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With inspiration from other libraries
// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html#License
/*
*******************************************************************************
*
* Copyright (C) 1999-2014, International Business Machines
* Corporation and others. All Rights Reserved.
*
*******************************************************************************
*/
package com.ibm.icu.lang;
import com.ibm.icu.text.UTF16;
/**
* UScriptRun is used to find runs of characters in
* the same script, as defined in the UScript class.
* It implements a simple iterator over an array of characters.
* The iterator will assign COMMON and INHERITED
* characters to the same script as the preceeding characters. If the
* COMMON and INHERITED characters are first, they will be assigned to
* the same script as the following characters.
*
* 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.
*
* No attempt is made to combine related scripts into a single run. In
* particular, Hiragana, Katakana, and Han characters will appear in separate
* runs.
* Here is an example of how to iterate over script runs:
*
* 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 + ".");
* }
* }
*
*
* @internal
* @deprecated This API is ICU internal only.
*/
@Deprecated
public final class UScriptRun
{
/**
* Construct an empty UScriptRun object. The next()
* method will return false 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 UScriptRun 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 UScriptRun object which iterates over a subrange
* of the characetrs 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 UScriptRun object which iterates over the given
* characetrs.
*
* @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 UScriptRun object which iterates over a subrange
* of the given characetrs.
*
* @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 count characters
* in chars starting at start. 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 chars. 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 count characters
* in text starting at start. 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 text. 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 false if there
* isn't another run, returns true if there is.
*
* @return false if there isn't another run, true 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 true 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;
}