import unittest
import weakref

from test.support import check_syntax_error, cpython_only


class ScopeTests(unittest.TestCase):

    def testSimpleNesting(self):

        def make_adder(x):
            def adder(y):
                return x + y
            return adder

        inc = make_adder(1)
        plus10 = make_adder(10)

        self.assertEqual(inc(1), 2)
        self.assertEqual(plus10(-2), 8)

    def testExtraNesting(self):

        def make_adder2(x):
            def extra(): # check freevars passing through non-use scopes
                def adder(y):
                    return x + y
                return adder
            return extra()

        inc = make_adder2(1)
        plus10 = make_adder2(10)

        self.assertEqual(inc(1), 2)
        self.assertEqual(plus10(-2), 8)

    def testSimpleAndRebinding(self):

        def make_adder3(x):
            def adder(y):
                return x + y
            x = x + 1 # check tracking of assignment to x in defining scope
            return adder

        inc = make_adder3(0)
        plus10 = make_adder3(9)

        self.assertEqual(inc(1), 2)
        self.assertEqual(plus10(-2), 8)

    def testNestingGlobalNoFree(self):

        def make_adder4(): # XXX add exta level of indirection
            def nest():
                def nest():
                    def adder(y):
                        return global_x + y # check that plain old globals work
                    return adder
                return nest()
            return nest()

        global_x = 1
        adder = make_adder4()
        self.assertEqual(adder(1), 2)

        global_x = 10
        self.assertEqual(adder(-2), 8)

    def testNestingThroughClass(self):

        def make_adder5(x):
            class Adder:
                def __call__(self, y):
                    return x + y
            return Adder()

        inc = make_adder5(1)
        plus10 = make_adder5(10)

        self.assertEqual(inc(1), 2)
        self.assertEqual(plus10(-2), 8)

    def testNestingPlusFreeRefToGlobal(self):

        def make_adder6(x):
            global global_nest_x
            def adder(y):
                return global_nest_x + y
            global_nest_x = x
            return adder

        inc = make_adder6(1)
        plus10 = make_adder6(10)

        self.assertEqual(inc(1), 11) # there's only one global
        self.assertEqual(plus10(-2), 8)

    def testNearestEnclosingScope(self):

        def f(x):
            def g(y):
                x = 42 # check that this masks binding in f()
                def h(z):
                    return x + z
                return h
            return g(2)

        test_func = f(10)
        self.assertEqual(test_func(5), 47)

    def testMixedFreevarsAndCellvars(self):

        def identity(x):
            return x

        def f(x, y, z):
            def g(a, b, c):
                a = a + x # 3
                def h():
                    # z * (4 + 9)
                    # 3 * 13
                    return identity(z * (b + y))
                y = c + z # 9
                return h
            return g

        g = f(1, 2, 3)
        h = g(2, 4, 6)
        self.assertEqual(h(), 39)

    def testFreeVarInMethod(self):

        def test():
            method_and_var = "var"
            class Test:
                def method_and_var(self):
                    return "method"
                def test(self):
                    return method_and_var
                def actual_global(self):
                    return str("global")
                def str(self):
                    return str(self)
            return Test()

        t = test()
        self.assertEqual(t.test(), "var")
        self.assertEqual(t.method_and_var(), "method")
        self.assertEqual(t.actual_global(), "global")

        method_and_var = "var"
        class Test:
            # this class is not nested, so the rules are different
            def method_and_var(self):
                return "method"
            def test(self):
                return method_and_var
            def actual_global(self):
                return str("global")
            def str(self):
                return str(self)

        t = Test()
        self.assertEqual(t.test(), "var")
        self.assertEqual(t.method_and_var(), "method")
        self.assertEqual(t.actual_global(), "global")

    def testCellIsKwonlyArg(self):
        # Issue 1409: Initialisation of a cell value,
        # when it comes from a keyword-only parameter
        def foo(*, a=17):
            def bar():
                return a + 5
            return bar() + 3

        self.assertEqual(foo(a=42), 50)
        self.assertEqual(foo(), 25)

    def testRecursion(self):

        def f(x):
            def fact(n):
                if n == 0:
                    return 1
                else:
                    return n * fact(n - 1)
            if x >= 0:
                return fact(x)
            else:
                raise ValueError("x must be >= 0")

        self.assertEqual(f(6), 720)


    def testUnoptimizedNamespaces(self):

        check_syntax_error(self, """if 1:
            def unoptimized_clash1(strip):
                def f(s):
                    from sys import *
                    return getrefcount(s) # ambiguity: free or local
                return f
            """)

        check_syntax_error(self, """if 1:
            def unoptimized_clash2():
                from sys import *
                def f(s):
                    return getrefcount(s) # ambiguity: global or local
                return f
            """)

        check_syntax_error(self, """if 1:
            def unoptimized_clash2():
                from sys import *
                def g():
                    def f(s):
                        return getrefcount(s) # ambiguity: global or local
                    return f
            """)

        check_syntax_error(self, """if 1:
            def f():
                def g():
                    from sys import *
                    return getrefcount # global or local?
            """)

    def testLambdas(self):

        f1 = lambda x: lambda y: x + y
        inc = f1(1)
        plus10 = f1(10)
        self.assertEqual(inc(1), 2)
        self.assertEqual(plus10(5), 15)

        f2 = lambda x: (lambda : lambda y: x + y)()
        inc = f2(1)
        plus10 = f2(10)
        self.assertEqual(inc(1), 2)
        self.assertEqual(plus10(5), 15)

        f3 = lambda x: lambda y: global_x + y
        global_x = 1
        inc = f3(None)
        self.assertEqual(inc(2), 3)

        f8 = lambda x, y, z: lambda a, b, c: lambda : z * (b + y)
        g = f8(1, 2, 3)
        h = g(2, 4, 6)
        self.assertEqual(h(), 18)

    def testUnboundLocal(self):

        def errorInOuter():
            print(y)
            def inner():
                return y
            y = 1

        def errorInInner():
            def inner():
                return y
            inner()
            y = 1

        self.assertRaises(UnboundLocalError, errorInOuter)
        self.assertRaises(NameError, errorInInner)

    def testUnboundLocal_AfterDel(self):
        # #4617: It is now legal to delete a cell variable.
        # The following functions must obviously compile,
        # and give the correct error when accessing the deleted name.
        def errorInOuter():
            y = 1
            del y
            print(y)
            def inner():
                return y

        def errorInInner():
            def inner():
                return y
            y = 1
            del y
            inner()

        self.assertRaises(UnboundLocalError, errorInOuter)
        self.assertRaises(NameError, errorInInner)

    def testUnboundLocal_AugAssign(self):
        # test for bug #1501934: incorrect LOAD/STORE_GLOBAL generation
        exec("""if 1:
            global_x = 1
            def f():
                global_x += 1
            try:
                f()
            except UnboundLocalError:
                pass
            else:
                fail('scope of global_x not correctly determined')
            """, {'fail': self.fail})

    def testComplexDefinitions(self):

        def makeReturner(*lst):
            def returner():
                return lst
            return returner

        self.assertEqual(makeReturner(1,2,3)(), (1,2,3))

        def makeReturner2(**kwargs):
            def returner():
                return kwargs
            return returner

        self.assertEqual(makeReturner2(a=11)()['a'], 11)

    def testScopeOfGlobalStmt(self):
        # Examples posted by Samuele Pedroni to python-dev on 3/1/2001

        exec("""if 1:
            # I
            x = 7
            def f():
                x = 1
                def g():
                    global x
                    def i():
                        def h():
                            return x
                        return h()
                    return i()
                return g()
            self.assertEqual(f(), 7)
            self.assertEqual(x, 7)

            # II
            x = 7
            def f():
                x = 1
                def g():
                    x = 2