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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 org.apache.commons.lang3.builder;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Objects;
/**
* A {@link DiffResult} contains a collection of the differences between two
* {@link Diffable} objects. Typically these differences are displayed using
* {@link #toString()} method, which returns a string describing the fields that
* differ between the objects.
*
* <p>
* Use a {@link DiffBuilder} to build a {@link DiffResult} comparing two objects.
* </p>
* @param <T> type of the left and right object.
*
* @since 3.3
*/
public class DiffResult<T> implements Iterable<Diff<?>> {
/**
* The {@link String} returned when the objects have no differences:
* {@value}
*
*/
public static final String OBJECTS_SAME_STRING = "";
private static final String DIFFERS_STRING = "differs from";
private final List<Diff<?>> diffList;
private final T lhs;
private final T rhs;
private final ToStringStyle style;
/**
* Creates a {@link DiffResult} containing the differences between two
* objects.
*
* @param lhs
* the left-hand object
* @param rhs
* the right-hand object
* @param diffList
* the list of differences, may be empty
* @param style
* the style to use for the {@link #toString()} method. May be
* {@code null}, in which case
* {@link ToStringStyle#DEFAULT_STYLE} is used
* @throws NullPointerException if {@code lhs}, {@code rhs} or {@code diffs} is {@code null}
*/
DiffResult(final T lhs, final T rhs, final List<Diff<?>> diffList,
final ToStringStyle style) {
Objects.requireNonNull(lhs, "lhs");
Objects.requireNonNull(rhs, "rhs");
Objects.requireNonNull(diffList, "diffList");
this.diffList = diffList;
this.lhs = lhs;
this.rhs = rhs;
if (style == null) {
this.style = ToStringStyle.DEFAULT_STYLE;
} else {
this.style = style;
}
}
/**
* Returns the object the right object has been compared to.
*
* @return the left object of the diff
* @since 3.10
*/
public T getLeft() {
return this.lhs;
}
/**
* Returns the object the left object has been compared to.
*
* @return the right object of the diff
* @since 3.10
*/
public T getRight() {
return this.rhs;
}
/**
* Returns an unmodifiable list of {@link Diff}s. The list may be empty if
* there were no differences between the objects.
*
* @return an unmodifiable list of {@link Diff}s
*/
public List<Diff<?>> getDiffs() {
return Collections.unmodifiableList(diffList);
}
/**
* Returns the number of differences between the two objects.
*
* @return the number of differences
*/
public int getNumberOfDiffs() {
return diffList.size();
}
/**
* Returns the style used by the {@link #toString()} method.
*
* @return the style
*/
public ToStringStyle getToStringStyle() {
return style;
}
/**
* Builds a {@link String} description of the differences contained within
* this {@link DiffResult}. A {@link ToStringBuilder} is used for each object
* and the style of the output is governed by the {@link ToStringStyle}
* passed to the constructor.
*
* <p>
* If there are no differences stored in this list, the method will return
* {@link #OBJECTS_SAME_STRING}. Otherwise, using the example given in
* {@link Diffable} and {@link ToStringStyle#SHORT_PREFIX_STYLE}, an output
* might be:
* </p>
*
* <pre>
* Person[name=John Doe,age=32] differs from Person[name=Joe Bloggs,age=26]
* </pre>
*
* <p>
* This indicates that the objects differ in name and age, but not in
* smoking status.
* </p>
*
* <p>
* To use a different {@link ToStringStyle} for an instance of this class,
* use {@link #toString(ToStringStyle)}.
* </p>
*
* @return a {@link String} description of the differences.
*/
@Override
public String toString() {
return toString(style);
}
/**
* Builds a {@link String} description of the differences contained within
* this {@link DiffResult}, using the supplied {@link ToStringStyle}.
*
* @param style
* the {@link ToStringStyle} to use when outputting the objects
*
* @return a {@link String} description of the differences.
*/
public String toString(final ToStringStyle style) {
if (diffList.isEmpty()) {
return OBJECTS_SAME_STRING;
}
final ToStringBuilder lhsBuilder = new ToStringBuilder(lhs, style);
final ToStringBuilder rhsBuilder = new ToStringBuilder(rhs, style);
diffList.forEach(diff -> {
lhsBuilder.append(diff.getFieldName(), diff.getLeft());
rhsBuilder.append(diff.getFieldName(), diff.getRight());
});
return String.format("%s %s %s", lhsBuilder.build(), DIFFERS_STRING, rhsBuilder.build());
}
/**
* Returns an iterator over the {@link Diff} objects contained in this list.
*
* @return the iterator
*/
@Override
public Iterator<Diff<?>> iterator() {
return diffList.iterator();
}
}
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