Lib/test/test_grammar.py

# Python test set -- part 1, grammar.
# This just tests whether the parser accepts them all.

# NOTE: When you run this test as a script from the command line, you
# get warnings about certain hex/oct constants.  Since those are
# issued by the parser, you can't suppress them by adding a
# filterwarnings() call to this module.  Therefore, to shut up the
# regression test, the filterwarnings() call has been added to
# regrtest.py.

from test.test_support import run_unittest, check_syntax_error
import unittest
import sys
# testing import *
from sys import *

class TokenTests(unittest.TestCase):

    def testBackslash(self):
        # Backslash means line continuation:
        x = 1 \
        + 1
        self.assertEquals(x, 2, 'backslash for line continuation')

        # Backslash does not means continuation in comments :\
        x = 0
        self.assertEquals(x, 0, 'backslash ending comment')

    def testPlainIntegers(self):
        self.assertEquals(0xff, 255)
        self.assertEquals(0377, 255)
        self.assertEquals(2147483647, 017777777777)
        # "0x" is not a valid literal
        self.assertRaises(SyntaxError, eval, "0x")
        from sys import maxint
        if maxint == 2147483647:
            self.assertEquals(-2147483647-1, -020000000000)
            # XXX -2147483648
            self.assert_(037777777777 > 0)
            self.assert_(0xffffffff > 0)
            for s in '2147483648', '040000000000', '0x100000000':
                try:
                    x = eval(s)
                except OverflowError:
                    self.fail("OverflowError on huge integer literal %r" % s)
        elif maxint == 9223372036854775807:
            self.assertEquals(-9223372036854775807-1, -01000000000000000000000)
            self.assert_(01777777777777777777777 > 0)
            self.assert_(0xffffffffffffffff > 0)
            for s in '9223372036854775808', '02000000000000000000000', \
                     '0x10000000000000000':
                try:
                    x = eval(s)
                except OverflowError:
                    self.fail("OverflowError on huge integer literal %r" % s)
        else:
            self.fail('Weird maxint value %r' % maxint)

    def testLongIntegers(self):
        x = 0L
        x = 0l
        x = 0xffffffffffffffffL
        x = 0xffffffffffffffffl
        x = 077777777777777777L
        x = 077777777777777777l
        x = 123456789012345678901234567890L
        x = 123456789012345678901234567890l

    def testFloats(self):
        x = 3.14
        x = 314.
        x = 0.314
        # XXX x = 000.314
        x = .314
        x = 3e14
        x = 3E14
        x = 3e-14
        x = 3e+14
        x = 3.e14
        x = .3e14
        x = 3.1e4

    def testStringLiterals(self):
        x = ''; y = ""; self.assert_(len(x) == 0 and x == y)
        x = '\''; y = "'"; self.assert_(len(x) == 1 and x == y and ord(x) == 39)
        x = '"'; y = "\""; self.assert_(len(x) == 1 and x == y and ord(x) == 34)
        x = "doesn't \"shrink\" does it"
        y = 'doesn\'t "shrink" does it'
        self.assert_(len(x) == 24 and x == y)
        x = "does \"shrink\" doesn't it"
        y = 'does "shrink" doesn\'t it'
        self.assert_(len(x) == 24 and x == y)
        x = """
The "quick"
brown fox
jumps over
the 'lazy' dog.
"""
        y = '\nThe "quick"\nbrown fox\njumps over\nthe \'lazy\' dog.\n'
        self.assertEquals(x, y)
        y = '''
The "quick"
brown fox
jumps over
the 'lazy' dog.
'''
        self.assertEquals(x, y)
        y = "\n\
The \"quick\"\n\
brown fox\n\
jumps over\n\
the 'lazy' dog.\n\
"
        self.assertEquals(x, y)
        y = '\n\
The \"quick\"\n\
brown fox\n\
jumps over\n\
the \'lazy\' dog.\n\
'
        self.assertEquals(x, y)


class GrammarTests(unittest.TestCase):

    # single_input: NEWLINE | simple_stmt | compound_stmt NEWLINE
    # XXX can't test in a script -- this rule is only used when interactive

    # file_input: (NEWLINE | stmt)* ENDMARKER
    # Being tested as this very moment this very module

    # expr_input: testlist NEWLINE
    # XXX Hard to test -- used only in calls to input()

    def testEvalInput(self):
        # testlist ENDMARKER
        x = eval('1, 0 or 1')

    def testFuncdef(self):
        ### 'def' NAME parameters ':' suite
        ### parameters: '(' [varargslist] ')'
        ### varargslist: (fpdef ['=' test] ',')* ('*' NAME [',' ('**'|'*' '*') NAME]
        ###            | ('**'|'*' '*') NAME)
        ###            | fpdef ['=' test] (',' fpdef ['=' test])* [',']
        ### fpdef: NAME | '(' fplist ')'
        ### fplist: fpdef (',' fpdef)* [',']
        ### arglist: (argument ',')* (argument | *' test [',' '**' test] | '**' test)
        ### argument: [test '='] test   # Really [keyword '='] test
        def f1(): pass
        f1()
        f1(*())
        f1(*(), **{})
        def f2(one_argument): pass
        def f3(two, arguments): pass
        def f4(two, (compound, (argument, list))): pass
        def f5((compound, first), two): pass
        self.assertEquals(f2.func_code.co_varnames, ('one_argument',))
        self.assertEquals(f3.func_code.co_varnames, ('two', 'arguments'))
        if sys.platform.startswith('java'):
            self.assertEquals(f4.func_code.co_varnames,
                   ('two', '(compound, (argument, list))', 'compound', 'argument',
                                'list',))
            self.assertEquals(f5.func_code.co_varnames,
                   ('(compound, first)', 'two', 'compound', 'first'))
        else:
            self.assertEquals(f4.func_code.co_varnames,
                  ('two', '.1', 'compound', 'argument',  'list'))
            self.assertEquals(f5.func_code.co_varnames,
                  ('.0', 'two', 'compound', 'first'))
        def a1(one_arg,): pass
        def a2(two, args,): pass
        def v0(*rest): pass
        def v1(a, *rest): pass
        def v2(a, b, *rest): pass
        def v3(a, (b, c), *rest): return a, b, c, rest

        f1()
        f2(1)
        f2(1,)
        f3(1, 2)
        f3(1, 2,)
        f4(1, (2, (3, 4)))
        v0()
        v0(1)
        v0(1,)
        v0(1,2)
        v0(1,2,3,4,5,6,7,8,9,0)
        v1(1)
        v1(1,)
        v1(1,2)
        v1(1,2,3)
        v1(1,2,3,4,5,6,7,8,9,0)
        v2(1,2)
        v2(1,2,3)
        v2(1,2,3,4)
        v2(1,2,3,4,5,6,7,8,9,0)
        v3(1,(2,3))
        v3(1,(2,3),4)
        v3(1,(2,3),4,5,6,7,8,9,0)

        # ceval unpacks the formal arguments into the first argcount names;
        # thus, the names nested inside tuples must appear after these names.
        if sys.platform.startswith('java'):
            self.assertEquals(v3.func_code.co_varnames, ('a', '(b, c)', 'rest', 'b', 'c'))
        else:
            self.assertEquals(v3.func_code.co_varnames, ('a', '.1', 'rest', 'b', 'c'))
        self.assertEquals(v3(1, (2, 3), 4), (1, 2, 3, (4,)))
        def d01(a=1): pass
        d01()
        d01(1)
        d01(*(1,))
        d01(**{'a':2})
        def d11(a, b=1): pass
        d11(1)
        d11(1, 2)
        d11(1, **{'b':2})
        def d21(a, b, c=1): pass
        d21(1, 2)
        d21(1, 2, 3)
        d21(*(1, 2, 3))
        d21(1, *(2, 3))
        d21(1, 2, *(3,))
        d21(1, 2, **{'c':3})
        def d02(a=1, b=2): pass
        d02()
        d02(1)
        d02(1, 2)
        d02(*(1, 2))
        d02(1, *(2,))
        d02(1, **{'b':2})
        d02(**{'a': 1, 'b': 2})
        def d12(a, b=1, c=2): pass
        d12(1)
        d12(1, 2)
        d12(1, 2, 3)
        def d22(a, b, c=1, d=2): pass
        d22(1, 2)
        d22(1, 2, 3)
        d22(1, 2, 3, 4)
        def d01v(a=1, *rest): pass
        d01v()
        d01v(1)
        d01v(1, 2)
        d01v(*(1, 2, 3, 4))
        d01v(*(1,))
        d01v(**{'a':2})
        def d11v(a, b=1, *rest): pass
        d11v(1)
        d11v(1, 2)
        d11v(1, 2, 3)
        def d21v(a, b, c=1, *rest): pass
        d21v(1, 2)
        d21v(1, 2, 3)
        d21v(1, 2, 3, 4)
        d21v(*(1, 2, 3, 4))
        d21v(1, 2, **{'c': 3})
        def d02v(a=1, b=2, *rest): pass
        d02v()
        d02v(1)
        d02v(1, 2)
        d02v(1, 2, 3)
        d02v(1, *(2, 3, 4))
        d02v(**{'a': 1, 'b': 2})
        def d12v(a, b=1, c=2, *rest): pass
        d12v(1)
        d12v(1, 2)
        d12v(1, 2, 3)
        d12v(1, 2, 3, 4)
        d12v(*(1, 2, 3, 4))
        d12v(1, 2, *(3, 4, 5))
        d12v(1, *(2,), **{'c': 3})
        def d22v(a, b, c=1, d=2, *rest): pass
        d22v(1, 2)
        d22v(1, 2, 3)
        d22v(1, 2, 3, 4)
        d22v(1, 2, 3, 4, 5)
        d22v(*(1, 2, 3, 4))
        d22v(1, 2, *(3, 4, 5))
        d22v(1, *(2, 3), **{'d': 4})
        def d31v((x)): pass
        d31v(1)
        def d32v((x,)): pass
        d32v((1,))

        # keyword arguments after *arglist
        def f(*args, **kwargs):
            return args, kwargs
        self.assertEquals(f(1, x=2, *[3, 4], y=5), ((1, 3, 4),
                                                    {'x':2, 'y':5}))
        self.assertRaises(SyntaxError, eval, "f(1, *(2,3), 4)")
        self.assertRaises(SyntaxError, eval, "f(1, x=2, *(3,4), x=5)")

        # Check ast errors in *args and *kwargs
        check_syntax_error(self, "f(*g(1=2))")
        check_syntax_error(self, "f(**g(1=2))")

    def testLambdef(self):
        ### lambdef: 'lambda' [varargslist] ':' test
        l1 = lambda : 0
        self.assertEquals(l1(), 0)
        l2 = lambda : a[d] # XXX just testing the expression
        l3 = lambda : [2 < x for x in [-1, 3, 0L]]
        self.assertEquals(l3(), [0, 1, 0])
        l4 = lambda x = lambda y = lambda z=1 : z : y() : x()
        self.assertEquals(l4(), 1)
        l5 = lambda x, y, z=2: x + y + z
        self.assertEquals(l5(1, 2), 5)
        self.assertEquals(l5(1, 2, 3), 6)
        check_syntax_error(self, "lambda x: x = 2")
        check_syntax_error(self, "lambda (None,): None")

    ### stmt: simple_stmt | compound_stmt
    # Tested below

    def testSimpleStmt(self):
        ### simple_stmt: small_stmt (';' small_stmt)* [';']
        x = 1; pass; del x
        def foo():
            # verify statments that end with semi-colons
            x = 1; pass; del x;
        foo()

    ### small_stmt: expr_stmt | print_stmt  | pass_stmt | del_stmt | flow_stmt | import_stmt | global_stmt | access_stmt | exec_stmt
    # Tested below

    def testExprStmt(self):
        # (exprlist '=')* exprlist
        1
        1, 2, 3
        x = 1
        x = 1, 2, 3
        x = y = z = 1, 2, 3
        x, y, z = 1, 2, 3
        abc = a, b, c = x, y, z = xyz = 1, 2, (3, 4)

        check_syntax_error(self, "x + 1 = 1")
        check_syntax_error(self, "a + 1 = b + 2")

    def testPrintStmt(self):
        # 'print' (test ',')* [test]
        import StringIO

        # Can't test printing to real stdout without comparing output
        # which is not available in unittest.
        save_stdout = sys.stdout
        sys.stdout = StringIO.StringIO()

        print 1, 2, 3
        print 1, 2, 3,
        print
        print 0 or 1, 0 or 1,
        print 0 or 1

        # 'print' '>>' test ','
        print >> sys.stdout, 1, 2, 3
        print >> sys.stdout, 1, 2, 3,
        print >> sys.stdout
        print >> sys.stdout, 0 or 1, 0 or 1,
        print >> sys.stdout, 0 or 1

        # test printing to an instance
        class Gulp:
            def write(self, msg): pass

        gulp = Gulp()
        print >> gulp, 1, 2, 3
        print >> gulp, 1, 2, 3,
        print >> gulp
        print >> gulp, 0 or 1, 0 or 1,
        print >> gulp, 0 or 1

        # test print >> None
        def driver():
            oldstdout = sys.stdout
            sys.stdout = Gulp()
            try:
                tellme(Gulp())
                tellme()
            finally:
                sys.stdout = oldstdout

        # we should see this once
        def tellme(file=sys.stdout):
            print >> file, 'hello world'

        driver()

        # we should not see this at all
        def tellme(file=None):
            print >> file, 'goodbye universe'

        driver()

        self.assertEqual(sys.stdout.getvalue(), '''\
1 2 3
1 2 3
1 1 1
1 2 3
1 2 3
1 1 1
hello world
''')
        sys.stdout = save_stdout

        # syntax errors
        check_syntax_error(self, 'print ,')
        check_syntax_error(self, 'print >> x,')

    def testDelStmt(self):
        # 'del' exprlist
        abc = [1,2,3]
        x, y, z = abc
        xyz = x, y, z

        del abc
        del x, y, (z, xyz)

    def testPassStmt(self):
        # 'pass'
        pass

    # flow_stmt: break_stmt | continue_stmt | return_stmt | raise_stmt
    # Tested below

    def testBreakStmt(self):
        # 'break'
        while 1: break

    def testContinueStmt(self):
        # 'continue'
        i = 1
        while i: i = 0; continue

        msg = ""
        while not msg:
            msg = "ok"
            try:
                continue
                msg = "continue failed to continue inside try"
            except:
                msg = "continue inside try called except block"
        if msg != "ok":
            self.fail(msg)

        msg = ""
        while not msg:
            msg = "finally block not called"
            try:
                continue
            finally:
                msg = "ok"
        if msg != "ok":
            self.fail(msg)

    def test_break_continue_loop(self):
        # This test warrants an explanation. It is a test specifically for SF bugs
        # #463359 and #462937. The bug is that a 'break' statement executed or
        # exception raised inside a try/except inside a loop, *after* a continue
        # statement has been executed in that loop, will cause the wrong number of
        # arguments to be popped off the stack and the instruction pointer reset to
        # a very small number (usually 0.) Because of this, the following test
        # *must* written as a function, and the tracking vars *must* be function
        # arguments with default values. Otherwise, the test will loop and loop.

        def test_inner(extra_burning_oil = 1, count=0):
            big_hippo = 2
            while big_hippo:
                count += 1
                try:
                    if extra_burning_oil and big_hippo == 1:
                        extra_burning_oil -= 1
                        break
                    big_hippo -= 1
                    continue
                except:
                    raise
            if count > 2 or big_hippo <> 1:
                self.fail("continue then break in try/except in loop broken!")
        test_inner()

    def testReturn(self):
        # 'return' [testlist]
        def g1(): return
        def g2(): return 1
        g1()
        x = g2()
        check_syntax_error(self, "class foo:return 1")

    def testYield(self):
        check_syntax_error(self, "class foo:yield 1")

    def testRaise(self):
        # 'raise' test [',' test]
        try: raise RuntimeError, 'just testing'
        except RuntimeError: pass
        try: raise KeyboardInterrupt
        except KeyboardInterrupt: pass

    def testImport(self):
        # 'import' dotted_as_names
        import sys
        import time, sys
        # 'from' dotted_name 'import' ('*' | '(' import_as_names ')' | import_as_names)
        from time import time
        from time import (time)
        # not testable inside a function, but already done at top of the module
        # from sys import *
        from sys import path, argv
        from sys import (path, argv)
        from sys import (path, argv,)

    def testGlobal(self):
        # 'global' NAME (',' NAME)*
        global a
        global a, b
        global one, two, three, four, five, six, seven, eight, nine, ten

    def testExec(self):
        # 'exec' expr ['in' expr [',' expr]]
        z = None
        del z
        exec 'z=1+1\n'
        if z != 2: self.fail('exec \'z=1+1\'\\n')
        del z
        exec 'z=1+1'
        if z != 2: self.fail('exec \'z=1+1\'')
        z = None
        del z
        import types
        if hasattr(types, "UnicodeType"):
            exec r"""if 1:
            exec u'z=1+1\n'
            if z != 2: self.fail('exec u\'z=1+1\'\\n')
            del z
            exec u'z=1+1'
            if z != 2: self.fail('exec u\'z=1+1\'')"""
        g = {}
        exec 'z = 1' in g
        if g.has_key('__builtins__'): del g['__builtins__']
        if g != {'z': 1}: self.fail('exec \'z = 1\' in g')
        g = {}
        l = {}

        import warnings
        warnings.filterwarnings("ignore", "global statement", module="<string>")
        exec 'global a; a = 1; b = 2' in g, l
        if g.has_key('__builtins__'): del g['__builtins__']
        if l.has_key('__builtins__'): del l['__builtins__']
        if (g, l) != ({'a':1}, {'b':2}):
            self.fail('exec ... in g (%s), l (%s)' %(g,l))

    def testAssert(self):
        # assert_stmt: 'assert' test [',' test]
        assert 1
        assert 1, 1
        assert lambda x:x
        assert 1, lambda x:x+1
        try:
            assert 0, "msg"
        except AssertionError, e:
            self.assertEquals(e.args[0], "msg")
        else:
            if __debug__:
                self.fail("AssertionError not raised by assert 0")

    ### compound_stmt: if_stmt | while_stmt | for_stmt | try_stmt | funcdef | classdef
    # Tested below

    def testIf(self):
        # 'if' test ':' suite ('elif' test ':' suite)* ['else' ':' suite]
        if 1: pass
        if 1: pass
        else: pass
        if 0: pass
        elif 0: pass
        if 0: pass
        elif 0: pass
        elif 0: pass
        elif 0: pass
        else: pass

    def testWhile(self):
        # 'while' test ':' suite ['else' ':' suite]
        while 0: pass
        while 0: pass
        else: pass

        # Issue1920: "while 0" is optimized away,
        # ensure that the "else" clause is still present.
        x = 0
        while 0:
            x = 1
        else:
            x = 2
        self.assertEquals(x, 2)

    def testFor(self):
        # 'for' exprlist 'in' exprlist ':' suite ['else' ':' suite]
        for i in 1, 2, 3: pass
        for i, j, k in (): pass
        else: pass
        class Squares:
            def __init__(self, max):
                self.max = max
                self.sofar = []
            def __len__(self): return len(self.sofar)
            def __getitem__(self, i):
                if not 0 <= i < self.max: raise IndexError
                n = len(self.sofar)
                while n <= i:
                    self.sofar.append(n*n)
                    n = n+1
                return self.sofar[i]
        n = 0
        for x in Squares(10): n = n+x
        if n != 285:
            self.fail('for over growing sequence')

        result = []
        for x, in [(1,), (2,), (3,)]:
            result.append(x)
        self.assertEqual(result, [1, 2, 3])

    def testTry(self):
        ### try_stmt: 'try' ':' suite (except_clause ':' suite)+ ['else' ':' suite]
        ###         | 'try' ':' suite 'finally' ':' suite
        ### except_clause: 'except' [expr [('as' | ',') expr]]
        try:
            1/0
        except ZeroDivisionError:
            pass
        else:
            pass
        try: 1/0
        except EOFError: pass
        except TypeError as msg: pass
        except RuntimeError, msg: pass
        except: pass
        else: pass
        try: 1/0
        except (EOFError, TypeError, ZeroDivisionError): pass
        try: 1/0
        except (EOFError, TypeError, ZeroDivisionError), msg: pass
        try: pass
        finally: pass

    def testSuite(self):
        # simple_stmt | NEWLINE INDENT NEWLINE* (stmt NEWLINE*)+ DEDENT
        if 1: pass
        if 1:
            pass
        if 1:
            #
            #
            #
            pass
            pass
            #
            pass
            #

    def testTest(self):
        ### and_test ('or' and_test)*
        ### and_test: not_test ('and' not_test)*
        ### not_test: 'not' not_test | comparison
        if not 1: pass
        if 1 and 1: pass
        if 1 or 1: pass
        if not not not 1: pass
        if not 1 and 1 and 1: pass
        if 1 and 1 or 1 and 1 and 1 or not 1 and 1: pass

    def testComparison(self):
        ### comparison: expr (comp_op expr)*
        ### comp_op: '<'|'>'|'=='|'>='|'<='|'<>'|'!='|'in'|'not' 'in'|'is'|'is' 'not'
        if 1: pass
        x = (1 == 1)
        if 1 == 1: pass
        if 1 != 1: pass
        if 1 <> 1: pass
        if 1 < 1: pass
        if 1 > 1: pass
        if 1 <= 1: pass
        if 1 >= 1: pass
        if 1 is 1: pass
        if 1 is not 1: pass
        if 1 in (): pass
        if 1 not in (): pass
        if 1 < 1 > 1 == 1 >= 1 <= 1 <> 1 != 1 in 1 not in 1 is 1 is not 1: pass

    def testBinaryMaskOps(self):
        x = 1 & 1
        x = 1 ^ 1
        x = 1 | 1

    def testShiftOps(self):
        x = 1 << 1
        x = 1 >> 1
        x = 1 << 1 >> 1

    def testAdditiveOps(self):
        x = 1
        x = 1 + 1
        x = 1 - 1 - 1
        x = 1 - 1 + 1 - 1 + 1

    def testMultiplicativeOps(self):
        x = 1 * 1
        x = 1 / 1
        x = 1 % 1
        x = 1 / 1 * 1 % 1

    def testUnaryOps(self):
        x = +1
        x = -1
        x = ~1
        x = ~1 ^ 1 & 1 | 1 & 1 ^ -1
        x = -1*1/1 + 1*1 - ---1*1

    def testSelectors(self):
        ### trailer: '(' [testlist] ')' | '[' subscript ']' | '.' NAME
        ### subscript: expr | [expr] ':' [expr]

        import sys, time
        c = sys.path[0]
        x = time.time()
        x = sys.modules['time'].time()
        a = '01234'
        c = a[0]
        c = a[-1]
        s = a[0:5]
        s = a[:5]
        s = a[0:]
        s = a[:]
        s = a[-5:]
        s = a[:-1]
        s = a[-4:-3]
        # A rough test of SF bug 1333982.  http://python.org/sf/1333982
        # The testing here is fairly incomplete.
        # Test cases should include: commas with 1 and 2 colons
        d = {}
        d[1] = 1
        d[1,] = 2
        d[1,2] = 3
        d[1,2,3] = 4
        L = list(d)
        L.sort()
        self.assertEquals(str(L), '[1, (1,), (1, 2), (1, 2, 3)]')

    def testAtoms(self):
        ### atom: '(' [testlist] ')' | '[' [testlist] ']' | '{' [dictmaker] '}' | '`' testlist '`' | NAME | NUMBER | STRING
        ### dictmaker: test ':' test (',' test ':' test)* [',']

        x = (1)
        x = (1 or 2 or 3)
        x = (1 or 2 or 3, 2, 3)

        x = []
        x = [1]
        x = [1 or 2 or 3]
        x = [1 or 2 or 3, 2, 3]
        x = []

        x = {}
        x = {'one': 1}
        x = {'one': 1,}
        x = {'one' or 'two': 1 or 2}
        x = {'one': 1, 'two': 2}
        x = {'one': 1, 'two': 2,}
        x = {'one': 1, 'two': 2, 'three': 3, 'four': 4, 'five': 5, 'six': 6}

        x = `x`
        x = `1 or 2 or 3`
        self.assertEqual(`1,2`, '(1, 2)')

        x = x
        x = 'x'
        x = 123

    ### exprlist: expr (',' expr)* [',']
    ### testlist: test (',' test)* [',']
    # These have been exercised enough above

    def testClassdef(self):
        # 'class' NAME ['(' [testlist] ')'] ':' suite
        class B: pass
        class B2(): pass
        class C1(B): pass
        class C2(B): pass
        class D(C1, C2, B): pass
        class C:
            def meth1(self): pass
            def meth2(self, arg): pass
            def meth3(self, a1, a2): pass
        # decorator: '@' dotted_name [ '(' [arglist] ')' ] NEWLINE
        # decorators: decorator+
        # decorated: decorators (classdef | funcdef)
        def class_decorator(x):
            x.decorated = True
            return x
        @class_decorator
        class G:
            pass
        self.assertEqual(G.decorated, True)

    def testListcomps(self):
        # list comprehension tests
        nums = [1, 2, 3, 4, 5]
        strs = ["Apple", "Banana", "Coconut"]
        spcs = ["  Apple", " Banana ", "Coco  nut  "]

        self.assertEqual([s.strip() for s in spcs], ['Apple', 'Banana', 'Coco  nut'])
        self.assertEqual([3 * x for x in nums], [3, 6, 9, 12, 15])
        self.assertEqual([x for x in nums if x > 2], [3, 4, 5])
        self.assertEqual([(i, s) for i in nums for s in strs],
                         [(1, 'Apple'), (1, 'Banana'), (1, 'Coconut'),
                          (2, 'Apple'), (2, 'Banana'), (2, 'Coconut'),
                          (3, 'Apple'), (3, 'Banana'), (3, 'Coconut'),
                          (4, 'Apple'), (4, 'Banana'), (4, 'Coconut'),
                          (5, 'Apple'), (5, 'Banana'), (5, 'Coconut')])
        self.assertEqual([(i, s) for i in nums for s in [f for f in strs if "n" in f]],
                         [(1, 'Banana'), (1, 'Coconut'), (2, 'Banana'), (2, 'Coconut'),
                          (3, 'Banana'), (3, 'Coconut'), (4, 'Banana'), (4, 'Coconut'),
                          (5, 'Banana'), (5, 'Coconut')])
        self.assertEqual([(lambda a:[a**i for i in range(a+1)])(j) for j in range(5)],
                         [[1], [1, 1], [1, 2, 4], [1, 3, 9, 27], [1, 4, 16, 64, 256]])

        def test_in_func(l):
            return [None < x < 3 for x in l if x > 2]

        self.assertEqual(test_in_func(nums), [False, False, False])

        def test_nested_front():
            self.assertEqual([[y for y in [x, x + 1]] for x in [1,3,5]],
                             [[1, 2], [3, 4], [5, 6]])

        test_nested_front()

        check_syntax_error(self, "[i, s for i in nums for s in strs]")
        check_syntax_error(self, "[x if y]")

        suppliers = [
          (1, "Boeing"),
          (2, "Ford"),
          (3, "Macdonalds")
        ]

        parts = [
          (10, "Airliner"),
          (20, "Engine"),
          (30, "Cheeseburger")
        ]

        suppart = [
          (1, 10), (1, 20), (2, 20), (3, 30)
        ]

        x = [
          (sname, pname)
            for (sno, sname) in suppliers
              for (pno, pname) in parts
                for (sp_sno, sp_pno) in suppart
                  if sno == sp_sno and pno == sp_pno
        ]

        self.assertEqual(x, [('Boeing', 'Airliner'), ('Boeing', 'Engine'), ('Ford', 'Engine'),
                             ('Macdonalds', 'Cheeseburger')])

    def testGenexps(self):
        # generator expression tests
        g = ([x for x in range(10)] for x in range(1))
        self.assertEqual(g.next(), [x for x in range(10)])
        try:
            g.next()
            self.fail('should produce StopIteration exception')
        except StopIteration:
            pass

        a = 1
        try:
            g = (a for d in a)
            g.next()
            self.fail('should produce TypeError')
        except TypeError:
            pass

        self.assertEqual(list((x, y) for x in 'abcd' for y in 'abcd'), [(x, y) for x in 'abcd' for y in 'abcd'])
        self.assertEqual(list((x, y) for x in 'ab' for y in 'xy'), [(x, y) for x in 'ab' for y in 'xy'])

        a = [x for x in range(10)]
        b = (x for x in (y for y in a))
        self.assertEqual(sum(b), sum([x for x in range(10)]))

        self.assertEqual(sum(x**2 for x in range(10)), sum([x**2 for x in range(10)]))
        self.assertEqual(sum(x*x for x in range(10) if x%2), sum([x*x for x in range(10) if x%2]))
        self.assertEqual(sum(x for x in (y for y in range(10))), sum([x for x in range(10)]))
        self.assertEqual(sum(x for x in (y for y in (z for z in range(10)))), sum([x for x in range(10)]))
        self.assertEqual(sum(x for x in [y for y in (z for z in range(10))]), sum([x for x in range(10)]))
        self.assertEqual(sum(x for x in (y for y in (z for z in range(10) if True)) if True), sum([x for x in range(10)]))
        self.assertEqual(sum(x for x in (y for y in (z for z in range(10) if True) if False) if True), 0)
        check_syntax_error(self, "foo(x for x in range(10), 100)")
        check_syntax_error(self, "foo(100, x for x in range(10))")

    def testComprehensionSpecials(self):
        # test for outmost iterable precomputation
        x = 10; g = (i for i in range(x)); x = 5
        self.assertEqual(len(list(g)), 10)

        # This should hold, since we're only precomputing outmost iterable.
        x = 10; t = False; g = ((i,j) for i in range(x) if t for j in range(x))
        x = 5; t = True;
        self.assertEqual([(i,j) for i in range(10) for j in range(5)], list(g))

        # Grammar allows multiple adjacent 'if's in listcomps and genexps,
        # even though it's silly. Make sure it works (ifelse broke this.)
        self.assertEqual([ x for x in range(10) if x % 2 if x % 3 ], [1, 5, 7])
        self.assertEqual(list(x for x in range(10) if x % 2 if x % 3), [1, 5, 7])

        # verify unpacking single element tuples in listcomp/genexp.
        self.assertEqual([x for x, in [(4,), (5,), (6,)]], [4, 5, 6])
        self.assertEqual(list(x for x, in [(7,), (8,), (9,)]), [7, 8, 9])

    def test_with_statement(self):
        class manager(object):
            def __enter__(self):
                return (1, 2)
            def __exit__(self, *args):
                pass

        with manager():
            pass
        with manager() as x:
            pass
        with manager() as (x, y):
            pass
        with manager(), manager():
            pass
        with manager() as x, manager() as y:
            pass
        with manager() as x, manager():
            pass

    def testIfElseExpr(self):
        # Test ifelse expressions in various cases
        def _checkeval(msg, ret):
            "helper to check that evaluation of expressions is done correctly"
            print x
            return ret

        self.assertEqual([ x() for x in lambda: True, lambda: False if x() ], [True])
        self.assertEqual([ x() for x in (lambda: True, lambda: False) if x() ], [True])
        self.assertEqual([ x(False) for x in (lambda x: False if x else True, lambda x: True if x else False) if x(False) ], [True])
        self.assertEqual((5 if 1 else _checkeval("check 1", 0)), 5)
        self.assertEqual((_checkeval("check 2", 0) if 0 else 5), 5)
        self.assertEqual((5 and 6 if 0 else 1), 1)
        self.assertEqual(((5 and 6) if 0 else 1), 1)
        self.assertEqual((5 and (6 if 1 else 1)), 6)
        self.assertEqual((0 or _checkeval("check 3", 2) if 0 else 3), 3)
        self.assertEqual((1 or _checkeval("check 4", 2) if 1 else _checkeval("check 5", 3)), 1)
        self.assertEqual((0 or 5 if 1 else _checkeval("check 6", 3)), 5)
        self.assertEqual((not 5 if 1 else 1), False)
        self.assertEqual((not 5 if 0 else 1), 1)
        self.assertEqual((6 + 1 if 1 else 2), 7)
        self.assertEqual((6 - 1 if 1 else 2), 5)
        self.assertEqual((6 * 2 if 1 else 4), 12)
        self.assertEqual((6 / 2 if 1 else 3), 3)
        self.assertEqual((6 < 4 if 0 else 2), 2)


def test_main():
    run_unittest(TokenTests, GrammarTests)

if __name__ == '__main__':
    test_main()