org.egothor.stemmer.MultiTrie2 Maven / Gradle / Ivy
/*
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 [email protected]
4. Products derived from this software may not be called "Egothor",
nor may "Egothor" appear in their name, without prior written
permission from [email protected].
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 ([email protected]).
*/
package org.egothor.stemmer;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
/**
* The MultiTrie is a Trie of Tries.
*
* It stores words and their associated patch commands. The MultiTrie handles
* patch commmands broken into their constituent parts, as a MultiTrie does, but
* the commands are delimited by the skip command.
*/
public class MultiTrie2 extends MultiTrie {
/**
* Constructor for the MultiTrie object.
*
* @param is the input stream
* @exception IOException if an I/O error occurs
*/
public MultiTrie2(DataInput is) throws IOException {
super(is);
}
/**
* Constructor for the MultiTrie2 object
*
* @param forward set to true if the elements should be read left to
* right
*/
public MultiTrie2(boolean forward) {
super(forward);
}
/**
* Return the element that is stored in a cell associated with the given key.
*
* @param key the key to the cell holding the desired element
* @return the element
*/
@Override
public CharSequence getFully(CharSequence key) {
StringBuilder result = new StringBuilder(tries.size() * 2);
try {
CharSequence lastkey = key;
CharSequence p[] = new CharSequence[tries.size()];
char lastch = ' ';
for (int i = 0; i < tries.size(); i++) {
CharSequence r = tries.get(i).getFully(lastkey);
if (r == null || (r.length() == 1 && r.charAt(0) == EOM)) {
return result;
}
if (cannotFollow(lastch, r.charAt(0))) {
return result;
} else {
lastch = r.charAt(r.length() - 2);
}
// key=key.substring(lengthPP(r));
p[i] = r;
if (p[i].charAt(0) == '-') {
if (i > 0) {
key = skip(key, lengthPP(p[i - 1]));
}
key = skip(key, lengthPP(p[i]));
}
// key = skip(key, lengthPP(r));
result.append(r);
if (key.length() != 0) {
lastkey = key;
}
}
} catch (IndexOutOfBoundsException x) {}
return result;
}
/**
* Return the element that is stored as last on a path belonging to the given
* key.
*
* @param key the key associated with the desired element
* @return the element that is stored as last on a path
*/
@Override
public CharSequence getLastOnPath(CharSequence key) {
StringBuilder result = new StringBuilder(tries.size() * 2);
try {
CharSequence lastkey = key;
CharSequence p[] = new CharSequence[tries.size()];
char lastch = ' ';
for (int i = 0; i < tries.size(); i++) {
CharSequence r = tries.get(i).getLastOnPath(lastkey);
if (r == null || (r.length() == 1 && r.charAt(0) == EOM)) {
return result;
}
// System.err.println("LP:"+key+" last:"+lastch+" new:"+r);
if (cannotFollow(lastch, r.charAt(0))) {
return result;
} else {
lastch = r.charAt(r.length() - 2);
}
// key=key.substring(lengthPP(r));
p[i] = r;
if (p[i].charAt(0) == '-') {
if (i > 0) {
key = skip(key, lengthPP(p[i - 1]));
}
key = skip(key, lengthPP(p[i]));
}
// key = skip(key, lengthPP(r));
result.append(r);
if (key.length() != 0) {
lastkey = key;
}
}
} catch (IndexOutOfBoundsException x) {}
return result;
}
/**
* Write this data structure to the given output stream.
*
* @param os the output stream
* @exception IOException if an I/O error occurs
*/
@Override
public void store(DataOutput os) throws IOException {
super.store(os);
}
/**
* Add an element to this structure consisting of the given key and patch
* command.
*
* This method will return without executing if the cmd
* parameter's length is 0.
*
* @param key the key
* @param cmd the patch command
*/
@Override
public void add(CharSequence key, CharSequence cmd) {
if (cmd.length() == 0) {
return;
}
// System.err.println( cmd );
CharSequence p[] = decompose(cmd);
int levels = p.length;
// System.err.println("levels "+key+" cmd "+cmd+"|"+levels);
while (levels >= tries.size()) {
tries.add(new Trie(forward));
}
CharSequence lastkey = key;
for (int i = 0; i < levels; i++) {
if (key.length() > 0) {
tries.get(i).add(key, p[i]);
lastkey = key;
} else {
tries.get(i).add(lastkey, p[i]);
}
// System.err.println("-"+key+" "+p[i]+"|"+key.length());
/*
* key=key.substring(lengthPP(p[i]));
*/
if (p[i].length() > 0 && p[i].charAt(0) == '-') {
if (i > 0) {
key = skip(key, lengthPP(p[i - 1]));
}
key = skip(key, lengthPP(p[i]));
}
// System.err.println("--->"+key);
}
if (key.length() > 0) {
tries.get(levels).add(key, EOM_NODE);
} else {
tries.get(levels).add(lastkey, EOM_NODE);
}
}
/**
* Break the given patch command into its constituent pieces. The pieces are
* delimited by NOOP commands.
*
* @param cmd the patch command
* @return an array containing the pieces of the command
*/
public CharSequence[] decompose(CharSequence cmd) {
int parts = 0;
for (int i = 0; 0 <= i && i < cmd.length();) {
int next = dashEven(cmd, i);
if (i == next) {
parts++;
i = next + 2;
} else {
parts++;
i = next;
}
}
CharSequence part[] = new CharSequence[parts];
int x = 0;
for (int i = 0; 0 <= i && i < cmd.length();) {
int next = dashEven(cmd, i);
if (i == next) {
part[x++] = cmd.subSequence(i, i + 2);
i = next + 2;
} else {
part[x++] = (next < 0) ? cmd.subSequence(i, cmd.length()) : cmd.subSequence(i, next);
i = next;
}
}
return part;
}
/**
* Remove empty rows from the given Trie and return the newly reduced Trie.
*
* @param by the Trie to reduce
* @return the newly reduced Trie
*/
@Override
public Trie reduce(Reduce by) {
List h = new ArrayList();
for (Trie trie : tries)
h.add(trie.reduce(by));
MultiTrie2 m = new MultiTrie2(forward);
m.tries = h;
return m;
}
private boolean cannotFollow(char after, char goes) {
switch (after) {
case '-':
case 'D':
return after == goes;
}
return false;
}
private CharSequence skip(CharSequence in, int count) {
if (forward) {
return in.subSequence(count, in.length());
} else {
return in.subSequence(0, in.length() - count);
}
}
private int dashEven(CharSequence in, int from) {
while (from < in.length()) {
if (in.charAt(from) == '-') {
return from;
} else {
from += 2;
}
}
return -1;
}
@SuppressWarnings("fallthrough")
private int lengthPP(CharSequence cmd) {
int len = 0;
for (int i = 0; i < cmd.length(); i++) {
switch (cmd.charAt(i++)) {
case '-':
case 'D':
len += cmd.charAt(i) - 'a' + 1;
break;
case 'R':
len++; /* intentional fallthrough */
case 'I':
break;
}
}
return len;
}
}