/**
* Copyright (C) 2009-2013 FoundationDB, LLC
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package com.foundationdb.sql.optimizer.plan;
import com.foundationdb.server.types.TInstance;
import com.foundationdb.server.types.TPreptimeValue;
import com.foundationdb.server.types.common.types.StringAttribute;
import com.foundationdb.server.types.common.types.StringFactory;
import com.foundationdb.server.types.common.types.TString;
import com.foundationdb.server.types.value.ValueSource;
import com.foundationdb.server.types.value.ValueSources;
import com.foundationdb.sql.types.DataTypeDescriptor;
import com.foundationdb.sql.parser.ValueNode;
import com.foundationdb.util.AkibanAppender;
/** An operand with a constant value. */
public class ConstantExpression extends BaseExpression
{
private Object value;
public static ConstantExpression typedNull(DataTypeDescriptor sqlType, ValueNode sqlSource, TInstance type) {
if (sqlType == null) {
ValueSource nullSource = ValueSources.getNullSource(null);
ConstantExpression result = new ConstantExpression(new TPreptimeValue(nullSource));
return result;
}
ConstantExpression result = new ConstantExpression((Object)null, sqlType, sqlSource, null);
if (type != null) {
ValueSource nullSource = ValueSources.getNullSource(type);
result.setPreptimeValue(new TPreptimeValue(type, nullSource));
} else {
result.setPreptimeValue(new TPreptimeValue());
}
return result;
}
public ConstantExpression (Object value, DataTypeDescriptor sqlType, ValueNode sqlSource, TInstance type) {
super (sqlType, sqlSource, null);
this.value = value;
// For constant strings, reset the CollationID to NULL,
// meaning they defer collation ordering to the other operand.
if (type != null && type.typeClass() instanceof TString) {
type = type.typeClass().instance(
type.attribute(StringAttribute.MAX_LENGTH),
type.attribute(StringAttribute.CHARSET),
StringFactory.NULL_COLLATION_ID,
type.nullability());
}
setPreptimeValue(ValueSources.fromObject(value, type));
}
public ConstantExpression (Object value, TInstance type) {
this(value, type.dataTypeDescriptor(), null, type);
}
public ConstantExpression(TPreptimeValue preptimeValue) {
super (preptimeValue.type() == null ? null : preptimeValue.type().dataTypeDescriptor(), null, null);
setPreptimeValue(preptimeValue);
}
@Override
public boolean isConstant() {
return true;
}
public boolean isNullable() {
if (value == null && getType() != null) {
return getType().nullability();
}
return false;
}
public Object getValue() {
if (value == null) {
ValueSource valueSource = getPreptimeValue().value();
if (valueSource == null || valueSource.isNull())
return null;
value = ValueSources.toObject(valueSource);
}
return value;
}
@Override
public boolean equals(Object obj) {
if (!(obj instanceof ConstantExpression)) return false;
ConstantExpression other = (ConstantExpression)obj;
// Normalize to the value (from TPreptimeContext)
ensureValueObject(this);
ensureValueObject(other);
return ((value == null) ?
(other.value == null) :
value.equals(other.value));
}
@Override
public int hashCode() {
ensureValueObject(this);
return (value == null) ? 0 : value.hashCode();
}
private static void ensureValueObject(ConstantExpression constantExpression) {
if (constantExpression.value == null)
constantExpression.getValue();
}
@Override
public boolean accept(ExpressionVisitor v) {
return v.visit(this);
}
@Override
public ExpressionNode accept(ExpressionRewriteVisitor v) {
return v.visit(this);
}
@Override
public String toString() {
ValueSource valueSource = getPreptimeValue().value();
if (valueSource == null || valueSource.isNull())
return "NULL";
StringBuilder sb = new StringBuilder();
getType().format(valueSource, AkibanAppender.of(sb));
return sb.toString();
}
@Override
protected void deepCopy(DuplicateMap map) {
super.deepCopy(map);
// Do not copy object.
}
}