/*
* 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.log4j.pattern;
import java.util.ArrayList;
import java.util.List;
/**
* NameAbbreviator generates abbreviated logger and class names.
*
*/
public abstract class NameAbbreviator {
/**
* Default (no abbreviation) abbreviator.
*/
private static final NameAbbreviator DEFAULT = new NOPAbbreviator();
/**
* Gets an abbreviator.
*
* For example, "%logger{2}" will output only 2 elements of the logger name,
* %logger{-2} will drop 2 elements from the logger name,
* "%logger{1.}" will output only the first character of the non-final elements in the name,
* "%logger{1~.2~} will output the first character of the first element, two characters of
* the second and subsequent elements and will use a tilde to indicate abbreviated characters.
*
* @param pattern abbreviation pattern.
* @return abbreviator, will not be null.
*/
public static NameAbbreviator getAbbreviator(final String pattern) {
if (pattern.length() > 0) {
// if pattern is just spaces and numbers then
// use MaxElementAbbreviator
String trimmed = pattern.trim();
if (trimmed.length() == 0) {
return DEFAULT;
}
int i = 0;
if (trimmed.length() > 0) {
if (trimmed.charAt(0) == '-') {
i++;
}
for (;
(i < trimmed.length()) &&
(trimmed.charAt(i) >= '0') &&
(trimmed.charAt(i) <= '9');
i++) {
}
}
//
// if all blanks and digits
//
if (i == trimmed.length()) {
int elements = Integer.parseInt(trimmed);
if (elements >= 0) {
return new MaxElementAbbreviator(elements);
} else {
return new DropElementAbbreviator(-elements);
}
}
ArrayList fragments = new ArrayList(5);
char ellipsis;
int charCount;
int pos = 0;
while ((pos < trimmed.length()) && (pos >= 0)) {
int ellipsisPos = pos;
if (trimmed.charAt(pos) == '*') {
charCount = Integer.MAX_VALUE;
ellipsisPos++;
} else {
if ((trimmed.charAt(pos) >= '0') && (trimmed.charAt(pos) <= '9')) {
charCount = trimmed.charAt(pos) - '0';
ellipsisPos++;
} else {
charCount = 0;
}
}
ellipsis = '\0';
if (ellipsisPos < trimmed.length()) {
ellipsis = trimmed.charAt(ellipsisPos);
if (ellipsis == '.') {
ellipsis = '\0';
}
}
fragments.add(new PatternAbbreviatorFragment(charCount, ellipsis));
pos = trimmed.indexOf(".", pos);
if (pos == -1) {
break;
}
pos++;
}
return new PatternAbbreviator(fragments);
}
//
// no matching abbreviation, return defaultAbbreviator
//
return DEFAULT;
}
/**
* Gets default abbreviator.
*
* @return default abbreviator.
*/
public static NameAbbreviator getDefaultAbbreviator() {
return DEFAULT;
}
/**
* Abbreviates a name in a StringBuffer.
*
* @param nameStart starting position of name in buf.
* @param buf buffer, may not be null.
*/
public abstract void abbreviate(final int nameStart, final StringBuffer buf);
/**
* Abbreviator that simply appends full name to buffer.
*/
private static class NOPAbbreviator extends NameAbbreviator {
/**
* Constructor.
*/
public NOPAbbreviator() {
}
/**
* {@inheritDoc}
*/
public void abbreviate(final int nameStart, final StringBuffer buf) {
}
}
/**
* Abbreviator that drops starting path elements.
*/
private static class MaxElementAbbreviator extends NameAbbreviator {
/**
* Maximum number of path elements to output.
*/
private final int count;
/**
* Create new instance.
* @param count maximum number of path elements to output.
*/
public MaxElementAbbreviator(final int count) {
this.count = count;
}
/**
* Abbreviate name.
* @param buf buffer to append abbreviation.
* @param nameStart start of name to abbreviate.
*/
public void abbreviate(final int nameStart, final StringBuffer buf) {
// We substract 1 from 'len' when assigning to 'end' to avoid out of
// bounds exception in return r.substring(end+1, len). This can happen if
// precision is 1 and the category name ends with a dot.
int end = buf.length() - 1;
String bufString = buf.toString();
for (int i = count; i > 0; i--) {
end = bufString.lastIndexOf(".", end - 1);
if ((end == -1) || (end < nameStart)) {
return;
}
}
buf.delete(nameStart, end + 1);
}
}
/**
* Abbreviator that drops starting path elements.
*/
private static class DropElementAbbreviator extends NameAbbreviator {
/**
* Maximum number of path elements to output.
*/
private final int count;
/**
* Create new instance.
* @param count maximum number of path elements to output.
*/
public DropElementAbbreviator(final int count) {
this.count = count;
}
/**
* Abbreviate name.
* @param buf buffer to append abbreviation.
* @param nameStart start of name to abbreviate.
*/
public void abbreviate(final int nameStart, final StringBuffer buf) {
int i = count;
for(int pos = buf.indexOf(".", nameStart);
pos != -1;
pos = buf.indexOf(".", pos + 1)) {
if(--i == 0) {
buf.delete(nameStart, pos + 1);
break;
}
}
}
}
/**
* Fragment of an pattern abbreviator.
*
*/
private static class PatternAbbreviatorFragment {
/**
* Count of initial characters of element to output.
*/
private final int charCount;
/**
* Character used to represent dropped characters.
* '\0' indicates no representation of dropped characters.
*/
private final char ellipsis;
/**
* Creates a PatternAbbreviatorFragment.
* @param charCount number of initial characters to preserve.
* @param ellipsis character to represent elimination of characters,
* '\0' if no ellipsis is desired.
*/
public PatternAbbreviatorFragment(
final int charCount, final char ellipsis) {
this.charCount = charCount;
this.ellipsis = ellipsis;
}
/**
* Abbreviate element of name.
* @param buf buffer to receive element.
* @param startPos starting index of name element.
* @return starting index of next element.
*/
public int abbreviate(final StringBuffer buf, final int startPos) {
int nextDot = buf.toString().indexOf(".", startPos);
if (nextDot != -1) {
if ((nextDot - startPos) > charCount) {
buf.delete(startPos + charCount, nextDot);
nextDot = startPos + charCount;
if (ellipsis != '\0') {
buf.insert(nextDot, ellipsis);
nextDot++;
}
}
nextDot++;
}
return nextDot;
}
}
/**
* Pattern abbreviator.
*
*
*/
private static class PatternAbbreviator extends NameAbbreviator {
/**
* Element abbreviation patterns.
*/
private final PatternAbbreviatorFragment[] fragments;
/**
* Create PatternAbbreviator.
*
* @param fragments element abbreviation patterns.
*/
public PatternAbbreviator(List fragments) {
if (fragments.size() == 0) {
throw new IllegalArgumentException(
"fragments must have at least one element");
}
this.fragments = new PatternAbbreviatorFragment[fragments.size()];
fragments.toArray(this.fragments);
}
/**
* Abbreviate name.
* @param buf buffer that abbreviated name is appended.
* @param nameStart start of name.
*/
public void abbreviate(final int nameStart, final StringBuffer buf) {
//
// all non-terminal patterns are executed once
//
int pos = nameStart;
for (int i = 0; (i < (fragments.length - 1)) && (pos < buf.length());
i++) {
pos = fragments[i].abbreviate(buf, pos);
}
//
// last pattern in executed repeatedly
//
PatternAbbreviatorFragment terminalFragment =
fragments[fragments.length - 1];
while ((pos < buf.length()) && (pos >= 0)) {
pos = terminalFragment.abbreviate(buf, pos);
}
}
}
}