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 TestFailed, verify, vereq, check_syntax
import sys

print '1. Parser'

print '1.1 Tokens'

print '1.1.1 Backslashes'

# Backslash means line continuation:
x = 1 \
+ 1
if x != 2: raise TestFailed, 'backslash for line continuation'

# Backslash does not means continuation in comments :\
x = 0
if x != 0: raise TestFailed, 'backslash ending comment'

print '1.1.2 Numeric literals'

print '1.1.2.1 Plain integers'
if 0xff != 255: raise TestFailed, 'hex int'
if 0377 != 255: raise TestFailed, 'octal int'
if  2147483647   != 017777777777: raise TestFailed, 'large positive int'
try:
    from sys import maxint
except ImportError:
    maxint = 2147483647
if maxint == 2147483647:
    # The following test will start to fail in Python 2.4;
    # change the 020000000000 to -020000000000
    if -2147483647-1 != -020000000000: raise TestFailed, 'max negative int'
    # XXX -2147483648
    if 037777777777 < 0: raise TestFailed, 'large oct'
    if 0xffffffff < 0: raise TestFailed, 'large hex'
    for s in '2147483648', '040000000000', '0x100000000':
        try:
            x = eval(s)
        except OverflowError:
            print "OverflowError on huge integer literal " + repr(s)
elif eval('maxint == 9223372036854775807'):
    if eval('-9223372036854775807-1 != -01000000000000000000000'):
        raise TestFailed, 'max negative int'
    if eval('01777777777777777777777') < 0: raise TestFailed, 'large oct'
    if eval('0xffffffffffffffff') < 0: raise TestFailed, 'large hex'
    for s in '9223372036854775808', '02000000000000000000000', \
             '0x10000000000000000':
        try:
            x = eval(s)
        except OverflowError:
            print "OverflowError on huge integer literal " + repr(s)
else:
    print 'Weird maxint value', maxint

print '1.1.2.2 Long integers'
x = 0L
x = 0l
x = 0xffffffffffffffffL
x = 0xffffffffffffffffl
x = 077777777777777777L
x = 077777777777777777l
x = 123456789012345678901234567890L
x = 123456789012345678901234567890l

print '1.1.2.3 Floating point'
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

print '1.1.3 String literals'

x = ''; y = ""; verify(len(x) == 0 and x == y)
x = '\''; y = "'"; verify(len(x) == 1 and x == y and ord(x) == 39)
x = '"'; y = "\""; verify(len(x) == 1 and x == y and ord(x) == 34)
x = "doesn't \"shrink\" does it"
y = 'doesn\'t "shrink" does it'
verify(len(x) == 24 and x == y)
x = "does \"shrink\" doesn't it"
y = 'does "shrink" doesn\'t it'
verify(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'
verify(x == y)
y = '''
The "quick"
brown fox
jumps over
the 'lazy' dog.
'''; verify(x == y)
y = "\n\
The \"quick\"\n\
brown fox\n\
jumps over\n\
the 'lazy' dog.\n\
"; verify(x == y)
y = '\n\
The \"quick\"\n\
brown fox\n\
jumps over\n\
the \'lazy\' dog.\n\
'; verify(x == y)


print '1.2 Grammar'

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

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

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

print 'eval_input' # testlist ENDMARKER
x = eval('1, 0 or 1')

print 'funcdef'
### '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
vereq(f2.func_code.co_varnames, ('one_argument',))
vereq(f3.func_code.co_varnames, ('two', 'arguments'))
if sys.platform.startswith('java'):
    vereq(f4.func_code.co_varnames,
           ('two', '(compound, (argument, list))', 'compound', 'argument',
                        'list',))
    vereq(f5.func_code.co_varnames,
           ('(compound, first)', 'two', 'compound', 'first'))
else:
    vereq(f4.func_code.co_varnames,
          ('two', '.1', 'compound', 'argument',  'list'))
    vereq(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
# 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'):
    verify(v3.func_code.co_varnames == ('a', '(b, c)', 'rest', 'b', 'c'))
else:
    vereq(v3.func_code.co_varnames, ('a', '.1', 'rest', 'b', 'c'))
verify(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,))

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

### lambdef: 'lambda' [varargslist] ':' test
print 'lambdef'
l1 = lambda : 0
verify(l1() == 0)
l2 = lambda : a[d] # XXX just testing the expression
l3 = lambda : [2 < x for x in [-1, 3, 0L]]
verify(l3() == [0, 1, 0])
l4 = lambda x = lambda y = lambda z=1 : z : y() : x()
verify(l4() == 1)
l5 = lambda x, y, z=2: x + y + z
verify(l5(1, 2) == 5)
verify(l5(1, 2, 3) == 6)
check_syntax("lambda x: x = 2")

### stmt: simple_stmt | compound_stmt
# Tested below

### simple_stmt: small_stmt (';' small_stmt)* [';']
print 'simple_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

print 'expr_stmt' # (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)
# NB these variables are deleted below

check_syntax("x + 1 = 1")
check_syntax("a + 1 = b + 2")

print 'print_stmt' # 'print' (test ',')* [test]
print 1, 2, 3
print 1, 2, 3,
print
print 0 or 1, 0 or 1,
print 0 or 1

print 'extended print_stmt' # 'print' '>>' test ','
import sys
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()

# syntax errors
check_syntax('print ,')
check_syntax('print >> x,')

print 'del_stmt' # 'del' exprlist
del abc
del x, y, (z, xyz)

print 'pass_stmt' # 'pass'
pass

print 'flow_stmt' # break_stmt | continue_stmt | return_stmt | raise_stmt
# Tested below

print 'break_stmt' # 'break'
while 1: break

print 'continue_stmt' # 'continue'
i = 1
while i: i = 0; continue

msg = ""
while not msg:
    msg = "continue + try/except ok"
    try:
        continue
        msg = "continue failed to continue inside try"
    except:
        msg = "continue inside try called except block"
print msg

msg = ""
while not msg:
    msg = "finally block not called"
    try:
        continue
    finally:
        msg = "continue + try/finally ok"
print msg


# 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.

print "testing continue and break in try/except in loop"
def test_break_continue_loop(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:
        print "continue then break in try/except in loop broken!"
test_break_continue_loop()

print 'return_stmt' # 'return' [testlist]
def g1(): return
def g2(): return 1
g1()
x = g2()
check_syntax("class foo:return 1")

print 'yield_stmt'
check_syntax("class foo:yield 1")

print 'raise_stmt' # 'raise' test [',' test]
try: raise RuntimeError, 'just testing'
except RuntimeError: pass
try: raise KeyboardInterrupt
except KeyboardInterrupt: pass

print 'import_name' # 'import' dotted_as_names
import sys
import time, sys
print 'import_from' # 'from' dotted_name 'import' ('*' | '(' import_as_names ')' | import_as_names)
from time import time
from time import (time)
from sys import *
from sys import path, argv
from sys import (path, argv)
from sys import (path, argv,)

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

print 'exec_stmt' # 'exec' expr ['in' expr [',' expr]]
def f():
    z = None
    del z
    exec 'z=1+1\n'
    if z != 2: raise TestFailed, 'exec \'z=1+1\'\\n'
    del z
    exec 'z=1+1'
    if z != 2: raise TestFailed, '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: raise TestFailed, 'exec u\'z=1+1\'\\n'
    del z
    exec u'z=1+1'
    if z != 2: raise TestFailed, 'exec u\'z=1+1\''
"""
f()
g = {}
exec 'z = 1' in g
if g.has_key('__builtins__'): del g['__builtins__']
if g != {'z': 1}: raise TestFailed, '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}): raise TestFailed, 'exec ... in g (%s), l (%s)' %(g,l)


print "assert_stmt" # assert_stmt: 'assert' test [',' test]
assert 1
assert 1, 1
assert lambda x:x
assert 1, lambda x:x+1

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

print 'if_stmt' # '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

print 'while_stmt' # '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
assert x == 2

print 'for_stmt' # '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: raise TestFailed, 'for over growing sequence'

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

print 'try_stmt'
### try_stmt: 'try' ':' suite (except_clause ':' suite)+ ['else' ':' suite]
###         | 'try' ':' suite 'finally' ':' suite
### except_clause: 'except' [expr [',' expr]]
try:
    1/0
except ZeroDivisionError:
    pass
else:
    pass
try: 1/0
except EOFError: pass
except TypeError, 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

print 'suite' # simple_stmt | NEWLINE INDENT NEWLINE* (stmt NEWLINE*)+ DEDENT
if 1: pass
if 1:
    pass
if 1:
    #
    #
    #
    pass
    pass
    #
    pass
    #

print 'test'
### 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

print 'comparison'
### 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

print 'binary mask ops'
x = 1 & 1
x = 1 ^ 1
x = 1 | 1

print 'shift ops'
x = 1 << 1
x = 1 >> 1
x = 1 << 1 >> 1

print 'additive ops'
x = 1
x = 1 + 1
x = 1 - 1 - 1
x = 1 - 1 + 1 - 1 + 1

print 'multiplicative ops'
x = 1 * 1
x = 1 / 1
x = 1 % 1
x = 1 / 1 * 1 % 1

print 'unary ops'
x = +1
x = -1
x = ~1
x = ~1 ^ 1 & 1 | 1 & 1 ^ -1
x = -1*1/1 + 1*1 - ---1*1

print 'selectors'
### trailer: '(' [testlist] ')' | '[' subscript ']' | '.' NAME
### subscript: expr | [expr] ':' [expr]
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)
print
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()
print L


print 'atoms'
### 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`
x = `1,2`
x = x
x = 'x'
x = 123

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

print 'classdef' # '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

# list comprehension tests
nums = [1, 2, 3, 4, 5]
strs = ["Apple", "Banana", "Coconut"]
spcs = ["  Apple", " Banana ", "Coco  nut  "]

print [s.strip() for s in spcs]
print [3 * x for x in nums]
print [x for x in nums if x > 2]
print [(i, s) for i in nums for s in strs]
print [(i, s) for i in nums for s in [f for f in strs if "n" in f]]
print [(lambda a:[a**i for i in range(a+1)])(j) for j in range(5)]

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

print test_in_func(nums)

def test_nested_front():
    print [[y for y in [x, x + 1]] for x in [1,3,5]]

test_nested_front()

check_syntax("[i, s for i in nums for s in strs]")
check_syntax("[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)
]

print [
  (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
]

# generator expression tests
g = ([x for x in range(10)] for x in range(1))
verify(g.next() == [x for x in range(10)])
try:
    g.next()
    raise TestFailed, 'should produce StopIteration exception'
except StopIteration:
    pass

a = 1
try:
    g = (a for d in a)
    g.next()
    raise TestFailed, 'should produce TypeError'
except TypeError:
    pass

verify(list((x, y) for x in 'abcd' for y in 'abcd') == [(x, y) for x in 'abcd' for y in 'abcd'])
verify(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))
verify(sum(b) == sum([x for x in range(10)]))

verify(sum(x**2 for x in range(10)) == sum([x**2 for x in range(10)]))
verify(sum(x*x for x in range(10) if x%2) == sum([x*x for x in range(10) if x%2]))
verify(sum(x for x in (y for y in range(10))) == sum([x for x in range(10)]))
verify(sum(x for x in (y for y in (z for z in range(10)))) == sum([x for x in range(10)]))
verify(sum(x for x in [y for y in (z for z in range(10))]) == sum([x for x in range(10)]))
verify(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)]))
verify(sum(x for x in (y for y in (z for z in range(10) if True) if False) if True) == 0)
check_syntax("foo(x for x in range(10), 100)")
check_syntax("foo(100, x for x in range(10))")

# test for outmost iterable precomputation
x = 10; g = (i for i in range(x)); x = 5
verify(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;
verify([(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.)
verify([ x for x in range(10) if x % 2 if x % 3 ], [1, 5, 7])
verify((x for x in range(10) if x % 2 if x % 3), [1, 5, 7])

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

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

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