Just tested it, swapping body of stackPop with (aget data depth) has the
same effect as swapping it with zero, i.e. it fixes the error,
unfortunately, not in the correct way.
вторник, 18 декабря 2012 г., 22:46:53 UTC+4 пользователь Vladimir Matveev
написал:
>
> Well, it is news for me since it is not documented anywhere. Why is this
> so? BTW, typehinting value in '(let [value (aget data depth)]' binding
> gives an error "Can't type hint a local with a primitive initializer" so I
> think since this value considered primitive then I actually can hint the
> fields to be primitive arrays.
> Nonetheless, it does not look like that problem is in the field array:
> wrapping aget form with (int) does not help.
>
> вторник, 18 декабря 2012 г., 17:46:14 UTC+4 пользователь David Nolen
> написал:
>>
>> I don't think you can type hint a field as a primitive array.
>>
>> On Tuesday, December 18, 2012, Vladimir Matveev wrote:
>>
>>> Hello,
>>>
>>> Consider the following code
>>>
>>> (gen-interface
>>> :name IntStack
>>> :methods [[stackPeek [] int]
>>> [stackPush [int] void]
>>> [stackPop [] int]
>>> [stackDepth [] int]])
>>>
>>> (deftype IntStackImpl
>>> [^{:tag ints :unsynchronized-mutable true} data
>>> ^{:tag int :unsynchronized-mutable true} depth]
>>> IntStack
>>> (stackPeek [this]
>>> (aget data depth))
>>> (stackPush [this value]
>>> (when (>= (inc depth) (alength data))
>>> (let [data-length (alength data)
>>> new-data (int-array (* data-length 2))]
>>> (System/arraycopy data 0 new-data 0 data-length)
>>> (set! data new-data)))
>>> (set! depth (inc depth))
>>> (aset data depth value))
>>> (stackPop [this]
>>> (if (> depth 0)
>>> (let [value (aget data depth)]
>>> (set! depth (dec depth))
>>> value)
>>> (throw (IllegalStateException. "Stack is already empty!"))))
>>> (stackDepth [this]
>>> depth))
>>>
>>> This is very simple stack implementation over plain java array. It does
>>> not compile with the following message:
>>> CompilerException java.lang.VerifyError: (class:
>>> clojure/data/xml/IntStackImpl, method: stackPop signature: ()I) Expecting
>>> to find integer on stack
>>>
>>> However, when I replace the body of stackPop with, say, plain zero
>>> literal 0, the method seems to pass the compilation, because then I'm
>>> getting similar error on stackPush method instead.
>>> Placing type hints inside stackPop method does not work (in fact, it is
>>> even an error to place them, say, on value local binding).
>>>
>>> What am I doing wrong here? How to make the class compile?
>>>
>>> Cheers,
>>> Vladimir.
>>>
>>>
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>>
>>
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