oracle.toplink.essentials.internal.expressions.DataExpression Maven / Gradle / Ivy
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package oracle.toplink.essentials.internal.expressions;
import java.util.*;
import java.io.*;
import oracle.toplink.essentials.expressions.*;
import oracle.toplink.essentials.internal.helper.*;
import oracle.toplink.essentials.mappings.*;
import oracle.toplink.essentials.querykeys.*;
import oracle.toplink.essentials.descriptors.ClassDescriptor;
/**
* Superclass for all expression that have a context.
* i.e. a base expression.
*/
public abstract class DataExpression extends Expression {
protected Vector derivedTables;
protected Vector derivedFields;
protected Expression baseExpression;
protected boolean hasBeenNormalized = false;
protected TableAliasLookup tableAliases;
/**
* DataExpression constructor comment.
*/
public DataExpression() {
super();
}
public void addDerivedField(Expression addThis) {
if (derivedFields == null) {
derivedFields = oracle.toplink.essentials.internal.helper.NonSynchronizedVector.newInstance(4);
}
derivedFields.addElement(addThis);
}
public void addDerivedTable(Expression addThis) {
if (derivedTables == null) {
derivedTables = oracle.toplink.essentials.internal.helper.NonSynchronizedVector.newInstance(4);
}
derivedTables.addElement(addThis);
}
/**
* INTERNAL:
* Find the alias for a given table
*/
public DatabaseTable aliasForTable(DatabaseTable table) {
if (tableAliases == null) {
if (getBaseExpression() == null) {
return null;
}
return getBaseExpression().aliasForTable(table);
}
return tableAliases.keyAtValue(table);
}
/**
* INTERNAL:
* Alias a particular table within this node
*/
protected void assignAlias(String name, DatabaseTable table) {
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 Vector copyCollection(Vector in, Dictionary alreadyDone) {
if (in == null) {
return null;
}
Vector result = oracle.toplink.essentials.internal.helper.NonSynchronizedVector.newInstance(in.size());
for (Enumeration e = in.elements(); e.hasMoreElements();) {
Expression exp = (Expression)e.nextElement();
result.addElement(exp.copiedVersionFrom(alreadyDone));
}
return result;
}
/**
* INTERNAL:
*/
public Expression existingDerivedField(DatabaseField field) {
if (derivedFields == null) {
return null;
}
for (Enumeration e = derivedFields.elements(); e.hasMoreElements();) {
FieldExpression exp = (FieldExpression)e.nextElement();
if (exp.getField().equals(field)) {
return exp;
}
}
return null;
}
/**
* INTERNAL:
*/
public Expression existingDerivedTable(DatabaseTable table) {
if (derivedTables == null) {
return null;
}
for (Enumeration e = derivedTables.elements(); e.hasMoreElements();) {
TableExpression exp = (TableExpression)e.nextElement();
if (exp.getTable().equals(table)) {
return exp;
}
}
return null;
}
/**
* INTERNAL:
* Return the field appropriately aliased
*/
public DatabaseField getAliasedField() {
return null;
}
public Expression getBaseExpression() {
return baseExpression;
}
/**
* 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() {
if (getBaseExpression() == null) {
return null;
}
return getBaseExpression().getBuilder();
}
public ClassDescriptor getDescriptor() {
return null;
}
/**
* INTERNAL:
*/
public DatabaseField getField() {
return null;
}
public Expression getField(String fieldName) {
DatabaseField field = new DatabaseField(fieldName);
return getField(field);
}
public Expression getField(DatabaseField field) {
Expression existing = existingDerivedField(field);
if (existing != null) {
return existing;
}
return newDerivedField(field);
}
public DatabaseMapping getMapping() {
if (getBaseExpression() == null) {
return null;
}
ClassDescriptor aDescriptor = ((DataExpression)getBaseExpression()).getDescriptor();
if (aDescriptor == null) {
return null;
}
return aDescriptor.getObjectBuilder().getMappingForAttributeName(getName());
}
/**
* INTERNAL:
*/
public Vector getOwnedTables() {
if (getDescriptor() == null) {
return null;
} else {
if (getDescriptor().isAggregateDescriptor()) {
return null;
} else {
return getDescriptor().getTables();
}
}
}
public QueryKey getQueryKeyOrNull() {
return null;
}
public Expression getTable(String tableName) {
DatabaseTable table = new DatabaseTable(tableName);
return getTable(table);
}
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.
*/
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;
}
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;
}
public boolean isDataExpression() {
return true;
}
/**
* INTERNAL:
* For iterating using an inner class
*/
public void iterateOn(ExpressionIterator iterator) {
super.iterateOn(iterator);
if (baseExpression != null) {
baseExpression.iterateOn(iterator);
}
}
public Expression mappingCriteria() {
return null;
}
/**
* 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;
}
/**
* INTERNAL:
* Normalize the expression into a printable structure.
* Any joins must be added to form a new root.
*/
public Expression normalize(ExpressionNormalizer normalizer) {
if (getBaseExpression() != null) {
// First normalize the base.
setBaseExpression(getBaseExpression().normalize(normalizer));
}
return super.normalize(normalizer);
}
/**
* INTERNAL:
* Used for cloning.
*/
protected void postCopyIn(Dictionary alreadyDone) {
super.postCopyIn(alreadyDone);
clearAliases();
if (baseExpression != null) {
baseExpression = baseExpression.copiedVersionFrom(alreadyDone);
}
derivedFields = copyCollection(derivedFields, alreadyDone);
derivedTables = copyCollection(derivedTables, alreadyDone);
}
/**
* INTERNAL:
* Print SQL onto the stream, using the ExpressionPrinter for context
*/
public void printSQL(ExpressionSQLPrinter printer) {
printer.printField(getAliasedField());
}
protected void setBaseExpression(Expression e) {
baseExpression = e;
}
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.
*/
public void writeSubexpressionsTo(BufferedWriter writer, int indent) throws IOException {
if (getBaseExpression() != null) {
getBaseExpression().toString(writer, indent);
}
}
}