org.eclipse.lsp4e.debug/src/org/eclipse/lsp4e/debug/breakpoints/TextSelectionToIVariable.java

/*******************************************************************************
 * Copyright (c) 2018 Red Hat Inc. and others.
 * This program and the accompanying materials are made
 * available under the terms of the Eclipse Public License 2.0
 * which is available at https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *******************************************************************************/
package org.eclipse.lsp4e.debug.breakpoints;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.concurrent.ExecutionException;

import org.eclipse.core.runtime.Adapters;
import org.eclipse.core.runtime.IAdaptable;
import org.eclipse.core.runtime.IAdapterFactory;
import org.eclipse.debug.core.DebugException;
import org.eclipse.debug.core.model.IValue;
import org.eclipse.debug.core.model.IVariable;
import org.eclipse.debug.ui.DebugUITools;
import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.TextSelection;
import org.eclipse.lsp4e.debug.DSPPlugin;
import org.eclipse.lsp4e.debug.debugmodel.DSPStackFrame;

public class TextSelectionToIVariable implements IAdapterFactory {

	@Override
	public <T> T getAdapter(Object adaptableObject, Class<T> adapterType) {
		if (!(adaptableObject instanceof TextSelection)) {
			return null;
		}
		if (!IVariable.class.isAssignableFrom(adapterType)) {
			return null;
		}
		TextSelection selection = (TextSelection) adaptableObject;
		return (T) getVariableFor(selection);
	}

	@Override
	public Class<?>[] getAdapterList() {
		return new Class<?>[] { IVariable.class };
	}

	private IVariable getVariableFor(TextSelection selection) {
		IDocument document = getDocument(selection);
		if (document == null) {
			return null;
		}
		DSPStackFrame frame = getFrame();
		if (frame == null) {
			return null;
		}
		try {
			String variableName = document.get(selection.getOffset(), selection.getLength());
			if (variableName.isEmpty()) {
				variableName = findVariableName(document, selection.getOffset());
			}

			if (Boolean.TRUE.equals(frame.getDebugTarget().getCapabilities().getSupportsEvaluateForHovers())) {
				try {
					// ok to call get as it should be a different thread.
					return frame.evaluate(variableName).get();
				} catch (ExecutionException e) {
					DSPPlugin.logError(e);
					// will fall back by looking by looking up in current frame
				} catch (InterruptedException e) {
					Thread.currentThread().interrupt();
					DSPPlugin.logError(e);
					// will fall back by looking by looking up in current frame
				}

			}

			try {
				for (IVariable scopeVariable : frame.getVariables()) {
					IValue scope = scopeVariable.getValue();
					if (scope != null) {
						IVariable[] vars = scope.getVariables();
						for (IVariable var : vars) {
							if (var.getName().equals(variableName)) {
								return var;
							}
						}
					}
				}
			} catch (DebugException de) {
				DSPPlugin.logError(de);
			}

		} catch (BadLocationException e) {
			DSPPlugin.logError(e);
		}
		return null;
	}

	private String findVariableName(IDocument document, int offset) {
		try {
			if (!Character.isJavaIdentifierPart(document.getChar(offset))) {
				return null;
			}
			int startOffset = offset;
			while (startOffset - 1 >= 0 && Character.isJavaIdentifierPart(document.getChar(startOffset - 1)))
				startOffset--;
			int endOffset = offset;
			while (endOffset + 1 < document.getLength()
					&& Character.isJavaIdentifierPart(document.getChar(endOffset + 1)))
				endOffset++;
			return document.get(startOffset, endOffset - startOffset + 1);
		} catch (BadLocationException ex) {
			DSPPlugin.logError(ex);
			return null;
		}
	}

	protected DSPStackFrame getFrame() {
		IAdaptable adaptable = DebugUITools.getDebugContext();
		if (adaptable != null) {
			return Adapters.adapt(adaptable, DSPStackFrame.class);
		}
		return null;
	}

	private IDocument getDocument(TextSelection sel) {
		try {
			Method documentMethod = TextSelection.class.getDeclaredMethod("getDocument"); //$NON-NLS-1$
			documentMethod.setAccessible(true);
			return (IDocument) documentMethod.invoke(sel);
		} catch (NoSuchMethodException | IllegalArgumentException | IllegalAccessException
				| InvocationTargetException e) {
			DSPPlugin.logError(e);
			return null;
		}
	}

}