scriptella.configuration.ContentEl Maven / Gradle / Ivy
/*
* Copyright 2006-2012 The Scriptella Project Team.
*
* 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 scriptella.configuration;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.Text;
import scriptella.spi.Resource;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.Reader;
import java.util.ArrayList;
import java.util.List;
/**
* TODO: Add documentation
*
* @author Fyodor Kupolov
* @version 1.0
*/
public class ContentEl extends XmlConfigurableBase implements Resource {
/**
* Max length of string resource to concat with the previous one.
* This limitation is necessary to avoid concatenation of large text blocks, because in this
* case too much memory is used.
*/
private static final int MAX_CONCAT_RESOURCE_LENGTH = 1024 * 128; //128Kb
private List content = new ArrayList();
/**
* Null-Object to use instead of null if necessary
*/
public static final Resource NULL_CONTENT = new StringResource("", "Empty Content");
public ContentEl() {
}
public ContentEl(XmlElement element) {
configure(element);
}
public Reader open() throws IOException {
if (content.isEmpty()) {
return NULL_CONTENT.open();
}
//If content consists of only one resource - open it
if (content.size() == 1) {
return content.get(0).open();
}
//Otherwise create a multipart reader.
return new BufferedReader(new MultipartReader());
}
public void configure(final XmlElement element) {
for (Node node = element.getElement().getFirstChild(); node != null; node = node.getNextSibling()) {
append(asResource(element, node));
}
}
/**
* Creates a resource using content from the specified node.
* If node is not textual content or not include element, the content is skipped and null is returned.
*
* @param parentElement parent element of this node.
* @param node node to get content from.
* @return parsed resource or null.
*/
static Resource asResource(final XmlElement parentElement, final Node node) {
if (node == null) {
return null;
}
if (node instanceof Text) {
return new StringResource(((Text) node).getData());
} else if (node instanceof Element && "include".equals(node.getNodeName())) {
return new IncludeEl(new XmlElement((Element) node, parentElement));
}
return null;
}
/**
* Merges this content with specified one and returns this element.
*
* @param contentEl content to merge with.
* @return this instance with merged content.
*/
final ContentEl merge(final ContentEl contentEl) {
content.addAll(contentEl.content);
return this;
}
/**
* Appends a resource to this content.
*
* @param resource resource to append. Nulls are ignored.
*/
final void append(final Resource resource) {
if (resource != null) {
//If string resource and we already have content
if (resource instanceof StringResource && !content.isEmpty()) {
final int lastIndex = content.size() - 1;
Resource last = content.get(lastIndex);
if (last instanceof StringResource) { //If last resource is also a string resource
//Concat them and produce a new resource if new size does not exceed the memory limit
StringResource nextRes = (StringResource) resource;
StringResource prevRes = (StringResource) last;
if (prevRes.getString().length() + nextRes.getString().length() < MAX_CONCAT_RESOURCE_LENGTH) {
content.set(lastIndex, new StringResource(prevRes.getString() + nextRes.getString()));
return;
}
}
}
content.add(resource);
}
}
/**
* Returns resources represented by this content.
*
* @return list of resources represented by this content.
*/
public List getResources() {
return content;
}
@Override
public String toString() {
Location loc = getLocation();
return loc != null ? loc.toString() : ("ContentEl{" + "content=" + content + '}');
}
class MultipartReader extends Reader {
private int pos = 0;
private Reader current;
private int blocksCount = content.size();
public int read(final char cbuf[], final int off, final int len) throws IOException {
if ((pos < 0) || ((pos >= blocksCount) && (current == null))) {
return -1;
}
int l = len;
int o = off;
while (l > 0) {
if (current == null) {
if (pos < blocksCount) {
current = content.get(pos).open();
pos++;
} else {
return ((len - l) <= 0) ? (-1) : (len - l);
}
} else {
final int r = current.read(cbuf, o, l);
if (r <= 0) {
current.close();
current = null;
} else if (r <= l) {
l -= r;
o += r;
}
}
}
return len - l;
}
public void close() throws IOException {
if (current != null) {
current.close();
current = null;
}
pos = -1;
}
}
}