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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.apache.openjpa.jdbc.kernel.exps;
import java.sql.SQLException;
import org.apache.openjpa.jdbc.meta.JavaSQLTypes;
import org.apache.openjpa.jdbc.sql.Joins;
import org.apache.openjpa.jdbc.sql.Raw;
import org.apache.openjpa.jdbc.sql.Result;
import org.apache.openjpa.jdbc.sql.SQLBuffer;
import org.apache.openjpa.jdbc.sql.Select;
import org.apache.openjpa.kernel.Filters;
import org.apache.openjpa.kernel.exps.ExpressionVisitor;
import org.apache.openjpa.kernel.exps.Value;
import org.apache.openjpa.meta.ClassMetaData;
/**
* Coalesce expression.
*
* @author Catalina Wei
*/
public class CoalesceExpression
extends AbstractVal {
private static final long serialVersionUID = 1L;
private final Val[] _vals;
private ClassMetaData _meta = null;
private Class _cast = null;
private Value other = null;
private ExpState otherState = null;
/**
* Constructor.
*/
public CoalesceExpression(Val[] vals) {
_vals = vals;
}
public Val[] getVal() {
return _vals;
}
@Override
public Class getType() {
if (_cast != null)
return _cast;
Class type = _vals[0].getType();
for (int i = 1; i < _vals.length; i++)
type = Filters.promote(type, _vals[i].getType());
if (type == Raw.class)
return String.class;
return type;
}
@Override
public ExpState initialize(Select sel, ExpContext ctx, int flags) {
ExpState[] states = new ExpState[_vals.length];
Joins joins = null;
for (int i = 0; i < _vals.length; i++) {
states[i] = _vals[i].initialize(sel, ctx, flags);
if (joins == null)
joins = states[i].joins;
else
joins = sel.and(joins, states[i].joins);
}
return new CoalesceExpState(joins, states);
}
private static class CoalesceExpState
extends ExpState {
public ExpState[] states;
public CoalesceExpState(Joins joins, ExpState[] states) {
super(joins);
this.states = states;
}
}
@Override
public void appendTo(Select sel, ExpContext ctx, ExpState state,
SQLBuffer buf, int index) {
CoalesceExpState cstate = (CoalesceExpState) state;
buf.append(" COALESCE("); // MySQL does not like space before bracket
for (int i = 0; i < _vals.length; i++) {
if (i > 0)
buf.append(",");
_vals[i].appendTo(sel, ctx, cstate.states[i], buf, 0);
}
buf.append(")");
}
@Override
public void selectColumns(Select sel, ExpContext ctx, ExpState state,
boolean pks) {
CoalesceExpState cstate = (CoalesceExpState) state;
for (int i = 0; i < _vals.length; i++)
_vals[i].selectColumns(sel, ctx, cstate.states[i], pks);
}
@Override
public void acceptVisit(ExpressionVisitor visitor) {
visitor.enter(this);
for (Val val : _vals) {
val.acceptVisit(visitor);
}
visitor.exit(this);
}
@Override
public int getId() {
return Val.COALESCE_VAL;
}
@Override
public void calculateValue(Select sel, ExpContext ctx, ExpState state,
Val other, ExpState otherState) {
CoalesceExpState cstate = (CoalesceExpState) state;
for (int i = 0; i < _vals.length; i++)
_vals[i].calculateValue(sel, ctx, cstate.states[i], other, otherState);
}
@Override
public void groupBy(Select sel, ExpContext ctx, ExpState state) {
sel.groupBy(newSQLBuffer(sel, ctx, state));
}
@Override
public int length(Select sel, ExpContext ctx, ExpState state) {
return 1;
}
private SQLBuffer newSQLBuffer(Select sel, ExpContext ctx, ExpState state) {
calculateValue(sel, ctx, state, (Val)other, otherState);
SQLBuffer buf = new SQLBuffer(ctx.store.getDBDictionary());
appendTo(sel, ctx, state, buf, 0);
return buf;
}
@Override
public Object load(ExpContext ctx, ExpState state, Result res)
throws SQLException {
return Filters.convert(res.getObject(this,
JavaSQLTypes.JDBC_DEFAULT, null), getType());
}
@Override
public void orderBy(Select sel, ExpContext ctx, ExpState state,
boolean asc) {
sel.orderBy(newSQLBuffer(sel, ctx, state), asc, false, getSelectAs());
}
@Override
public void select(Select sel, ExpContext ctx, ExpState state, boolean pks){
sel.select(newSQLBuffer(sel, ctx, state), this);
}
@Override
public ClassMetaData getMetaData() {
return _meta;
}
@Override
public void setImplicitType(Class type) {
_cast = type;
}
@Override
public void setMetaData(ClassMetaData meta) {
_meta = meta;
}
public void setOtherPath(Value other) {
this.other = other;
}
public Value getOtherPath() {
return other;
}
public void setOtherState(ExpState otherState) {
this.otherState = otherState;
}
public ExpState getOtherState() {
return otherState;
}
}
