org.eclipse.persistence.internal.expressions.DataExpression Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of eclipselink Show documentation
Show all versions of eclipselink Show documentation
EclipseLink build based upon Git transaction f2b9fc5
/*
* Copyright (c) 1998, 2021 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 from Oracle TopLink
package org.eclipse.persistence.internal.expressions;
import java.io.BufferedWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import org.eclipse.persistence.descriptors.ClassDescriptor;
import org.eclipse.persistence.expressions.Expression;
import org.eclipse.persistence.history.AsOfClause;
import org.eclipse.persistence.internal.helper.DatabaseField;
import org.eclipse.persistence.internal.helper.DatabaseTable;
import org.eclipse.persistence.internal.history.DecoratedDatabaseTable;
import org.eclipse.persistence.mappings.DatabaseMapping;
import org.eclipse.persistence.mappings.querykeys.QueryKey;
/**
* Superclass for all expression that have a context.
* i.e. a base expression.
*/
public abstract class DataExpression extends BaseExpression {
protected List derivedTables;
protected List derivedFields;
protected boolean hasBeenNormalized;
protected TableAliasLookup tableAliases;
protected AsOfClause asOfClause;
/**
* DataExpression constructor comment.
*/
protected DataExpression() {
super();
}
/**
* INTERNAL:
* Return if the expression is equal to the other.
* This is used to allow dynamic expression's SQL to be cached.
*/
@Override
public boolean equals(Object object) {
if (this == object) {
return true;
}
if (!super.equals(object)) {
return false;
}
DataExpression expression = (DataExpression) object;
return ((this.baseExpression == expression.getBaseExpression()) || ((this.baseExpression != null) && this.baseExpression.equals(expression.getBaseExpression())))
&& ((getAsOfClause() == expression.getAsOfClause()) || ((getAsOfClause() != null) && getAsOfClause().equals(expression.getAsOfClause())));
}
public void addDerivedField(Expression addThis) {
if (derivedFields == null) {
derivedFields = new ArrayList();
}
derivedFields.add(addThis);
}
public void addDerivedTable(Expression addThis) {
if (derivedTables == null) {
derivedTables = new ArrayList();
}
derivedTables.add(addThis);
}
@Override
public Expression asOf(AsOfClause clause) {
asOfClause = clause;
return this;
}
/**
* INTERNAL:
* Find the alias for a given table
*/
@Override
public DatabaseTable aliasForTable(DatabaseTable table) {
if (tableAliases == null) {
if (this.baseExpression == null) {
return null;
}
return this.baseExpression.aliasForTable(table);
}
return tableAliases.keyAtValue(table);
}
/**
* INTERNAL:
* Alias a particular table within this node
*/
@Override
protected void assignAlias(String name, DatabaseTable table) {
if (!getBuilder().getSession().getProject().hasGenericHistorySupport()) {
assignAlias(new DecoratedDatabaseTable(name, getAsOfClause()), table);
} else {
assignAlias(new DatabaseTable(name), table);
}
}
/**
* INTERNAL:
* Alias a particular table within this node
*/
protected void assignAlias(DatabaseTable alias, DatabaseTable table) {
if (tableAliases == null) {
tableAliases = new TableAliasLookup();
}
tableAliases.put(alias, table);
}
/**
* INTERNAL:
*/
public void clearAliases() {
tableAliases = null;
}
public List copyCollection(List in, Map alreadyDone) {
if (in == null) {
return null;
}
List result = new ArrayList(in.size());
for (Expression exp : in) {
result.add(exp.copiedVersionFrom(alreadyDone));
}
return result;
}
/**
* INTERNAL:
*/
public Expression existingDerivedField(DatabaseField field) {
if (this.derivedFields == null) {
return null;
}
for (Expression exp : this.derivedFields) {
if (((FieldExpression)exp).getField().equals(field)) {
return exp;
}
}
return null;
}
/**
* INTERNAL:
*/
public Expression existingDerivedTable(DatabaseTable table) {
if (this.derivedTables == null) {
return null;
}
for (Expression exp : this.derivedTables) {
if (((TableExpression)exp).getTable().equals(table)) {
return exp;
}
}
return null;
}
/**
* INTERNAL:
* Return the field appropriately aliased
*/
public DatabaseField getAliasedField() {
return null;
}
@Override
public AsOfClause getAsOfClause() {
return asOfClause;
}
public ClassDescriptor getDescriptor() {
return null;
}
/**
* INTERNAL:
*/
public DatabaseField getField() {
return null;
}
@Override
public Expression getField(String fieldName) {
DatabaseField field = new DatabaseField(fieldName);
return getField(field);
}
@Override
public Expression getField(DatabaseField field) {
Expression existing = existingDerivedField(field);
if (existing != null) {
return existing;
}
return newDerivedField(field);
}
/**
* INTERNAL:
* Return the descriptor which contains this query key.
*/
public ClassDescriptor getContainingDescriptor() {
return ((DataExpression)this.baseExpression).getDescriptor();
}
public DatabaseMapping getMapping() {
if (this.baseExpression == null) {
return null;
}
ClassDescriptor descriptor = getContainingDescriptor();
if (descriptor == null) {
return null;
}
return descriptor.getObjectBuilder().getMappingForAttributeName(getName());
}
public QueryKey getQueryKeyOrNull() {
return null;
}
@Override
public Expression getTable(String tableName) {
DatabaseTable table = new DatabaseTable(tableName);
return getTable(table);
}
@Override
public Expression getTable(DatabaseTable table) {
Expression existing = existingDerivedTable(table);
if (existing != null) {
return existing;
}
return newDerivedTable(table);
}
/**
* INTERNAL:
* Return the aliases used. For CR#2456 must never lazily initialize as also used for Expression identity.
*/
@Override
public TableAliasLookup getTableAliases() {
return tableAliases;
}
/**
* INTERNAL:
* Did the normalizer already add additional joins to the where clause due to
* this query key representing a foreign reference mapping?
* This insures that join criteria (for any query key expression) is not
* added twice.
*
* New meaning: DataExpressions are often iterated on multiple times during
* normalize, but Function/Relation expressions only once. Adding a has
* been normalized flag improves performance and is required in some
* applications, such as have temporal query criteria been added.
*/
public boolean hasBeenNormalized() {
return hasBeenNormalized;
}
@Override
public boolean hasAsOfClause() {
return ((getAsOfClause() != null) && (getAsOfClause().getValue() != null));
}
@Override
public boolean hasBeenAliased() {
return ((tableAliases != null) && (tableAliases.size() != 0));
}
protected boolean hasDerivedFields() {
return derivedFields != null;
}
protected boolean hasDerivedTables() {
return derivedTables != null;
}
/**
* INTERNAL:
*/
public boolean isAttribute() {
return false;
}
@Override
public boolean isDataExpression() {
return true;
}
/**
* INTERNAL:
* For iterating using an inner class
*/
@Override
public void iterateOn(ExpressionIterator iterator) {
super.iterateOn(iterator);
if (baseExpression != null) {
baseExpression.iterateOn(iterator);
}
}
/**
* INTERNAL:
*/
public Expression newDerivedField(DatabaseField field) {
FieldExpression result = new FieldExpression(field, this);
addDerivedField(result);
return result;
}
/**
* INTERNAL:
*/
public Expression newDerivedTable(DatabaseTable table) {
TableExpression result = new TableExpression(table);
result.setBaseExpression(this);
addDerivedTable(result);
return result;
}
/**
* ADVANCED: Return an expression representing a sub-select in the from clause.
*
Example:
*
* builder.getAlias(builder.subQuery(reportQuery)).get("type").equal("S");
*
*/
@Override
public Expression getAlias(Expression subSelect) {
TableExpression result = new FromSubSelectExpression((SubSelectExpression)subSelect);
result.setBaseExpression(this);
return result;
}
/**
* INTERNAL:
* Normalize the expression into a printable structure.
* Any joins must be added to form a new root.
*/
@Override
public Expression normalize(ExpressionNormalizer normalizer) {
if (this.hasBeenNormalized) {
return this;
}
this.hasBeenNormalized = true;
if (this.baseExpression != null) {
// First normalize the base.
setBaseExpression(this.baseExpression.normalize(normalizer));
if (getAsOfClause() == null) {
asOf(this.baseExpression.getAsOfClause());
}
}
return super.normalize(normalizer);
}
/**
* INTERNAL:
* Used for cloning.
*/
@Override
protected void postCopyIn(Map alreadyDone) {
super.postCopyIn(alreadyDone);
clearAliases();
this.derivedFields = copyCollection(this.derivedFields, alreadyDone);
this.derivedTables = copyCollection(this.derivedTables, alreadyDone);
}
/**
* INTERNAL:
* Print SQL onto the stream, using the ExpressionPrinter for context
*/
@Override
public void printSQL(ExpressionSQLPrinter printer) {
printer.printField(getAliasedField());
}
public void setHasBeenNormalized(boolean value) {
hasBeenNormalized = value;
}
/**
* INTERNAL:
* For CR#2456, Table identity involves having two tables sharing the same
* aliasing table.
*/
public void setTableAliases(TableAliasLookup tableAliases) {
if (this.tableAliases == null) {
this.tableAliases = tableAliases;
}
}
public String tableAliasesDescription() {
if (tableAliases == null) {
return "";
}
return tableAliases.toString();
}
/**
* Print the base for debuggin purposes.
*/
@Override
public void writeSubexpressionsTo(BufferedWriter writer, int indent) throws IOException {
if (this.baseExpression != null) {
this.baseExpression.toString(writer, indent);
}
}
}