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package oracle.toplink.essentials.internal.parsing;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.Set;
import oracle.toplink.essentials.expressions.Expression;
import oracle.toplink.essentials.internal.sessions.AbstractSession;
/**
* INTERNAL:
* An extension of GenerationContext the provides SELECT specfic behavior.
* Used when building the query features that are not usable in other types of queries
*/
public class SelectGenerationContext extends GenerationContext {
//if a 1:1 is SELECTed in the EJBQL, then we need to use parallel expressions
//with each ExpressionBuilder created using "new ExpressionBuilder(MyClass.class)"
private boolean useParallelExpressions = false;
//BUG 3105651: If a variable is SELECTed, and it's in an ORDER BY, then
//we want the ExpressionBuilder to be instantiated using an empty constructor
private boolean shouldCheckSelectNodeBeforeResolving = false;
private boolean isNotIndicatedInMemberOf = false;
//If a NOT MEMBER OF is encountered, we need to store the MEMBER OF
//so that the right side of the member of can use the stored expression
//from the left
private MemberOfNode memberOfNode = null;
//Do we want to use outer joins? get("address") vs getAllowingNull("address")
private boolean shouldUseOuterJoins = false;
//Outer SelectGenerationContext
private GenerationContext outer = null;
public SelectGenerationContext() {
super();
}
/**
* Constructor used to create the context for a subquery.
*/
public SelectGenerationContext(GenerationContext outer, ParseTree newParseTree) {
this(outer.getParseTreeContext(), outer.getSession(), newParseTree);
this.outer = outer;
}
public SelectGenerationContext(ParseTreeContext newContext, AbstractSession newSession, ParseTree newParseTree) {
super(newContext, newSession, newParseTree);
//indicate if we want parallel expressions or not
useParallelExpressions = this.computeUseParallelExpressions();
}
//Set and get the contained MemberOfNode. This is for handling NOT MEMBER OF.
public void setMemberOfNode(MemberOfNode newMemberOfNode) {
memberOfNode = newMemberOfNode;
}
public MemberOfNode getMemberOfNode() {
return memberOfNode;
}
private boolean computeUseParallelExpressions() {
boolean computedUseParallelExpressions;
//use parallel expressions if I have a 1:1 selected, and the same class isn't
//declared in the FROM
computedUseParallelExpressions = ((SelectNode)this.parseTree.getQueryNode()).hasOneToOneSelected(this);
//check if they've SELECTed a variable declared in the IN clause in the FROM,
//or they've mapped more than one variable to the same type in the FROM
computedUseParallelExpressions = computedUseParallelExpressions || ((SelectNode)this.parseTree.getQueryNode()).isVariableInINClauseSelected(this) || this.parseTree.getContext().hasMoreThanOneVariablePerType() || this.parseTree.getContext().hasMoreThanOneAliasInFrom();
return computedUseParallelExpressions;
}
//Answer true if we need to use parallel expressions
//This will be the case if a 1:1 is SELECTed in the EJBQL.
public boolean useParallelExpressions() {
return useParallelExpressions;
}
//Indicate that we want VariableNodes to check if they're
//SELECTed first, to determine how to instantiate the ExpressionBuilder
public void checkSelectNodeBeforeResolving(boolean shouldCheck) {
shouldCheckSelectNodeBeforeResolving = shouldCheck;
}
//Answer true if we want VariableNodes to check if they're
//SELECTed first, to determine how to instantiate the ExpressionBuilder
public boolean shouldCheckSelectNodeBeforeResolving() {
return shouldCheckSelectNodeBeforeResolving;
}
//Answer true if we should use outer joins in our get() (vs getAllowingNull())
public boolean shouldUseOuterJoins() {
return shouldUseOuterJoins;
}
public void useOuterJoins() {
shouldUseOuterJoins = true;
}
public void dontUseOuterJoins() {
shouldUseOuterJoins = false;
}
//Answer true if we have a MemberOfNode contained. This is for handling NOT MEMBER OF
public boolean hasMemberOfNode() {
return memberOfNode != null;
}
/** */
public GenerationContext getOuterContext() {
return outer;
}
/**
* Iterate the set of variables declared in an outer scope and
* connect the inner varaible expression with the outer one.
*/
public Expression joinVariables(Set variables) {
if ((outer == null) || (variables == null) || variables.isEmpty()) {
// not an inner query or no variables to join
return null;
}
Expression expr = null;
for (Iterator i = variables.iterator(); i.hasNext(); ) {
String name = (String)i.next();
VariableNode var = new VariableNode(name);
Expression innerExpr = var.generateExpression(this);
Expression outerExpr = var.generateExpression(outer);
Expression join = innerExpr.equal(outerExpr);
expr = var.appendExpression(expr, join);
}
return expr;
}
}