2]             node = node[1]             n = node[0]          if n == symbol["single_input"]:             return self.single_input(node[1:])         if n == symbol["file_input"]:             return self.file_input(node[1:])         if n == symbol["eval_input"]:             return self.eval_input(node[1:])         if n == symbol["lambdef"]:             return self.lambdef(node[1:])         if n == symbol["funcdef"]:             return self.funcdef(node[1:])         if n == symbol["classdef"]:             return self.classdef(node[1:])          raise WalkerError, ('unexpected node type', n)      def single_input(self, node):         ### do we want to do anything about being "interactive" ?          # NEWLINE | simple_stmt | compound_stmt NEWLINE         n = node[0][0]         if n != token["NEWLINE"]:             return self.com_stmt(node[0])          return Pass()      def file_input(self, nodelist):         doc = self.get_docstring(nodelist, symbol["file_input"])         if doc is not None:             i = 1         else:             i = 0         stmts = []         for node in nodelist[i:]:             if node[0] != token["ENDMARKER"] and node[0] != token["NEWLINE"]:                 self.com_append_stmt(stmts, node)         return Module(doc, Stmt(stmts))      def eval_input(self, nodelist):         # from the built-in function input()         ### is this sufficient?         return Expression(self.com_node(nodelist[0]))      def funcdef(self, nodelist):         #          -5    -4   -3         -2  -1         # funcdef: 'def' NAME parameters ':' suite         # parameters: '(' [varargslist] ')'          assert len(nodelist) == 5         decorators = None          lineno = nodelist[-4][2]         name = nodelist[-4][1]         args = nodelist[-3][2]          if args[0] == symbol["varargslist"]:             names, defaults, flags = self.com_arglist(args[1:])         else:             names = defaults = ()             flags = 0         doc = self.get_docstring(nodelist[-1])          # code for function         code = self.com_node(nodelist[-1])          if doc is not None:             assert isinstance(code, Stmt)             assert isinstance(code.nodes[0], Discard)             del code.nodes[0]         return Function(decorators, name, names, defaults, flags, doc, code,                      lineno=lineno)      def lambdef(self, nodelist):         # lambdef: 'lambda' [varargslist] ':' test         if nodelist[2][0] == symbol["varargslist"]:             names, defaults, flags = self.com_arglist(nodelist[2][1:])         else:             names = defaults = ()             flags = 0          # code for lambda         code = self.com_node(nodelist[-1])          return Lambda(names, defaults, flags, code, lineno=nodelist[1][2])     old_lambdef = lambdef      def classdef(self, nodelist):         # classdef: 'class' NAME ['(' [testlist] ')'] ':' suite          name = nodelist[1][1]         doc = self.get_docstring(nodelist[-1])         if nodelist[2][0] == token["COLON"]:             bases = []         elif nodelist[3][0] == token["RPAR"]:             bases = []         else:             bases = self.com_bases(nodelist[3])          # code for class         code = self.com_node(nodelist[-1])          if doc is not None:             assert isinstance(code, Stmt)             assert isinstance(code.nodes[0], Discard)             del code.nodes[0]          return Class(name, bases, doc, code, lineno=nodelist[1][2])      def stmt(self, nodelist):         return self.com_stmt(nodelist[0])      small_stmt = stmt     flow_stmt = stmt     compound_stmt = stmt      def simple_stmt(self, nodelist):         # small_stmt (';' small_stmt)* [';'] NEWLINE         stmts = []         for i in range(0, len(nodelist), 2):             self.com_append_stmt(stmts, nodelist[i])         return Stmt(stmts)      def parameters(self, nodelist):         raise WalkerError      def varargslist(self, nodelist):         raise WalkerError      def fpdef(self, nodelist):         raise WalkerError      def fplist(self, nodelist):         raise WalkerError      def dotted_name(self, nodelist):         raise WalkerError      def comp_op(self, nodelist):         raise WalkerError      def trailer(self, nodelist):         raise WalkerError      def sliceop(self, nodelist):         raise WalkerError      def argument(self, nodelist):         raise WalkerError      # --------------------------------------------------------------     #     # STATEMENT NODES  (invoked by com_node())     #      def expr_stmt(self, nodelist):         # augassign testlist | testlist ('=' testlist)*         en = nodelist[-1]         exprNode = self.lookup_node(en)(en[1:])         if len(nodelist) == 1:             return Discard(exprNode, lineno=exprNode.lineno)         if nodelist[1][0] == token["EQUAL"]:             nodesl = []             for i in range(0, len(nodelist) - 2, 2):                 nodesl.append(self.com_assign(nodelist[i], OP_ASSIGN))             return Assign(nodesl, exprNode, lineno=nodelist[1][2])         else:             lval = self.com_augassign(nodelist[0])             op = self.com_augassign_op(nodelist[1])             return AugAssign(lval, op[1], exprNode, lineno=op[2])         raise WalkerError, "can't get here"      def print_stmt(self, nodelist):         # print ([ test (',' test)* [','] ] | '>>' test [ (',' test)+ [','] ])         items = []         if len(nodelist) == 1:             start = 1             dest = None         elif nodelist[1][0] == token["RIGHTSHIFT"]:             assert len(nodelist) == 3 \                    or nodelist[3][0] == token["COMMA"]             dest = self.com_node(nodelist[2])             start = 4         else:             dest = None             start = 1         for i in range(start, len(nodelist), 2):             items.append(self.com_node(nodelist[i]))         if nodelist[-1][0] == token["COMMA"]:             return Print(items, dest, lineno=nodelist[0][2])         return Printnl(items, dest, lineno=nodelist[0][2])      def del_stmt(self, nodelist):         return self.com_assign(nodelist[1], OP_DELETE)      def pass_stmt(self, nodelist):         return Pass(lineno=nodelist[0][2])      def break_stmt(self, nodelist):         return Break(lineno=nodelist[0][2])      def continue_stmt(self, nodelist):         return Continue(lineno=nodelist[0][2])      def return_stmt(self, nodelist):         # return: [testlist]         if len(nodelist) < 2:             return Return(Const(None), lineno=nodelist[0][2])         return Return(self.com_node(nodelist[1]), lineno=nodelist[0][2])      def raise_stmt(self, nodelist):         # raise: [test [',' test [',' test]]]         if len(nodelist) > 5:             expr3 = self.com_node(nodelist[5])         else:             expr3 = None         if len(nodelist) > 3:             expr2 = self.com_node(nodelist[3])         else:             expr2 = None         if len(nodelist) > 1:             expr1 = self.com_node(nodelist[1])         else:             expr1 = None         return Raise(expr1, expr2, expr3, lineno=nodelist[0][2])      def import_stmt(self, nodelist):         # import_stmt: import_name | import_from         assert len(nodelist) == 1         return self.com_node(nodelist[0])      def import_name(self, nodelist):         # import_name: 'import' dotted_as_names         return Import(self.com_dotted_as_names(nodelist[1]),                       lineno=nodelist[0][2])      def import_from(self, nodelist):         # import_from: 'from' ('.'* dotted_name | '.') 'import' ('*' |         #    '(' import_as_names ')' | import_as_names)         assert nodelist[0][1] == 'from'         idx = 1         while nodelist[idx][1] == '.':             idx += 1         level = idx - 1         if nodelist[idx][0] == symbol["dotted_name"]:             fromname = self.com_dotted_name(nodelist[idx])             idx += 1         else:             fromname = ""         assert nodelist[idx][1] == 'import'         if nodelist[idx + 1][0] == token["STAR"]:             return From(fromname, [('*', None)], level,                         lineno=nodelist[0][2])         else:             node = nodelist[idx + 1 + (nodelist[idx + 1][0] == token["LPAR"])]             return From(fromname, self.com_import_as_names(node), level,                         lineno=nodelist[0][2])      def global_stmt(self, nodelist):         # global: NAME (',' NAME)*         names = []         for i in range(1, len(nodelist), 2):             names.append(nodelist[i][1])         return Global(names, lineno=nodelist[0][2])      def exec_stmt(self, nodelist):         # exec_stmt: 'exec' expr ['in' expr [',' expr]]         expr1 = self.com_node(nodelist[1])         if len(nodelist) >= 4:             expr2 = self.com_node(nodelist[3])             if len(nodelist) >= 6:                 expr3 = self.com_node(nodelist[5])             else:                 expr3 = None         else:             expr2 = expr3 = None          return Exec(expr1, expr2, expr3, lineno=nodelist[0][2])      def assert_stmt(self, nodelist):         # 'assert': test, [',' test]         expr1 = self.com_node(nodelist[1])         if (len(nodelist) == 4):             expr2 = self.com_node(nodelist[3])         else:             expr2 = None         return Assert(expr1, expr2, lineno=nodelist[0][2])      def if_stmt(self, nodelist):         # if: test ':' suite ('elif' test ':' suite)* ['else' ':' suite]         tests = []         for i in range(0, len(nodelist) - 3, 4):             testNode = self.com_node(nodelist[i + 1])             suiteNode = self.com_node(nodelist[i + 3])             tests.append((testNode, suiteNode))          if len(nodelist) % 4 == 3:             elseNode = self.com_node(nodelist[-1]) ##      elseNode.lineno = nodelist[-1][1][2]         else:             elseNode = None         return If(tests, elseNode, lineno=nodelist[0][2])      def while_stmt(self, nodelist):         # 'while' test ':' suite ['else' ':' suite]          testNode = self.com_node(nodelist[1])         bodyNode = self.com_node(nodelist[3])          if len(nodelist) > 4:             elseNode = self.com_node(nodelist[6])         else:             elseNode = None          return While(testNode, bodyNode, elseNode, lineno=nodelist[0][2])      def for_stmt(self, nodelist):         # 'for' exprlist 'in' exprlist ':' suite ['else' ':' suite]          assignNode = self.com_assign(nodelist[1], OP_ASSIGN)         listNode = self.com_node(nodelist[3])         bodyNode = self.com_node(nodelist[5])          if len(nodelist) > 8:             elseNode = self.com_node(nodelist[8])         else:             elseNode = None          return For(assignNode, listNode, bodyNode, elseNode,                    lineno=nodelist[0][2])      def try_stmt(self, nodelist):         return self.com_try_except_finally(nodelist)      def with_stmt(self, nodelist):         return self.com_with(nodelist)      def suite(self, nodelist):         # simple_stmt | NEWLINE INDENT NEWLINE* (stmt NEWLINE*)+ DEDENT         if len(nodelist) == 1:             return self.com_stmt(nodelist[0])          stmts = []         for node in nodelist:             if node[0] == symbol["stmt"]:                 self.com_append_stmt(stmts, node)         return Stmt(stmts)      # --------------------------------------------------------------     #     # EXPRESSION NODES  (invoked by com_node())     #      def testlist(self, nodelist):         # testlist: expr (',' expr)* [',']         # testlist_safe: test [(',' test)+ [',']]         # exprlist: expr (',' expr)* [',']         return self.com_binary(Tuple, nodelist)      testlist_safe = testlist # XXX     testlist1 = testlist     exprlist = testlist      def testlist_comp(self, nodelist):         # test ( (',' test)* [','] )         assert nodelist[0][0] == symbol["test"]         return self.testlist(nodelist)      def test(self, nodelist):         # or_test | lambdef         if len(nodelist) == 1 and nodelist[0][0] == symbol["lambdef"]:             return self.lambdef(nodelist[0])         then = self.com_node(nodelist[0])         return then      def or_test(self, nodelist):         # and_test ('or' and_test)* | lambdef         if len(nodelist) == 1 and nodelist[0][0] == symbol["lambdef"]:             return self.lambdef(nodelist[0])         return self.com_binary(Or, nodelist)     old_test = or_test      def and_test(self, nodelist):         # not_test ('and' not_test)*         return self.com_binary(And, nodelist)      def not_test(self, nodelist):         # 'not' not_test | comparison         result = self.com_node(nodelist[-1])         if len(nodelist) == 2:             return Not(result, lineno=nodelist[0][2])         return result      def comparison(self, nodelist):         # comparison: expr (comp_op expr)*         node = self.com_node(nodelist[0])         if len(nodelist) == 1:             return node          results = []         for i in range(2, len(nodelist), 2):             nl = nodelist[i-1]              # comp_op: '<' | '>' | '=' | '>=' | '<=' | '<>' | '!=' | '=='             #          | 'in' | 'not' 'in' | 'is' | 'is' 'not'             n = nl[1]             if n[0] == token["NAME"]:                 type = n[1]                 if len(nl) == 3:                     if type == 'not':                         type = 'not in'                     else:                         type = 'is not'             else:                 type = _cmp_types[n[0]]              lineno = nl[1][2]             results.append((type, self.com_node(nodelist[i])))          # we need a special "compare" node so that we can distinguish         #   3 < x < 5   from    (3 < x) < 5         # the two have very different semantics and results (note that the         # latter form is always true)          return Compare(node, results, lineno=lineno)      def expr(self, nodelist):         # xor_expr ('|' xor_expr)*         return self.com_binary(Bitor, nodelist)      def xor_expr(self, nodelist):         # xor_expr ('^' xor_expr)*         return self.com_binary(Bitxor, nodelist)      def and_expr(self, nodelist):         # xor_expr ('&' xor_expr)*         return self.com_binary(Bitand, nodelist)      def shift_expr(self, nodelist):         # shift_expr ('<<'|'>>' shift_expr)*         node = self.com_node(nodelist[0])         for i in range(2, len(nodelist), 2):             right = self.com_node(nodelist[i])             if nodelist[i-1][0] == token["LEFTSHIFT"]:                 node = LeftShift([node, right], lineno=nodelist[1][2])             elif nodelist[i-1][0] == token["RIGHTSHIFT"]:                 node = RightShift([node, right], lineno=nodelist[1][2])             else:                 raise ValueError, "unexpected token: %s" % nodelist[i-1][0]         return node      def arith_expr(self, nodelist):         node = self.com_node(nodelist[0])         for i in range(2, len(nodelist), 2):             right = self.com_node(nodelist[i])             if nodelist[i-1][0] == token["PLUS"]:                 node = Add([node, right], lineno=nodelist[1][2])             elif nodelist[i-1][0] == token["MINUS"]:                 node = Sub([node, right], lineno=nodelist[1][2])             else:                 raise ValueError, "unexpected token: %s" % nodelist[i-1][0]         return node      def term(self, nodelist):         node = self.com_node(nodelist[0])         for i in range(2, len(nodelist), 2):             right = self.com_node(nodelist[i])             t = nodelist[i-1][0]             if t == token["STAR"]:                 node = Mul([node, right])             elif t == token["SLASH"]:                 node = Div([node, right])             elif t == token["PERCENT"]:                 node = Mod([node, right])             elif t == token["DOUBLESLASH"]:                 node = FloorDiv([node, right])             else:                 raise ValueError, "unexpected token: %s" % t             node.lineno = nodelist[1][2]         return node      def factor(self, nodelist):         elt = nodelist[0]         t = elt[0]         node = self.lookup_node(nodelist[-1])(nodelist[-1][1:])         # need to handle (unary op)constant here...         if t == token["PLUS"]:             return UnaryAdd(node, lineno=elt[2])         elif t == token["MINUS"]:             return UnarySub(node, lineno=elt[2])         elif t == token["TILDE"]:             node = Invert(node, lineno=elt[2])         return node      def power(self, nodelist):         # power: atom trailer* ('**' factor)*         node = self.com_node(nodelist[0])         for i in range(1, len(nodelist)):             elt = nodelist[i]             if elt[0] == token["DOUBLESTAR"]:                 return Power([node, self.com_node(nodelist[i+1])],                              lineno=elt[2])              node = self.com_apply_trailer(node, elt)          return node      def atom(self, nodelist):         return self._atom_dispatch[nodelist[0][0]](nodelist)      def atom_lpar(self, nodelist):         if nodelist[1][0] == token["RPAR"]:             return Tuple((), lineno=nodelist[0][2])         return self.com_node(nodelist[1])      def atom_lsqb(self, nodelist):         if nodelist[1][0] == token["RSQB"]:             return List((), lineno=nodelist[0][2])         return self.com_list_constructor(nodelist[1])      def atom_lbrace(self, nodelist):         if nodelist[1][0] == token["RBRACE"]:             return Dict((), lineno=nodelist[0][2])         return self.com_dictorsetmaker(nodelist[1])      def atom_backquote(self, nodelist):         return Backquote(self.com_node(nodelist[1]))      def atom_number(self, nodelist):         ### need to verify this matches compile.c         k = eval(nodelist[0][1])         return Const(k, nodelist[0][1], lineno=nodelist[0][2])      def decode_literal(self, lit):         if self.encoding:             # this is particularly fragile & a bit of a             # hack... changes in compile.c:parsestr and             # tokenizer.c must be reflected here.             if self.encoding != 'utf-8':                 lit = unicode(lit, 'utf-8').encode(self.encoding)             return eval("# coding: %s\n%s" % (self.encoding, lit))         else:             return eval(lit)      def atom_string(self, nodelist):         k = ''         l = []         for node in nodelist:             k += self.decode_literal(node[1])             l.append(node[1])         return Const(k, l, lineno=nodelist[0][2])      def atom_name(self, nodelist):         return Name(nodelist[0][1], lineno=nodelist[0][2])      # --------------------------------------------------------------     #     # INTERNAL PARSING UTILITIES     #      # The use of com_node() introduces a lot of extra stack frames,     # enough to cause a stack overflow compiling test.test_parser with     # the standard interpreter recursionlimit.  The com_node() is a     # convenience function that hides the dispatch details, but comes     # at a very high cost.  It is more efficient to dispatch directly     # in the callers.  In these cases, use lookup_node() and call the     # dispatched node directly.      def lookup_node(self, node):         return self._dispatch[node[0]]      def com_node(self, node):         # Note: compile.c has handling in com_node for del_stmt, pass_stmt,         #       break_stmt, stmt, small_stmt, flow_stmt, simple_stmt,         #       and compound_stmt.         #       We'll just dispatch them.         return self._dispatch[node[0]](node[1:])      def com_NEWLINE(self, *args):         # A ';' at the end of a line can make a NEWLINE token appear         # here, Render it harmless. (genc discards ('discard',         # ('const', xxxx)) Nodes)         return Discard(Const(None))      def com_arglist(self, nodelist):         # varargslist:         #     (fpdef ['=' test] ',')* ('*' NAME [',' '**' NAME] | '**' NAME)         #   | fpdef ['=' test] (',' fpdef ['=' test])* [',']         # fpdef: NAME | '(' fplist ')'         # fplist: fpdef (',' fpdef)* [',']         names = []         defaults = []         flags = 0          i = 0         while i < len(nodelist):             node = nodelist[i]             if node[0] == token["STAR"] or node[0] == token["DOUBLESTAR"]:                 if node[0] == token["STAR"]:                     node = nodelist[i+1]                     if node[0] == token["NAME"]:                         names.append(node[1])                         flags = flags | CO_VARARGS                         i = i + 3                  if i < len(nodelist):                     # should be DOUBLESTAR                     t = nodelist[i][0]                     if t == token["DOUBLESTAR"]:                         node = nodelist[i+1]                     else:                         raise ValueError, "unexpected token: %s" % t                     names.append(node[1])                     flags = flags | CO_VARKEYWORDS                  break              # fpdef: NAME | '(' fplist ')'             names.append(self.com_fpdef(node))              i = i + 1             if i < len(nodelist) and nodelist[i][0] == token["EQUAL"]:                 defaults.append(self.com_node(nodelist[i + 1]))                 i = i + 2             elif len(defaults):                 # we have already seen an argument with default, but here                 # came one without                 raise SyntaxError, "non-default argument follows default argument"              # skip the comma             i = i + 1          return names, defaults, flags      def com_fpdef(self, node):         # fpdef: NAME | '(' fplist ')'         if node[1][0] == token["LPAR"]:             return self.com_fplist(node[2])         return node[1][1]      def com_fplist(self, node):         # fplist: fpdef (',' fpdef)* [',']         if len(node) == 2:             return self.com_fpdef(node[1])         list = []         for i in range(1, len(node), 2):             list.append(self.com_fpdef(node[i]))         return tuple(list)      def com_dotted_name(self, node):         # String together the dotted names and return the string         name = ""         for n in node:             if type(n) == type(()) and n[0] == 1:                 name = name + n[1] + '.'         return name[:-1]      def com_dotted_as_name(self, node):         assert node[0] == symbol["dotted_as_name"]         node = node[1:]         dot = self.com_dotted_name(node[0][1:])         if len(node) == 1:             return dot, None         assert node[1][1] == 'as'         assert node[2][0] == token["NAME"]         return dot, node[2][1]      def com_dotted_as_names(self, node):         assert node[0] == symbol["dotted_as_names"]         node = node[1:]         names = [self.com_dotted_as_name(node[0])]         for i in range(2, len(node), 2):             names.append(self.com_dotted_as_name(node[i]))         return names      def com_import_as_name(self, node):         assert node[0] == symbol["import_as_name"]         node = node[1:]         assert node[0][0] == token["NAME"]         if len(node) == 1:             return node[0][1], None         assert node[1][1] == 'as', node         assert node[2][0] == token["NAME"]         return node[0][1], node[2][1]      def com_import_as_names(self, node):         assert node[0] == symbol["import_as_names"]         node = node[1:]         names = [self.com_import_as_name(node[0])]         for i in range(2, len(node), 2):             names.append(self.com_import_as_name(node[i]))         return names      def com_bases(self, node):         bases = []         for i in range(1, len(node), 2):             bases.append(self.com_node(node[i]))         return bases      def com_try_except_finally(self, nodelist):         # ('try' ':' suite         #  ((except_clause ':' suite)+ ['else' ':' suite] ['finally' ':' suite]         #   | 'finally' ':' suite))          if nodelist[3][0] == token["NAME"]:             # first clause is a finally clause: only try-finally             return TryFinally(self.com_node(nodelist[2]),                               self.com_node(nodelist[5]),                               lineno=nodelist[0][2])          #tryexcept:  [TryNode, [except_clauses], elseNode)]         clauses = []         elseNode = None         finallyNode = None         for i in range(3, len(nodelist), 3):             node = nodelist[i]             if node[0] == symbol["except_clause"]:                 # except_clause: 'except' [expr [(',' | 'as') expr]] */                 if len(node) > 2:                     expr1 = self.com_node(node[2])                     if len(node) > 4:                         expr2 = self.com_assign(node[4], OP_ASSIGN)                     else:                         expr2 = None                 else:                     expr1 = expr2 = None                 clauses.append((expr1, expr2, self.com_node(nodelist[i+2])))              if node[0] == token["NAME"]:                 if node[1] == 'else':                     elseNode = self.com_node(nodelist[i+2])                 elif node[1] == 'finally':                     finallyNode = self.com_node(nodelist[i+2])         try_except = TryExcept(self.com_node(nodelist[2]), clauses, elseNode,                                lineno=nodelist[0][2])         if finallyNode:             return TryFinally(try_except, finallyNode, lineno=nodelist[0][2])         else:             return try_except      def com_with(self, nodelist):         # with_stmt: 'with' with_item (',' with_item)* ':' suite         body = self.com_node(nodelist[-1])         for i in range(len(nodelist) - 3, 0, -2):             ret = self.com_with_item(nodelist[i], body, nodelist[0][2])             if i == 1:                 return ret             body = ret      def com_with_item(self, nodelist, body, lineno):         # with_item: test ['as' expr]         if len(nodelist) == 4:             var = self.com_assign(nodelist[3], OP_ASSIGN)         else:             var = None         expr = self.com_node(nodelist[1])         return With(expr, var, body, lineno=lineno)      def com_augassign_op(self, node):         assert node[0] == symbol["augassign"]         return node[1]      def com_augassign(self, node):         """Return node suitable for lvalue of augmented assignment          Names, slices, and attributes are the only allowable nodes.         """         l = self.com_node(node)         if l.__class__ in (Name, Slice, Subscript, Getattr):             return l         raise SyntaxError, "can't assign to %s" % l.__class__.__name__      def com_assign(self, node, assigning):         # return a node suitable for use as an "lvalue"         # loop to avoid trivial recursion         while 1:             t = node[0]             if t in (symbol["exprlist"], symbol["testlist"], symbol["testlist_safe"], symbol["testlist_comp"]):                 if len(node) > 2:                     return self.com_assign_tuple(node, assigning)                 node = node[1]             elif t in _assign_types:                 if len(node) > 2:                     raise SyntaxError, "can't assign to operator"                 node = node[1]             elif t == symbol["power"]:                 if node[1][0] != symbol["atom"]:                     raise SyntaxError, "can't assign to operator"                 if len(node) > 2:                     primary = self.com_node(node[1])                     for i in range(2, len(node)-1):                         ch = node[i]                         if ch[0] == token["DOUBLESTAR"]:                             raise SyntaxError, "can't assign to operator"                         primary = self.com_apply_trailer(primary, ch)                     return self.com_assign_trailer(primary, node[-1],                                                    assigning)                 node = node[1]             elif t == symbol["atom"]:                 t = node[1][0]                 if t == token["LPAR"]:                     node = node[2]                     if node[0] == token["RPAR"]:                         raise SyntaxError, "can't assign to ()"                 elif t == token["LSQB"]:                     node = node[2]                     if node[0] == token["RSQB"]:                         raise SyntaxError, "can't assign to []"                     return self.com_assign_list(node, assigning)                 elif t == token["NAME"]:                     return self.com_assign_name(node[1], assigning)                 else:                     raise SyntaxError, "can't assign to literal"             else:                 raise SyntaxError, "bad assignment (%s)" % t      def com_assign_tuple(self, node, assigning):         assigns = []         for i in range(1, len(node), 2):             assigns.append(self.com_assign(node[i], assigning))         return AssTuple(assigns, lineno=extractLineNo(node))      def com_assign_list(self, node, assigning):         assigns = []         for i in range(1, len(node), 2):             if i + 1 < len(node):                 if node[i + 1][0] == symbol["list_for"]:                     raise SyntaxError, "can't assign to list comprehension"                 assert node[i + 1][0] == token["COMMA"], node[i + 1]             assigns.append(self.com_assign(node[i], assigning))         return AssList(assigns, lineno=extractLineNo(node))      def com_assign_name(self, node, assigning):         return AssName(node[1], assigning, lineno=node[2])      def com_assign_trailer(self, primary, node, assigning):         t = node[1][0]         if t == token["DOT"]:             return self.com_assign_attr(primary, node[2], assigning)         if t == token["LSQB"]:             return self.com_subscriptlist(primary, node[2], assigning)         if t == token["LPAR"]:             raise SyntaxError, "can't assign to function call"         raise SyntaxError, "unknown trailer type: %s" % t      def com_assign_attr(self, primary, node, assigning):         return AssAttr(primary, node[1], assigning, lineno=node[-1])      def com_binary(self, constructor, nodelist):         "Compile 'NODE (OP NODE)*' into (type, [ node1, ..., nodeN ])."         l = len(nodelist)         if l == 1:             n = nodelist[0]             return self.lookup_node(n)(n[1:])         items = []         for i in range(0, l, 2):             n = nodelist[i]             items.append(self.lookup_node(n)(n[1:]))         return constructor(items, lineno=extractLineNo(nodelist))      def com_stmt(self, node):         result = self.lookup_node(node)(node[1:])         assert result is not None         if isinstance(result, Stmt):             return result         return Stmt([result])      def com_append_stmt(self, stmts, node):         result = self.lookup_node(node)(node[1:])         assert result is not None         if isinstance(result, Stmt):             stmts.extend(result.nodes)         else:             stmts.append(result)      def com_list_constructor(self, nodelist):         # listmaker: test ( (',' test)* [','] )         values = []         for i in range(1, len(nodelist)):             if nodelist[i][0] == token["COMMA"]:                 continue             values.append(self.com_node(nodelist[i]))         return List(values, lineno=values[0].lineno)      def com_dictorsetmaker(self, nodelist):         # dictorsetmaker: ( (test ':' test ( (',' test ':' test)* [','])) |         #                   (test ( (',' test)* [','])) )         assert nodelist[0] == symbol["dictorsetmaker"]         nodelist = nodelist[1:]         if len(nodelist) == 1 or nodelist[1][0] == token["COMMA"]:             # set literal             items = []             for i in range(0, len(nodelist), 2):                 items.append(self.com_node(nodelist[i]))             return Set(items, lineno=items[0].lineno)         else:             # dict literal             items = []             for i in range(0, len(nodelist), 4):                 items.append((self.com_node(nodelist[i]),                               self.com_node(nodelist[i+2])))             return Dict(items, lineno=items[0][0].lineno)      def com_apply_trailer(self, primaryNode, nodelist):         t = nodelist[1][0]         if t == token["LPAR"]:             return self.com_call_function(primaryNode, nodelist[2])         if t == token["DOT"]:             return self.com_select_member(primaryNode, nodelist[2])         if t == token["LSQB"]:             return self.com_subscriptlist(primaryNode, nodelist[2], OP_APPLY)          raise SyntaxError, 'unknown node type: %s' % t      def com_select_member(self, primaryNode, nodelist):         if nodelist[0] != token["NAME"]:             raise SyntaxError, "member must be a name"         return Getattr(primaryNode, nodelist[1], lineno=nodelist[2])      def com_call_function(self, primaryNode, nodelist):         if nodelist[0] == token["RPAR"]:             return CallFunc(primaryNode, [], lineno=extractLineNo(nodelist))         args = []         kw = 0         star_node = dstar_node = None         len_nodelist = len(nodelist)         i = 1         while i < len_nodelist:             node = nodelist[i]              if node[0]==token["STAR"]:                 if star_node is not None:                     raise SyntaxError, 'already have the varargs indentifier'                 star_node = self.com_node(nodelist[i+1])                 i = i + 3                 continue             elif node[0]==token["DOUBLESTAR"]:                 if dstar_node is not None:                     raise SyntaxError, 'already have the kwargs indentifier'                 dstar_node = self.com_node(nodelist[i+1])                 i = i + 3                 continue              # positional or named parameters             kw, result = self.com_argument(node, kw, star_node)              args.append(result)             i = i + 2          return CallFunc(primaryNode, args, star_node, dstar_node,                         lineno=extractLineNo(nodelist))      def com_argument(self, nodelist, kw, star_node):         if len(nodelist) == 2:             if kw:                 raise SyntaxError, "non-keyword arg after keyword arg"             if star_node:                 raise SyntaxError, "only named arguments may follow *expression"             return 0, self.com_node(nodelist[1])         result = self.com_node(nodelist[3])         n = nodelist[1]         while len(n) == 2 and n[0] != token["NAME"]:             n = n[1]         if n[0] != token["NAME"]:             raise SyntaxError, "keyword can't be an expression (%s)"%n[0]         node = Keyword(n[1], result, lineno=n[2])         return 1, node      def com_subscriptlist(self, primary, nodelist, assigning):         # slicing:      simple_slicing | extended_slicing         # simple_slicing:   primary "[" short_slice "]"         # extended_slicing: primary "[" slice_list "]"         # slice_list:   slice_item ("," slice_item)* [","]          # backwards compat slice for '[i:j]'         if len(nodelist) == 2:             sub = nodelist[1]             if (sub[1][0] == token["COLON"] or \                             (len(sub) > 2 and sub[2][0] == token["COLON"])) and \                             sub[-1][0] != symbol["sliceop"]:                 return self.com_slice(primary, sub, assigning)          subscripts = []         for i in range(1, len(nodelist), 2):             subscripts.append(self.com_subscript(nodelist[i]))         return Subscript(primary, assigning, subscripts,                          lineno=extractLineNo(nodelist))      def com_subscript(self, node):         # slice_item: expression | proper_slice | ellipsis         ch = node[1]         t = ch[0]         if t == token["DOT"] and node[2][0] == token["DOT"]:             return Ellipsis()         if t == token["COLON"] or len(node) > 2:             return self.com_sliceobj(node)         return self.com_node(ch)      def com_sliceobj(self, node):         # proper_slice: short_slice | long_slice         # short_slice:  [lower_bound] ":" [upper_bound]         # long_slice:   short_slice ":" [stride]         # lower_bound:  expression         # upper_bound:  expression         # stride:       expression         #         # Note: a stride may be further slicing...          items = []          if node[1][0] == token["COLON"]:             items.append(Const(None))             i = 2         else:             items.append(self.com_node(node[1]))             # i == 2 is a COLON             i = 3          if i < len(node) and node[i][0] == symbol["test"]:             items.append(self.com_node(node[i]))             i = i + 1         else:             items.append(Const(None))          # a short_slice has been built. look for long_slice now by looking         # for strides...         for j in range(i, len(node)):             ch = node[j]             if len(ch) == 2:                 items.append(Const(None))             else:                 items.append(self.com_node(ch[2]))         return Sliceobj(items, lineno=extractLineNo(node))      def com_slice(self, primary, node, assigning):         # short_slice:  [lower_bound] ":" [upper_bound]         lower = upper = None         if len(node) == 3:             if node[1][0] == token["COLON"]:                 upper = self.com_node(node[2])             else:                 lower = self.com_node(node[1])         elif len(node) == 4:             lower = self.com_node(node[1])             upper = self.com_node(node[3])         return Slice(primary, assigning, lower, upper,                      lineno=extractLineNo(node))      def get_docstring(self, node, n=None):         if n is None:             n = node[0]             node = node[1:]         if n == symbol["suite"]:             if len(node) == 1:                 return self.get_docstring(node[0])             for sub in node:                 if sub[0] == symbol["stmt"]:                     return self.get_docstring(sub)             return None         if n == symbol["file_input"]:             for sub in node:                 if sub[0] == symbol["stmt"]:                     return self.get_docstring(sub)             return None         if n == symbol["atom"]:             if node[0][0] == token["STRING"]:                 s = ''                 for t in node:                     s = s + eval(t[1])                 return s             return None         if n == symbol["stmt"] or n == symbol["simple_stmt"] \            or n == symbol["small_stmt"]:             return self.get_docstring(node[0])         if n in _doc_nodes and len(node) == 1:             return self.get_docstring(node[0])         return None   _doc_nodes = [     symbol["expr_stmt"],     symbol["testlist"],     symbol["testlist_safe"],     symbol["test"],     symbol["or_test"],     symbol["and_test"],     symbol["not_test"],     symbol["comparison"],     symbol["expr"],     symbol["xor_expr"],     symbol["and_expr"],     symbol["shift_expr"],     symbol["arith_expr"],     symbol["term"],     symbol["factor"],     symbol["power"],     ]  # comp_op: '<' | '>' | '=' | '>=' | '<=' | '<>' | '!=' | '==' #             | 'in' | 'not' 'in' | 'is' | 'is' 'not' _cmp_types = {     token["LESS"] : '<',     token["GREATER"] : '>',     token["EQEQUAL"] : '==',     token["EQUAL"] : '==',     token["LESSEQUAL"] : '<=',     token["GREATEREQUAL"] : '>=',     token["NOTEQUAL"] : '!=',     }  _legal_node_types = [     symbol["funcdef"],     symbol["classdef"],     symbol["stmt"],     symbol["small_stmt"],     symbol["flow_stmt"],     symbol["simple_stmt"],     symbol["compound_stmt"],     symbol["expr_stmt"],     symbol["print_stmt"],     symbol["del_stmt"],     symbol["pass_stmt"],     symbol["break_stmt"],     symbol["continue_stmt"],     symbol["return_stmt"],     symbol["raise_stmt"],     symbol["import_stmt"],     symbol["global_stmt"],     symbol["exec_stmt"],     symbol["assert_stmt"],     symbol["if_stmt"],     symbol["while_stmt"],     symbol["for_stmt"],     symbol["try_stmt"],     symbol["with_stmt"],     symbol["suite"],     symbol["testlist"],     symbol["testlist_safe"],     symbol["test"],     symbol["and_test"],     symbol["not_test"],     symbol["comparison"],     symbol["exprlist"],     symbol["expr"],     symbol["xor_expr"],     symbol["and_expr"],     symbol["shift_expr"],     symbol["arith_expr"],     symbol["term"],     symbol["factor"],     symbol["power"],     symbol["atom"],     ]  _assign_types = [     symbol["test"],     symbol["or_test"],     symbol["and_test"],     symbol["not_test"],     symbol["comparison"],     symbol["expr"],     symbol["xor_expr"],     symbol["and_expr"],     symbol["shift_expr"],     symbol["arith_expr"],     symbol["term"],     symbol["factor"],     ]  _names = {} for k, v in sym_name.items():     _names[k] = v for k, v in tok_name.items():     _names[k] = v  def debug_tree(tree):     l = []     for elt in tree:         if isinstance(elt, int):             l.append(_names.get(elt, elt))         elif isinstance(elt, str):             l.append(elt)         else:             l.append(debug_tree(elt))     return l