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| <h3>Platform debug model</h3> |
| <p>The platform debug model defines generic debug interfaces that are intended |
| to be implemented and extended in concrete, language-specific implementations.</p> |
| <h4>Artifacts</h4> |
| <p>The model includes classes that represent different artifacts in a program |
| under debug. All of the artifacts implement <a href="../reference/api/org/eclipse/debug/core/model/IDebugElement.html"><b>IDebugElement</b></a> |
| in addition to their own interfaces. The model includes definitions for |
| the following artifacts:</p> |
| <ul> |
| <li>Debug targets (<a href="../reference/api/org/eclipse/debug/core/model/IDebugTarget.html"><b>IDebugTarget</b></a>) |
| - a debuggable execution context, such as a process or virtual machine</li> |
| <li>Expressions (<a href="../reference/api/org/eclipse/debug/core/model/IExpression.html"><b>IExpression</b></a>) |
| - a snippet of code that can be evaluated to produce a value</li> |
| <li>Memory blocks (<a href="../reference/api/org/eclipse/debug/core/model/IMemoryBlock.html"><b>IMemoryBlock</b></a>) |
| - a contiguous segment of memory in an execution context</li> |
| <li>Registers (<a href="../reference/api/org/eclipse/debug/core/model/IRegister.html"><b>IRegister</b></a>) |
| - a named variable in a register group</li> |
| <li>Register groups (<a href="../reference/api/org/eclipse/debug/core/model/IRegisterGroup.html"><b>IRegisterGroup</b></a>) |
| - a group of registers assigned to a stack frame</li> |
| <li>Stack frames (<a href="../reference/api/org/eclipse/debug/core/model/IStackFrame.html"><b>IStackFrame</b></a>) |
| - an execution context in a suspended thread containing local variables and |
| arguments</li> |
| <li>Threads (<a href="../reference/api/org/eclipse/debug/core/model/IThread.html"><b>IThread</b></a>) |
| - a sequential flow of execution in a debug target containing stack frames</li> |
| <li>Values (<a href="../reference/api/org/eclipse/debug/core/model/IValue.html"><b>IValue</b></a>) |
| - the value of a variable</li> |
| <li>Variables (<a href="../reference/api/org/eclipse/debug/core/model/IVariable.html"><b>IVariable</b></a>) |
| - a visible data structure in a stack frame or value</li> |
| <li>Watch expressions (<a href="../reference/api/org/eclipse/debug/core/model/IWatchExpression.html"><b>IWatchExpression</b></a>) |
| - an expression that updates its value when provided with a particular context</li> |
| </ul> |
| <p>Plug-ins that implement language-specific debuggers typically extend these |
| interfaces to include language-specific behavior. All debug elements can |
| return the id of the plug-in that originated them. This is important for |
| registering other classes that are associated with a debug model, such as UI |
| classes.</p> |
| <h4>Actions</h4> |
| <p>The model also includes interfaces that define a set of debug actions that |
| are common behaviors among debug artifacts. These interfaces are |
| implemented by debug elements where appropriate. They include the |
| following actions:</p> |
| <ul> |
| <li>Disconnect (<a href="../reference/api/org/eclipse/debug/core/model/IDisconnect.html"><b>IDisconnect</b></a>) |
| - the ability to end a debug session with a target program and allow the target |
| to continue running</li> |
| <li>Step (<a href="../reference/api/org/eclipse/debug/core/model/IStep.html"><b>IStep</b></a>) |
| - the ability to step into, over, and return from the current execution point</li> |
| <li>Step filters (<a href="../reference/api/org/eclipse/debug/core/model/IStepFilters.html"><b>IStepFilters</b></a>) |
| - the ability to enable or disable filtering of step operations so that a debug target can apply filters to |
| steps when appropriate</li> |
| <li>Suspend and resume (<a href="../reference/api/org/eclipse/debug/core/model/ISuspendResume.html"><b>ISuspendResume</b></a>) |
| - the ability to suspend and resume execution</li> |
| <li>Terminate (<a href="../reference/api/org/eclipse/debug/core/model/ITerminate.html"><b>ITerminate</b></a>) |
| - the ability to terminate an execution context</li> |
| <li>Modify a value (<a href="../reference/api/org/eclipse/debug/core/model/IValueModification.html"><b>IValueModification</b></a>) |
| - the ability to modify the value of a variable</li> |
| </ul> |
| <p>If you look at the definitions for the platform debug elements, you will see |
| that different elements implement different debug actions. Standard |
| interfaces for the elements and their behaviors allow the platform to provide |
| abstract implementations of utility classes and UI support that can be extended |
| for concrete implementations of debuggers.</p> |
| <h4>Events</h4> |
| <p>Debug events (<a href="../reference/api/org/eclipse/debug/core/DebugEvent.html"><b>DebugEvent</b></a>) |
| are used to describe events that occur as a program is being debugged. |
| Debug events include the debug element that is associated with the event. |
| Each kind of debug element has a specific set of events that it supports as |
| documented in <a href="../reference/api/org/eclipse/debug/core/DebugEvent.html"><b>DebugEvent</b></a>. |
| Debugger implementations can add application specific debug events using a designation of |
| <b>DebugEvent.MODEL_SPECIFIC</b> as the kind of event. A client data field can be used in this case |
| to add model-specific information about the event.</p> |
| <p>Debugger UI classes typically listen to specific events for elements in order |
| display information about changes that occur in the elements. Debug events |
| arrive in groups called <b>debug event sets</b>. Events that occur at the |
| same point of execution in a program arrive in the same set. Clients |
| should implement an <a href="../reference/api/org/eclipse/debug/core/IDebugEventSetListener.html"><b>IDebugEventSetListener</b></a> |
| and register the listener with the <a href="../reference/api/org/eclipse/debug/core/package-summary.html"><b>org.eclipse.debug.core</b></a> |
| plug-in in order to receive debug events.</p> |
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