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org.apache.openjpa.jdbc.kernel.exps.SimpleCaseExpression Maven / Gradle / Ivy
/*
* 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.DBDictionary;
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;
/**
* Simple case expression.
*
* @author Catalina Wei
*/
public class SimpleCaseExpression
extends AbstractVal {
private static final long serialVersionUID = 1L;
private final Val _caseOperand;
private final Exp[] _exp;
private final Val _val;
private ClassMetaData _meta = null;
private Class _cast = null;
private Value other = null;
private ExpState otherState = null;
/**
* Constructor.
*/
public SimpleCaseExpression(Val caseOperand, Exp[] exp, Val val) {
_caseOperand = caseOperand;
_exp = exp;
_val = val;
}
public Val getCaseOperand() {
return _caseOperand;
}
public Exp[] getExp() {
return _exp;
}
public Val getVal() {
return _val;
}
@Override
public Class getType() {
if (_cast != null)
return _cast;
Class type = _val.getType();
for (Exp exp : _exp)
type = Filters.promote(type,
((WhenScalar) exp).getVal2().getType());
if (type == Raw.class)
return String.class;
return type;
}
@Override
public ExpState initialize(Select sel, ExpContext ctx, int flags) {
ExpState[] states = new ExpState[_exp.length+2];
Joins joins = null;
states[0] = _caseOperand.initialize(sel, ctx, 0);
if (joins == null)
joins = states[0].joins;
else
joins = sel.and(joins, states[0].joins);
for (int i = 0; i < _exp.length; i++) {
states[i+1] = _exp[i].initialize(sel, ctx, null);
if (joins == null)
joins = states[i+1].joins;
else
joins = sel.and(joins, states[i+1].joins);
}
states[_exp.length+1] = _val.initialize(sel, ctx, 0);
if (joins == null)
joins = states[_exp.length+1].joins;
else
joins = sel.and(joins, states[_exp.length+1].joins);
return new SimpleCaseExpState(joins, states);
}
private static class SimpleCaseExpState
extends ExpState {
public ExpState[] states;
public SimpleCaseExpState(Joins joins, ExpState[] states) {
super(joins);
this.states = states;
}
}
@Override
public void appendTo(Select sel, ExpContext ctx, ExpState state,
SQLBuffer buf, int index) {
SimpleCaseExpState cstate = (SimpleCaseExpState) state;
DBDictionary dict = ctx.store.getDBDictionary();
buf.append(" CASE ");
for (int i = 0; i < _exp.length; i++) {
// if back-end does not support simple case expression,
// pushdown sql as general case expression.
if (!dict.supportsSimpleCaseExpression)
buf.append(" WHEN ");
if (i == 0 || !dict.supportsSimpleCaseExpression)
_caseOperand.appendTo(sel, ctx, cstate.states[0], buf, 0);
if (!dict.supportsSimpleCaseExpression)
buf.append(" = ");
else
buf.append(" WHEN ");
_exp[i].appendTo(sel, ctx, cstate.states[i+1], buf);
}
buf.append(" ELSE ");
_val.appendTo(sel, ctx, cstate.states[_exp.length+1], buf, 0);
buf.append(" END ");
}
@Override
public void selectColumns(Select sel, ExpContext ctx, ExpState state,
boolean pks) {
SimpleCaseExpState cstate = (SimpleCaseExpState) state;
_caseOperand.selectColumns(sel, ctx, cstate.states[0], pks);
for (int i = 0; i < _exp.length; i++)
_exp[i].selectColumns(sel, ctx, cstate.states[i+1], pks);
_val.selectColumns(sel, ctx, cstate.states[_exp.length+1], pks);
}
@Override
public void acceptVisit(ExpressionVisitor visitor) {
visitor.enter(this);
_caseOperand.acceptVisit(visitor);
for (Exp exp : _exp) {
exp.acceptVisit(visitor);
}
_val.acceptVisit(visitor);
visitor.exit(this);
}
@Override
public int getId() {
return Val.SIMPLECASE_VAL;
}
@Override
public void calculateValue(Select sel, ExpContext ctx, ExpState state,
Val other, ExpState otherState) {
SimpleCaseExpState cstate = (SimpleCaseExpState) state;
_caseOperand.calculateValue(sel, ctx, cstate.states[0], other,
otherState);
for (int i = 0; i < _exp.length; i++) {
BinaryOpExpState bstate = (BinaryOpExpState) cstate.states[i+1];
((WhenScalar) _exp[i]).getVal1().calculateValue(sel, ctx,
bstate.state1, null, null);
((WhenScalar) _exp[i]).getVal2().calculateValue(sel, ctx,
bstate.state2, other, otherState);
}
_val.calculateValue(sel, ctx, cstate.states[_exp.length+1], 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;
}
}
