docs: add doc for DAP evaluation/completion/setValue features

Signed-off-by: azerr <[email protected]>

docs/dap/DAP.md

@@ -26,9 +26,38 @@ To configure debugging with DAP, you need to fill in:
 
   ![DAP Configuration Type/Server](./images/DAP_config_type_server.png)
 
+## Evaluate expression
+
+Evaluate expression is available by consuming the [Evaluate request](https://microsoft.github.io/debug-adapter-protocol//specification.html#Requests_Evaluate) 
+
+![Evaluate expression](./images/DAP_debugging_evaluate.png)
+
+### Completion
+
+If debug adapter [supports the `completions` request](https://microsoft.github.io/debug-adapter-protocol//specification.html#Types_Capabilities),
+completion should be available in the expression editor by consuming the
+[Completion request](https://microsoft.github.io/debug-adapter-protocol//specification.html#Requests_Completions):
+
+![Completion](images/DAP_debugging_completion.png)
+
+## Set value
+
+If debug adapter [supports setting a variable to a value](https://microsoft.github.io/debug-adapter-protocol//specification.html#Types_Capabilities),
+the `Set Value...` contextual menu should be available: 
+
+![Set Value/Menu](images/DAP_debugging_setValue_menu.png)
+
+You should edit the variable:
+
+![Set Value/Edit](images/DAP_debugging_setValue_edit.png)
+
+the edit apply will consume the
+[SetVariable request](https://microsoft.github.io/debug-adapter-protocol//specification.html#Requests_SetVariable):
+
 ## Templates
 
-- [Go Delv DAP server](./user-defined-dap/go-delve.md)
-- [Swift DAP Server](./user-defined-dap/swift-lldb.md)
-- [VSCode JS Debug DAP Server](./user-defined-dap/vscode-js-debug.md)
+LSP4IJ provides DAP templates that allow to initialize a given DAP server very quickly:
 
+- [Go Delve DAP server](./user-defined-dap/go-delve.md) which allows you to debug `Go` files.
+- [Swift DAP Server](./user-defined-dap/swift-lldb.md) which allows you to debug `Swift` files.
+- [VSCode JS Debug DAP Server](./user-defined-dap/vscode-js-debug.md) which allows you to debug `JavaScript/TypeScript` files.

src/main/java/com/redhat/devtools/lsp4ij/dap/client/DAPClient.java

@@ -469,14 +469,36 @@ public CompletableFuture<SetVariableResponse> setVariable(String name,
     // Capabilities
 
 
+    /**
+     * Returns true if the debug adapter supports the 'terminate' request and false otherwise.
+     *
+     * @return true if the debug adapter supports the 'terminate' request and false otherwise.
+     */
     public boolean isSupportsTerminateRequest() {
+        var capabilities = getCapabilities();
         return capabilities != null && Boolean.TRUE.equals(capabilities.getSupportsTerminateRequest());
     }
 
+    /**
+     * Returns true if the debug adapter supports the 'completions' request and false otherwise.
+     *
+     * @return true if the debug adapter supports the 'completions' request and false otherwise.
+     */
     public boolean isSupportsCompletionsRequest() {
+        var capabilities = getCapabilities();
         return capabilities != null && Boolean.TRUE.equals(capabilities.getSupportsCompletionsRequest());
     }
 
+    /**
+     * Returns true if the debug adapter supports setting a variable to a value and false otherwise.
+     *
+     * @return true if the debug adapter supports setting a variable to a value and false otherwise.
+     */
+    public boolean isSupportsSetVariable() {
+        var capabilities = getCapabilities();
+        return capabilities != null && Boolean.TRUE.equals(capabilities.getSupportsSetVariable());
+    }
+
     @NotNull
     public DebugAdapterDescriptor getServerDescriptor() {
         return debugProcess.getServerDescriptor();

src/main/java/com/redhat/devtools/lsp4ij/dap/client/DAPValue.java

@@ -74,6 +74,10 @@ public void computeChildren(@NotNull XCompositeNode node) {
     @Nullable
     @Override
     public XValueModifier getModifier() {
+        if (!client.isSupportsSetVariable()) {
+            // The DAP server doesn't support the setting variable, Disable the 'Set Value...' menu.
+            return null;
+        }
         return new DAPValueModifier(this);
     }