/*
* Copyright 2015, The Querydsl Team (http://www.querydsl.com/team)
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* http://www.apache.org/licenses/LICENSE-2.0
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.querydsl.jpa;
import java.util.Map;
import javax.annotation.Nullable;
import com.google.common.collect.Maps;
import com.querydsl.core.JoinType;
import com.querydsl.core.QueryMetadata;
import com.querydsl.core.support.ReplaceVisitor;
import com.querydsl.core.types.*;
import com.querydsl.core.types.dsl.Expressions;
class JPAListAccessVisitor extends ReplaceVisitor<Void> {
private final QueryMetadata metadata;
private final Map<Expression<?>, Path<?>> aliases;
private final Map<Path<?>, Path<?>> replacements = Maps.newHashMap();
public JPAListAccessVisitor(QueryMetadata metadata, Map<Expression<?>, Path<?>> aliases) {
this.metadata = metadata;
this.aliases = aliases;
}
@SuppressWarnings("unchecked")
@Override
public Expression<?> visit(Path<?> expr, @Nullable Void context) {
expr = (Path<?>) super.visit(expr, null);
PathMetadata pathMetadata = expr.getMetadata();
if (pathMetadata.getPathType() == PathType.LISTVALUE
|| pathMetadata.getPathType() == PathType.LISTVALUE_CONSTANT) {
Path<?> replacement = replacements.get(expr);
if (replacement == null) {
// join parent as path123 on index(path123) = ...
Path parent = shorten(pathMetadata.getParent(), true);
replacement = ExpressionUtils.path(expr.getType(),
ExpressionUtils.createRootVariable(parent, replacements.size()));
metadata.addJoin(JoinType.LEFTJOIN, ExpressionUtils.as(parent, replacement));
metadata.addJoinCondition(ExpressionUtils.eq(
(Expression) Expressions.operation(Integer.class, JPQLOps.INDEX, replacement),
ExpressionUtils.toExpression(pathMetadata.getElement())));
replacements.put(expr, replacement);
}
return replacement;
} else {
return super.visit(expr, context);
}
}
/**
* Shorten the parent path to a length of max 2 elements
*/
private Path<?> shorten(Path<?> path, boolean outer) {
if (aliases.containsKey(path)) {
return aliases.get(path);
} else if (path.getMetadata().isRoot()) {
return path;
} else if (path.getMetadata().getParent().getMetadata().isRoot() && outer) {
return path;
} else {
Class<?> type = JPAQueryMixin.getElementTypeOrType(path);
Path<?> parent = shorten(path.getMetadata().getParent(), false);
Path oldPath = ExpressionUtils.path(path.getType(),
new PathMetadata(parent, path.getMetadata().getElement(), path.getMetadata().getPathType()));
if (oldPath.getMetadata().getParent().getMetadata().isRoot() && outer) {
return oldPath;
} else {
Path newPath = ExpressionUtils.path(type, ExpressionUtils.createRootVariable(oldPath));
aliases.put(path, newPath);
metadata.addJoin(JoinType.LEFTJOIN, ExpressionUtils.as(oldPath, newPath));
return newPath;
}
}
}
}