org.apache.logging.log4j.util.StringBuilders Maven / Gradle / Ivy
/*
* 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 org.apache.logging.log4j.util;
import java.util.Map.Entry;
import static java.lang.Character.toLowerCase;
/**
* Consider this class private.
*/
public final class StringBuilders {
private StringBuilders() {
}
/**
* Appends in the following format: double quoted value.
*
* @param sb a string builder
* @param value a value
* @return {@code "value"}
*/
public static StringBuilder appendDqValue(final StringBuilder sb, final Object value) {
return sb.append(Chars.DQUOTE).append(value).append(Chars.DQUOTE);
}
/**
* Appends in the following format: key=double quoted value.
*
* @param sb a string builder
* @param entry a map entry
* @return {@code key="value"}
*/
public static StringBuilder appendKeyDqValue(final StringBuilder sb, final Entry entry) {
return appendKeyDqValue(sb, entry.getKey(), entry.getValue());
}
/**
* Appends in the following format: key=double quoted value.
*
* @param sb a string builder
* @param key a key
* @param value a value
* @return the specified StringBuilder
*/
public static StringBuilder appendKeyDqValue(final StringBuilder sb, final String key, final Object value) {
return sb.append(key).append(Chars.EQ).append(Chars.DQUOTE).append(value).append(Chars.DQUOTE);
}
/**
* Appends a text representation of the specified object to the specified StringBuilder,
* if possible without allocating temporary objects.
*
* @param stringBuilder the StringBuilder to append the value to
* @param obj the object whose text representation to append to the StringBuilder
*/
public static void appendValue(final StringBuilder stringBuilder, final Object obj) {
if (!appendSpecificTypes(stringBuilder, obj)) {
stringBuilder.append(obj);
}
}
public static boolean appendSpecificTypes(final StringBuilder stringBuilder, final Object obj) {
if (obj == null || obj instanceof String) {
stringBuilder.append((String) obj);
} else if (obj instanceof StringBuilderFormattable) {
((StringBuilderFormattable) obj).formatTo(stringBuilder);
} else if (obj instanceof CharSequence) {
stringBuilder.append((CharSequence) obj);
} else if (obj instanceof Integer) { // LOG4J2-1437 unbox auto-boxed primitives to avoid calling toString()
stringBuilder.append(((Integer) obj).intValue());
} else if (obj instanceof Long) {
stringBuilder.append(((Long) obj).longValue());
} else if (obj instanceof Double) {
stringBuilder.append(((Double) obj).doubleValue());
} else if (obj instanceof Boolean) {
stringBuilder.append(((Boolean) obj).booleanValue());
} else if (obj instanceof Character) {
stringBuilder.append(((Character) obj).charValue());
} else if (obj instanceof Short) {
stringBuilder.append(((Short) obj).shortValue());
} else if (obj instanceof Float) {
stringBuilder.append(((Float) obj).floatValue());
} else if (obj instanceof Byte) {
stringBuilder.append(((Byte) obj).byteValue());
} else {
return false;
}
return true;
}
/**
* Returns true if the specified section of the left CharSequence equals the specified section of the right
* CharSequence.
*
* @param left the left CharSequence
* @param leftOffset start index in the left CharSequence
* @param leftLength length of the section in the left CharSequence
* @param right the right CharSequence to compare a section of
* @param rightOffset start index in the right CharSequence
* @param rightLength length of the section in the right CharSequence
* @return true if equal, false otherwise
*/
public static boolean equals(final CharSequence left, final int leftOffset, final int leftLength,
final CharSequence right, final int rightOffset, final int rightLength) {
if (leftLength == rightLength) {
for (int i = 0; i < rightLength; i++) {
if (left.charAt(i + leftOffset) != right.charAt(i + rightOffset)) {
return false;
}
}
return true;
}
return false;
}
/**
* Returns true if the specified section of the left CharSequence equals, ignoring case, the specified section of
* the right CharSequence.
*
* @param left the left CharSequence
* @param leftOffset start index in the left CharSequence
* @param leftLength length of the section in the left CharSequence
* @param right the right CharSequence to compare a section of
* @param rightOffset start index in the right CharSequence
* @param rightLength length of the section in the right CharSequence
* @return true if equal ignoring case, false otherwise
*/
public static boolean equalsIgnoreCase(final CharSequence left, final int leftOffset, final int leftLength,
final CharSequence right, final int rightOffset, final int rightLength) {
if (leftLength == rightLength) {
for (int i = 0; i < rightLength; i++) {
if (toLowerCase(left.charAt(i + leftOffset)) != toLowerCase(right.charAt(i + rightOffset))) {
return false;
}
}
return true;
}
return false;
}
/**
* Ensures that the char[] array of the specified StringBuilder does not exceed the specified number of characters.
* This method is useful to ensure that excessively long char[] arrays are not kept in memory forever.
*
* @param stringBuilder the StringBuilder to check
* @param maxSize the maximum number of characters the StringBuilder is allowed to have
* @since 2.9
*/
public static void trimToMaxSize(final StringBuilder stringBuilder, final int maxSize) {
if (stringBuilder != null && stringBuilder.capacity() > maxSize) {
stringBuilder.setLength(maxSize);
stringBuilder.trimToSize();
}
}
public static void escapeJson(final StringBuilder toAppendTo, final int start) {
int escapeCount = 0;
for (int i = start; i < toAppendTo.length(); i++) {
final char c = toAppendTo.charAt(i);
switch (c) {
case '\b':
case '\t':
case '\f':
case '\n':
case '\r':
case '"':
case '\\':
escapeCount++;
break;
default:
if (Character.isISOControl(c)) {
escapeCount += 5;
}
}
}
final int lastChar = toAppendTo.length() - 1;
toAppendTo.setLength(toAppendTo.length() + escapeCount);
int lastPos = toAppendTo.length() - 1;
for (int i = lastChar; lastPos > i; i--) {
final char c = toAppendTo.charAt(i);
switch (c) {
case '\b':
lastPos = escapeAndDecrement(toAppendTo, lastPos, 'b');
break;
case '\t':
lastPos = escapeAndDecrement(toAppendTo, lastPos, 't');
break;
case '\f':
lastPos = escapeAndDecrement(toAppendTo, lastPos, 'f');
break;
case '\n':
lastPos = escapeAndDecrement(toAppendTo, lastPos, 'n');
break;
case '\r':
lastPos = escapeAndDecrement(toAppendTo, lastPos, 'r');
break;
case '"':
case '\\':
lastPos = escapeAndDecrement(toAppendTo, lastPos, c);
break;
default:
if (Character.isISOControl(c)) {
// all iso control characters are in U+00xx, JSON output format is "\\u00XX"
toAppendTo.setCharAt(lastPos--, Chars.getUpperCaseHex(c & 0xF));
toAppendTo.setCharAt(lastPos--, Chars.getUpperCaseHex((c & 0xF0) >> 4));
toAppendTo.setCharAt(lastPos--, '0');
toAppendTo.setCharAt(lastPos--, '0');
toAppendTo.setCharAt(lastPos--, 'u');
toAppendTo.setCharAt(lastPos--, '\\');
} else {
toAppendTo.setCharAt(lastPos, c);
lastPos--;
}
}
}
}
private static int escapeAndDecrement(final StringBuilder toAppendTo, int lastPos, final char c) {
toAppendTo.setCharAt(lastPos--, c);
toAppendTo.setCharAt(lastPos--, '\\');
return lastPos;
}
public static void escapeXml(final StringBuilder toAppendTo, final int start) {
int escapeCount = 0;
for (int i = start; i < toAppendTo.length(); i++) {
final char c = toAppendTo.charAt(i);
switch (c) {
case '&':
escapeCount += 4;
break;
case '<':
case '>':
escapeCount += 3;
break;
case '"':
case '\'':
escapeCount += 5;
}
}
final int lastChar = toAppendTo.length() - 1;
toAppendTo.setLength(toAppendTo.length() + escapeCount);
int lastPos = toAppendTo.length() - 1;
for (int i = lastChar; lastPos > i; i--) {
final char c = toAppendTo.charAt(i);
switch (c) {
case '&':
toAppendTo.setCharAt(lastPos--, ';');
toAppendTo.setCharAt(lastPos--, 'p');
toAppendTo.setCharAt(lastPos--, 'm');
toAppendTo.setCharAt(lastPos--, 'a');
toAppendTo.setCharAt(lastPos--, '&');
break;
case '<':
toAppendTo.setCharAt(lastPos--, ';');
toAppendTo.setCharAt(lastPos--, 't');
toAppendTo.setCharAt(lastPos--, 'l');
toAppendTo.setCharAt(lastPos--, '&');
break;
case '>':
toAppendTo.setCharAt(lastPos--, ';');
toAppendTo.setCharAt(lastPos--, 't');
toAppendTo.setCharAt(lastPos--, 'g');
toAppendTo.setCharAt(lastPos--, '&');
break;
case '"':
toAppendTo.setCharAt(lastPos--, ';');
toAppendTo.setCharAt(lastPos--, 't');
toAppendTo.setCharAt(lastPos--, 'o');
toAppendTo.setCharAt(lastPos--, 'u');
toAppendTo.setCharAt(lastPos--, 'q');
toAppendTo.setCharAt(lastPos--, '&');
break;
case '\'':
toAppendTo.setCharAt(lastPos--, ';');
toAppendTo.setCharAt(lastPos--, 's');
toAppendTo.setCharAt(lastPos--, 'o');
toAppendTo.setCharAt(lastPos--, 'p');
toAppendTo.setCharAt(lastPos--, 'a');
toAppendTo.setCharAt(lastPos--, '&');
break;
default:
toAppendTo.setCharAt(lastPos--, c);
}
}
}
}
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