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/*
**********************************************************************
*   Copyright (c) 2001-2011, International Business Machines
*   Corporation and others.  All Rights Reserved.
**********************************************************************
*   Date        Name        Description
*   11/19/2001  aliu        Creation.
**********************************************************************
*/
package com.ibm.icu.text;
import com.ibm.icu.impl.Utility;

/**
 * A transliterator that converts Unicode characters to an escape
 * form.  Examples of escape forms are "U+4E01" and "􏿿".
 * Escape forms have a prefix and suffix, either of which may be
 * empty, a radix, typically 16 or 10, a minimum digit count,
 * typically 1, 4, or 8, and a boolean that specifies whether
 * supplemental characters are handled as 32-bit code points or as two
 * 16-bit code units.  Most escape forms handle 32-bit code points,
 * but some, such as the Java form, intentionally break them into two
 * surrogate pairs, for backward compatibility.
 *
 * 

Some escape forms actually have two different patterns, one for * BMP characters (0..FFFF) and one for supplements (>FFFF). To * handle this, a second EscapeTransliterator may be defined that * specifies the pattern to be produced for supplementals. An example * of a form that requires this is the C form, which uses "\\uFFFF" * for BMP characters and "\\U0010FFFF" for supplementals. * *

This class is package private. It registers several standard * variants with the system which are then accessed via their IDs. * * @author Alan Liu */ class EscapeTransliterator extends Transliterator { /** * The prefix of the escape form; may be empty, but usually isn't. * May not be null. */ private String prefix; /** * The prefix of the escape form; often empty. May not be null. */ private String suffix; /** * The radix to display the number in. Typically 16 or 10. Must * be in the range 2 to 36. */ private int radix; /** * The minimum number of digits. Typically 1, 4, or 8. Values * less than 1 are equivalent to 1. */ private int minDigits; /** * If true, supplementals are handled as 32-bit code points. If * false, they are handled as two 16-bit code units. */ private boolean grokSupplementals; /** * The form to be used for supplementals. If this is null then * the same form is used for BMP characters and supplementals. If * this is not null and if grokSupplementals is true then the * prefix, suffix, radix, and minDigits of this object are used * for supplementals. */ private EscapeTransliterator supplementalHandler; /** * Registers standard variants with the system. Called by * Transliterator during initialization. */ static void register() { // Unicode: "U+10FFFF" hex, min=4, max=6 Transliterator.registerFactory("Any-Hex/Unicode", new Transliterator.Factory() { public Transliterator getInstance(String ID) { return new EscapeTransliterator("Any-Hex/Unicode", "U+", "", 16, 4, true, null); } }); // Java: "\\uFFFF" hex, min=4, max=4 Transliterator.registerFactory("Any-Hex/Java", new Transliterator.Factory() { public Transliterator getInstance(String ID) { return new EscapeTransliterator("Any-Hex/Java", "\\u", "", 16, 4, false, null); } }); // C: "\\uFFFF" hex, min=4, max=4; \\U0010FFFF hex, min=8, max=8 Transliterator.registerFactory("Any-Hex/C", new Transliterator.Factory() { public Transliterator getInstance(String ID) { return new EscapeTransliterator("Any-Hex/C", "\\u", "", 16, 4, true, new EscapeTransliterator("", "\\U", "", 16, 8, true, null)); } }); // XML: "􏿿" hex, min=1, max=6 Transliterator.registerFactory("Any-Hex/XML", new Transliterator.Factory() { public Transliterator getInstance(String ID) { return new EscapeTransliterator("Any-Hex/XML", "&#x", ";", 16, 1, true, null); } }); // XML10: "&1114111;" dec, min=1, max=7 (not really "Any-Hex") Transliterator.registerFactory("Any-Hex/XML10", new Transliterator.Factory() { public Transliterator getInstance(String ID) { return new EscapeTransliterator("Any-Hex/XML10", "&#", ";", 10, 1, true, null); } }); // Perl: "\\x{263A}" hex, min=1, max=6 Transliterator.registerFactory("Any-Hex/Perl", new Transliterator.Factory() { public Transliterator getInstance(String ID) { return new EscapeTransliterator("Any-Hex/Perl", "\\x{", "}", 16, 1, true, null); } }); // Plain: "FFFF" hex, min=4, max=6 Transliterator.registerFactory("Any-Hex/Plain", new Transliterator.Factory() { public Transliterator getInstance(String ID) { return new EscapeTransliterator("Any-Hex/Plain", "", "", 16, 4, true, null); } }); // Generic Transliterator.registerFactory("Any-Hex", new Transliterator.Factory() { public Transliterator getInstance(String ID) { return new EscapeTransliterator("Any-Hex", "\\u", "", 16, 4, false, null); } }); } /** * Constructs an escape transliterator with the given ID and * parameters. See the class member documentation for details. */ EscapeTransliterator(String ID, String prefix, String suffix, int radix, int minDigits, boolean grokSupplementals, EscapeTransliterator supplementalHandler) { super(ID, null); this.prefix = prefix; this.suffix = suffix; this.radix = radix; this.minDigits = minDigits; this.grokSupplementals = grokSupplementals; this.supplementalHandler = supplementalHandler; } /** * Implements {@link Transliterator#handleTransliterate}. */ protected void handleTransliterate(Replaceable text, Position pos, boolean incremental) { int start = pos.start; int limit = pos.limit; StringBuilder buf = new StringBuilder(prefix); int prefixLen = prefix.length(); boolean redoPrefix = false; while (start < limit) { int c = grokSupplementals ? text.char32At(start) : text.charAt(start); int charLen = grokSupplementals ? UTF16.getCharCount(c) : 1; if ((c & 0xFFFF0000) != 0 && supplementalHandler != null) { buf.setLength(0); buf.append(supplementalHandler.prefix); Utility.appendNumber(buf, c, supplementalHandler.radix, supplementalHandler.minDigits); buf.append(supplementalHandler.suffix); redoPrefix = true; } else { if (redoPrefix) { buf.setLength(0); buf.append(prefix); redoPrefix = false; } else { buf.setLength(prefixLen); } Utility.appendNumber(buf, c, radix, minDigits); buf.append(suffix); } text.replace(start, start + charLen, buf.toString()); start += buf.length(); limit += buf.length() - charLen; } pos.contextLimit += limit - pos.limit; pos.limit = limit; pos.start = start; } /* (non-Javadoc) * @see com.ibm.icu.text.Transliterator#addSourceTargetSet(com.ibm.icu.text.UnicodeSet, com.ibm.icu.text.UnicodeSet, com.ibm.icu.text.UnicodeSet) */ @Override public void addSourceTargetSet(UnicodeSet inputFilter, UnicodeSet sourceSet, UnicodeSet targetSet) { sourceSet.addAll(getFilterAsUnicodeSet(inputFilter)); for (EscapeTransliterator it = this; it != null ; it = it.supplementalHandler) { if (inputFilter.size() != 0) { targetSet.addAll(it.prefix); targetSet.addAll(it.suffix); StringBuilder buffer = new StringBuilder(); for (int i = 0; i < it.radix; ++i) { Utility.appendNumber(buffer, i, it.radix, it.minDigits); } targetSet.addAll(buffer.toString()); // TODO drop once String is changed to CharSequence in UnicodeSet } } } }





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