package com.hankcs.lucene;
import org.apache.lucene.util.ArrayUtil;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import static org.apache.lucene.util.RamUsageEstimator.NUM_BYTES_CHAR;
/**
* 抄袭lucene的英文处理
* Stemmer, implementing the Porter Stemming Algorithm
* <p/>
* The Stemmer class transforms a word into its root form. The input word can be
* provided a character at time (by calling add()), or at once by calling one of
* the various stem(something) methods.
*/
public class PorterStemmer
{
private char[] b;
private int i, /* offset into b */
j, k, k0;
private boolean dirty = false;
private static final int INITIAL_SIZE = 50;
public PorterStemmer()
{
b = new char[INITIAL_SIZE];
i = 0;
}
/**
* reset() resets the stemmer so it can stem another word. If you invoke the
* stemmer by calling add(char) and then stem(), you must call reset()
* before starting another word.
*/
public void reset()
{
i = 0;
dirty = false;
}
/**
* Add a character to the word being stemmed. When you are finished adding
* characters, you can call stem(void) to process the word.
*/
public void add(char ch)
{
if (b.length <= i)
{
b = ArrayUtil.grow(b, i + 1);
}
b[i++] = ch;
}
/**
* After a word has been stemmed, it can be retrieved by toString(), or a
* reference to the internal buffer can be retrieved by getResultBuffer and
* getResultLength (which is generally more efficient.)
*/
@Override
public String toString()
{
return new String(b, 0, i);
}
/**
* Returns the length of the word resulting from the stemming process.
*/
public int getResultLength()
{
return i;
}
/**
* Returns a reference to a character buffer containing the results of the
* stemming process. You also need to consult getResultLength() to determine
* the length of the result.
*/
public char[] getResultBuffer()
{
return b;
}
/* cons(i) is true <=> b[i] is a consonant. */
private boolean cons(int i)
{
switch (b[i])
{
case 'a':
case 'e':
case 'i':
case 'o':
case 'u':
return false;
case 'y':
return (i == k0) || !cons(i - 1);
default:
return true;
}
}
/*
* m() measures the number of consonant sequences between k0 and j. if c is
* a consonant sequence and v a vowel sequence, and <..> indicates arbitrary
* presence,
*
* <c><v> gives 0 <c>vc<v> gives 1 <c>vcvc<v> gives 2 <c>vcvcvc<v> gives 3
* ....
*/
private int m()
{
int n = 0;
int i = k0;
while (true)
{
if (i > j) return n;
if (!cons(i)) break;
i++;
}
i++;
while (true)
{
while (true)
{
if (i > j) return n;
if (cons(i)) break;
i++;
}
i++;
n++;
while (true)
{
if (i > j) return n;
if (!cons(i)) break;
i++;
}
i++;
}
}
/* vowelinstem() is true <=> k0,...j contains a vowel */
private boolean vowelinstem()
{
int i;
for (i = k0; i <= j; i++)
if (!cons(i)) return true;
return false;
}
/* doublec(j) is true <=> j,(j-1) contain a double consonant. */
private boolean doublec(int j)
{
if (j < k0 + 1) return false;
if (b[j] != b[j - 1]) return false;
return cons(j);
}
/*
* cvc(i) is true <=> i-2,i-1,i has the form consonant - vowel - consonant
* and also if the second c is not w,x or y. this is used when trying to
* restore an e at the end of a short word. e.g.
*
* cav(e), lov(e), hop(e), crim(e), but snow, box, tray.
*/
private boolean cvc(int i)
{
if (i < k0 + 2 || !cons(i) || cons(i - 1) || !cons(i - 2)) return false;
else
{
int ch = b[i];
if (ch == 'w' || ch == 'x' || ch == 'y') return false;
}
return true;
}
private boolean ends(String s)
{
int l = s.length();
int o = k - l + 1;
if (o < k0) return false;
for (int i = 0; i < l; i++)
if (b[o + i] != s.charAt(i)) return false;
j = k - l;
return true;
}
/*
* setto(s) sets (j+1),...k to the characters in the string s, readjusting
* k.
*/
void setto(String s)
{
int l = s.length();
int o = j + 1;
for (int i = 0; i < l; i++)
b[o + i] = s.charAt(i);
k = j + l;
dirty = true;
}
/* r(s) is used further down. */
void r(String s)
{
if (m() > 0) setto(s);
}
/*
* step1() gets rid of plurals and -ed or -ing. e.g.
*
* caresses -> caress ponies -> poni ties -> ti caress -> caress cats -> cat
*
* feed -> feed agreed -> agree disabled -> disable
*
* matting -> mat mating -> mate meeting -> meet milling -> mill messing ->
* mess
*
* meetings -> meet
*/
private void step1()
{
if (b[k] == 's')
{
if (ends("sses")) k -= 2;
else if (ends("ies")) setto("i");
else if (b[k - 1] != 's') k--;
}
if (ends("eed"))
{
if (m() > 0) k--;
}
else if ((ends("ed") || ends("ing")) && vowelinstem())
{
k = j;
if (ends("at")) setto("ate");
else if (ends("bl")) setto("ble");
else if (ends("iz")) setto("ize");
else if (doublec(k))
{
int ch = b[k--];
if (ch == 'l' || ch == 's' || ch == 'z') k++;
}
else if (m() == 1 && cvc(k)) setto("e");
}
}
/* step2() turns terminal y to i when there is another vowel in the stem. */
private void step2()
{
if (ends("y") && vowelinstem())
{
b[k] = 'i';
dirty = true;
}
}
/*
* step3() maps double suffices to single ones. so -ization ( = -ize plus
* -ation) maps to -ize etc. note that the string before the suffix must
* give m() > 0.
*/
private void step3()
{
if (k == k0) return; /* For Bug 1 */
switch (b[k - 1])
{
case 'a':
if (ends("ational"))
{
r("ate");
break;
}
if (ends("tional"))
{
r("tion");
break;
}
break;
case 'c':
if (ends("enci"))
{
r("ence");
break;
}
if (ends("anci"))
{
r("ance");
break;
}
break;
case 'e':
if (ends("izer"))
{
r("ize");
break;
}
break;
case 'l':
if (ends("bli"))
{
r("ble");
break;
}
if (ends("alli"))
{
r("al");
break;
}
if (ends("entli"))
{
r("ent");
break;
}
if (ends("eli"))
{
r("e");
break;
}
if (ends("ousli"))
{
r("ous");
break;
}
break;
case 'o':
if (ends("ization"))
{
r("ize");
break;
}
if (ends("ation"))
{
r("ate");
break;
}
if (ends("ator"))
{
r("ate");
break;
}
break;
case 's':
if (ends("alism"))
{
r("al");
break;
}
if (ends("iveness"))
{
r("ive");
break;
}
if (ends("fulness"))
{
r("ful");
break;
}
if (ends("ousness"))
{
r("ous");
break;
}
break;
case 't':
if (ends("aliti"))
{
r("al");
break;
}
if (ends("iviti"))
{
r("ive");
break;
}
if (ends("biliti"))
{
r("ble");
break;
}
break;
case 'g':
if (ends("logi"))
{
r("log");
break;
}
}
}
/* step4() deals with -ic-, -full, -ness etc. similar strategy to step3. */
private void step4()
{
switch (b[k])
{
case 'e':
if (ends("icate"))
{
r("ic");
break;
}
if (ends("ative"))
{
r("");
break;
}
if (ends("alize"))
{
r("al");
break;
}
break;
case 'i':
if (ends("iciti"))
{
r("ic");
break;
}
break;
case 'l':
if (ends("ical"))
{
r("ic");
break;
}
if (ends("ful"))
{
r("");
break;
}
break;
case 's':
if (ends("ness"))
{
r("");
break;
}
break;
}
}
/* step5() takes off -ant, -ence etc., in context <c>vcvc<v>. */
private void step5()
{
if (k == k0) return; /* for Bug 1 */
switch (b[k - 1])
{
case 'a':
if (ends("al")) break;
return;
case 'c':
if (ends("ance")) break;
if (ends("ence")) break;
return;
case 'e':
if (ends("er")) break;
return;
case 'i':
if (ends("ic")) break;
return;
case 'l':
if (ends("able")) break;
if (ends("ible")) break;
return;
case 'n':
if (ends("ant")) break;
if (ends("ement")) break;
if (ends("ment")) break;
/* element etc. not stripped before the m */
if (ends("ent")) break;
return;
case 'o':
if (ends("ion") && j >= 0 && (b[j] == 's' || b[j] == 't')) break;
/* j >= 0 fixes Bug 2 */
if (ends("ou")) break;
return;
/* takes care of -ous */
case 's':
if (ends("ism")) break;
return;
case 't':
if (ends("ate")) break;
if (ends("iti")) break;
return;
case 'u':
if (ends("ous")) break;
return;
case 'v':
if (ends("ive")) break;
return;
case 'z':
if (ends("ize")) break;
return;
default:
return;
}
if (m() > 1) k = j;
}
/* step6() removes a final -e if m() > 1. */
private void step6()
{
j = k;
if (b[k] == 'e')
{
int a = m();
if (a > 1 || a == 1 && !cvc(k - 1)) k--;
}
if (b[k] == 'l' && doublec(k) && m() > 1) k--;
}
/**
* Stem a word provided as a String. Returns the result as a String.
*/
public String stem(String s)
{
if (stem(s.toCharArray(), s.length())) return toString();
else return s;
}
/**
* Stem a word contained in a char[]. Returns true if the stemming process
* resulted in a word different from the input. You can retrieve the result
* with getResultLength()/getResultBuffer() or toString().
*/
public boolean stem(char[] word)
{
return stem(word, word.length);
}
/**
* Stem a word contained in a portion of a char[] array. Returns true if the
* stemming process resulted in a word different from the input. You can
* retrieve the result with getResultLength()/getResultBuffer() or
* toString().
*/
public boolean stem(char[] wordBuffer, int offset, int wordLen)
{
reset();
if (b.length < wordLen)
{
b = new char[ArrayUtil.oversize(wordLen, NUM_BYTES_CHAR)];
}
System.arraycopy(wordBuffer, offset, b, 0, wordLen);
i = wordLen;
return stem(0);
}
/**
* Stem a word contained in a leading portion of a char[] array. Returns
* true if the stemming process resulted in a word different from the input.
* You can retrieve the result with getResultLength()/getResultBuffer() or
* toString().
*/
public boolean stem(char[] word, int wordLen)
{
return stem(word, 0, wordLen);
}
/**
* Stem the word placed into the Stemmer buffer through calls to add().
* Returns true if the stemming process resulted in a word different from
* the input. You can retrieve the result with
* getResultLength()/getResultBuffer() or toString().
*/
public boolean stem()
{
return stem(0);
}
public boolean stem(int i0)
{
k = i - 1;
k0 = i0;
if (k > k0 + 1)
{
step1();
step2();
step3();
step4();
step5();
step6();
}
// Also, a word is considered dirty if we lopped off letters
// Thanks to Ifigenia Vairelles for pointing this out.
if (i != k + 1) dirty = true;
i = k + 1;
return dirty;
}
/**
* Test program for demonstrating the Stemmer. It reads a file and stems
* each word, writing the result to standard out. Usage: Stemmer file-name
*/
public static void main(String[] args)
{
PorterStemmer s = new PorterStemmer();
for (String arg : args)
{
try (InputStream in = new FileInputStream(arg))
{
byte[] buffer = new byte[1024];
int bufferLen, offset, ch;
bufferLen = in.read(buffer);
offset = 0;
s.reset();
while (true)
{
if (offset < bufferLen) ch = buffer[offset++];
else
{
bufferLen = in.read(buffer);
offset = 0;
if (bufferLen < 0) ch = -1;
else ch = buffer[offset++];
}
if (Character.isLetter((char) ch))
{
s.add(Character.toLowerCase((char) ch));
}
else
{
s.stem();
System.out.print(s.toString());
s.reset();
if (ch < 0) break;
else
{
System.out.print((char) ch);
}
}
}
}
catch (IOException e)
{
System.out.println("error reading " + arg);
}
}
}
}
