UScriptRun.java
// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
/*
*******************************************************************************
*
* Copyright (C) 1999-2014, International Business Machines
* Corporation and others. All Rights Reserved.
*
*******************************************************************************
*/
package com.ibm.icu.lang;
import com.ibm.icu.text.UTF16;
/**
* <code>UScriptRun</code> is used to find runs of characters in the same script, as defined in the
* <code>UScript</code> class. It implements a simple iterator over an array of characters. The
* iterator will assign <code>COMMON</code> and <code>INHERITED</code> characters to the same script
* as the preceding characters. If the COMMON and INHERITED characters are first, they will be
* assigned to the same script as the following characters.
*
* <p>The iterator will try to match paired punctuation. If it sees an opening punctuation
* character, it will remember the script that was assigned to that character, and assign the same
* script to the matching closing punctuation.
*
* <p>No attempt is made to combine related scripts into a single run. In particular, Hiragana,
* Katakana, and Han characters will appear in separate runs.
*
* <p>Here is an example of how to iterate over script runs:
*
* <pre>
* void printScriptRuns(char[] text)
* {
* UScriptRun scriptRun = new UScriptRun(text);
*
* while (scriptRun.next()) {
* int start = scriptRun.getScriptStart();
* int limit = scriptRun.getScriptLimit();
* int script = scriptRun.getScriptCode();
*
* System.out.println("Script \"" + UScript.getName(script) + "\" from " +
* start + " to " + limit + ".");
* }
* }
* </pre>
*
* @internal
* @deprecated This API is ICU internal only.
*/
@Deprecated
public final class UScriptRun {
/**
* Construct an empty <code>UScriptRun</code> object. The <code>next()</code> method will return
* <code>false</code> the first time it is called.
*
* @internal
* @deprecated This API is ICU internal only.
*/
@Deprecated
public UScriptRun() {
char[] nullChars = null;
reset(nullChars, 0, 0);
}
/**
* Construct a <code>UScriptRun</code> object which iterates over the characters in the given
* string.
*
* @param text the string of characters over which to iterate.
* @internal
* @deprecated This API is ICU internal only.
*/
@Deprecated
public UScriptRun(String text) {
reset(text);
}
/**
* Construct a <code>UScriptRun</code> object which iterates over a subrange of the characters
* in the given string.
*
* @param text the string of characters over which to iterate.
* @param start the index of the first character over which to iterate
* @param count the number of characters over which to iterate
* @internal
* @deprecated This API is ICU internal only.
*/
@Deprecated
public UScriptRun(String text, int start, int count) {
reset(text, start, count);
}
/**
* Construct a <code>UScriptRun</code> object which iterates over the given characters.
*
* @param chars the array of characters over which to iterate.
* @internal
* @deprecated This API is ICU internal only.
*/
@Deprecated
public UScriptRun(char[] chars) {
reset(chars);
}
/**
* Construct a <code>UScriptRun</code> object which iterates over a subrange of the given
* characters.
*
* @param chars the array of characters over which to iterate.
* @param start the index of the first character over which to iterate
* @param count the number of characters over which to iterate
* @internal
* @deprecated This API is ICU internal only.
*/
@Deprecated
public UScriptRun(char[] chars, int start, int count) {
reset(chars, start, count);
}
/**
* Reset the iterator to the start of the text.
*
* @internal
* @deprecated This API is ICU internal only.
*/
@Deprecated
public final void reset() {
// empty any old parenStack contents.
// NOTE: this is not the most efficient way
// to do this, but it's the easiest to write...
while (stackIsNotEmpty()) {
pop();
}
scriptStart = textStart;
scriptLimit = textStart;
scriptCode = UScript.INVALID_CODE;
parenSP = -1;
pushCount = 0;
fixupCount = 0;
textIndex = textStart;
}
/**
* Reset the iterator to iterate over the given range of the text. Throws
* IllegalArgumentException if the range is outside of the bounds of the character array.
*
* @param start the index of the new first character over which to iterate
* @param count the new number of characters over which to iterate.
* @exception IllegalArgumentException If invalid arguments are passed.
* @internal
* @deprecated This API is ICU internal only.
*/
@Deprecated
public final void reset(int start, int count) throws IllegalArgumentException {
int len = 0;
if (text != null) {
len = text.length;
}
if (start < 0 || count < 0 || start > len - count) {
throw new IllegalArgumentException();
}
textStart = start;
textLimit = start + count;
reset();
}
/**
* Reset the iterator to iterate over <code>count</code> characters in <code>chars</code>
* starting at <code>start</code>. This allows clients to reuse an iterator.
*
* @param chars the new array of characters over which to iterate.
* @param start the index of the first character over which to iterate.
* @param count the number of characters over which to iterate.
* @internal
* @deprecated This API is ICU internal only.
*/
@Deprecated
public final void reset(char[] chars, int start, int count) {
if (chars == null) {
chars = emptyCharArray;
}
text = chars;
reset(start, count);
}
/**
* Reset the iterator to iterate over the characters in <code>chars</code>. This allows clients
* to reuse an iterator.
*
* @param chars the new array of characters over which to iterate.
* @internal
* @deprecated This API is ICU internal only.
*/
@Deprecated
public final void reset(char[] chars) {
int length = 0;
if (chars != null) {
length = chars.length;
}
reset(chars, 0, length);
}
/**
* Reset the iterator to iterate over <code>count</code> characters in <code>text</code>
* starting at <code>start</code>. This allows clients to reuse an iterator.
*
* @param str the new string of characters over which to iterate.
* @param start the index of the first character over which to iterate.
* @param count the nuber of characters over which to iterate.
* @internal
* @deprecated This API is ICU internal only.
*/
@Deprecated
public final void reset(String str, int start, int count) {
char[] chars = null;
if (str != null) {
chars = str.toCharArray();
}
reset(chars, start, count);
}
/**
* Reset the iterator to iterate over the characters in <code>text</code>. This allows clients
* to reuse an iterator.
*
* @param str the new string of characters over which to iterate.
* @internal
* @deprecated This API is ICU internal only.
*/
@Deprecated
public final void reset(String str) {
int length = 0;
if (str != null) {
length = str.length();
}
reset(str, 0, length);
}
/**
* Get the starting index of the current script run.
*
* @return the index of the first character in the current script run.
* @internal
* @deprecated This API is ICU internal only.
*/
@Deprecated
public final int getScriptStart() {
return scriptStart;
}
/**
* Get the index of the first character after the current script run.
*
* @return the index of the first character after the current script run.
* @internal
* @deprecated This API is ICU internal only.
*/
@Deprecated
public final int getScriptLimit() {
return scriptLimit;
}
/**
* Get the script code for the script of the current script run.
*
* @return the script code for the script of the current script run.
* @see com.ibm.icu.lang.UScript
* @internal
* @deprecated This API is ICU internal only.
*/
@Deprecated
public final int getScriptCode() {
return scriptCode;
}
/**
* Find the next script run. Returns <code>false</code> if there isn't another run, returns
* <code>true</code> if there is.
*
* @return <code>false</code> if there isn't another run, <code>true</code> if there is.
* @internal
* @deprecated This API is ICU internal only.
*/
@Deprecated
public final boolean next() {
// if we've fallen off the end of the text, we're done
if (scriptLimit >= textLimit) {
return false;
}
scriptCode = UScript.COMMON;
scriptStart = scriptLimit;
syncFixup();
while (textIndex < textLimit) {
int ch = UTF16.charAt(text, textStart, textLimit, textIndex - textStart);
int codePointCount = UTF16.getCharCount(ch);
int sc = UScript.getScript(ch);
int pairIndex = getPairIndex(ch);
textIndex += codePointCount;
// Paired character handling:
//
// if it's an open character, push it onto the stack.
// if it's a close character, find the matching open on the
// stack, and use that script code. Any non-matching open
// characters above it on the stack will be poped.
if (pairIndex >= 0) {
if ((pairIndex & 1) == 0) {
push(pairIndex, scriptCode);
} else {
int pi = pairIndex & ~1;
while (stackIsNotEmpty() && top().pairIndex != pi) {
pop();
}
if (stackIsNotEmpty()) {
sc = top().scriptCode;
}
}
}
if (sameScript(scriptCode, sc)) {
if (scriptCode <= UScript.INHERITED && sc > UScript.INHERITED) {
scriptCode = sc;
fixup(scriptCode);
}
// if this character is a close paired character,
// pop the matching open character from the stack
if (pairIndex >= 0 && (pairIndex & 1) != 0) {
pop();
}
} else {
// We've just seen the first character of
// the next run. Back over it so we'll see
// it again the next time.
textIndex -= codePointCount;
break;
}
}
scriptLimit = textIndex;
return true;
}
/**
* Compare two script codes to see if they are in the same script. If one script is a strong
* script, and the other is INHERITED or COMMON, it will compare equal.
*
* @param scriptOne one of the script codes.
* @param scriptTwo the other script code.
* @return <code>true</code> if the two scripts are the same.
* @see com.ibm.icu.lang.UScript
*/
private static boolean sameScript(int scriptOne, int scriptTwo) {
return scriptOne <= UScript.INHERITED
|| scriptTwo <= UScript.INHERITED
|| scriptOne == scriptTwo;
}
/*
* An internal class which holds entries on the paren stack.
*/
private static final class ParenStackEntry {
int pairIndex;
int scriptCode;
public ParenStackEntry(int thePairIndex, int theScriptCode) {
pairIndex = thePairIndex;
scriptCode = theScriptCode;
}
}
private static final int mod(int sp) {
return sp % PAREN_STACK_DEPTH;
}
private static final int inc(int sp, int count) {
return mod(sp + count);
}
private static final int inc(int sp) {
return inc(sp, 1);
}
private static final int dec(int sp, int count) {
return mod(sp + PAREN_STACK_DEPTH - count);
}
private static final int dec(int sp) {
return dec(sp, 1);
}
private static final int limitInc(int count) {
if (count < PAREN_STACK_DEPTH) {
count += 1;
}
return count;
}
private final boolean stackIsEmpty() {
return pushCount <= 0;
}
private final boolean stackIsNotEmpty() {
return !stackIsEmpty();
}
private final void push(int pairIndex, int scrptCode) {
pushCount = limitInc(pushCount);
fixupCount = limitInc(fixupCount);
parenSP = inc(parenSP);
parenStack[parenSP] = new ParenStackEntry(pairIndex, scrptCode);
}
private final void pop() {
if (stackIsEmpty()) {
return;
}
parenStack[parenSP] = null;
if (fixupCount > 0) {
fixupCount -= 1;
}
pushCount -= 1;
parenSP = dec(parenSP);
// If the stack is now empty, reset the stack
// pointers to their initial values.
if (stackIsEmpty()) {
parenSP = -1;
}
}
private final ParenStackEntry top() {
return parenStack[parenSP];
}
private final void syncFixup() {
fixupCount = 0;
}
private final void fixup(int scrptCode) {
int fixupSP = dec(parenSP, fixupCount);
while (fixupCount-- > 0) {
fixupSP = inc(fixupSP);
parenStack[fixupSP].scriptCode = scrptCode;
}
}
private char[] emptyCharArray = {};
private char[] text;
private int textIndex;
private int textStart;
private int textLimit;
private int scriptStart;
private int scriptLimit;
private int scriptCode;
private static int PAREN_STACK_DEPTH = 32;
private static ParenStackEntry parenStack[] = new ParenStackEntry[PAREN_STACK_DEPTH];
private int parenSP = -1;
private int pushCount = 0;
private int fixupCount = 0;
/**
* Find the highest bit that's set in a word. Uses a binary search through the bits.
*
* @param n the word in which to find the highest bit that's set.
* @return the bit number (counting from the low order bit) of the highest bit.
*/
private static final byte highBit(int n) {
if (n <= 0) {
return -32;
}
byte bit = 0;
if (n >= 1 << 16) {
n >>= 16;
bit += 16;
}
if (n >= 1 << 8) {
n >>= 8;
bit += 8;
}
if (n >= 1 << 4) {
n >>= 4;
bit += 4;
}
if (n >= 1 << 2) {
n >>= 2;
bit += 2;
}
if (n >= 1 << 1) {
n >>= 1;
bit += 1;
}
return bit;
}
/**
* Search the pairedChars array for the given character.
*
* @param ch the character for which to search.
* @return the index of the character in the table, or -1 if it's not there.
*/
private static int getPairIndex(int ch) {
int probe = pairedCharPower;
int index = 0;
if (ch >= pairedChars[pairedCharExtra]) {
index = pairedCharExtra;
}
while (probe > (1 << 0)) {
probe >>= 1;
if (ch >= pairedChars[index + probe]) {
index += probe;
}
}
if (pairedChars[index] != ch) {
index = -1;
}
return index;
}
private static int pairedChars[] = {
0x0028, 0x0029, // ascii paired punctuation
0x003c, 0x003e,
0x005b, 0x005d,
0x007b, 0x007d,
0x00ab, 0x00bb, // guillemets
0x2018, 0x2019, // general punctuation
0x201c, 0x201d,
0x2039, 0x203a,
0x3008, 0x3009, // chinese paired punctuation
0x300a, 0x300b,
0x300c, 0x300d,
0x300e, 0x300f,
0x3010, 0x3011,
0x3014, 0x3015,
0x3016, 0x3017,
0x3018, 0x3019,
0x301a, 0x301b
};
private static int pairedCharPower = 1 << highBit(pairedChars.length);
private static int pairedCharExtra = pairedChars.length - pairedCharPower;
}