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Re: [cdt-dev] DSF/GDB: context types required to create an expression

On 21/06/2010 5:44 PM, Pawel Piech wrote:

On 06/21/2010 12:16 PM, Mikhail Khodjaiants wrote:
It seems the following is a better option, but I haven't tried it yet.

public interface IGDBRegisters extends IRegisters {

    public interface IGDBRegisterDMContext extends IRegisterDMContext {

         IExpressionDMContext getExpressionDMC();

    public interface IGDBRegisterDMData extends IRegisterDMData {

        IExpressionDMData getExpressionData();

To me it seems that you'll have more flexibility if you keep the fact that the registers use expressions underneath as an implementation detail and not expose it in any API.

You're right, I can do it without exposing as an API.

In this case I can pass IRegisterDMContext as a parent to MIExpressionDMC.

I see, though I'm not entirely clear on why you need the register as a parent context of the expression. The parent relationship in contexts is mainly intended to allow you to implement equals() and hashCode() of contexts properly. So for example, frame 0 of one thread is different than frame 0 of another thread. In case of register service using the expression service, a "#pc" expression created by the registers service should be the same as a "#pc" expression typed in by the user in the expressions view, and the same as "#pc" evaluated by some other client (like the disassembly view). This will allow the expressions service to user the same cach value of "#pc" for all the clients.

Which means the disassembly view has to create an expression for #pc with the same context as if it was created by the register service. If disassembly "knows" that pc is a register name, it can use the register service to evaluate it not the expression service directly. I have also noticed that IExpressionDMData interface has getRegister() method. What's the purpose of it? To identify expressions created for registers?


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