UnescapeTransliterator.java
// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
/*
**********************************************************************
* 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;
import com.ibm.icu.lang.UCharacter;
/**
* A transliterator that converts Unicode escape forms to the characters they represent. Escape
* forms have a prefix, a suffix, a radix, and minimum and maximum digit counts.
*
* <p>This class is package private. It registers several standard variants with the system which
* are then accessed via their IDs.
*
* @author Alan Liu
*/
class UnescapeTransliterator extends Transliterator {
/**
* The encoded pattern specification. The pattern consists of zero or more forms. Each form
* consists of a prefix, suffix, radix, minimum digit count, and maximum digit count. These
* values are stored as a five character header. That is, their numeric values are cast to
* 16-bit characters and stored in the string. Following these five characters, the prefix
* characters, then suffix characters are stored. Each form thus takes n+5 characters, where n
* is the total length of the prefix and suffix. The end is marked by a header of length one
* consisting of the character END.
*/
private char spec[];
/** Special character marking the end of the spec[] array. */
private static final char END = 0xFFFF;
/**
* Registers standard variants with the system. Called by Transliterator during initialization.
*/
static void register() {
// Unicode: "U+10FFFF" hex, min=4, max=6
Transliterator.registerFactory(
"Hex-Any/Unicode",
new Transliterator.Factory() {
@Override
public Transliterator getInstance(String ID) {
return new UnescapeTransliterator(
"Hex-Any/Unicode", new char[] {2, 0, 16, 4, 6, 'U', '+', END});
}
});
// Java: "\\uFFFF" hex, min=4, max=4
Transliterator.registerFactory(
"Hex-Any/Java",
new Transliterator.Factory() {
@Override
public Transliterator getInstance(String ID) {
return new UnescapeTransliterator(
"Hex-Any/Java", new char[] {2, 0, 16, 4, 4, '\\', 'u', END});
}
});
// C: "\\uFFFF" hex, min=4, max=4; \\U0010FFFF hex, min=8, max=8
Transliterator.registerFactory(
"Hex-Any/C",
new Transliterator.Factory() {
@Override
public Transliterator getInstance(String ID) {
return new UnescapeTransliterator(
"Hex-Any/C",
new char[] {
2, 0, 16, 4, 4, '\\', 'u', 2, 0, 16, 8, 8, '\\', 'U', END
});
}
});
// XML: "" hex, min=1, max=6
Transliterator.registerFactory(
"Hex-Any/XML",
new Transliterator.Factory() {
@Override
public Transliterator getInstance(String ID) {
return new UnescapeTransliterator(
"Hex-Any/XML",
new char[] {3, 1, 16, 1, 6, '&', '#', 'x', ';', END});
}
});
// XML10: "&1114111;" dec, min=1, max=7 (not really "Hex-Any")
Transliterator.registerFactory(
"Hex-Any/XML10",
new Transliterator.Factory() {
@Override
public Transliterator getInstance(String ID) {
return new UnescapeTransliterator(
"Hex-Any/XML10", new char[] {2, 1, 10, 1, 7, '&', '#', ';', END});
}
});
// Perl: "\\x{263A}" hex, min=1, max=6
Transliterator.registerFactory(
"Hex-Any/Perl",
new Transliterator.Factory() {
@Override
public Transliterator getInstance(String ID) {
return new UnescapeTransliterator(
"Hex-Any/Perl",
new char[] {3, 1, 16, 1, 6, '\\', 'x', '{', '}', END});
}
});
// All: Java, C, Perl, XML, XML10, Unicode
Transliterator.registerFactory(
"Hex-Any",
new Transliterator.Factory() {
@Override
public Transliterator getInstance(String ID) {
return new UnescapeTransliterator(
"Hex-Any",
new char[] {
2, 0, 16, 4, 6, 'U', '+', // Unicode
2, 0, 16, 4, 4, '\\', 'u', // Java
2, 0, 16, 8, 8, '\\', 'U', // C (surrogates)
3, 1, 16, 1, 6, '&', '#', 'x', ';', // XML
2, 1, 10, 1, 7, '&', '#', ';', // XML10
3, 1, 16, 1, 6, '\\', 'x', '{', '}', // Perl
END
});
}
});
}
/** Package private constructor. Takes the encoded spec array. */
UnescapeTransliterator(String ID, char spec[]) {
super(ID, null);
this.spec = spec;
}
/** Implements {@link Transliterator#handleTransliterate}. */
@Override
protected void handleTransliterate(Replaceable text, Position pos, boolean isIncremental) {
int start = pos.start;
int limit = pos.limit;
int i, ipat;
loop:
while (start < limit) {
// Loop over the forms in spec[]. Exit this loop when we
// match one of the specs. Exit the outer loop if a
// partial match is detected and isIncremental is true.
for (ipat = 0; spec[ipat] != END; ) {
// Read the header
int prefixLen = spec[ipat++];
int suffixLen = spec[ipat++];
int radix = spec[ipat++];
int minDigits = spec[ipat++];
int maxDigits = spec[ipat++];
// s is a copy of start that is advanced over the
// characters as we parse them.
int s = start;
boolean match = true;
for (i = 0; i < prefixLen; ++i) {
if (s >= limit) {
if (i > 0) {
// We've already matched a character. This is
// a partial match, so we return if in
// incremental mode. In non-incremental mode,
// go to the next spec.
if (isIncremental) {
break loop;
}
match = false;
break;
}
}
char c = text.charAt(s++);
if (c != spec[ipat + i]) {
match = false;
break;
}
}
if (match) {
int u = 0;
int digitCount = 0;
for (; ; ) {
if (s >= limit) {
// Check for partial match in incremental mode.
if (s > start && isIncremental) {
break loop;
}
break;
}
int ch = text.char32At(s);
int digit = UCharacter.digit(ch, radix);
if (digit < 0) {
break;
}
s += UTF16.getCharCount(ch);
u = (u * radix) + digit;
if (++digitCount == maxDigits) {
break;
}
}
match = (digitCount >= minDigits);
if (match) {
for (i = 0; i < suffixLen; ++i) {
if (s >= limit) {
// Check for partial match in incremental mode.
if (s > start && isIncremental) {
break loop;
}
match = false;
break;
}
char c = text.charAt(s++);
if (c != spec[ipat + prefixLen + i]) {
match = false;
break;
}
}
if (match) {
// At this point, we have a match
String str = UTF16.valueOf(u);
text.replace(start, s, str);
limit -= s - start - str.length();
// The following break statement leaves the
// loop that is traversing the forms in
// spec[]. We then parse the next input
// character.
break;
}
}
}
ipat += prefixLen + suffixLen;
}
if (start < limit) {
start += UTF16.getCharCount(text.char32At(start));
}
}
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) {
// Each form consists of a prefix, suffix,
// * radix, minimum digit count, and maximum digit count. These
// * values are stored as a five character header. ...
UnicodeSet myFilter = getFilterAsUnicodeSet(inputFilter);
UnicodeSet items = new UnicodeSet();
StringBuilder buffer = new StringBuilder();
for (int i = 0; spec[i] != END; ) {
// first 5 items are header
int end = i + spec[i] + spec[i + 1] + 5;
int radix = spec[i + 2];
for (int j = 0; j < radix; ++j) {
Utility.appendNumber(buffer, j, radix, 0);
}
// then add the characters
for (int j = i + 5; j < end; ++j) {
items.add(spec[j]);
}
// and go to next block
i = end;
}
items.addAll(buffer.toString());
items.retainAll(myFilter);
if (items.size() > 0) {
sourceSet.addAll(items);
targetSet.addAll(0, 0x10FFFF); // assume we can produce any character
}
}
}