/**
* 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.server.types.texpressions.std;
import com.foundationdb.server.types.LazyList;
import com.foundationdb.server.types.TClass;
import com.foundationdb.server.types.TExecutionContext;
import com.foundationdb.server.types.TOverloadResult;
import com.foundationdb.server.types.value.ValueSource;
import com.foundationdb.server.types.value.ValueTarget;
import com.foundationdb.server.types.texpressions.TInputSetBuilder;
import com.foundationdb.server.types.texpressions.TScalarBase;
public abstract class NoArgExpression extends TScalarBase
{
public abstract void evaluate(TExecutionContext context, ValueTarget target);
public boolean constantPerPreparation()
{
return constPerPrep;
}
@Override
protected void buildInputSets(TInputSetBuilder builder)
{
// does nothing. (no input)
}
@Override
public String displayName()
{
return name;
}
@Override
protected void doEvaluate(TExecutionContext context, LazyList<? extends ValueSource> inputs, ValueTarget output)
{
assert inputs.size() == 0 : "unexpected input";
evaluate(context, output);
}
@Override
protected boolean neverConstant() {
return true;
}
@Override
public TOverloadResult resultType()
{
return TOverloadResult.fixed(resultTClass(), resultAttrs());
}
protected int[] resultAttrs() {
return NO_ATTRS;
}
protected abstract TClass resultTClass();
public NoArgExpression(String name, boolean constPerPrep)
{
this.name = name;
this.constPerPrep = constPerPrep;
}
private final String name;
private boolean constPerPrep;
private static final int[] NO_ATTRS = new int[0];
}