content: /*******************************************************************************
   * Copyright (c) 2005, 2009 IBM 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:
   *     IBM Corporation - initial API and implementation
   *******************************************************************************/
  package org.eclipse.wst.jsdt.ui.text.java;
  
  import org.eclipse.jface.text.ITextViewer;
  import org.eclipse.ui.IEditorPart;
  import org.eclipse.wst.jsdt.core.CompletionContext;
  import org.eclipse.wst.jsdt.core.CompletionProposal;
  import org.eclipse.wst.jsdt.core.IJavaScriptUnit;
  import org.eclipse.wst.jsdt.core.IJavaScriptElement;
  import org.eclipse.wst.jsdt.core.IJavaScriptProject;
  import org.eclipse.wst.jsdt.core.IType;
  import org.eclipse.wst.jsdt.core.JavaScriptModelException;
  import org.eclipse.wst.jsdt.internal.corext.template.java.SignatureUtil;
  import org.eclipse.wst.jsdt.internal.ui.JavaScriptPlugin;
  import org.eclipse.wst.jsdt.internal.ui.javaeditor.EditorUtility;
  import org.eclipse.wst.jsdt.internal.ui.text.java.ContentAssistHistory.RHSHistory;
  
  /**
   * Describes the context of a content assist invocation in a JavaScript editor.
   * <p>
   * Clients may use but not subclass this class.
   * </p>
   * 
   *
   * Provisional API: This class/interface is part of an interim API that is still under development and expected to
   * change significantly before reaching stability. It is being made available at this early stage to solicit feedback
   * from pioneering adopters on the understanding that any code that uses this API will almost certainly be broken
   * (repeatedly) as the API evolves. */
  public class JavaContentAssistInvocationContext extends ContentAssistInvocationContext {
  	private final IEditorPart fEditor;
  	
  	private IJavaScriptUnit fCU= null;
  	private boolean fCUComputed= false;
  	
  	private CompletionProposalLabelProvider fLabelProvider;
  	private CompletionProposalCollector fCollector;
  	private RHSHistory fRHSHistory;
  	private IType fType;
  
  	private IJavaCompletionProposal[] fKeywordProposals= null;
  	private CompletionContext fCoreContext= null;
  
  	/**
  	 * Creates a new context.
  	 * 
  	 * @param viewer the viewer used by the editor
  	 * @param offset the invocation offset
  	 * @param editor the editor that content assist is invoked in
  	 */
  	public JavaContentAssistInvocationContext(ITextViewer viewer, int offset, IEditorPart editor) {
  		super(viewer, offset);
  		
  		fEditor= editor;
  	}
  	
  	/**
  	 * Creates a new context.
  	 * 
  	 * @param unit the compilation unit in <code>document</code>
  	 */
  	public JavaContentAssistInvocationContext(IJavaScriptUnit unit) {
  		super();
  		fCU= unit;
  		fCUComputed= true;
  		fEditor= null;
  	}
  	
  	/**
  	 * Returns the compilation unit that content assist is invoked in, <code>null</code> if there
  	 * is none.
  	 * 
  	 * @return the compilation unit that content assist is invoked in, possibly <code>null</code>
  	 */
  	public IJavaScriptUnit getCompilationUnit() {
  		if (!fCUComputed) {
  			fCUComputed= true;
  			if (fCollector != null)
  				fCU= fCollector.getCompilationUnit();
  			else {
  				IJavaScriptElement je= EditorUtility.getEditorInputJavaElement(fEditor, false);
  				if (je instanceof IJavaScriptUnit)
  					fCU= (IJavaScriptUnit)je;
  			}
  		}
  		return fCU;
  	}
  	
  	/**
  	 * Returns the project of the compilation unit that content assist is invoked in,
  	 * <code>null</code> if none.
  	 * 
  	 * @return the current JavaScript project, possibly <code>null</code>
  	 */
  	public IJavaScriptProject getProject() {
  		IJavaScriptUnit unit= getCompilationUnit();
  		return unit == null ? null : unit.getJavaScriptProject();
  	}
  	
  	/**
  	 * Returns the keyword proposals that are available in this context, possibly none.
  	 * <p>
  	 * <strong>Note:</strong> This method may run
  	 * {@linkplain org.eclipse.wst.jsdt.core.ICodeAssist#codeComplete(int, org.eclipse.wst.jsdt.core.CompletionRequestor) codeComplete}
  	 * on the compilation unit.
  	 * </p>
  	 * 
  	 * @return the available keyword proposals
  	 */
  	public IJavaCompletionProposal[] getKeywordProposals() {
  		if (fKeywordProposals == null) {
  			if (fCollector != null && !fCollector.isIgnored(CompletionProposal.KEYWORD) && fCollector.getContext() != null) {
  				// use the existing collector if it exists, collects keywords, and has already been invoked
  				fKeywordProposals= fCollector.getKeywordCompletionProposals();
  			} else {
  				// otherwise, retrieve keywords ourselves
  				computeKeywordsAndContext();
  			}
  		}
  		
  		return fKeywordProposals;
  	}
  
  	/**
  	 * Returns the {@link CompletionContext core completion context} if available, <code>null</code>
  	 * otherwise.
  	 * <p>
  	 * <strong>Note:</strong> This method may run
  	 * {@linkplain org.eclipse.wst.jsdt.core.ICodeAssist#codeComplete(int, org.eclipse.wst.jsdt.core.CompletionRequestor) codeComplete}
  	 * on the compilation unit.
  	 * </p>
  	 * 
  	 * @return the core completion context if available, <code>null</code> otherwise
  	 */
  	public CompletionContext getCoreContext() {
  		if (fCoreContext == null) {
  			// use the context from the existing collector if it exists, retrieve one ourselves otherwise
  			if (fCollector != null)
  				fCoreContext= fCollector.getContext();
  			if (fCoreContext == null)
  				computeKeywordsAndContext();
  		}
  		return fCoreContext;
  	}
  
  	/**
  	 * Returns an float in [0.0,&nbsp;1.0] based on whether the type has been recently used as a
  	 * right hand side for the type expected in the current context. 0 signals that the
  	 * <code>qualifiedTypeName</code> does not match the expected type, while 1.0 signals that
  	 * <code>qualifiedTypeName</code> has most recently been used in a similar context.
  	 * <p>
  	 * <strong>Note:</strong> This method may run
  	 * {@linkplain org.eclipse.wst.jsdt.core.ICodeAssist#codeComplete(int, org.eclipse.wst.jsdt.core.CompletionRequestor) codeComplete}
  	 * on the compilation unit.
  	 * </p>
  	 * 
  	 * @param qualifiedTypeName the type name of the type of interest
  	 * @return a relevance in [0.0,&nbsp;1.0] based on previous content assist invocations
  	 */
  	public float getHistoryRelevance(String qualifiedTypeName) {
  		return getRHSHistory().getRank(qualifiedTypeName);
  	}
  	
  	/**
  	 * Returns the content assist type history for the expected type.
  	 * 
  	 * @return the content assist type history for the expected type
  	 */
  	private RHSHistory getRHSHistory() {
  		if (fRHSHistory == null) {
  			CompletionContext context= getCoreContext();
  			if (context != null) {
  				char[][] expectedTypes= context.getExpectedTypesSignatures();
  				if (expectedTypes != null && expectedTypes.length > 0) {
  					String expected= SignatureUtil.stripSignatureToFQN(String.valueOf(expectedTypes[0]));
  					fRHSHistory= JavaScriptPlugin.getDefault().getContentAssistHistory().getHistory(expected);
  				}
  			}
  			if (fRHSHistory == null)
  				fRHSHistory= JavaScriptPlugin.getDefault().getContentAssistHistory().getHistory(null);
  		}
  		return fRHSHistory;
  	}
  	
  	/**
  	 * Returns the expected type if any, <code>null</code> otherwise.
  	 * <p>
  	 * <strong>Note:</strong> This method may run
  	 * {@linkplain org.eclipse.wst.jsdt.core.ICodeAssist#codeComplete(int, org.eclipse.wst.jsdt.core.CompletionRequestor) codeComplete}
  	 * on the compilation unit.
  	 * </p>
  	 * 
  	 * @return the expected type if any, <code>null</code> otherwise
  	 */
  	public IType getExpectedType() {
  		if (fType == null && getCompilationUnit() != null) {
  			CompletionContext context= getCoreContext();
  			if (context != null) {
  				char[][] expectedTypes= context.getExpectedTypesSignatures();
  				if (expectedTypes != null && expectedTypes.length > 0) {
  					IJavaScriptProject project= getCompilationUnit().getJavaScriptProject();
  					if (project != null) {
  						try {
  							fType= project.findType(SignatureUtil.stripSignatureToFQN(String.valueOf(expectedTypes[0])));
  						} catch (JavaScriptModelException x) {
  							JavaScriptPlugin.log(x);
  						}
  					}
  				}
  			}
  		}
  		return fType;
  	}
  	
  	/**
  	 * Returns a label provider that can be used to compute proposal labels.
  	 * 
  	 * @return a label provider that can be used to compute proposal labels
  	 */
  	public CompletionProposalLabelProvider getLabelProvider() {
  		if (fLabelProvider == null) {
  			if (fCollector != null)
  				fLabelProvider= fCollector.getLabelProvider();
  			else
  				fLabelProvider= new CompletionProposalLabelProvider();
  		}
  
  		return fLabelProvider;
  	}
  	
  	/**
  	 * Sets the collector, which is used to access the compilation unit, the core context and the
  	 * label provider. This is a performance optimization: {@link IJavaCompletionProposalComputer}s
  	 * may instantiate a {@link CompletionProposalCollector} and set this invocation context via
  	 * {@link CompletionProposalCollector#setInvocationContext(JavaContentAssistInvocationContext)},
  	 * which in turn calls this method. This allows the invocation context to retrieve the core
  	 * context and keyword proposals from the existing collector, instead of computing theses values
  	 * itself via {@link #computeKeywordsAndContext()}.
  	 * 
  	 * @param collector the collector
  	 */
  	protected void setCollector(CompletionProposalCollector collector) {
  		fCollector= collector;
  	}
  	
  	/**
  	 * Fallback to retrieve a core context and keyword proposals when no collector is available.
  	 * Runs code completion on the cu and collects keyword proposals. {@link #fKeywordProposals} is
  	 * non-<code>null</code> after this call.
  	 * 
  	 * 
  	 */
  	private void computeKeywordsAndContext() {
  		IJavaScriptUnit cu= getCompilationUnit();
  		if (cu == null) {
  			if (fKeywordProposals == null)
  				fKeywordProposals= new IJavaCompletionProposal[0];
  			return;
  		}
  		
  		CompletionProposalCollector collector= new CompletionProposalCollector(cu);
  		collector.setIgnored(CompletionProposal.KEYWORD, false);
  		collector.setIgnored(CompletionProposal.ANONYMOUS_CLASS_DECLARATION, true);
  		collector.setIgnored(CompletionProposal.FIELD_REF, true);
  		collector.setIgnored(CompletionProposal.LABEL_REF, true);
  		collector.setIgnored(CompletionProposal.LOCAL_VARIABLE_REF, true);
  		collector.setIgnored(CompletionProposal.METHOD_DECLARATION, true);
  		collector.setIgnored(CompletionProposal.METHOD_NAME_REFERENCE, true);
  		collector.setIgnored(CompletionProposal.METHOD_REF, true);
  		collector.setIgnored(CompletionProposal.PACKAGE_REF, true);
  		collector.setIgnored(CompletionProposal.POTENTIAL_METHOD_DECLARATION, true);
  		collector.setIgnored(CompletionProposal.VARIABLE_DECLARATION, true);
  		collector.setIgnored(CompletionProposal.JSDOC_BLOCK_TAG, true);
  		collector.setIgnored(CompletionProposal.JSDOC_FIELD_REF, true);
  		collector.setIgnored(CompletionProposal.JSDOC_INLINE_TAG, true);
  		collector.setIgnored(CompletionProposal.JSDOC_METHOD_REF, true);
  		collector.setIgnored(CompletionProposal.JSDOC_PARAM_REF, true);
  		collector.setIgnored(CompletionProposal.JSDOC_TYPE_REF, true);
  		collector.setIgnored(CompletionProposal.TYPE_REF, true);
  		
  		try {
  			cu.codeComplete(getInvocationOffset(), collector);
  			if (fCoreContext == null)
  				fCoreContext= collector.getContext();
  			if (fKeywordProposals == null)
  				fKeywordProposals= collector.getKeywordCompletionProposals();
  			if (fLabelProvider == null)
  				fLabelProvider= collector.getLabelProvider();
  		} catch (JavaScriptModelException x) {
  			JavaScriptPlugin.log(x);
  			if (fKeywordProposals == null)
  				fKeywordProposals= new IJavaCompletionProposal[0];
  		}
  	}
  	
  	/*
  	 * Implementation note: There is no need to override hashCode and equals, as we only add cached
  	 * values shared across one assist invocation.
  	 */
  }
  