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describe :kernel_instance_callcc, :shared => true do
it "is a private method" do
Kernel.should have_private_instance_method(:callcc)
end
end
describe :kernel_callcc, :shared => true do
it "is possible to exit a loop like a break" do
i = 0
@object.callcc do |x|
loop do
i += 1
x.call() if i == 5
end
end.should == nil
i.should == 5
end
it "is possible to call a continuation multiple times" do
i = 0
cont = nil
@cont = nil
@object.callcc {|cont| @cont = cont}
i += 1
@cont.call() if i < 5
i.should == 5
end
it "returns the results of a block if continuation is not called" do
cont = nil
a = @object.callcc {|cont| 0}
a.should == 0
end
it "returns the results of continuation once called" do
cont = nil
@cont = nil
a = @object.callcc {|cont| @cont = cont; 0}
@cont.call(1) if a == 0
a.should == 1
end
it "returns the arguments to call" do
@object.callcc {|cont| cont.call }.should == nil
@object.callcc {|cont| cont.call 1 }.should == 1
@object.callcc {|cont| cont.call 1,2,3 }.should == [1,2,3]
end
it "preserves changes to block-local scope" do
i = "before"
cont = @object.callcc { |c| c }
if cont # nil the second time
i = "after"
cont.call
end
i.should == "after"
end
it "preserves changes to method-local scope" do
# This spec tests that a continuation shares the same locals
# tuple as the scope that created it.
KernelSpecs.before_and_after.should == "after"
end
it "raises a LocalJumpError if callcc is not given a block" do
lambda { @object.callcc }.should raise_error(LocalJumpError)
end
end
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