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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package net.dongliu.apk.parser.utils.xml;
import java.io.IOException;
import java.io.StringWriter;
import java.io.Writer;
import java.util.Locale;
/**
* An API for translating text.
* Its core use is to escape and unescape text. Because escaping and unescaping
* is completely contextual, the API does not present two separate signatures.
*
*/
abstract class CharSequenceTranslator {
/**
* Translate a set of codepoints, represented by an int index into a CharSequence,
* into another set of codepoints. The number of codepoints consumed must be returned,
* and the only IOExceptions thrown must be from interacting with the Writer so that
* the top level API may reliably ignore StringWriter IOExceptions.
*
* @param input CharSequence that is being translated
* @param index int representing the current point of translation
* @param out Writer to translate the text to
* @return int count of codepoints consumed
* @throws IOException if and only if the Writer produces an IOException
*/
public abstract int translate(CharSequence input, int index, Writer out) throws IOException;
/**
* Helper for non-Writer usage.
* @param input CharSequence to be translated
* @return String output of translation
*/
public final String translate(final CharSequence input) {
if (input == null) {
return null;
}
try {
final StringWriter writer = new StringWriter(input.length() * 2);
translate(input, writer);
return writer.toString();
} catch (final IOException ioe) {
// this should never ever happen while writing to a StringWriter
throw new RuntimeException(ioe);
}
}
/**
* Translate an input onto a Writer. This is intentionally final as its algorithm is
* tightly coupled with the abstract method of this class.
*
* @param input CharSequence that is being translated
* @param out Writer to translate the text to
* @throws IOException if and only if the Writer produces an IOException
*/
public final void translate(final CharSequence input, final Writer out) throws IOException {
if (out == null) {
throw new IllegalArgumentException("The Writer must not be null");
}
if (input == null) {
return;
}
int pos = 0;
final int len = input.length();
while (pos < len) {
final int consumed = translate(input, pos, out);
if (consumed == 0) {
final char[] c = Character.toChars(Character.codePointAt(input, pos));
out.write(c);
pos+= c.length;
continue;
}
// contract with translators is that they have to understand codepoints
// and they just took care of a surrogate pair
for (int pt = 0; pt < consumed; pt++) {
pos += Character.charCount(Character.codePointAt(input, pos));
}
}
}
/**
* Helper method to create a merger of this translator with another set of
* translators. Useful in customizing the standard functionality.
*
* @param translators CharSequenceTranslator array of translators to merge with this one
* @return CharSequenceTranslator merging this translator with the others
*/
public final CharSequenceTranslator with(final CharSequenceTranslator... translators) {
final CharSequenceTranslator[] newArray = new CharSequenceTranslator[translators.length + 1];
newArray[0] = this;
System.arraycopy(translators, 0, newArray, 1, translators.length);
return new AggregateTranslator(newArray);
}
/**
* Returns an upper case hexadecimal String for the given
* character.
*
* @param codepoint The codepoint to convert.
* @return An upper case hexadecimal String
*/
public static String hex(final int codepoint) {
return Integer.toHexString(codepoint).toUpperCase(Locale.ENGLISH);
}
}