io.continual.util.data.exprEval.ExprDataSource Maven / Gradle / Ivy
/*
* Copyright 2019, Continual.io
*
* Licensed 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 io.continual.util.data.exprEval;
/**
* A source of data for the expression evaluator
*/
public interface ExprDataSource
{
/**
* get the value of an object given a label
* @param label the data value's key
* @return a data object
*/
Object eval ( String label );
default String evalToString ( String label )
{
return evalToString ( label, null );
}
default String evalToString ( String label, String defval )
{
final Object val = eval ( label );
if ( val != null ) return val.toString ();
return defval;
}
}