/*
* Copyright 2014, Mysema Ltd
*
* 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.mysema.query.support;
import javax.annotation.Nullable;
import java.util.List;
import java.util.Map;
import com.google.common.collect.ImmutableList;
import com.mysema.query.*;
import com.mysema.query.types.*;
import com.mysema.query.types.template.BooleanTemplate;
/**
* ReplaceVisitor is a deep visitor that can be customized to replace segments of
* expression trees
*/
public class ReplaceVisitor implements Visitor<Expression<?>, Void> {
@Override
public Expression<?> visit(Constant<?> expr, @Nullable Void context) {
return expr;
}
@Override
public Expression<?> visit(FactoryExpression<?> expr, @Nullable Void context) {
List<Expression<?>> args = visit(expr.getArgs());
if (args.equals(expr.getArgs())) {
return expr;
} else {
return FactoryExpressionUtils.wrap(expr, args);
}
}
@Override
public Expression<?> visit(Operation<?> expr, @Nullable Void context) {
ImmutableList<Expression<?>> args = visit(expr.getArgs());
if (args.equals(expr.getArgs())) {
return expr;
} else if (expr instanceof Predicate) {
return new PredicateOperation((Operator)expr.getOperator(), args);
} else {
return new OperationImpl(expr.getType(), expr.getOperator(), args);
}
}
@Override
public Expression<?> visit(ParamExpression<?> expr, @Nullable Void context) {
return expr;
}
@Override
public Expression<?> visit(Path<?> expr, @Nullable Void context) {
if (expr.getMetadata().isRoot()) {
return expr;
} else {
PathMetadata metadata = expr.getMetadata();
Path<?> parent = (Path)metadata.getParent().accept(this, null);
if (parent.equals(metadata.getParent())) {
return expr;
} else {
metadata = new PathMetadata(parent, metadata.getElement(),
metadata.getPathType());
return new PathImpl(expr.getType(), metadata);
}
}
}
@Override
public Expression<?> visit(SubQueryExpression<?> expr, @Nullable Void context) {
QueryMetadata md = new DefaultQueryMetadata();
md.setValidate(false);
md.setDistinct(expr.getMetadata().isDistinct());
md.setModifiers(expr.getMetadata().getModifiers());
md.setUnique(expr.getMetadata().isUnique());
for (QueryFlag flag : expr.getMetadata().getFlags()) {
md.addFlag(new QueryFlag(flag.getPosition(), flag.getFlag().accept(this, null)));
}
for (Expression<?> e : expr.getMetadata().getGroupBy()) {
md.addGroupBy(e.accept(this, null));
}
Predicate having = expr.getMetadata().getHaving();
if (having != null) {
md.addHaving((Predicate)having.accept(this, null));
}
for (JoinExpression je : expr.getMetadata().getJoins()) {
md.addJoin(je.getType(), je.getTarget().accept(this, null));
if (je.getCondition() != null) {
md.addJoinCondition((Predicate)je.getCondition().accept(this, null));
}
for (JoinFlag jf : je.getFlags()) {
md.addJoinFlag(new JoinFlag(jf.getFlag().accept(this, null), jf.getPosition()));
}
}
for (OrderSpecifier<?> os : expr.getMetadata().getOrderBy()) {
OrderSpecifier<?> os2 = new OrderSpecifier(os.getOrder(), os.getTarget().accept(this,
null));
switch (os.getNullHandling()) {
case NullsFirst: os2 = os2.nullsFirst(); break;
case NullsLast: os2 = os2.nullsLast(); break;
}
md.addOrderBy(os2);
}
for (Map.Entry<ParamExpression<?>, Object> entry : expr.getMetadata().getParams()
.entrySet()) {
md.setParam((ParamExpression)entry.getKey().accept(this, null), entry.getValue());
}
for (Expression<?> e : expr.getMetadata().getProjection()) {
md.addProjection(e.accept(this, null));
}
Predicate where = expr.getMetadata().getWhere();
if (where != null) {
md.addWhere((Predicate)where.accept(this, null));
}
if (expr.getMetadata().equals(md)) {
return expr;
} else {
return new SubQueryExpressionImpl(expr.getType(), md);
}
}
@Override
public Expression<?> visit(TemplateExpression<?> expr, @Nullable Void context) {
ImmutableList.Builder builder = ImmutableList.builder();
for (Object arg : expr.getArgs()) {
if (arg instanceof Expression) {
builder.add(((Expression)arg).accept(this, null));
} else {
builder.add(arg);
}
}
ImmutableList args = builder.build();
if (args.equals(expr.getArgs())) {
return expr;
} else {
if (expr instanceof Predicate) {
return BooleanTemplate.create(expr.getTemplate(), args);
} else {
return new TemplateExpressionImpl(expr.getType(), expr.getTemplate(), args);
}
}
}
private ImmutableList<Expression<?>> visit(List<Expression<?>> args) {
ImmutableList.Builder<Expression<?>> builder = ImmutableList.builder();
for (Expression<?> arg : args) {
builder.add(arg.accept(this, null));
}
return builder.build();
}
}