/*
* Copyright 2004-2009 the original author or authors.
*
* Licensed 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.compass.core.util;
import java.io.Writer;
/**
* A Writer based on {@link StringBuilder}. Also alows for thread local reuse of {@link StringBuilder}
* by using: <code>StringBuilderWriter.Cached.cached()</code> in order to obtain the cached writer. Note,
* in such cases, the {@link #getBuilder()} should be called and used (usually <code>toString</code> it)
* before another usage of the writer.
*
* @author kimchy
*/
public class StringBuilderWriter extends Writer {
public static class Cached {
private static final ThreadLocal<StringBuilderWriter> cache = new ThreadLocal<StringBuilderWriter>() {
@Override
protected StringBuilderWriter initialValue() {
return new StringBuilderWriter();
}
};
public static StringBuilderWriter cached() {
StringBuilderWriter writer = cache.get();
writer.getBuilder().setLength(0);
return writer;
}
}
private final StringBuilder builder;
/**
* Construct a new {@link StringBuilder} instance with default capacity.
*/
public StringBuilderWriter() {
this.builder = new StringBuilder();
}
/**
* Construct a new {@link StringBuilder} instance with the specified capacity.
*
* @param capacity The initial capacity of the underlying {@link StringBuilder}
*/
public StringBuilderWriter(int capacity) {
this.builder = new StringBuilder(capacity);
}
/**
* Construct a new instance with the specified {@link StringBuilder}.
*
* @param builder The String builder
*/
public StringBuilderWriter(StringBuilder builder) {
this.builder = (builder != null ? builder : new StringBuilder());
}
/**
* Append a single character to this Writer.
*
* @param value The character to append
* @return This writer instance
*/
public Writer append(char value) {
builder.append(value);
return this;
}
/**
* Append a character sequence to this Writer.
*
* @param value The character to append
* @return This writer instance
*/
public Writer append(CharSequence value) {
builder.append(value);
return this;
}
/**
* Append a portion of a character sequence to the {@link StringBuilder}.
*
* @param value The character to append
* @param start The index of the first character
* @param end The index of the last character + 1
* @return This writer instance
*/
public Writer append(CharSequence value, int start, int end) {
builder.append(value, start, end);
return this;
}
/**
* Closing this writer has no effect.
*/
public void close() {
}
/**
* Flushing this writer has no effect.
*/
public void flush() {
}
/**
* Write a String to the {@link StringBuilder}.
*
* @param value The value to write
*/
public void write(String value) {
if (value != null) {
builder.append(value);
}
}
/**
* Write a portion of a character array to the {@link StringBuilder}.
*
* @param value The value to write
* @param offset The index of the first character
* @param length The number of characters to write
*/
public void write(char[] value, int offset, int length) {
if (value != null) {
builder.append(value, offset, length);
}
}
/**
* Return the underlying builder.
*
* @return The underlying builder
*/
public StringBuilder getBuilder() {
return builder;
}
/**
* Returns {@link StringBuilder#toString()}.
*
* @return The contents of the String builder.
*/
public String toString() {
return builder.toString();
}
}