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package oracle.toplink.essentials.expressions;
import java.util.*;
import java.io.*;
import oracle.toplink.essentials.exceptions.*;
import oracle.toplink.essentials.queryframework.*;
import oracle.toplink.essentials.internal.helper.*;
import oracle.toplink.essentials.internal.expressions.*;
import oracle.toplink.essentials.internal.sessions.AbstractRecord;
import oracle.toplink.essentials.internal.sessions.AbstractSession;
import oracle.toplink.essentials.descriptors.ClassDescriptor;
/**
* <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>:
* <PRE><BLOCKQUOTE>
* ExpressionBuilder employee = new ExpressionBuilder();
* employee.get("firstName").equal("Bob").and(employee.get("lastName").equal("Smith"))
*
* >> equivalent Java code: (employee.getFirstName().equals("Bob")) && (employee.getLastName().equals("Smith"))
*
* >> equivalent SQL: (F_NAME = 'Bob') AND (L_NAME = 'Smith')
* </BLOCKQUOTE></PRE>
*
* @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: 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 (Enumeration e = derivedTables.elements(); e.hasMoreElements();) {
TableExpression t = (TableExpression)e.nextElement();
DatabaseTable result = t.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 = (DatabaseTable)viewTable.clone();
String alias = "t" + initialValue;
aliased.setName(alias);
assignAlias(alias, viewTable);
aliasedViewTable = aliased;
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());
}
}
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.
*/
public Expression normalize(ExpressionNormalizer normalizer) {
if (hasBeenNormalized()) {
return this;
} else {
setHasBeenNormalized(true);
}
// This is required for parralel selects,
// the session must be set and the addtional 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() && getSession().getPlatform().shouldPrintOuterJoinInWhereClause()) {
Expression childrenCriteria = getDescriptor().getInheritancePolicy().getChildrenJoinExpression();
childrenCriteria = this.twist(childrenCriteria, this);
childrenCriteria.convertToUseOuterJoin();
if(criteria == null) {
criteria = childrenCriteria;
} else {
criteria = criteria.and(childrenCriteria);
}
}
if (isUsingOuterJoinForMultitableInheritance() && (!getSession().getPlatform().shouldPrintOuterJoinInWhereClause())) {
normalizer.getStatement().getOuterJoinExpressions().addElement(null);
normalizer.getStatement().getOuterJoinedMappingCriteria().addElement(null);
normalizer.getStatement().getOuterJoinedAdditionalJoinCriteria().addElement(additionalExpressionCriteriaMap());
normalizer.getStatement().getDescriptorsForMultitableInheritanceOnly().add(this.getDescriptor());
// fall through to the main case
}
normalizer.addAdditionalExpression(criteria);
}
setStatement(normalizer.getStatement());
return super.normalize(normalizer);
}
/**
* 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:
* Override Expression.registerIn to check if the new base expression
* has already been provided for the clone.
* @see oracle.toplink.essentials.expressions.Expression#cloneUsing(Expression)
* @bug 2637484 INVALID QUERY KEY EXCEPTION THROWN USING BATCH READS AND PARALLEL EXPRESSIONS
*/
protected Expression registerIn(Dictionary 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 = copyCollection(this.derivedExpressions, alreadyDone);
} else {
copy.derivedExpressions.addAll(copyCollection(this.derivedExpressions, 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 session in which we expect this expression to be translated.
*/
public void setSession(AbstractSession session) {
this.session = session;
}
/**
* 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"
* @param newBase
* @param context
* @return
*/
public Expression twistedForBaseAndContext(Expression newBase, Expression context) {
return newBase;
}
/**
* INTERNAL:
* The expression builder represent the entire object, just return it.
*/
public Object valueFromObject(Object object, AbstractSession session, AbstractRecord translationRow, InMemoryQueryIndirectionPolicy 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 appoased 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:
* 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());
}
}
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