alexh.weak.XmlDynamic Maven / Gradle / Ivy
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/*
* Copyright 2015 Alex Butler
*
* 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 alexh.weak;
import static alexh.Unchecker.uncheckedGet;
import static java.util.Objects.requireNonNull;
import static java.util.stream.Collectors.toList;
import java.io.Reader;
import java.io.StringReader;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.function.Predicate;
import java.util.stream.IntStream;
import java.util.stream.Stream;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathFactory;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.ls.DOMImplementationLS;
import org.w3c.dom.ls.LSSerializer;
import org.xml.sax.InputSource;
/**
* Dynamic implementation for XML documents
* All keys & values in an XmlDynamic unwrap to Strings, try {@link Dynamic#convert()}
* to implement basic string->type conversions
*
* As an example consider the following XML structure stored in a String 'xmlMessage'
*
{@code
*
*
*
*
* some name
*
*
*
*
* }
* We can select the nested 'name' element value with
*
{@code new XmlDynamic(xmlMessage).get("product.investment.info.current.name", ".").asString()}
*
* Also since XML has certain key name restrictions the pipe character '|' can be used as a splitter without declaration
*
ie {@code new XmlDynamic(xmlMessage).get("product|investment|info|current|name").asString()}
* @see XmlDynamic#get(Object)
*
* @author Alex Butler
*/
public class XmlDynamic extends AbstractDynamic implements Describer {
private static final String FALLBACK_TO_STRING = "Xml[unable to serialize]";
private static final String NONE_NAMESPACE = "none";
private static final String NS_INDICATOR = "::";
/** Needs to be thread-safe, childNodes NodeList is not! */
private static Stream streamChildNodes(Node node) {
int children = node.getChildNodes().getLength();
Node firstChild = node.getFirstChild();
if (firstChild == null) return Stream.empty();
return Stream.iterate(firstChild, prev -> prev != null ? prev.getNextSibling() : null)
.limit(children)
.filter(n -> n != null);
}
/** Needs to be thread-safe */
private static Stream streamAttributes(Node node) {
final NamedNodeMap attributes = node.getAttributes();
if (attributes == null) return Stream.empty();
return IntStream.range(0, attributes.getLength()).mapToObj(attributes::item);
}
private static Node inputSourceToNode(InputSource xml) {
final XPathExpression all = uncheckedGet(() -> XPathFactory.newInstance().newXPath().compile("//*"));
synchronized (XPathExpression.class) { // evaluate not thread-safe
return uncheckedGet(() -> (Node) all.evaluate(xml, XPathConstants.NODE));
}
}
/**
* Predicate for an xml element's name as it appears in the xml itself (case insensitive)
* Inside the xml dynamic multiple elements with the same names have unique suffices ie
*
* 1
* 2
*
* the 'child' elements have internal names 'child' and 'child[1]' a predicate
* {@code dynamic -> dynamic.key().asString().equals("child")} would only match the first
*
* {@code hasElementName("child")} matches both
*
* @param elementName xml element name
* @return predicate to match XmlDynamic instances of elements with input name
*/
public static Predicate hasElementName(String elementName) {
final String[] nsKey = elementName.split(NS_INDICATOR);
return element -> {
if (!(element instanceof XmlDynamic)) return false;
String simpleName = elementName;
if (nsKey.length == 2) {
String namespace = nsKey[0];
String elNamespace = ((XmlDynamic) element).inner.getNamespaceURI();
if (NONE_NAMESPACE.equals(namespace)) {
if (elNamespace != null) return false;
}
else if (!namespace.equals(elNamespace)) return false;
simpleName = nsKey[1];
}
String key = element.key().asString();
if (key.endsWith("]"))
key = key.substring(0, key.lastIndexOf("["));
return key.equalsIgnoreCase(simpleName);
};
}
public XmlDynamic(Node inner) {
super(inner);
}
public XmlDynamic(InputSource xml) {
this(inputSourceToNode(xml));
}
public XmlDynamic(Reader xml) {
this(new InputSource(xml));
}
public XmlDynamic(String xml) {
this(new StringReader(xml));
}
/** Dynamic Xml values are always {@link String}s */
@Override
public boolean is(Class type) {
return String.class.equals(type);
}
/**
* {@inheritDoc}
*
* The pipe character '|' can be used as a splitter without declaration
* ie {@code xmlDynamic.get("product|investment|info|current|name").asString()}.
*
* Multiple child elements with the same local-name effectively have [i] appended to them where i is their
* index counting from top to bottom.
* For example:
*
{@code
*
* hello
* hey
* hi
* howdy
*
* }
*
{@code xmlDynamic.get("product|string")} returns "hello"
*
{@code xmlDynamic.get("product|string[0]")} also returns "hello"
*
{@code xmlDynamic.get("product|string[1]")} returns "hey"
*
{@code xmlDynamic.get("product|string[2]")} returns "hi"
*
{@code xmlDynamic.get("product|string[3]")} returns "howdy"
*
* Attributes can be accessed in exactly the same way as elements, or explicitly
*
{@code xmlDynamic.get("product|id").asString()} return "1234"
*
{@code xmlDynamic.get("product|@id").asString()} also returns "1234"
*
* Namespaces are ignored by default, but can be used explicitly using the "::" separator
* For example:
*
{@code
*
* hello
*
* }
*
{@code xmlDynamic.get("product|message")} returns "hello"
*
{@code xmlDynamic.get("http://example.com/example::product|none::message")} also returns "hello"
*/
@Override
public Dynamic get(Object keyObject) {
final String keyToString = keyObject.toString();
if (keyToString.contains("|")) return get(keyToString, "|");
if (children().allMatch(o -> false)) {
if (asString().isEmpty()) return new ParentAbsence.Empty<>(this, keyObject);
return new ParentAbsence.Barren<>(this, keyObject);
}
final String key = keyToString.endsWith("[0]") ? keyToString.substring(0, keyToString.length() - 3) : keyToString;
final String[] nsKey = key.split(NS_INDICATOR);
if (nsKey.length == 2) return getWithNamespace(nsKey[0], nsKey[1]);
final Optional match;
if (key.isEmpty()) match = Optional.empty();
else if (key.startsWith("@")) match = attributes().filter(attr -> attr.key.equals(key)).findAny();
else if (key.endsWith("]")) match = elements().filter(el -> el.key.equals(key)).findAny();
else {
match = Stream.concat(elements().filter(el -> el.key.equals(key)),
attributes().filter(attr -> attr.key.equals("@"+ key))).findFirst();
}
return match.map(Dynamic.class::cast).orElse(new ChildAbsence.Missing<>(this, keyObject));
}
protected Dynamic getWithNamespace(String namespace, String key) {
final Optional match;
final Predicate nodeInNamespace;
if (NONE_NAMESPACE.equals(namespace)) nodeInNamespace = node -> node.getNamespaceURI() == null;
else nodeInNamespace = node -> namespace.equals(node.getNamespaceURI());
if (key.isEmpty()) match = Optional.empty();
else if (key.startsWith("@")) {
match = attributesWith(nodeInNamespace).filter(attr -> attr.key.equals(key)).findAny();
}
else if (key.endsWith("]")) {
match = elementsWith(nodeInNamespace).filter(el -> el.key.equals(key)).findAny();
}
else {
match = Stream.concat(elementsWith(nodeInNamespace).filter(el -> el.key.equals(key)),
attributesWith(nodeInNamespace).filter(attr -> attr.key.equals("@"+ key))).findFirst();
}
return match.map(Dynamic.class::cast).orElse(new ChildAbsence.Missing<>(this, namespace + NS_INDICATOR + key));
}
protected Stream attributes() {
return attributesWith(n -> true);
}
protected Stream attributesWith(Predicate predicate) {
return Stream.empty();
}
protected Stream elements() {
return elementsWith(n -> true);
}
protected Stream elementsWith(Predicate predicate) {
return Stream.of(inner).filter(predicate).map(n -> childElement(n, 0));
}
@Override
public Stream children() {
synchronized (inner.getOwnerDocument()) {
return Stream.concat(elements(), attributes());
}
}
@Override
protected Object keyLiteral() {
return ROOT_KEY;
}
@Override
public String describe() {
if (isString() && asString().isEmpty())
return "Empty-Xml";
List keys = Stream.concat(elements(), attributes())
.map(child -> child.key)
.collect(toList());
Map keyLastIndex = new HashMap<>();
keys.forEach(key -> {
if (key.endsWith("]")) {
StringBuilder index = new StringBuilder();
for (int i = key.length()-2; i != -1; --i) {
char c = key.charAt(i);
if (c == '[') break;
else index.append(c);
}
if (index.length() != 0) {
keyLastIndex.put(key.substring(0, key.indexOf("[")), Integer.valueOf(index.toString()));
}
}
});
keyLastIndex.forEach((multiKey, maxIndex) -> {
keys.removeIf(key ->
key.equals(multiKey) || key.endsWith("]") && key.substring(0, key.indexOf("[")).equals(multiKey));
keys.add(multiKey + "[0.." + maxIndex + "]");
});
return keys.isEmpty() ? "Xml" : "Xml" + keys.toString();
}
Child childElement(Node inner, int index) {
return new Child(inner, this, index == 0 ? inner.getLocalName() : inner.getLocalName() + '[' + index + ']');
}
@Override
public int hashCode() {
final String toString = fullXml();
return FALLBACK_TO_STRING.equals(toString) ? super.hashCode() : toString.hashCode();
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
final String otherAsString = ((XmlDynamic)o).fullXml();
return !FALLBACK_TO_STRING.equals(otherAsString) && otherAsString.equals(this.fullXml());
}
protected LSSerializer serializer() {
LSSerializer serializer = ((DOMImplementationLS) inner.getOwnerDocument()
.getImplementation()
.getFeature("LS", "3.0"))
.createLSSerializer();
serializer.getDomConfig().setParameter("xml-declaration", false);
return serializer;
}
@Override
public String asObject() {
synchronized (inner.getOwnerDocument()) {
return serializer().writeToString(inner);
}
}
/** @return this dynamic key->value entry as an XML string */
public String fullXml() {
try {
synchronized (inner.getOwnerDocument()) {
return serializer().writeToString(inner);
}
}
catch (RuntimeException ex) { return FALLBACK_TO_STRING; }
}
@Override
public String toString() {
return keyLiteral() + ":"+ describe();
}
static class Child extends XmlDynamic implements DynamicChild {
private final Dynamic parent;
private final String key;
Child(Node inner, Dynamic parent, String key) {
super(inner);
this.parent = parent;
this.key = requireNonNull(key);
}
@Override
public String asObject() {
synchronized (inner.getOwnerDocument()) {
return Optional.ofNullable(inner.getFirstChild())
.map(Node::getNodeValue)
.orElseGet(() -> elements().map(Child::fullXml)
.map(String::trim)
.reduce((s1, s2) -> s1 + s2)
.orElse(""));
}
}
@Override
protected Stream attributesWith(Predicate predicate) {
final Map keyLastIndex = new HashMap<>();
return streamAttributes(inner)
.filter(predicate)
.map(attr -> {
final Integer index = Optional.ofNullable(keyLastIndex.get(attr.getLocalName())).map(i -> i + 1).orElse(0);
keyLastIndex.put(attr.getLocalName(), index);
return childAttribute(attr, index);
});
}
@Override
protected Stream elementsWith(Predicate predicate) {
final Map keyLastIndex = new HashMap<>();
return streamChildNodes(inner)
.filter(node -> node.getLocalName() != null)
.filter(predicate)
.map(node -> {
final Integer index = Optional.ofNullable(keyLastIndex.get(node.getLocalName())).map(i -> i + 1).orElse(0);
keyLastIndex.put(node.getLocalName(), index);
return childElement(node, index);
});
}
@Override
public Dynamic parent() {
return parent;
}
@Override
public Object keyLiteral() {
return key;
}
Child childAttribute(Node inner, int index) {
String name = "@" + inner.getLocalName();
return new Child(inner, this, index == 0 ? name : name + '[' + index + ']');
}
}
}