+++ /dev/null
-/*
- Egothor Software License version 1.00
- Copyright (C) 1997-2004 Leo Galambos.
- Copyright (C) 2002-2004 "Egothor developers"
- on behalf of the Egothor Project.
- All rights reserved.
-
- This software is copyrighted by the "Egothor developers". If this
- license applies to a single file or document, the "Egothor developers"
- are the people or entities mentioned as copyright holders in that file
- or document. If this license applies to the Egothor project as a
- whole, the copyright holders are the people or entities mentioned in
- the file CREDITS. This file can be found in the same location as this
- license in the distribution.
-
- Redistribution and use in source and binary forms, with or without
- modification, are permitted provided that the following conditions are
- met:
- 1. Redistributions of source code must retain the above copyright
- notice, the list of contributors, this list of conditions, and the
- following disclaimer.
- 2. Redistributions in binary form must reproduce the above copyright
- notice, the list of contributors, this list of conditions, and the
- disclaimer that follows these conditions in the documentation
- and/or other materials provided with the distribution.
- 3. The name "Egothor" must not be used to endorse or promote products
- derived from this software without prior written permission. For
- written permission, please contact Leo.G@seznam.cz
- 4. Products derived from this software may not be called "Egothor",
- nor may "Egothor" appear in their name, without prior written
- permission from Leo.G@seznam.cz.
-
- In addition, we request that you include in the end-user documentation
- provided with the redistribution and/or in the software itself an
- acknowledgement equivalent to the following:
- "This product includes software developed by the Egothor Project.
- http://egothor.sf.net/"
-
- THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
- WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
- MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
- IN NO EVENT SHALL THE EGOTHOR PROJECT OR ITS CONTRIBUTORS BE LIABLE
- FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
- CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
- SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
- BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
- WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
- OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
- IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
- This software consists of voluntary contributions made by many
- individuals on behalf of the Egothor Project and was originally
- created by Leo Galambos (Leo.G@seznam.cz).
- */
-package org.egothor.stemmer;
-
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.Iterator;
-import java.util.List;
-
-/**
- * The Lift class is a data structure that is a variation of a Patricia trie.
- * <p>
- * Lift's <i>raison d'etre</i> is to implement reduction of the trie via the
- * Lift-Up method., which makes the data structure less liable to overstemming.
- */
-public class Lift extends Reduce {
- boolean changeSkip;
-
- /**
- * Constructor for the Lift object.
- *
- * @param changeSkip when set to <tt>true</tt>, comparison of two Cells takes
- * a skip command into account
- */
- public Lift(boolean changeSkip) {
- this.changeSkip = changeSkip;
- }
-
- /**
- * Optimize (eliminate rows with no content) the given Trie and return the
- * reduced Trie.
- *
- * @param orig the Trie to optimized
- * @return the reduced Trie
- */
- @Override
- public Trie optimize(Trie orig) {
- List<CharSequence> cmds = orig.cmds;
- List<Row> rows = new ArrayList<Row>();
- List<Row> orows = orig.rows;
- int remap[] = new int[orows.size()];
-
- for (int j = orows.size() - 1; j >= 0; j--) {
- liftUp(orows.get(j), orows);
- }
-
- Arrays.fill(remap, -1);
- rows = removeGaps(orig.root, orows, new ArrayList<Row>(), remap);
-
- return new Trie(orig.forward, remap[orig.root], cmds, rows);
- }
-
- /**
- * Reduce the trie using Lift-Up reduction.
- * <p>
- * The Lift-Up reduction propagates all leaf-values (patch commands), where
- * possible, to higher levels which are closer to the root of the trie.
- *
- * @param in the Row to consider when optimizing
- * @param nodes contains the patch commands
- */
- public void liftUp(Row in, List<Row> nodes) {
- Iterator<Cell> i = in.cells.values().iterator();
- for (; i.hasNext();) {
- Cell c = i.next();
- if (c.ref >= 0) {
- Row to = nodes.get(c.ref);
- int sum = to.uniformCmd(changeSkip);
- if (sum >= 0) {
- if (sum == c.cmd) {
- if (changeSkip) {
- if (c.skip != to.uniformSkip + 1) {
- continue;
- }
- c.skip = to.uniformSkip + 1;
- } else {
- c.skip = 0;
- }
- c.cnt += to.uniformCnt;
- c.ref = -1;
- } else if (c.cmd < 0) {
- c.cnt = to.uniformCnt;
- c.cmd = sum;
- c.ref = -1;
- if (changeSkip) {
- c.skip = to.uniformSkip + 1;
- } else {
- c.skip = 0;
- }
- }
- }
- }
- }
- }
-}
fnp / pylucene.git / blobdiff