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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.prelude.query.parser;
import com.yahoo.prelude.query.AndItem;
import com.yahoo.prelude.query.CompositeItem;
import com.yahoo.prelude.query.Item;
import com.yahoo.prelude.query.NotItem;
import com.yahoo.prelude.query.OrItem;
import com.yahoo.prelude.query.WordItem;
import com.yahoo.search.query.parser.ParserEnvironment;
/**
* Parser for web search queries. Language:
*
* <ul>
* <li>+item: always include this item as-is when searching (term becomes <i>protected</i>)
* <li>-item: Exclude item when searching (terms becomes <i>protected</i>)
* <li>a OR b (capital or): Or search for a or b
* <li>"a b": Phrase search for a followed by b
* </ul>
*
* @author bratseth
*/
public class WebParser extends AllParser {
public WebParser(ParserEnvironment environment) {
super(environment, false);
}
@Override
protected Item parseItemsBody() {
// Algorithm: Collect positive, negative, and'ed and or'ed elements, then combine.
CompositeItem and = null;
OrItem or = null;
NotItem not = null; // Store negatives here as we go
Item current;
// Find all items
do {
current = negativeItem();
if (current != null) {
not = addNot(current, not);
continue;
}
current = positiveItem();
if (current == null)
current = indexableItem().getFirst();
if (current != null) {
if (and != null && (current instanceof WordItem) && "OR".equals(((WordItem)current).getRawWord())) {
if (or == null)
or = addOr(and, or);
and = new AndItem();
or.addItem(and);
}
else {
and = addAnd(current, and);
}
}
if (current == null) // Change
tokens.skip();
} while (tokens.hasNext());
// Combine the items
Item topLevel = and;
if (or != null)
topLevel = or;
if (not != null && topLevel != null) {
not.setPositiveItem(topLevel);
topLevel = not;
}
return simplifyUnnecessaryComposites(topLevel);
}
}
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