# SimpleXMLEventAllocator.java

    /*
     * Copyright 2011, 2012 Odysseus Software GmbH
     *
     * 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.apache.synapse.commons.staxon.core.event;

    import java.io.IOException;
    import java.io.StringWriter;
    import java.io.Writer;
    import java.util.ArrayList;
    import java.util.Collections;
    import java.util.Iterator;
    import java.util.List;

    import javax.xml.XMLConstants;
    import javax.xml.namespace.NamespaceContext;
    import javax.xml.namespace.QName;
    import javax.xml.stream.Location;
    import javax.xml.stream.XMLStreamConstants;
    import javax.xml.stream.XMLStreamException;
    import javax.xml.stream.XMLStreamReader;
    import javax.xml.stream.events.Attribute;
    import javax.xml.stream.events.Characters;
    import javax.xml.stream.events.Comment;
    import javax.xml.stream.events.EndDocument;
    import javax.xml.stream.events.EndElement;
    import javax.xml.stream.events.EntityDeclaration;
    import javax.xml.stream.events.EntityReference;
    import javax.xml.stream.events.Namespace;
    import javax.xml.stream.events.ProcessingInstruction;
    import javax.xml.stream.events.StartDocument;
    import javax.xml.stream.events.StartElement;
    import javax.xml.stream.events.XMLEvent;
    import javax.xml.stream.util.XMLEventAllocator;
    import javax.xml.stream.util.XMLEventConsumer;

    /**
     * Simple implementation of {@link XMLEventAllocator}.
     */
    public class SimpleXMLEventAllocator implements XMLEventAllocator {
        static abstract class AbstractXMLEvent implements XMLEvent {
            static <E> List<E> toList(Iterator<E> iterator) {
                if (iterator == null || !iterator.hasNext()) {
                    return Collections.emptyList();
                } else {
                    List<E> list = new ArrayList<E>();
                    while (iterator.hasNext()) {
                        list.add(iterator.next());
                    }
                    return list;
                }
            }

            final int eventType;
            final Location location;

            AbstractXMLEvent(int eventType, Location location) {
                this.eventType = eventType;
                this.location = location;
            }

            @Override
            public Characters asCharacters() {
                return (Characters) this;
            }

            @Override
            public StartElement asStartElement() {
                return (StartElement) this;
            }

            @Override
            public EndElement asEndElement() {
                return (EndElement) this;
            }

            @Override
            public int getEventType() {
                return eventType;
            }

            @Override
            public Location getLocation() {
                return location;
            }

            @Override
            public QName getSchemaType() {
                return null;
            }

            @Override
            public boolean isAttribute() {
                return eventType == XMLStreamConstants.ATTRIBUTE;
            }

            @Override
            public boolean isCharacters() {
                return eventType == XMLStreamConstants.CHARACTERS || eventType == XMLStreamConstants.CDATA;
            }

            @Override
            public boolean isEndDocument() {
                return eventType == XMLStreamConstants.END_DOCUMENT;
            }

            @Override
            public boolean isEndElement() {
                return eventType == XMLStreamConstants.END_ELEMENT;
            }

            @Override
            public boolean isEntityReference() {
                return eventType == XMLStreamConstants.ENTITY_REFERENCE;
            }

            @Override
            public boolean isNamespace() {
                return eventType == XMLStreamConstants.NAMESPACE;
            }

            @Override
            public boolean isProcessingInstruction() {
                return eventType == XMLStreamConstants.PROCESSING_INSTRUCTION;
            }

            @Override
            public boolean isStartDocument() {
                return eventType == XMLStreamConstants.START_DOCUMENT;
            }

            @Override
            public boolean isStartElement() {
                return eventType == XMLStreamConstants.START_ELEMENT;
            }

            @Override
            public String toString() {
                try {
                    Writer writer = new StringWriter();
                    writer.write(getClass().getSimpleName());
                    writer.write('(');
                    writeAsEncodedUnicodeInternal(writer);
                    writer.write(')');
                    return writer.toString();
                } catch (IOException e) {
                    return super.toString();
                }
            }

            @Override
            public void writeAsEncodedUnicode(Writer writer) throws XMLStreamException {
                try {
                    writeAsEncodedUnicodeInternal(writer);
                } catch (IOException e) {
                    throw new XMLStreamException(e);
                }

            }

            abstract void writeAsEncodedUnicodeInternal(Writer writer) throws IOException;
        }

        static class AttributeEvent extends AbstractXMLEvent implements Attribute {
            final QName name;
            final String value;
            final boolean specified;

            AttributeEvent(Location location, QName name, String value, boolean specified) {
                this(XMLStreamConstants.ATTRIBUTE, location, name, value, specified);
            }

            AttributeEvent(int eventType, Location location, QName name, String value, boolean specified) {
                super(eventType, location);
                assert eventType == XMLStreamConstants.ATTRIBUTE || eventType == XMLStreamConstants.NAMESPACE;
                this.name = name;
                this.value = value;
                this.specified = specified;
            }

            @Override
            public String getDTDType() {
                return "CDATA";
            }

            @Override
            public QName getName() {
                return name;
            }

            @Override
            public String getValue() {
                return value;
            }

            @Override
            public boolean isSpecified() {
                return specified;
            }

            @Override
            void writeAsEncodedUnicodeInternal(Writer writer) throws IOException {
                if (!XMLConstants.DEFAULT_NS_PREFIX.equals(name.getPrefix())) {
                    writer.write(name.getPrefix());
                    writer.write(':');
                }
                writer.write(name.getLocalPart());
                writer.write('=');
                writer.write('"');
                for (int i = 0; i < value.length(); i++) {
                    char c = value.charAt(i);
                    switch (c) {
                        case '<':
                            writer.write("&lt;");
                            break;
                        case '>':
                            writer.write("&gt;");
                            break;
                        case '&':
                            writer.write("&amp;");
                            break;
                        case '"':
                            writer.write("&quot;");
                            break;
                        default:
                            writer.write(c);
                    }
                }
                writer.write('"');
            }
        }

        static class CharactersEvent extends AbstractXMLEvent implements Characters {
            final String data;
            final boolean whitespace;

            CharactersEvent(XMLStreamReader reader) {
                this(reader.getEventType(), reader.getLocation(), reader.getText(), reader.isWhiteSpace());
            }

            CharactersEvent(int eventType, Location location, String data, boolean whitespace) {
                super(eventType, location);
                assert eventType == XMLStreamConstants.CHARACTERS
                        || eventType == XMLStreamConstants.CDATA
                        || eventType == XMLStreamConstants.SPACE;
                this.data = data;
                this.whitespace = whitespace;
            }

            @Override
            public String getData() {
                return data;
            }

            @Override
            public boolean isCData() {
                return eventType == XMLStreamConstants.CDATA;
            }

            @Override
            public boolean isIgnorableWhiteSpace() {
                return eventType == XMLStreamConstants.SPACE;
            }

            @Override
            public boolean isWhiteSpace() {
                return whitespace;
            }

            @Override
            void writeAsEncodedUnicodeInternal(Writer writer) throws IOException {
                if (isCData()) {
                    writer.write("<![CDATA[");
                    writer.write(data);
                    writer.write("]]>");
                } else if (!isIgnorableWhiteSpace()) { // API doc: No indentation or whitespace should be "outputted".
                    for (int i = 0; i < data.length(); i++) {
                        char c = data.charAt(i);
                        switch (c) {
                            case '<':
                                writer.write("&lt;");
                                break;
                            case '>':
                                writer.write("&gt;");
                                break;
                            case '&':
                                writer.write("&amp;");
                                break;
                            default:
                                writer.write(c);
                        }
                    }
                }
            }
        }

        static class CommentEvent extends AbstractXMLEvent implements Comment {
            final String text;

            CommentEvent(XMLStreamReader reader) {
                super(reader.getEventType(), reader.getLocation());
                assert eventType == XMLStreamConstants.COMMENT;
                text = reader.getText();
            }

            CommentEvent(Location location, String text) {
                super(XMLStreamConstants.COMMENT, location);
                this.text = text;
            }

            @Override
            public String getText() {
                return text;
            }

            @Override
            void writeAsEncodedUnicodeInternal(Writer writer) throws IOException {
                writer.write("<!--");
                writer.write(text);
                writer.write("-->");
            }
        }

        static class EndDocumentEvent extends AbstractXMLEvent implements EndDocument {
            EndDocumentEvent(XMLStreamReader reader) {
                super(reader.getEventType(), reader.getLocation());
                assert eventType == XMLStreamConstants.END_DOCUMENT;
            }

            EndDocumentEvent(Location location) {
                super(XMLStreamConstants.END_DOCUMENT, location);
            }

            @Override
            void writeAsEncodedUnicodeInternal(Writer writer) {
                // silence
            }
        }

        static class EndElementEvent extends AbstractXMLEvent implements EndElement {
            final QName name;
            final List<NamespaceEvent> namespaces;

            EndElementEvent(XMLStreamReader reader) {
                super(reader.getEventType(), reader.getLocation());
                assert eventType == XMLStreamConstants.END_ELEMENT;
                name = reader.getName();
                if (reader.getNamespaceCount() == 0) {
                    namespaces = Collections.emptyList();
                } else {
                    namespaces = new ArrayList<NamespaceEvent>(reader.getNamespaceCount());
                    for (int i = 0; i < reader.getNamespaceCount(); i++) {
                        namespaces.add(new NamespaceEvent(location, reader.getNamespaceURI(i), reader.getNamespacePrefix(i)));
                    }
                }
            }

            EndElementEvent(Location location, QName name, Iterator<NamespaceEvent> namespaces) {
                super(XMLStreamConstants.END_ELEMENT, location);
                this.name = name;
                this.namespaces = toList(namespaces);
            }

            @Override
            public QName getName() {
                return name;
            }

            @Override
            public Iterator<?> getNamespaces() {
                return namespaces.iterator();
            }

            @Override
            void writeAsEncodedUnicodeInternal(Writer writer) throws IOException {
                writer.write("</");
                if (!XMLConstants.DEFAULT_NS_PREFIX.equals(name.getPrefix())) {
                    writer.write(name.getPrefix());
                    writer.write(':');
                }
                writer.write(name.getLocalPart());
                writer.write('>');
            }
        }

        static class EntityReferenceEvent extends AbstractXMLEvent implements EntityReference {
            final String name;
            final EntityDeclaration declaration;

            EntityReferenceEvent(XMLStreamReader reader) {
                super(reader.getEventType(), reader.getLocation());
                assert eventType == XMLStreamConstants.ENTITY_REFERENCE;
                name = reader.getText();
                declaration = null; // TODO
            }

            EntityReferenceEvent(Location location, String name, EntityDeclaration declaration) {
                super(XMLStreamConstants.ENTITY_REFERENCE, location);
                this.name = name;
                this.declaration = declaration;
            }

            @Override
            public EntityDeclaration getDeclaration() {
                return declaration;
            }

            @Override
            public String getName() {
                return name;
            }

            @Override
            void writeAsEncodedUnicodeInternal(Writer writer) throws IOException {
                writer.write('&');
                writer.write(name);
                writer.write(';');
            }
        }

        static class NamespaceEvent extends AttributeEvent implements Namespace {
            static QName createName(String prefix) {
                if (prefix == null || XMLConstants.DEFAULT_NS_PREFIX.equals(prefix)) {
                    return new QName(XMLConstants.XMLNS_ATTRIBUTE_NS_URI, XMLConstants.XMLNS_ATTRIBUTE);
                } else {
                    return new QName(XMLConstants.XMLNS_ATTRIBUTE_NS_URI, prefix, XMLConstants.XMLNS_ATTRIBUTE);
                }
            }

            NamespaceEvent(Location location, String namespaceURI, String prefix) {
                super(XMLStreamConstants.NAMESPACE, location, createName(prefix), namespaceURI, true);
            }

            @Override
            public String getPrefix() {
                return isDefaultNamespaceDeclaration() ? XMLConstants.DEFAULT_NS_PREFIX : getName().getLocalPart();
            }

            @Override
            public String getNamespaceURI() {
                return getValue();
            }

            @Override
            public boolean isDefaultNamespaceDeclaration() {
                return XMLConstants.DEFAULT_NS_PREFIX.equals(getName().getPrefix());
            }
        }

        static class ProcessingInstructionEvent extends AbstractXMLEvent implements ProcessingInstruction {
            final String target;
            final String data;

            ProcessingInstructionEvent(XMLStreamReader reader) {
                super(reader.getEventType(), reader.getLocation());
                assert eventType == XMLStreamConstants.PROCESSING_INSTRUCTION;
                target = reader.getPITarget();
                data = reader.getPIData();
            }

            ProcessingInstructionEvent(Location location, String target, String data) {
                super(XMLStreamConstants.PROCESSING_INSTRUCTION, location);
                this.target = target;
                this.data = data;
            }

            @Override
            public String getTarget() {
                return target;
            }

            @Override
            public String getData() {
                return data;
            }

            @Override
            void writeAsEncodedUnicodeInternal(Writer writer) throws IOException {
                writer.write("<?");
                writer.write(target);
                if (data != null) {
                    writer.write(' ');
                    writer.write(data.trim());
                }
                writer.write("?>");
            }
        }

        static class StartDocumentEvent extends AbstractXMLEvent implements StartDocument {
            final String encodingScheme;
            final String version;
            final Boolean standalone;

            StartDocumentEvent(XMLStreamReader reader) {
                super(reader.getEventType(), reader.getLocation());
                assert eventType == XMLStreamConstants.START_DOCUMENT;
                encodingScheme = reader.getCharacterEncodingScheme();
                version = reader.getVersion() == null ? "1.0" : reader.getVersion();
                standalone = reader.standaloneSet() ? Boolean.valueOf(reader.isStandalone()) : null;
            }

            StartDocumentEvent(Location location, String encoding, String version, Boolean standalone) {
                super(XMLStreamConstants.START_DOCUMENT, location);
                this.encodingScheme = encoding;
                this.version = version == null ? "1.0" : version;
                this.standalone = standalone;
            }

            @Override
            public String getCharacterEncodingScheme() {
                return encodingSet() ? encodingScheme : "UTF-8";
            }

            @Override
            public boolean encodingSet() {
                return encodingScheme != null;
            }

            @Override
            public String getVersion() {
                return version;
            }

            @Override
            public boolean isStandalone() {
                return standaloneSet() ? standalone.booleanValue() : false;
            }

            @Override
            public boolean standaloneSet() {
                return standalone != null;
            }

            @Override
            public String getSystemId() {
                return location.getSystemId();
            }

            @Override
            void writeAsEncodedUnicodeInternal(Writer writer) throws IOException {
                writer.write("<?xml version=\"");
                writer.write(version);
                writer.write('"');
                if (encodingSet()) {
                    writer.write(" encoding=\"");
                    writer.write(encodingScheme);
                    writer.write('"');
                }
                if (standaloneSet()) {
                    writer.write(" standalone=\"");
                    writer.write(standalone ? "yes" : "no");
                    writer.write('"');
                }
                writer.write("?>");
            }
        }

        static class StartElementEvent extends AbstractXMLEvent implements StartElement {
            final QName name;
            final List<AttributeEvent> attributes;
            final List<NamespaceEvent> namespaces;
            final NamespaceContext context;

            StartElementEvent(XMLStreamReader reader) {
                super(reader.getEventType(), reader.getLocation());
                assert eventType == XMLStreamConstants.START_ELEMENT;
                name = reader.getName();
                context = reader.getNamespaceContext();
                if (reader.getAttributeCount() == 0) {
                    attributes = Collections.emptyList();
                } else {
                    attributes = new ArrayList<AttributeEvent>(reader.getAttributeCount());
                    for (int i = 0; i < reader.getAttributeCount(); i++) {
                        attributes.add(new AttributeEvent(location, reader.getAttributeName(i), reader.getAttributeValue(i), reader.isAttributeSpecified(i)));
                    }
                }
                if (reader.getNamespaceCount() == 0) {
                    namespaces = Collections.emptyList();
                } else {
                    namespaces = new ArrayList<NamespaceEvent>(reader.getNamespaceCount());
                    for (int i = 0; i < reader.getNamespaceCount(); i++) {
                        namespaces.add(new NamespaceEvent(location, reader.getNamespaceURI(i), reader.getNamespacePrefix(i)));
                    }
                }
            }

            StartElementEvent(Location location, QName name, Iterator<AttributeEvent> attributes, Iterator<NamespaceEvent> namespaces, NamespaceContext context) {
                super(XMLStreamConstants.START_ELEMENT, location);
                this.name = name;
                this.context = context;
                this.attributes = toList(attributes);
                this.namespaces = toList(namespaces);
            }

            @Override
            public Attribute getAttributeByName(QName name) {
                for (Attribute attribute : attributes) {
                    if (attribute.getName().equals(name)) {
                        return attribute;
                    }
                }
                return null;
            }

            @Override
            public Iterator<?> getAttributes() {
                return attributes.iterator();
            }

            @Override
            public QName getName() {
                return name;
            }

            @Override
            public NamespaceContext getNamespaceContext() {
                return context;
            }

            @Override
            public Iterator<?> getNamespaces() {
                return namespaces.iterator();
            }

            @Override
            public String getNamespaceURI(String prefix) {
                for (Namespace namespace : namespaces) {
                    if (namespace.getPrefix().equals(prefix)) {
                        return namespace.getNamespaceURI();
                    }
                }
                return null;
            }

            @Override
            void writeAsEncodedUnicodeInternal(Writer writer) throws IOException {
                writer.write('<');
                if (!XMLConstants.DEFAULT_NS_PREFIX.equals(name.getPrefix())) {
                    writer.write(name.getPrefix());
                    writer.write(':');
                }
                writer.write(name.getLocalPart());
                for (NamespaceEvent namespace : namespaces) {
                    writer.write(' ');
                    namespace.writeAsEncodedUnicodeInternal(writer);
                }
                for (AttributeEvent attribute : attributes) {
                    if (attribute.isSpecified()) {
                        writer.write(' ');
                        attribute.writeAsEncodedUnicodeInternal(writer);
                    }
                }
                writer.write('>');
            }
        }

        @Override
        public XMLEventAllocator newInstance() {
            return this;
        }

        @Override
        public XMLEvent allocate(XMLStreamReader reader) throws XMLStreamException {
            switch (reader.getEventType()) {
                case XMLStreamConstants.CDATA:
                case XMLStreamConstants.CHARACTERS:
                case XMLStreamConstants.SPACE:
                    return new CharactersEvent(reader);
                case XMLStreamConstants.COMMENT:
                    return new CommentEvent(reader);
                case XMLStreamConstants.DTD:
                    throw new UnsupportedOperationException();
                case XMLStreamConstants.END_DOCUMENT:
                    return new EndDocumentEvent(reader);
                case XMLStreamConstants.END_ELEMENT:
                    return new EndElementEvent(reader);
                case XMLStreamConstants.ENTITY_REFERENCE:
                    return new EntityReferenceEvent(reader);
                case XMLStreamConstants.NOTATION_DECLARATION:
                    throw new UnsupportedOperationException();
                case XMLStreamConstants.PROCESSING_INSTRUCTION:
                    return new ProcessingInstructionEvent(reader);
                case XMLStreamConstants.START_DOCUMENT:
                    return new StartDocumentEvent(reader);
                case XMLStreamConstants.START_ELEMENT:
                    return new StartElementEvent(reader);
                default:
                    throw new XMLStreamException("Unexpected event type: " + reader.getEventType());
            }
        }

        @Override
        public void allocate(XMLStreamReader reader, XMLEventConsumer consumer) throws XMLStreamException {
            consumer.add(allocate(reader));
        }
    }