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// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.prelude.query;
import com.yahoo.protect.Validator;
import java.util.Iterator;
/**
* <p>A composite item where the first item is positive and the following
* items are negative items which should be excluded from the result.
*
* @author bratseth
*/
// TODO: Handle nulls by creating nullItem or checking in encode/toString
public class NotItem extends CompositeItem {
public ItemType getItemType() {
return ItemType.NOT;
}
public String getName() {
return "NOT";
}
/**
* Adds an item. The first item is the positive
* the rest is negative
*/
public void addItem(Item item) {
super.addItem(item);
}
/**
* Adds a negative item. Like addItem but skips the first position
* (position 0) if it is not already set.
*/
public void addNegativeItem(Item negative) {
if (getItemCount() == 0) {
insertNullFirstItem();
}
addItem(negative);
}
/**
* Returns the positive item (the first subitem),
* or null if no positive items has been added
*/
public Item getPositiveItem() {
if (getItemCount() == 0) {
return null;
}
return getItem(0);
}
/**
* Sets the positive item (the first item)
*
* @return the old positive item, or null if there was no items
*/
public Item setPositiveItem(Item item) {
Validator.ensureNotNull("Positive item of " + this, item);
if (getItemCount() == 0) {
addItem(item);
return null;
} else {
return setItem(0, item);
}
}
/**
* Convenience method for adding a positive item.
* If a positive item is already present
* the positive item becomes an AndItem with the items added
*/
public void addPositiveItem(Item item) {
if (getPositiveItem() == null) {
setPositiveItem(item);
} else if (getPositiveItem() instanceof AndItem) {
((AndItem) getPositiveItem()).addItem(item);
} else {
AndItem positives = new AndItem();
positives.addItem(getPositiveItem());
positives.addItem(item);
setPositiveItem(positives);
}
}
public boolean removeItem(Item item) {
int removedIndex = getItemIndex(item);
boolean removed = super.removeItem(item);
if (removed && removedIndex == 0) {
insertNullFirstItem();
}
return removed;
}
public Item removeItem(int index) {
Item removed = super.removeItem(index);
if (index == 0) { // Don't make the first negative the positive
insertNullFirstItem();
}
return removed;
}
/** Not items uses a empty heading instead of "NOT " */
protected void appendHeadingString(StringBuilder buffer) {}
/**
* Overridden to tolerate nulls and to append "+"
* to the first item and "-" to the rest
*/
protected void appendBodyString(StringBuilder buffer) {
boolean isFirstItem = true;
for (Iterator<Item> i = getItemIterator(); i.hasNext();) {
Item item = i.next();
if (isFirstItem) {
buffer.append("+");
} else {
buffer.append(" -");
}
if (item == null) {
buffer.append("(null)");
} else {
buffer.append(item.toString());
}
isFirstItem = false;
}
}
/** Returns the number of actual *positive* terms in this */
@Override
public int getTermCount() {
Item positive = getPositiveItem();
return positive == null ? 0 : positive.getTermCount();
}
}
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