Add support for StepInTarget request

The change implement the StepInTarget request and also update the
StepRequestHandler to support StepInTarget as well.

Author: gayanper

com.microsoft.java.debug.core/src/main/java/com/microsoft/java/debug/core/adapter/DebugAdapter.java

@@ -44,6 +44,7 @@
 import com.microsoft.java.debug.core.adapter.handler.SetVariableRequestHandler;
 import com.microsoft.java.debug.core.adapter.handler.SourceRequestHandler;
 import com.microsoft.java.debug.core.adapter.handler.StackTraceRequestHandler;
+import com.microsoft.java.debug.core.adapter.handler.StepInTargetsRequestHandler;
 import com.microsoft.java.debug.core.adapter.handler.StepRequestHandler;
 import com.microsoft.java.debug.core.adapter.handler.ThreadsRequestHandler;
 import com.microsoft.java.debug.core.adapter.handler.VariablesRequestHandler;
@@ -131,6 +132,8 @@ private void initialize() {
         registerHandlerForDebug(new ProcessIdHandler());
         registerHandlerForDebug(new SetFunctionBreakpointsRequestHandler());
         registerHandlerForDebug(new BreakpointLocationsRequestHander());
+        registerHandlerForDebug(new StepInTargetsRequestHandler());
+
         // NO_DEBUG mode only
         registerHandlerForNoDebug(new DisconnectRequestWithoutDebuggingHandler());
         registerHandlerForNoDebug(new ProcessIdHandler());

com.microsoft.java.debug.core/src/main/java/com/microsoft/java/debug/core/adapter/ISourceLookUpProvider.java

@@ -11,10 +11,15 @@
 
 package com.microsoft.java.debug.core.adapter;
 
+import java.util.List;
+import java.util.Objects;
+
 import com.microsoft.java.debug.core.DebugException;
 import com.microsoft.java.debug.core.JavaBreakpointLocation;
 import com.microsoft.java.debug.core.protocol.Types.SourceBreakpoint;
 
+import com.sun.jdi.StackFrame;
+
 public interface ISourceLookUpProvider extends IProvider {
     boolean supportsRealtimeBreakpointVerification();
 
@@ -60,4 +65,51 @@ public interface ISourceLookUpProvider extends IProvider {
     default String getJavaRuntimeVersion(String projectName) {
         return null;
     }
+
+    /**
+     * Return method invocation found in the statement as the given line number of
+     * the source file.
+     *
+     * @param stackframe The stack frame where the invocation must be searched.
+     *
+     * @return List of found method invocation or empty if not method invocations
+     *         can be found.
+     */
+    List<MethodInvocation> findMethodInvocations(StackFrame stackframe);
+
+    public static class MethodInvocation {
+        public String expression;
+        public String methodName;
+        public String methodSignature;
+        public String declaringTypeName;
+        public int lineStart;
+        public int lineEnd;
+        public int columnStart;
+        public int columnEnd;
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(columnEnd, columnStart, declaringTypeName, expression, lineEnd, lineStart, methodName,
+                    methodSignature);
+        }
+
+        @Override
+        public boolean equals(Object obj) {
+            if (this == obj) {
+                return true;
+            }
+            if (obj == null) {
+                return false;
+            }
+            if (getClass() != obj.getClass()) {
+                return false;
+            }
+            MethodInvocation other = (MethodInvocation) obj;
+            return columnEnd == other.columnEnd && columnStart == other.columnStart
+                    && Objects.equals(declaringTypeName, other.declaringTypeName)
+                    && Objects.equals(expression, other.expression) && lineEnd == other.lineEnd
+                    && lineStart == other.lineStart && Objects.equals(methodName, other.methodName)
+                    && Objects.equals(methodSignature, other.methodSignature);
+        }
+    }
 }

com.microsoft.java.debug.core/src/main/java/com/microsoft/java/debug/core/adapter/handler/InitializeRequestHandler.java

@@ -65,6 +65,7 @@ public CompletableFuture<Messages.Response> handle(Requests.Command command, Req
         caps.supportsFunctionBreakpoints = true;
         caps.supportsClipboardContext = true;
         caps.supportsBreakpointLocationsRequest = true;
+        caps.supportsStepInTargetsRequest = true;
         response.body = caps;
         return CompletableFuture.completedFuture(response);
     }

com.microsoft.java.debug.core/src/main/java/com/microsoft/java/debug/core/adapter/handler/StepInTargetsRequestHandler.java

@@ -0,0 +1,81 @@
+/*******************************************************************************
+* Copyright (c) 2022 Microsoft Corporation and others.
+* All rights reserved. This program and the accompanying materials
+* are made available under the terms of the Eclipse Public License v1.0
+* which accompanies this distribution, and is available at
+* http://www.eclipse.org/legal/epl-v10.html
+*
+* Contributors:
+*     Gayan Perera - initial API and implementation
+*******************************************************************************/
+package com.microsoft.java.debug.core.adapter.handler;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import java.util.Optional;
+import java.util.concurrent.CompletableFuture;
+
+import com.microsoft.java.debug.core.adapter.IDebugAdapterContext;
+import com.microsoft.java.debug.core.adapter.IDebugRequestHandler;
+import com.microsoft.java.debug.core.adapter.ISourceLookUpProvider;
+import com.microsoft.java.debug.core.adapter.ISourceLookUpProvider.MethodInvocation;
+import com.microsoft.java.debug.core.adapter.variables.StackFrameReference;
+import com.microsoft.java.debug.core.protocol.Messages.Response;
+import com.microsoft.java.debug.core.protocol.Requests.Arguments;
+import com.microsoft.java.debug.core.protocol.Requests.Command;
+import com.microsoft.java.debug.core.protocol.Requests.StepInTargetsArguments;
+import com.microsoft.java.debug.core.protocol.Responses.StepInTargetsResponse;
+import com.microsoft.java.debug.core.protocol.Types.StepInTarget;
+import com.sun.jdi.StackFrame;
+
+public class StepInTargetsRequestHandler implements IDebugRequestHandler {
+
+    @Override
+    public List<Command> getTargetCommands() {
+        return Arrays.asList(Command.STEPIN_TARGETS);
+    }
+
+    @Override
+    public CompletableFuture<Response> handle(Command command, Arguments arguments, Response response,
+            IDebugAdapterContext context) {
+        final StepInTargetsArguments stepInTargetsArguments = (StepInTargetsArguments) arguments;
+
+        final int frameId = stepInTargetsArguments.frameId;
+        return CompletableFuture.supplyAsync(() -> {
+            response.body = new StepInTargetsResponse(
+                    findFrame(frameId, context).map(f -> findTargets(f.thread().uniqueID(), f, context))
+                            .orElse(Collections.emptyList()).toArray(StepInTarget[]::new));
+            return response;
+        });
+    }
+
+    private Optional<StackFrame> findFrame(int frameId, IDebugAdapterContext context) {
+        Object object = context.getRecyclableIdPool().getObjectById(frameId);
+        if (object instanceof StackFrameReference) {
+            return Optional.of(context.getStackFrameManager().getStackFrame((StackFrameReference) object));
+        }
+        return Optional.empty();
+    }
+
+    private List<StepInTarget> findTargets(long threadId, StackFrame stackframe, IDebugAdapterContext context) {
+        ISourceLookUpProvider sourceLookUpProvider = context.getProvider(ISourceLookUpProvider.class);
+        List<MethodInvocation> invocations = sourceLookUpProvider.findMethodInvocations(stackframe);
+        if (invocations.isEmpty()) {
+            return Collections.emptyList();
+        }
+
+        List<StepInTarget> targets = new ArrayList<>(invocations.size());
+        for (MethodInvocation methodInvocation : invocations) {
+            int id = context.getRecyclableIdPool().addObject(threadId, methodInvocation);
+            StepInTarget target = new StepInTarget(id, methodInvocation.expression);
+            target.column = methodInvocation.columnStart;
+            target.endColumn = methodInvocation.columnEnd;
+            target.line = methodInvocation.lineStart;
+            target.endLine = methodInvocation.lineEnd;
+            targets.add(target);
+        }
+        return targets;
+    }
+}