RubyDebugHover.java

/**
 * Aptana Studio
 * Copyright (c) 2005-2011 by Appcelerator, Inc. All Rights Reserved.
 * Licensed under the terms of the GNU Public License (GPL) v3 (with exceptions).
 * Please see the license.html included with this distribution for details.
 * Any modifications to this file must keep this entire header intact.
 */
package com.aptana.ruby.internal.debug.ui;

import org.eclipse.core.runtime.IAdaptable;
import org.eclipse.debug.core.DebugException;
import org.eclipse.debug.core.model.IVariable;
import org.eclipse.debug.ui.DebugUITools;
import org.eclipse.debug.ui.IDebugModelPresentation;
import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.IRegion;
import org.eclipse.jface.text.ITextHover;
import org.eclipse.jface.text.ITextHoverExtension2;
import org.eclipse.jface.text.ITextViewer;

import com.aptana.ruby.debug.core.RubyDebugModel;
import com.aptana.ruby.debug.core.model.IRubyStackFrame;

/**
 * @author Max Stepanov
 * @author cwilliams
 */
public class RubyDebugHover implements ITextHover, ITextHoverExtension2
{

	private static IDebugModelPresentation modelPresentation;

	/*
	 * (non-Javadoc)
	 * @see org.eclipse.jface.text.ITextHover#getHoverInfo(org.eclipse.jface.text.ITextViewer,
	 * org.eclipse.jface.text.IRegion)
	 */
	public String getHoverInfo(ITextViewer textViewer, IRegion hoverRegion)
	{
		Object info = getHoverInfo2(textViewer, hoverRegion);
		return info != null ? info.toString() : null;
	}

	/*
	 * (non-Javadoc)
	 * @see org.eclipse.jface.text.ITextHover#getHoverRegion(org.eclipse.jface.text.ITextViewer, int)
	 */
	public IRegion getHoverRegion(ITextViewer textViewer, int offset)
	{
		return null; // JavaWordFinder.findWord(textViewer.getDocument(), offset);
	}

	/*
	 * (non-Javadoc)
	 * @see org.eclipse.jface.text.ITextHoverExtension2#getHoverInfo2(org.eclipse.jface.text.ITextViewer,
	 * org.eclipse.jface.text.IRegion)
	 */
	public Object getHoverInfo2(ITextViewer textViewer, IRegion hoverRegion)
	{
		IRubyStackFrame frame = getFrame();
		if (frame != null)
		{
			IDocument document = textViewer.getDocument();
			if (document != null)
			{
				try
				{
					String variableName = document.get(hoverRegion.getOffset(), hoverRegion.getLength());
					try
					{
						IVariable[] variables = frame.getVariables();
						if (variables != null)
						{
							for (IVariable variable : variables)
							{
								if (variableName.equals(variable.getName()))
								{
									return getVariableText(variable);
								}
							}
						}
					}
					catch (DebugException e)
					{
						return null;
					}
				}
				catch (BadLocationException e)
				{
					return null;
				}
			}
		}
		return null;
	}

	private IRubyStackFrame getFrame()
	{
		IAdaptable adaptable = DebugUITools.getDebugContext();
		if (adaptable != null)
		{
			return (IRubyStackFrame) adaptable.getAdapter(IRubyStackFrame.class);
		}
		return null;
	}

	/*
	 * Returns HTML text for the given variable
	 */
	private String getVariableText(IVariable variable)
	{
		StringBuilder sb = new StringBuilder();
		IDebugModelPresentation modelPresentation = getModelPresentation();
		sb.append("<p><pre>"); //$NON-NLS-1$
		String variableText = modelPresentation.getText(variable);
		sb.append(replaceHTMLChars(variableText));
		sb.append("</pre></p>"); //$NON-NLS-1$
		if (sb.length() > 0)
		{
			return sb.toString();
		}
		return null;
	}

	/*
	 * Replaces reserved HTML characters in the given string with their escaped equivalents. This is to ensure that
	 * variable values containing reserved characters are correctly displayed.
	 */
	private static String replaceHTMLChars(String variableText)
	{
		StringBuilder sb = new StringBuilder(variableText.length());
		char[] characters = variableText.toCharArray();
		for (int i = 0; i < characters.length; i++)
		{
			char character = characters[i];
			switch (character)
			{
				case '<':
					sb.append("<"); //$NON-NLS-1$
					break;
				case '>':
					sb.append(">"); //$NON-NLS-1$
					break;
				case '&':
					sb.append("&"); //$NON-NLS-1$
					break;
				case '"':
					sb.append("""); //$NON-NLS-1$
					break;
				default:
					sb.append(character);
			}
		}
		return sb.toString();
	}

	private static IDebugModelPresentation getModelPresentation()
	{
		if (modelPresentation == null)
		{
			modelPresentation = DebugUITools.newDebugModelPresentation(RubyDebugModel.getModelIdentifier());
			modelPresentation.setAttribute(IDebugModelPresentation.DISPLAY_VARIABLE_TYPE_NAMES, Boolean.TRUE);
		}
		return modelPresentation;
	}

}