org.dellroad.querystream.jpa.CurrentQuery Maven / Gradle / Ivy
/*
* Copyright (C) 2018 Archie L. Cobbs. All rights reserved.
*/
package org.dellroad.querystream.jpa;
import javax.persistence.criteria.CommonAbstractCriteria;
import javax.persistence.criteria.CriteriaBuilder;
import javax.persistence.criteria.Subquery;
/**
* Holds the current Criteria API query object under construction while a stream is being realized by
* {@link QueryStream#toCriteriaQuery}.
*
*
* Because we can create {@link Subquery} objects, during construction there is actually a stack of
* {@link CurrentQuery} objects maintained. The first stack entry contains a {@link CommonAbstractCriteria}
* appropriate for the query being constructed, while all other stack entries contain {@link Subquery} objects.
*
*
* For details, see {@link QueryStreamImpl#withCurrentQuery} and {@link ExprStreamImpl#asSubquery}.
*/
class CurrentQuery {
private final CriteriaBuilder builder;
private final CommonAbstractCriteria query;
CurrentQuery(CriteriaBuilder builder, CommonAbstractCriteria query) {
if (builder == null)
throw new IllegalArgumentException("null builder");
if (query == null)
throw new IllegalArgumentException("null query");
this.builder = builder;
this.query = query;
}
public CriteriaBuilder getBuilder() {
return this.builder;
}
public CommonAbstractCriteria getQuery() {
return this.query;
}
public Subquery getSubquery() {
try {
return (Subquery)this.query;
} catch (ClassCastException e) {
throw new IllegalArgumentException("streams built with QueryBuilder.substream() can only be used in subqueries");
}
}
}