/*******************************************************************************
* Copyright (c) 1998, 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 from Oracle TopLink
******************************************************************************/
package org.eclipse.persistence.expressions;
import java.io.BufferedWriter;
import java.io.IOException;
import java.util.Map;
import org.eclipse.persistence.descriptors.ClassDescriptor;
import org.eclipse.persistence.exceptions.QueryException;
import org.eclipse.persistence.history.AsOfClause;
import org.eclipse.persistence.internal.expressions.ExpressionJavaPrinter;
import org.eclipse.persistence.internal.expressions.ExpressionNormalizer;
import org.eclipse.persistence.internal.expressions.ObjectExpression;
import org.eclipse.persistence.internal.expressions.SQLSelectStatement;
import org.eclipse.persistence.internal.helper.DatabaseTable;
import org.eclipse.persistence.internal.sessions.AbstractRecord;
import org.eclipse.persistence.internal.sessions.AbstractSession;
import org.eclipse.persistence.queries.DatabaseQuery;
import org.eclipse.persistence.queries.ReadQuery;
/**
* <P>
* <B>Purpose</B>: Allow for instances of expression to be created. Expressions are Java object-level representations of SQL "where" clauses.
* The expressions attempt to mirror Java code as closely as possible.</p>
*
* <P>
*
* <B>Example</B>:
* <BLOCKQUOTE><PRE>
* ExpressionBuilder employee = new ExpressionBuilder();
* employee.get("firstName").equal("Bob").and(employee.get("lastName").equal("Smith"))
*
* {@literal >>} equivalent Java code: (employee.getFirstName().equals("Bob")) {@literal &&} (employee.getLastName().equals("Smith"))
*
* {@literal >>} equivalent SQL: (F_NAME = 'Bob') AND (L_NAME = 'Smith')
* </PRE></BLOCKQUOTE>
*
* @see Expression
*/
public class ExpressionBuilder extends ObjectExpression {
protected transient AbstractSession session;
protected Class queryClass;
protected SQLSelectStatement statement;
protected DatabaseTable viewTable;
protected DatabaseTable aliasedViewTable;
protected boolean wasQueryClassSetInternally = true;
protected boolean wasAdditionJoinCriteriaUsed = false;
/**
* PUBLIC:
* Create a new ExpressionBuilder.
*/
public ExpressionBuilder() {
super();
}
/**
* ADVANCED:
* Create a new ExpressionBuilder representing instances of the argument class.
* This can be used for the purpose of parallel expressions.
* This is a type of query that searches on the relationship between to un-related objects.
*/
public ExpressionBuilder(Class queryClass) {
super();
this.queryClass = queryClass;
this.wasQueryClassSetInternally = false;
}
/**
* INTERNAL:
* Return if the expression is equal to the other.
* This is used to allow dynamic expression's SQL to be cached.
*/
public boolean equals(Object expression) {
if (this == expression) {
return true;
}
// Return false for parallel expressions, as equality is unknown.
return super.equals(expression) && ((getQueryClass() == null) && ((ExpressionBuilder)expression).getQueryClass() == null);
}
/**
* INTERNAL: Find the alias for a given table. Handle the special case where we are bogus
* and it should be aliased against our derived tables instead.
*/
public DatabaseTable aliasForTable(DatabaseTable table) {
if (hasViewTable()) {
return getAliasedViewTable();
}
if (doesNotRepresentAnObjectInTheQuery()) {
for (Expression expression : this.derivedTables) {
DatabaseTable result = expression.aliasForTable(table);
if (result != null) {
return result;
}
}
} else {
return super.aliasForTable(table);
}
return null; // No alias found in the derived tables
}
/**
* INTERNAL:
* Assign aliases to any tables which I own. Start with t(initialValue),
* and return the new value of the counter , i.e. if initialValue is one
* and I have tables ADDRESS and EMPLOYEE I will assign them t1 and t2 respectively, and return 3.
*/
public int assignTableAliasesStartingAt(int initialValue) {
if (hasBeenAliased()) {
return initialValue;
}
if (doesNotRepresentAnObjectInTheQuery()) {
return initialValue;
}
// This block should be removed I think.
// The only reason to clone might be to
// preserve the qualifier, but aliases need
// qualifiers? That seems strange.
// Also this will break AsOf queries. By
// inference if has view table the AliasTableLookup
// will contain one table, and that will be the
// table of the view...
if (hasViewTable()) {
DatabaseTable aliased = viewTable.clone();
String alias = "t" + initialValue;
aliased.setName(alias);
assignAlias(alias, viewTable);
aliasedViewTable = aliased;
hasBeenAliased = true;
return initialValue + 1;
}
return super.assignTableAliasesStartingAt(initialValue);
}
/**
* INTERNAL:
* Used for debug printing.
*/
public String descriptionOfNodeType() {
return "Base";
}
/**
* INTERNAL:
* There are cases (which we might want to eliminate?) where the expression builder
* doesn't actually correspond to an object to be read. Mostly this is the case where
* it's a data query in terms of tables, and the builder is only there to provide a base.
* It might be better to make tables able to serve as their own base, but it's very nice
* to have a known unique, shared base. In the meantime, this
* is a special case to make sure the builder doesn't get tables assigned.
*/
public boolean doesNotRepresentAnObjectInTheQuery() {
return (hasDerivedTables() && !hasDerivedFields() && !hasDerivedExpressions());
}
/**
* INTERNAL:
*/
public DatabaseTable getAliasedViewTable() {
return aliasedViewTable;
}
/**
* INTERNAL:
* Return the expression builder which is the ultimate base of this expression, or
* null if there isn't one (shouldn't happen if we start from a root)
*/
public ExpressionBuilder getBuilder() {
return this;
}
/**
* INTERNAL:
* Only usable after the session and class have been set. Return the
* descriptor for the class this node represents.
*/
public ClassDescriptor getDescriptor() {
if (descriptor == null) {
if (getQueryClass() == null) {
return null;
} else {
if (getSession() == null) {
throw QueryException.noExpressionBuilderFound(this);
}
descriptor = getSession().getDescriptor(getQueryClass());
descriptor = convertToCastDescriptor(descriptor, getSession());
}
}
return descriptor;
}
/**
* INTERNAL:
*/
public Class getQueryClass() {
return queryClass;
}
/**
* INTERNAL:
*/
public AbstractSession getSession() {
return session;
}
/**
* INTERNAL:
* Return the statement that expression is for.
* This is used for the context in subselects.
*/
public SQLSelectStatement getStatement() {
return statement;
}
/**
* INTERNAL:
*/
public DatabaseTable getViewTable() {
return viewTable;
}
/**
* INTERNAL:
*/
public boolean hasViewTable() {
return viewTable != null;
}
/**
* INTERNAL:
*/
public boolean isExpressionBuilder() {
return true;
}
/**
* 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 (hasBeenNormalized()) {
return this;
} else {
setHasBeenNormalized(true);
}
// Normalize the ON clause if present. Need to use rebuild, not twist as parameters are real parameters.
if (this.onClause != null) {
this.onClause = this.onClause.normalize(normalizer);
if (shouldUseOuterJoin() || (!getSession().getPlatform().shouldPrintInnerJoinInWhereClause())) {
normalizer.getStatement().addOuterJoinExpressionsHolders(this, null, null, null);
if ((getDescriptor() != null) && (getDescriptor().getHistoryPolicy() != null)) {
Expression historyCriteria = getDescriptor().getHistoryPolicy().additionalHistoryExpression(this, this);
if (historyCriteria != null) {
normalizer.addAdditionalExpression(historyCriteria);
}
}
} else {
normalizer.addAdditionalExpression(this.onClause);
}
}
// This is required for parallel selects,
// the session must be set and the additional join expression added.
if (this.queryClass != null) {
Expression criteria = null;
setSession(normalizer.getSession().getRootSession(null));
// The descriptor must be defined at this point.
if (getDescriptor() == null) {
throw QueryException.noExpressionBuilderFound(this);
}
if (!this.wasAdditionJoinCriteriaUsed) {
criteria = getDescriptor().getQueryManager().getAdditionalJoinExpression();
if (criteria != null) {
criteria = twist(criteria, this);
}
}
if (isUsingOuterJoinForMultitableInheritance()) {
if (getSession().getPlatform().shouldPrintOuterJoinInWhereClause()) {
Expression childrenCriteria = getDescriptor().getInheritancePolicy().getChildrenJoinExpression();
childrenCriteria = twist(childrenCriteria, this);
childrenCriteria.convertToUseOuterJoin();
if(criteria == null) {
criteria = childrenCriteria;
} else {
criteria = criteria.and(childrenCriteria);
}
} else {
normalizer.getStatement().addOuterJoinExpressionsHolders(null, null, additionalExpressionCriteriaMap(), this.getDescriptor());
// fall through to the main case
}
}
normalizer.addAdditionalExpression(criteria);
}
setStatement(normalizer.getStatement());
if (getAsOfClause() == null) {
asOf(AsOfClause.NO_CLAUSE);
}
if ((getDescriptor() != null) && (getDescriptor().getHistoryPolicy() != null)) {
Expression temporalCriteria = getDescriptor().getHistoryPolicy().additionalHistoryExpression(this, this);
normalizer.addAdditionalExpression(temporalCriteria);
}
ReadQuery query = normalizer.getStatement().getQuery();
// Record any class used in a join to invalidate query results cache.
if ((query != null) && query.shouldCacheQueryResults()) {
if (this.queryClass != null) {
query.getQueryResultsCachePolicy().getInvalidationClasses().add(this.queryClass);
}
}
return this;
}
/**
* INTERNAL:
* Print java
*/
public void printJava(ExpressionJavaPrinter printer) {
printer.printString(printer.getBuilderString());
}
/**
* INTERNAL:
* This expression is built on a different base than the one we want. Rebuild it and
* return the root of the new tree
* This assumes that the original expression has only a single builder.
*/
public Expression rebuildOn(Expression newBase) {
return newBase;
}
/**
* INTERNAL:
* Search the tree for any expressions (like SubSelectExpressions) that have been
* built using a builder that is not attached to the query. This happens in case of an Exists
* call using a new ExpressionBuilder(). This builder needs to be replaced with one from the query.
*/
public void resetPlaceHolderBuilder(ExpressionBuilder queryBuilder){
return;
}
/**
* INTERNAL:
* Override Expression.registerIn to check if the new base expression
* has already been provided for the clone.
* @see org.eclipse.persistence.expressions.Expression#cloneUsing(Expression)
* @bug 2637484 INVALID QUERY KEY EXCEPTION THROWN USING BATCH READS AND PARALLEL EXPRESSIONS
*/
protected Expression registerIn(Map alreadyDone) {
// Here do a special check to see if this a cloneUsing(newBase) call.
Object value = alreadyDone.get(alreadyDone);
if ((value == null) || (value == alreadyDone)) {
// This is a normal cloning operation.
return super.registerIn(alreadyDone);
}
ObjectExpression copy = (ObjectExpression)value;
// copy is actually the newBase of a cloneUsing.
alreadyDone.put(alreadyDone, alreadyDone);
alreadyDone.put(this, copy);
// Now need to copy over the derived expressions, etc.
if (this.derivedExpressions != null) {
if (copy.derivedExpressions == null) {
copy.derivedExpressions = copyDerivedExpressions(alreadyDone);
} else {
copy.derivedExpressions.addAll(copyDerivedExpressions(alreadyDone));
}
}
// Do the same for these protected fields.
copy.postCopyIn(alreadyDone, this.derivedFields, this.derivedTables);
return copy;
}
/**
* INTERNAL:
* Set the class which this node represents.
*/
public void setQueryClass(Class queryClass) {
this.queryClass = queryClass;
this.descriptor = null;
}
/**
* INTERNAL:
* Set the class and descriptor which this node represents.
*/
public void setQueryClassAndDescriptor(Class queryClass, ClassDescriptor descriptor) {
this.queryClass = queryClass;
this.descriptor = convertToCastDescriptor(descriptor, session);
}
/**
* INTERNAL:
* Set the session in which we expect this expression to be translated.
* Stored session shall always be root session.
*/
public void setSession(AbstractSession session) {
if (session != null) {
this.session = session.getRootSession(null);
} else {
this.session = null;
}
}
/**
* INTERNAL:
* Set the statement that expression is for.
* This is used for the context in subselects.
*/
public void setStatement(SQLSelectStatement statement) {
this.statement = statement;
}
/**
* INTERNAL:
* This expression represents something read through a view table.
*/
public void setViewTable(DatabaseTable theTable) {
viewTable = theTable;
}
/**
* INTERNAL:
* If the additional Join Criteria for the class this builder represents has
* been added to the statement then mark this as true. This will prevent
* TopLink from adding it again at normalization
*/
public void setWasAdditionJoinCriteriaUsed(boolean joinCriteriaUsed){
this.wasAdditionJoinCriteriaUsed = joinCriteriaUsed;
}
/**
* INTERNAL:
* Rebuild myself against the base, with the values of parameters supplied by the context
* expression. This is used for transforming a standalone expression (e.g. the join criteria of a mapping)
* into part of some larger expression. You normally would not call this directly, instead calling twist
* See the comment there for more details.
*/
@Override
public Expression twistedForBaseAndContext(Expression newBase, Expression context, Expression oldBase) {
if (oldBase == null || this == oldBase) {
return newBase;
}
return this;
}
/**
* INTERNAL:
* The expression builder represent the entire object, just return it.
*/
public Object valueFromObject(Object object, AbstractSession session, AbstractRecord translationRow, int valueHolderPolicy, boolean isObjectUnregistered) {
return object;
}
/**
* INTERNAL:
* If the additional Join Criteria for the class this builder represents has
* been added to the statement this method will return true;
*/
public boolean wasAdditionJoinCriteriaUsed(){
return this.wasAdditionJoinCriteriaUsed;
}
/**
* INTERNAL:
* Returns true if TopLink set the query class as opposed to the customer. This
* is important in determining if this Expression should be treated as a parallel
* expression during normalization
*/
public boolean wasQueryClassSetInternally(){
return this.wasQueryClassSetInternally;
}
/**
* INTERNAL:
* Lookup the descriptor for this item by traversing its expression recursively.
*/
@Override
public ClassDescriptor getLeafDescriptor(DatabaseQuery query, ClassDescriptor rootDescriptor, AbstractSession session) {
// The base case
// The following special case is where there is a parallel builder
// which has a different reference class as the primary builder.
Class queryClass = getQueryClass();
if ((queryClass != null) && ((query == null) || (queryClass != query.getReferenceClass()))) {
return convertToCastDescriptor( session.getDescriptor(queryClass), session);
}
return convertToCastDescriptor(rootDescriptor, session);//support casting
}
/**
* INTERNAL:
* For debug printing purposes.
*/
public void writeDescriptionOn(BufferedWriter writer) throws IOException {
String className;
if (getQueryClass() == null) {
className = "QUERY OBJECT";
} else {
className = getQueryClass().getName();
}
writer.write(className + tableAliasesDescription());
}
}