001/*
002 * ModeShape (http://www.modeshape.org)
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *       http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016package org.modeshape.schematic.internal.delta;
017
018import org.modeshape.schematic.document.Path;
019import org.modeshape.schematic.internal.HashCode;
020import org.modeshape.schematic.internal.document.MutableDocument;
021
022/**
023 * An atomic put-if-absent operation for SchematicValueDelta.
024 * 
025 * @author (various)
026 */
027public class PutIfAbsentOperation extends Operation {
028    protected final String fieldName;
029    protected final Object newValue;
030    private transient boolean absent = false;
031
032    public PutIfAbsentOperation( Path parentPath,
033                                 String fieldName,
034                                 Object newValue ) {
035        super(parentPath, HashCode.compute(parentPath, fieldName, newValue));
036        this.fieldName = fieldName;
037        this.newValue = newValue;
038    }
039
040    @Override
041    public PutIfAbsentOperation clone() {
042        return new PutIfAbsentOperation(getParentPath(), fieldName, cloneValue(newValue));
043    }
044
045    public Object getNewValue() {
046        return newValue;
047    }
048
049    public String getFieldName() {
050        return fieldName;
051    }
052
053    public boolean isApplied() {
054        return absent;
055    }
056
057    @Override
058    public void rollback( MutableDocument delegate ) {
059        MutableDocument parent = mutableParent(delegate);
060        assert parent != null;
061        if (absent) {
062            parent.remove(fieldName);
063        }
064    }
065
066    @Override
067    public void replay( MutableDocument delegate ) {
068        MutableDocument parent = mutableParent(delegate);
069        assert parent != null;
070        if (!parent.containsField(fieldName)) {
071            parent.put(fieldName, newValue);
072            absent = true;
073        }
074    }
075
076    @Override
077    public int hashCode() {
078        return super.hashCode();
079    }
080
081    @Override
082    public boolean equals( Object obj ) {
083        if (obj instanceof PutIfAbsentOperation) {
084            PutIfAbsentOperation other = (PutIfAbsentOperation)obj;
085            return equalsIfNotNull(fieldName, other.fieldName) && absent == other.absent
086                   && equalsIfNotNull(newValue, other.newValue) && getParentPath().equals(other.getParentPath());
087
088        }
089        return false;
090    }
091
092    @Override
093    public String toString() {
094        return "Put-if-absent at '" + parentPath + "' the '" + fieldName + "' field value '" + newValue + "'";
095    }
096}