co.elastic.logging.JsonUtils Maven / Gradle / Ivy
/*-
* #%L
* Java ECS logging
* %%
* Copyright (C) 2019 - 2020 Elastic and contributors
* %%
* Licensed to Elasticsearch B.V. under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch B.V. 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.
* #L%
*/
package co.elastic.logging;
/**
* This class is based on com.fasterxml.jackson.core.io.CharTypes,
* under Apache License 2.0
*/
public final class JsonUtils {
private final static char[] HC = "0123456789ABCDEF".toCharArray();
/**
* Lookup table used for determining which output characters in
* 7-bit ASCII range need to be quoted.
*/
private final static int[] sOutputEscapes128;
static {
int[] table = new int[128];
// Control chars need generic escape sequence
for (int i = 0; i < 32; ++i) {
// 04-Mar-2011, tatu: Used to use "-(i + 1)", replaced with constant
table[i] = -1;
}
// Others (and some within that range too) have explicit shorter sequences
table['"'] = '"';
table['\\'] = '\\';
// Escaping of slash is optional, so let's not add it
table[0x08] = 'b';
table[0x09] = 't';
table[0x0C] = 'f';
table[0x0A] = 'n';
table[0x0D] = 'r';
sOutputEscapes128 = table;
}
public static void quoteAsString(CharSequence content, StringBuilder sb) {
if (content == null) {
sb.append("null");
return;
}
quoteAsString(content, 0, content.length(), sb);
}
public static void quoteAsString(CharSequence content, int start, int end, StringBuilder sb) {
if (content == null) {
sb.append("null");
return;
}
final int[] escCodes = sOutputEscapes128;
final int escLen = escCodes.length;
for (int i = start; i < end; ++i) {
char c = content.charAt(i);
if (c >= escLen || escCodes[c] == 0) {
sb.append(c);
continue;
}
sb.append('\\');
int escCode = escCodes[c];
if (escCode < 0) { // generic quoting (hex value)
// The only negative value sOutputEscapes128 returns
// is CharacterEscapes.ESCAPE_STANDARD, which mean
// appendQuotes should encode using the Unicode encoding;
// not sure if this is the right way to encode for
// CharacterEscapes.ESCAPE_CUSTOM or other (future)
// CharacterEscapes.ESCAPE_XXX values.
// We know that it has to fit in just 2 hex chars
sb.append('u');
sb.append('0');
sb.append('0');
int value = c; // widening
sb.append(HC[value >> 4]);
sb.append(HC[value & 0xF]);
} else { // "named", i.e. prepend with slash
sb.append((char) escCode);
}
}
}
}