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// Copyright Yahoo. 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.EquivItem;
import com.yahoo.prelude.query.Item;
import com.yahoo.prelude.query.NearItem;
import com.yahoo.prelude.query.NotItem;
import com.yahoo.prelude.query.ONearItem;
import com.yahoo.prelude.query.OrItem;
import com.yahoo.prelude.query.RankItem;
import com.yahoo.prelude.query.SegmentItem;
import com.yahoo.prelude.query.WeakAndItem;
import com.yahoo.prelude.query.WordItem;
import com.yahoo.search.query.parser.ParserEnvironment;
import static com.yahoo.prelude.query.parser.Token.Kind.LBRACE;
import static com.yahoo.prelude.query.parser.Token.Kind.NUMBER;
/**
* Parser for queries of type 'advanced'.
*
* @author Steinar Knutsen
* @deprecated YQL should be used for formal queries
*/
@Deprecated // DO NOT REMOVE (we'll keep this around longer)
public class AdvancedParser extends StructuredParser {
public AdvancedParser(ParserEnvironment environment) {
super(environment);
}
@Override
protected Item parseItems() {
return advancedItems(true);
}
protected Item handleComposite(boolean topLevel) {
return advancedItems(false);
}
/**
* A collection of one or more advanced items.
*/
private Item advancedItems(boolean topLevel) {
int position = tokens.getPosition();
Item item = null;
try {
item = advancedItemsBody(topLevel);
return item;
} finally {
if (item == null) {
tokens.setPosition(position);
}
}
}
private Item advancedItemsBody(boolean topLevel) {
Item topLevelItem = null;
Item item;
boolean itemIsComposite;
boolean topLevelIsClosed = false;
boolean expectingOperator = false;
do {
item = indexableItem().getFirst();
if (item == null) {
item = compositeItem();
itemIsComposite = true;
} else {
itemIsComposite = false;
}
if (item != null) {
Item newTop = null;
if (expectingOperator) {
newTop = handleAdvancedOperator(topLevelItem, item, topLevelIsClosed);
}
if (newTop != null) { // Operator found
topLevelIsClosed = false;
expectingOperator = false;
topLevelItem = newTop;
} else if (topLevelItem == null) {
topLevelItem = item;
if (itemIsComposite) {
topLevelIsClosed = true;
}
expectingOperator = true;
} else if (topLevelItem instanceof CompositeItem && !(topLevelItem instanceof SegmentItem)) {
((CompositeItem) topLevelItem).addItem(item);
expectingOperator = true;
} else {
AndItem and = new AndItem();
and.addItem(topLevelItem);
and.addItem(item);
topLevelItem = and;
topLevelIsClosed = false;
expectingOperator = true;
}
}
if (topLevel && item == null) {
tokens.skip();
}
} while (tokens.hasNext() && (topLevel || item != null));
// Optimize away composites containing one item only
// (including nots with only a positive)
if (topLevelItem instanceof CompositeItem
&& ((CompositeItem) topLevelItem).getItemCount() == 1) {
return ((CompositeItem) topLevelItem).removeItem(0);
}
return topLevelItem;
}
/** Returns whether the item is a specific word item */
private boolean isTheWord(String word, Item item) {
if (!(item instanceof WordItem)) {
return false;
}
return word.equalsIgnoreCase(((WordItem) item).getRawWord()); // TODO: Why not search for getWord w.o lowercasing?
}
/** Returns the new top level, or null if the current item is not an operator */
private Item handleAdvancedOperator(Item topLevelItem, Item item, boolean topLevelIsClosed) {
if (isTheWord("and", item)) {
if (topLevelIsClosed || !(topLevelItem instanceof AndItem)) {
AndItem and = new AndItem();
and.addItem(topLevelItem);
return and;
}
return topLevelItem;
} else if (isTheWord("or", item)) {
if (topLevelIsClosed || !(topLevelItem instanceof OrItem)) {
OrItem or = new OrItem();
or.addItem(topLevelItem);
return or;
}
return topLevelItem;
} else if (isTheWord("equiv", item)) {
if (topLevelIsClosed || !(topLevelItem instanceof EquivItem)) {
EquivItem equiv = new EquivItem();
equiv.addItem(topLevelItem);
return equiv;
}
return topLevelItem;
} else if (isTheWord("wand", item) || isTheWord("weakand", item)) {
int n = consumeNumericArgument();
if (n == 0)
n = WeakAndItem.defaultN;
if (topLevelIsClosed || !(topLevelItem instanceof WeakAndItem) || n != ((WeakAndItem)topLevelItem).getN()) {
WeakAndItem wand = new WeakAndItem();
wand.setN(n);
wand.addItem(topLevelItem);
return wand;
}
return topLevelItem;
} else if (isTheWord("andnot", item)) {
if (topLevelIsClosed || !(topLevelItem instanceof NotItem)) {
NotItem not = new NotItem();
not.addPositiveItem(topLevelItem);
return not;
}
return topLevelItem;
} else if (isTheWord("rank", item)) {
if (topLevelIsClosed || !(topLevelItem instanceof RankItem)) {
RankItem rank = new RankItem();
rank.addItem(topLevelItem);
return rank;
}
return topLevelItem;
} else if (isTheWord("near", item)) {
int distance = consumeNumericArgument();
if (distance==0)
distance=NearItem.defaultDistance;
if (topLevelIsClosed || !(topLevelItem instanceof NearItem) || distance != ((NearItem)topLevelItem).getDistance()) {
NearItem near = new NearItem(distance);
near.addItem(topLevelItem);
return near;
}
return topLevelItem;
} else if (isTheWord("onear", item)) {
int distance = consumeNumericArgument();
if (distance==0)
distance= ONearItem.defaultDistance;
if (topLevelIsClosed || !(topLevelItem instanceof ONearItem) || distance!=((ONearItem)topLevelItem).getDistance()) {
ONearItem oNear = new ONearItem(distance);
oNear.addItem(topLevelItem);
return oNear;
}
return topLevelItem;
}
return null;
}
/** Returns the argument to this operator or 0 if none */
private int consumeNumericArgument() {
if (!tokens.currentIs(LBRACE)) return 0;
tokens.skip(LBRACE);
if (!tokens.currentIsNoIgnore(NUMBER)) throw new IllegalArgumentException("Expected an integer argument");
int distance = Integer.valueOf(tokens.next().image);
if (!tokens.skip(Token.Kind.RBRACE)) throw new IllegalArgumentException("Expected a right brace following the argument");
return distance;
}
}
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