/*******************************************************************************
* Copyright (c) 2006, 2015 Oracle and/or its affiliates. All rights reserved.
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
* which accompanies this distribution.
* The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
* and the Eclipse Distribution License is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* Contributors:
* Oracle - initial API and implementation
*
******************************************************************************/
package org.eclipse.persistence.jpa.jpql.tools;
import org.eclipse.persistence.jpa.jpql.parser.AbsExpression;
import org.eclipse.persistence.jpa.jpql.parser.ArithmeticFactor;
import org.eclipse.persistence.jpa.jpql.parser.AvgFunction;
import org.eclipse.persistence.jpa.jpql.parser.ConcatExpression;
import org.eclipse.persistence.jpa.jpql.parser.DefaultJPQLGrammar;
import org.eclipse.persistence.jpa.jpql.parser.JPQLGrammar;
import org.eclipse.persistence.jpa.jpql.parser.LengthExpression;
import org.eclipse.persistence.jpa.jpql.parser.LocateExpression;
import org.eclipse.persistence.jpa.jpql.parser.LowerExpression;
import org.eclipse.persistence.jpa.jpql.parser.ModExpression;
import org.eclipse.persistence.jpa.jpql.parser.SqrtExpression;
import org.eclipse.persistence.jpa.jpql.parser.SubstringExpression;
import org.eclipse.persistence.jpa.jpql.parser.SumFunction;
import org.eclipse.persistence.jpa.jpql.parser.TrimExpression;
import org.eclipse.persistence.jpa.jpql.parser.UpperExpression;
/**
* This visitor traverses the JPQL parsed tree and gathers the possible proposals at a given position.
* <p>
* Example:
* <pre><code> // Have the external form of an IQuery
* {@link org.eclipse.persistence.jpa.jpql.tools.spi.IQuery IQuery} query = ...
*
* // Create a JPQLQueryContext
* {@link JPQLQueryContext} context = new JPQLQueryContext();
* context.{@link JPQLQueryContext#setQuery(org.eclipse.persistence.jpa.jpql.tools.spi.IQuery) setQuery(query)};
*
* // Create a map of the positions within the parsed tree
* {@link org.eclipse.persistence.jpa.jpql.parser.QueryPosition QueryPosition} queryPosition = context.getJPQLExpression().buildPosition(query.getExpression(), position);
*
* // Either a real extension that adds additional support or
* ContentAssistExtension extension = {@link ContentAssistExtension#NULL_HELPER ContentAssistExtension.NULL_HELPER};
*
* // Create the visitor and visit the parsed tree
* DefaultContentAssistVisitor visitor = new DefaultContentAssistVisitor(context);
* visitor.{@link #buildProposals(int, ContentAssistExtension) buildProposals(queryPosition.getPosition(), extension)};
* queryPosition.getExpression().accept(visitor);
*
* // Retrieve the proposals
* {@link ContentAssistProposals} proposals = visitor.getProposals();
*
* // Only required if the visitor is cached
* visitor.dispose();
*
* // Only required if the context is cached
* context.dispose();
* </code></pre>
* <p>
* Provisional API: This interface is part of an interim API that is still under development and
* expected to change significantly before reaching stability. It is 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.
*
* @version 2.5.1
* @since 2.3
* @author Pascal Filion
*/
public class DefaultContentAssistVisitor extends AbstractContentAssistVisitor {
/**
* Creates a new <code>DefaultContentAssistVisitor</code>.
*
* @param queryContext The context used to query information about the query
* @exception NullPointerException The {@link JPQLQueryContext} cannot be <code>null</code>
*/
public DefaultContentAssistVisitor(JPQLQueryContext queryContext) {
super(queryContext);
}
/**
* {@inheritDoc}
*/
@Override
protected AcceptableTypeVisitor buildAcceptableTypeVisitor() {
return new AcceptableTypeVisitor();
}
/**
* {@inheritDoc}
*/
@Override
protected JPQLGrammar getLatestGrammar() {
return DefaultJPQLGrammar.instance();
}
/**
* {@inheritDoc}
*/
@Override
protected boolean isJoinFetchIdentifiable() {
// Generic JPA does not support identifying a JOIN FETCH with an identification variable
return false;
}
/**
* The concrete instance that determines the return type of a function expression.
*/
protected class AcceptableTypeVisitor extends AbstractContentAssistVisitor.AcceptableTypeVisitor {
/**
* {@inheritDoc}
*/
@Override
public void visit(AbsExpression expression) {
type = queryContext.getType(Number.class);
}
/**
* {@inheritDoc}
*/
@Override
public void visit(ArithmeticFactor expression) {
type = queryContext.getType(Number.class);
}
/**
* {@inheritDoc}
*/
@Override
public void visit(AvgFunction expression) {
type = queryContext.getType(Number.class);
}
/**
* {@inheritDoc}
*/
@Override
public void visit(ConcatExpression expression) {
type = queryContext.getType(CharSequence.class);
}
/**
* {@inheritDoc}
*/
@Override
public void visit(LengthExpression expression) {
type = queryContext.getType(CharSequence.class);
}
/**
* {@inheritDoc}
*/
@Override
public void visit(LocateExpression expression) {
// TODO: Handle the position
type = queryContext.getType(CharSequence.class);
}
/**
* {@inheritDoc}
*/
@Override
public void visit(LowerExpression expression) {
type = queryContext.getType(CharSequence.class);
}
/**
* {@inheritDoc}
*/
@Override
public void visit(ModExpression expression) {
// In theory we would only allow Long and Integer
type = queryContext.getType(Number.class);
}
/**
* {@inheritDoc}
*/
@Override
public void visit(SqrtExpression expression) {
type = queryContext.getType(Number.class);
}
/**
* {@inheritDoc}
*/
@Override
public void visit(SubstringExpression expression) {
// TODO: Handle the position
type = queryContext.getType(CharSequence.class);
}
/**
* {@inheritDoc}
*/
@Override
public void visit(SumFunction expression) {
type = queryContext.getType(Number.class);
}
/**
* {@inheritDoc}
*/
@Override
public void visit(TrimExpression expression) {
type = queryContext.getType(CharSequence.class);
}
/**
* {@inheritDoc}
*/
@Override
public void visit(UpperExpression expression) {
type = queryContext.getType(CharSequence.class);
}
}
}