com.ibm.icu.text.EscapeTransliterator Maven / Gradle / Ivy
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// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html#License
/*
**********************************************************************
* 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() {
@Override
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() {
@Override
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() {
@Override
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() {
@Override
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() {
@Override
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() {
@Override
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() {
@Override
public Transliterator getInstance(String ID) {
return new EscapeTransliterator("Any-Hex/Plain",
"", "", 16, 4, true, null);
}
});
// Generic
Transliterator.registerFactory("Any-Hex", new Transliterator.Factory() {
@Override
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}.
*/
@Override
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
}
}
}
}