minium.ConditionalElements Maven / Gradle / Ivy
/*
* Copyright (C) 2015 The Minium Authors
*
* 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 minium;
/**
* Logic operations over elements. We consider a elements expression to evaluate
* into a "true" value when its evaluated set is non-empty, and to be "false"
* when it is empty.
*/
public interface ConditionalElements extends Elements {
/**
* Intersects both evaluated sets. For instance, if this
* evaluates into { A, B, C } and elems evaluates
* into { B, C, D }, then this.and(elems)
* evaluates into { B, C }
*
* @param elems
* elements to intersect with
* @return new {@link Elements} that corresponds to the intersection of
* this and elems
*/
public abstract T and(Elements elems);
/**
* Represents the union both evaluated sets. For instance, if
* this evaluates into { A, B, C } and
* elems evaluates into { B, C, D }, then
* this.or(elems) evaluates into { A, B, C, D }
*
* @param elems
* elements to union with
* @return new {@link Elements} that corresponds to the union of
* this and elems
*/
public abstract T or(Elements elems);
/**
* Evaluates into elems if and only if this
* evaluates into a non-empty set, otherwise returns an empty set.
*
* For instance, if this evaluates into { A, B }
* and elems evaluates into { B, C } then
* this.then(elems) evaluates into { B, C }.
*
* If this evaluates into an empty set, then
* this.then(elems) evaluates into an empty set.
*
* @param elems
* elements to evaluate into if this is non-empty
* @return new {@link Elements} that evaluates into elems only
* and only if this evaluates into a non-empty set,
* otherwise returns an empty set.
*/
public abstract T then(Elements elems);
/**
* Evaluates into this if and only if elems
* evaluates into a non-empty set, otherwise returns an empty set.
* Basically, someElems.when(otherElems) is equivalent to
* otherElems.then(someElems).
*
* @param elems
* if non-empty, causes method to evaluate into this
* @return new {@link Elements} that evaluates into this only
* and only if elems evaluates into a non-empty set,
* otherwise returns an empty set.
*/
public abstract T when(Elements elems);
/**
* Evaluates into this if and only if elems
* evaluates into a empty set, otherwise returns an empty set.
*
* For instance, if this evaluates into { A, B }
* and elems evaluates into { B, C } then
* this.unless(elems) evaluates into an empty set.
*
* If elems evaluates into an empty set, then
* this.unless(elems) evaluates into { A, B }.
*
* @param elems
* if empty, causes method to evaluate into this
* @return new {@link Elements} that evaluates into this only
* and only if elems evaluates into a empty set,
* otherwise returns an empty set.
*/
public abstract T unless(Elements elems);
}