2014-03-21 09:51:52 +01:00
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/**
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*
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* Copyright 2014 Florian Schmaus
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.jivesoftware.smack.util;
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import java.util.ArrayList;
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2015-05-21 20:10:31 +02:00
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import java.util.Collections;
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2014-03-21 09:51:52 +01:00
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import java.util.List;
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public class LazyStringBuilder implements Appendable, CharSequence {
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private final List<CharSequence> list;
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2014-06-19 11:48:01 +02:00
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private String cache;
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private void invalidateCache() {
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cache = null;
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}
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2014-03-21 09:51:52 +01:00
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public LazyStringBuilder() {
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list = new ArrayList<CharSequence>(20);
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}
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public LazyStringBuilder append(LazyStringBuilder lsb) {
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list.addAll(lsb.list);
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2014-06-19 11:48:01 +02:00
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invalidateCache();
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2014-03-21 09:51:52 +01:00
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return this;
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}
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@Override
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public LazyStringBuilder append(CharSequence csq) {
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assert csq != null;
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list.add(csq);
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2014-06-19 11:48:01 +02:00
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invalidateCache();
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2014-03-21 09:51:52 +01:00
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return this;
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}
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@Override
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public LazyStringBuilder append(CharSequence csq, int start, int end) {
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CharSequence subsequence = csq.subSequence(start, end);
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list.add(subsequence);
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2014-06-19 11:48:01 +02:00
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invalidateCache();
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2014-03-21 09:51:52 +01:00
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return this;
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}
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@Override
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public LazyStringBuilder append(char c) {
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list.add(Character.toString(c));
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2014-06-19 11:48:01 +02:00
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invalidateCache();
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2014-03-21 09:51:52 +01:00
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return this;
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}
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@Override
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public int length() {
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2014-06-19 11:48:01 +02:00
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if (cache != null) {
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return cache.length();
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}
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2014-03-21 09:51:52 +01:00
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int length = 0;
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for (CharSequence csq : list) {
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length += csq.length();
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}
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return length;
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}
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@Override
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public char charAt(int index) {
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2014-06-19 11:48:01 +02:00
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if (cache != null) {
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return cache.charAt(index);
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}
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2014-03-21 09:51:52 +01:00
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for (CharSequence csq : list) {
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if (index < csq.length()) {
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return csq.charAt(index);
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} else {
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index -= csq.length();
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}
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}
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throw new IndexOutOfBoundsException();
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}
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@Override
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public CharSequence subSequence(int start, int end) {
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return toString().subSequence(start, end);
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}
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@Override
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public String toString() {
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2014-06-19 11:48:01 +02:00
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if (cache == null) {
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StringBuilder sb = new StringBuilder(length());
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for (CharSequence csq : list) {
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sb.append(csq);
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}
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cache = sb.toString();
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2014-03-21 09:51:52 +01:00
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}
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2014-06-19 11:48:01 +02:00
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return cache;
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2014-03-21 09:51:52 +01:00
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}
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2015-05-21 20:10:31 +02:00
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/**
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* Get the List of CharSequences representation of this instance. The list is unmodifiable. If
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* the resulting String was already cached, a list with a single String entry will be returned.
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*
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* @return a List of CharSequences representing this instance.
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*/
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public List<CharSequence> getAsList() {
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if (cache != null) {
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return Collections.singletonList((CharSequence) cache);
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}
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return Collections.unmodifiableList(list);
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}
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2014-03-21 09:51:52 +01:00
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}
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