/**
 * 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.common.funcs;

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 class Sqrt extends TScalarBase {

    private final TClass type; 
    
    public Sqrt(TClass type) {
        this.type = type;
    }
      
    @Override
    protected void buildInputSets(TInputSetBuilder builder)
    {
        builder.covers(type, 0);
    }
    
    @Override
    protected void doEvaluate(TExecutionContext context, LazyList<? extends ValueSource> inputs, ValueTarget output) {
        double value = inputs.get(0).getDouble();
        if (value < 0) {
            output.putNull();
        } else {
            output.putDouble(Math.sqrt(value));
        }
    }
      
    @Override
    public String displayName() {
        return "SQRT";
    }
    
    @Override
    public TOverloadResult resultType()
    {
        return TOverloadResult.fixed(type);
    }

}