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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.search.federation.vespa;
import java.util.Iterator;
import com.yahoo.prelude.query.*;
/**
* Marshal a query stack into an advanced query string suitable for
* passing to another QRS.
*
* @author Steinar Knutsen
* @author Rong-En Fan
* @deprecated use YQL
*/
// TODO: Remove on Vespa 7
@Deprecated // OK
public class QueryMarshaller {
private boolean atRoot = true;
public String marshal(Item root) {
if (root == null || root instanceof NullItem) {
return null;
}
StringBuilder s = new StringBuilder();
marshal(root, s);
atRoot = true;
return s.toString();
}
/**
* We do not yet care about exact match indices
*/
private void marshal(Item root, StringBuilder s) {
switch (root.getItemType()) {
case OR:
marshalOr((OrItem) root, s);
break;
case AND:
marshalAnd((CompositeItem) root, s);
break;
case NOT:
marshalNot((NotItem) root, s);
break;
case RANK:
marshalRank((RankItem) root, s);
break;
case WORD:
case INT:
case PREFIX:
case SUBSTRING:
case SUFFIX:
marshalWord((TermItem) root, s);
break;
case PHRASE:
// PhraseItem and PhraseSegmentItem don't add quotes for segmented
// termse
if (root instanceof PhraseSegmentItem) {
marshalPhrase((PhraseSegmentItem) root, s);
} else {
marshalPhrase((PhraseItem) root, s);
}
break;
case NEAR:
marshalNear((NearItem) root, s);
break;
case ONEAR:
marshalNear((ONearItem) root, s);
break;
case WEAK_AND:
marshalWeakAnd((WeakAndItem)root, s);
break;
default:
break;
}
}
private void marshalWord(TermItem item, StringBuilder s) {
String index = item.getIndexName();
if (index.length() != 0) {
s.append(item.getIndexName()).append(':');
}
s.append(item.stringValue());
if (item.getWeight() != Item.DEFAULT_WEIGHT)
s.append("!").append(item.getWeight());
}
private void marshalRank(RankItem root, StringBuilder s) {
marshalComposite("RANK", root, s);
}
private void marshalNot(NotItem root, StringBuilder s) {
marshalComposite("ANDNOT", root, s);
}
private void marshalOr(OrItem root, StringBuilder s) {
marshalComposite("OR", root, s);
}
/**
* Dump WORD items, and add space between each of them unless those
* words came from segmentation.
*
* @param root CompositeItem
* @param s current marshaled query
*/
private void dumpWords(CompositeItem root, StringBuilder s) {
for (Iterator<Item> i = root.getItemIterator(); i.hasNext();) {
Item word = i.next();
boolean useSeparator = true;
if (word instanceof TermItem) {
s.append(((TermItem) word).stringValue());
if (word instanceof WordItem) {
useSeparator = !((WordItem) word).isFromSegmented();
}
} else {
dumpWords((CompositeItem) word, s);
}
if (useSeparator && i.hasNext()) {
s.append(' ');
}
}
}
private void marshalPhrase(PhraseItem root, StringBuilder s) {
marshalPhrase(root, s, root.isExplicit(), false);
}
private void marshalPhrase(PhraseSegmentItem root, StringBuilder s) {
marshalPhrase(root, s, root.isExplicit(), true);
}
private void marshalPhrase(IndexedItem root, StringBuilder s, boolean isExplicit, boolean isSegmented) {
String index = root.getIndexName();
if (index.length() != 0) {
s.append(root.getIndexName()).append(':');
}
if (isExplicit || !isSegmented) s.append('"');
dumpWords((CompositeItem) root, s);
if (isExplicit || !isSegmented) s.append('"');
}
private void marshalNear(NearItem root, StringBuilder s) {
marshalComposite(root.getName() + "(" + root.getDistance() + ")", root, s);
}
// Not only AndItem returns ItemType.AND
private void marshalAnd(CompositeItem root, StringBuilder s) {
marshalComposite("AND", root, s);
}
private void marshalWeakAnd(WeakAndItem root, StringBuilder s) {
marshalComposite("WAND(" + root.getN() + ")", root, s);
}
private void marshalComposite(String operator, CompositeItem root, StringBuilder s) {
boolean useParen = !atRoot;
if (useParen) {
s.append("( ");
} else {
atRoot = false;
}
for (Iterator<Item> i = root.getItemIterator(); i.hasNext();) {
Item item = i.next();
marshal(item, s);
if (i.hasNext())
s.append(' ').append(operator).append(' ');
}
if (useParen) {
s.append(" )");
}
}
}
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