net.pwall.util.CharMapper Maven / Gradle / Ivy
/*
* @(#) CharMapper.java
*
* javautil Java Utility Library
* Copyright (c) 2013, 2014, 2017 Peter Wall
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
package net.pwall.util;
import java.io.IOException;
/**
* Character mapper interface for "escape" functions.
*
* @author Peter Wall
* @see Strings#escape(CharSequence, CharMapper)
* @see Strings#escape(String, CharMapper)
* @see Strings#escapeUTF16(CharSequence, CharMapper)
* @see Strings#escapeUTF16(String, CharMapper)
*/
@FunctionalInterface
public interface CharMapper {
/**
* Map character to it's "escaped" string equivalent, for example '+' to "%2B" in URL
* encoding. Return {@code null} if the character does not need to be converted.
*
* @param codePoint the Unicode code point of the character to be mapped
* @return the escaped string equivalent, or {@code null} if no escape needed
*/
String map(int codePoint);
/**
* Map a range of contiguous code points into strings using an array. The first entry in
* the array represents the code point specified by the base, the second is base + 1 etc.
*
* @param array the array of strings
* @param codePoint the Unicode code point
* @param base the code point representing the first entry in the array
* @return the string representing the code point, or {@code null} if the code
* point is outside the range
*/
static String arrayMapping(String[] array, int codePoint, int base) {
if (codePoint >= base && codePoint < base + array.length)
return array[codePoint - base];
return null;
}
/**
* Map a code point using a lookup table. The lookup uses a binary search so the table
* entries must be in ascending order by code point.
*
* @param table an array of mapping entries, each of which is an array of two strings:
* a single character string containing the character to be mapped, and the
* result string
* @param codePoint the Unicode code point
* @return the string representing the code point, or {@code null} if no entry
* exists in the table for the code point
*/
static String lookupMapping(String[][] table, int codePoint) {
int hi = table.length;
if (hi > 0 && codePoint >= table[0][0].charAt(0) &&
codePoint <= table[hi - 1][0].charAt(0)) {
int lo = 0;
while (lo < hi) {
int mid = (lo + hi) >>> 1;
String[] entry = table[mid];
char ch = entry[0].charAt(0);
if (codePoint == ch)
return entry[1];
if (codePoint < ch)
hi = mid;
else
lo = mid + 1;
}
}
return null;
}
/**
* Map a code point using a lookup table. The lookup uses a binary search so the table
* entries must be in ascending order by code point.
*
* @param table an array of mapping entries, each of which is an array of two strings:
* a single character string containing the character to be mapped, and the
* result string
* @param codePoint the Unicode code point
* @return the string representing the code point, or {@code null} if no entry
* exists in the table for the code point
*/
static String lookupMapping(CharMapperEntry[] table, int codePoint) {
int hi = table.length;
if (hi > 0 && codePoint >= table[0].getCodePoint() &&
codePoint <= table[hi - 1].getCodePoint()) {
int lo = 0;
while (lo < hi) {
int mid = (lo + hi) >>> 1;
CharMapperEntry entry = table[mid];
int entryCodePoint = entry.getCodePoint();
if (codePoint == entryCodePoint)
return entry.getString();
if (codePoint < entryCodePoint)
hi = mid;
else
lo = mid + 1;
}
}
return null;
}
/**
* Map a code point into a decimal string with prefix and optional suffix.
*
* @param codePoint the Unicode code point
* @param prefix the prefix string
* @param suffix the suffix string (or {@code null} if no suffix needed)
* @return the decimal representation of the code point, with the specified prefix
* and optional suffix
*/
static String decimalMapping(int codePoint, String prefix, String suffix) {
StringBuilder sb = new StringBuilder(prefix.length() + 7 +
(suffix != null ? suffix.length() : 0));
sb.append(prefix);
try {
Strings.appendPositiveInt(sb, codePoint);
}
catch (IOException e) {
// can't happen - StringBuilder doesn't throw IOException
}
if (suffix != null)
sb.append(suffix);
return sb.toString();
}
/**
* Map a code point into a fixed-length hexadecimal string with prefix and optional suffix.
*
* @param codePoint the Unicode code point
* @param length the number of hexadecimal digits
* @param prefix the prefix string
* @param suffix the suffix string (or {@code null} if no suffix needed)
* @return the hexadecimal representation of the code point, zero-padded to the
* required number of digits, with the specified prefix and optional suffix
*/
static String hexMapping(int codePoint, int length, String prefix, String suffix) {
StringBuilder sb = new StringBuilder(prefix.length() + length +
(suffix != null ? suffix.length() : 0));
sb.append(prefix);
try {
Strings.appendHex(sb, codePoint, length);
}
catch (IOException ioe) {
// can't happen - StringBuilder doesn't throw IOException
}
if (suffix != null)
sb.append(suffix);
return sb.toString();
}
/**
* Map a code point into a fixed-length hexadecimal string with prefix and no suffix. This
* is an optimization of the common case of no suffix being required.
*
* @param codePoint the Unicode code point
* @param length the number of hexadecimal digits
* @param prefix the prefix string
* @return the hexadecimal representation of the code point, zero-padded to the
* required number of digits, with the specified prefix
*/
static String hexMapping(int codePoint, int length, String prefix) {
StringBuilder sb = new StringBuilder(prefix.length() + length);
sb.append(prefix);
try {
Strings.appendHex(sb, codePoint, length);
}
catch (IOException ioe) {
// can't happen - StringBuilder doesn't throw IOException
}
return sb.toString();
}
}
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