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/*
 * Copyright (c) 2011, 2018 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 v. 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0,
 * or the Eclipse Distribution License v. 1.0 which is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
 */

// Contributors:
//     Oracle - initial API and implementation
//
package org.eclipse.persistence.jpa.jpql.tools.model.query;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import org.eclipse.persistence.jpa.jpql.parser.InternalSelectExpressionBNF;
import org.eclipse.persistence.jpa.jpql.parser.SelectClause;
import org.eclipse.persistence.jpa.jpql.parser.SelectExpressionBNF;
import org.eclipse.persistence.jpa.jpql.tools.model.IListChangeListener;
import org.eclipse.persistence.jpa.jpql.tools.model.ISelectExpressionStateObjectBuilder;
import org.eclipse.persistence.jpa.jpql.utility.iterable.ListIterable;
import org.eclipse.persistence.jpa.jpql.utility.iterable.SnapshotCloneListIterable;
import static org.eclipse.persistence.jpa.jpql.parser.AbstractExpression.*;
import static org.eclipse.persistence.jpa.jpql.parser.Expression.*;

/**
 * The SELECT statement queries data from entities, which determines the type of
 * the objects or values to be selected.
 *
 * 
BNF: select_clause ::= SELECT [DISTINCT] select_expression {, select_expression}*
 *     select_expression ::= single_valued_path_expression |
 *                           aggregate_expression |
 *                           identification_variable |
 *                           OBJECT(identification_variable) |
 *                           constructor_expression
* * @see SelectStatementStateObject * @see SelectClause * * @version 2.4 * @since 2.4 * @author Pascal Filion */ @SuppressWarnings({"nls", "unused"}) // unused used for the import statement: see bug 330740 public class SelectClauseStateObject extends AbstractSelectClauseStateObject implements ListHolderStateObject { /** * The builder is cached during the creation of the select expression. */ private ISelectExpressionStateObjectBuilder builder; /** * The list of select expressions. */ private List items; /** * A constant used to notify the list of select expressions has changed. */ public static final String SELECT_ITEMS_LIST = "selectItems"; /** * Creates a new SelectClauseStateObject. * * @param parent The parent of this state object, which cannot be null * @exception NullPointerException The given parent cannot be null */ public SelectClauseStateObject(SelectStatementStateObject parent) { super(parent); } /** * {@inheritDoc} */ public void accept(StateObjectVisitor visitor) { visitor.visit(this); } /** * {@inheritDoc} */ @Override protected void addChildren(List children) { super.addChildren(children); children.addAll(items); } /** * Adds the given {@link StateObject} as a select item. * * @param stateObject The {@link StateObject} representing the select expression * @param resultVariable The result variable identifying the select expression * @return The newly created {@link ResultVariableStateObject} */ public ResultVariableStateObject addItem(StateObject stateObject, String resultVariable) { ResultVariableStateObject item = new ResultVariableStateObject( this, stateObject, false, resultVariable ); addItem(item); return item; } /** * Adds the given path as a select item, which can either be an identification variable or a * state-field path expression. * * @param jpqlFragment The select expression to parse as a select item * @return The {@link StateObject} encapsulating the given path */ public StateObject addItem(String jpqlFragment) { StateObject item = buildStateObject(jpqlFragment, SelectExpressionBNF.ID); addItem(item); return item; } /** * Adds the given expression as a select item. * * @param jpqlFragment The select expression to parse as a select item * @param resultVariable The result variable identifying the select expression * @return The newly created {@link ResultVariableStateObject} */ public ResultVariableStateObject addItem(String jpqlFragment, String resultVariable) { ResultVariableStateObject item = new ResultVariableStateObject(this); item.parse(jpqlFragment); item.setResultVariable(resultVariable); addItem(item); return item; } /** * {@inheritDoc} */ public S addItem(S item) { getChangeSupport().addItem(this, items, SELECT_ITEMS_LIST, parent(item)); return item; } /** * Adds the given {@link StateObject} as a select item. * * @param stateObject The {@link StateObject} representing the select expression * @param resultVariable The result variable identifying the select expression * @return The newly created {@link ResultVariableStateObject} */ public ResultVariableStateObject addItemAs(StateObject stateObject, String resultVariable) { ResultVariableStateObject item = new ResultVariableStateObject( this, stateObject, true, resultVariable ); addItem(item); return item; } /** * Adds the given JPQL fragment as a select item. * * @param jpqlFragment The portion of a JPQL query that represents a select expression * @param resultVariable The result variable identifying the select expression * @return The newly created {@link ResultVariableStateObject} */ public ResultVariableStateObject addItemAs(String jpqlFragment, String resultVariable) { ResultVariableStateObject item = new ResultVariableStateObject(this); item.addAs(); item.parse(jpqlFragment); item.setResultVariable(resultVariable); addItem(item); return item; } /** * {@inheritDoc} */ public void addItems(List items) { getChangeSupport().addItems(this, this.items, SELECT_ITEMS_LIST, parent(items)); } /** * {@inheritDoc} */ public void addListChangeListener(String listName, IListChangeListener listener) { getChangeSupport().addListChangeListener(listName, listener); } /** * Determines whether the children of this {@link StateObject} are equivalent to the children * of the given one, i.e. the information of the {@link StateObject StateObjects} is the same. * * @param stateObject The {@link StateObject} to compare its children to this one's children * @return true if both have equivalent children; false otherwise */ protected boolean areChildrenEquivalent(SelectClauseStateObject stateObject) { int size = itemsSize(); if (size != stateObject.itemsSize()) { return false; } for (int index = size; --index >= 0; ) { StateObject child1 = getItem(index); StateObject child2 = stateObject.getItem(index); if (!child1.isEquivalent(child2)) { return false; } } return true; } /** * {@inheritDoc} */ public boolean canMoveDown(StateObject item) { return getChangeSupport().canMoveDown(items, item); } /** * {@inheritDoc} */ public boolean canMoveUp(StateObject item) { return getChangeSupport().canMoveUp(items, item); } /** * Creates and returns a new {@link ISelectExpressionStateObjectBuilder} that can be used to * programmatically create a single select expression and once the expression is complete, * {@link ISelectExpressionStateObjectBuilder#commit()} will push the {@link StateObject} * representation of that expression as this clause's select expression. * * @return A new builder that can be used to quickly create a select expression */ public ISelectExpressionStateObjectBuilder getBuilder() { if (builder == null) { builder = getQueryBuilder().buildStateObjectBuilder(this); } return builder; } /** * {@inheritDoc} */ @Override public SelectClause getExpression() { return (SelectClause) super.getExpression(); } /** * {@inheritDoc} */ @Override public FromClauseStateObject getFromClause() { return (FromClauseStateObject) super.getFromClause(); } /** * {@inheritDoc} */ public StateObject getItem(int index) { return items.get(index); } /** * {@inheritDoc} */ @Override public SelectStatementStateObject getParent() { return (SelectStatementStateObject) super.getParent(); } /** * {@inheritDoc} */ public boolean hasItems() { return items.size() > 0; } /** * {@inheritDoc} */ @Override public boolean hasSelectItem() { return hasItems(); } /** * {@inheritDoc} */ @Override protected void initialize() { super.initialize(); items = new ArrayList(); } /** * {@inheritDoc} */ @Override public boolean isEquivalent(StateObject stateObject) { return super.isEquivalent(stateObject) && areChildrenEquivalent((SelectClauseStateObject) stateObject); } /** * {@inheritDoc} */ public ListIterable items() { return new SnapshotCloneListIterable(items); } /** * {@inheritDoc} */ public int itemsSize() { return items.size(); } /** * {@inheritDoc} */ public StateObject moveDown(StateObject item) { getChangeSupport().moveDown(this, items, SELECT_ITEMS_LIST, item); return item; } /** * {@inheritDoc} */ public StateObject moveUp(StateObject item) { getChangeSupport().moveUp(this, items, SELECT_ITEMS_LIST, item); return item; } /** * {@inheritDoc} */ @Override public void parse(String jpqlFragment) { List stateObjects = buildStateObjects(jpqlFragment, InternalSelectExpressionBNF.ID); addItems(stateObjects); } /** * {@inheritDoc} */ public void removeItem(StateObject stateObject) { getChangeSupport().removeItem(this, items, SELECT_ITEMS_LIST, stateObject); } /** * {@inheritDoc} */ public void removeItems(Collection items) { getChangeSupport().removeItems(this, this.items, SELECT_ITEMS_LIST, items); } /** * {@inheritDoc} */ public void removeListChangeListener(String listName, IListChangeListener listener) { getChangeSupport().removeListChangeListener(listName, listener); } /** * Keeps a reference of the {@link SelectClause parsed object} object, which should only be * done when this object is instantiated during the conversion of a parsed JPQL query into * {@link StateObject StateObjects}. * * @param expression The {@link SelectClause parsed object} representing a SELECT * clause */ public void setExpression(SelectClause expression) { super.setExpression(expression); } /** * Sets the select expression to be those contained on the given collection. If any select items * were already set, they will be removed. * * @param stateObjects The new select expressions */ public void setItems(List stateObjects) { builder = null; getChangeSupport().replaceItems(this, items, SELECT_ITEMS_LIST, stateObjects); } /** * {@inheritDoc} */ @Override protected void toTextInternal(Appendable writer) throws IOException { // 'SELECT' writer.append(SELECT); // 'DISTINCT' if (hasDistinct()) { writer.append(SPACE); writer.append(DISTINCT); } // Select items if (hasItems()) { writer.append(SPACE); toStringItems(writer, items, true); } } }




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