Groovy example source code file (Node.java)

This example Groovy source code file (Node.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Groovy tags/keywords

closure, closure, groovyobject, io, iterator, list, map, map, node, object, object, replacementnode, string, string, util, writable

The Groovy Node.java source code

/*
 * Copyright 2003-2010 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 groovy.util.slurpersupport;

import groovy.lang.Buildable;
import groovy.lang.Closure;
import groovy.lang.GroovyObject;
import groovy.lang.Writable;

import java.io.IOException;
import java.io.Writer;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Stack;

/**
 * Represents a node.
 *
 * @author John Wilson
 */
public class Node implements Writable {
    private final String name;
    private final Map attributes;
    private final Map attributeNamespaces;
    private final String namespaceURI;
    private final List children = new LinkedList();
    private final Stack replacementNodeStack = new Stack();

    /**
     * @param parent the parent node
     * @param name the name for the node
     * @param attributes the attributes for the node
     * @param attributeNamespaces the namespace mappings for attributes
     * @param namespaceURI the namespace URI if any
     */
    public Node(final Node parent, final String name, final Map attributes, final Map attributeNamespaces, final String namespaceURI) {
        this.name = name;
        this.attributes = attributes;
        this.attributeNamespaces = attributeNamespaces;
        this.namespaceURI = namespaceURI;
    }

    public String name() {
        return this.name;
    }

    public String namespaceURI() {
        return this.namespaceURI;
    }

    public Map attributes() {
        return this.attributes;
    }

    public List children() {
        return this.children;
    }

    public void addChild(final Object child) {
        this.children.add(child);
    }

    public void replaceNode(final Closure replacementClosure, final GPathResult result) {
        this.replacementNodeStack.push(new ReplacementNode() {
            public void build(final GroovyObject builder, final Map namespaceMap, final Map<String, String> namespaceTagHints) {
                final Closure c = (Closure) replacementClosure.clone();
                Node.this.replacementNodeStack.pop(); // disable the replacement whilst the closure is being executed
                c.setDelegate(builder);
                c.call(new Object[]{result});
                Node.this.replacementNodeStack.push(this);
            }
        });
    }


    protected void replaceBody(final Object newValue) {
        this.children.clear();
        this.children.add(newValue);
    }

    protected void appendNode(final Object newValue, final GPathResult result) {
        if (newValue instanceof Closure) {
            this.children.add(new ReplacementNode() {
                public void build(final GroovyObject builder, final Map namespaceMap, final Map<String, String> namespaceTagHints) {
                    final Closure c = (Closure) ((Closure) newValue).clone();
                    c.setDelegate(builder);
                    c.call(new Object[]{result});
                }
            });
        } else {
            this.children.add(newValue);
        }
    }

    /* (non-Javadoc)
    * @see org.codehaus.groovy.sandbox.util.slurpersupport.Node#text()
    */
    public String text() {
        final StringBuffer buff = new StringBuffer();
        final Iterator iter = this.children.iterator();
        while (iter.hasNext()) {
            final Object child = iter.next();

            if (child instanceof Node) {
                buff.append(((Node) child).text());
            } else {
                buff.append(child);
            }
        }
        return buff.toString();
    }

    /* (non-Javadoc)
    * @see org.codehaus.groovy.sandbox.util.slurpersupport.Node#childNodes()
    */

    public Iterator childNodes() {
        return new Iterator() {
            private final Iterator iter = Node.this.children.iterator();
            private Object nextElementNodes = getNextElementNodes();

            public boolean hasNext() {
                return this.nextElementNodes != null;
            }

            public Object next() {
                try {
                    return this.nextElementNodes;
                } finally {
                    this.nextElementNodes = getNextElementNodes();
                }
            }

            public void remove() {
                throw new UnsupportedOperationException();
            }

            private Object getNextElementNodes() {
                while (iter.hasNext()) {
                    final Object node = iter.next();

                    if (node instanceof Node) {
                        return node;
                    }
                }
                return null;
            }
        };
    }

    /* (non-Javadoc)
    * @see org.codehaus.groovy.sandbox.util.slurpersupport.Node#writeTo(java.io.Writer)
    */
    public Writer writeTo(final Writer out) throws IOException {
        if (this.replacementNodeStack.empty()) {
            final Iterator iter = this.children.iterator();
            while (iter.hasNext()) {
                final Object child = iter.next();
                if (child instanceof Writable) {
                    ((Writable) child).writeTo(out);
                } else {
                    out.write(child.toString());
                }
            }
            return out;

        } else {
            return ((Writable) this.replacementNodeStack.peek()).writeTo(out);
        }
    }

    public void build(final GroovyObject builder, final Map namespaceMap, final Map<String, String> namespaceTagHints) {
        if (this.replacementNodeStack.empty()) {
            final Closure rest = new Closure(null) {
                public Object doCall(final Object o) {
                    buildChildren(builder, namespaceMap, namespaceTagHints);

                    return null;
                }
            };

            if (this.namespaceURI.length() == 0 && this.attributeNamespaces.isEmpty()) {
                builder.invokeMethod(this.name, new Object[]{this.attributes, rest});
            } else {
                final List newTags = new LinkedList();
                builder.getProperty("mkp");
                final List namespaces = (List) builder.invokeMethod("getNamespaces", new Object[]{});

                final Map current = (Map) namespaces.get(0);
                final Map pending = (Map) namespaces.get(1);

                if (this.attributeNamespaces.isEmpty()) {
                    builder.getProperty(getTagFor(this.namespaceURI, current, pending, namespaceMap, namespaceTagHints, newTags, builder));
                    builder.invokeMethod(this.name, new Object[]{this.attributes, rest});
                } else {
                    final Map attributesWithNamespaces = new HashMap(this.attributes);
                    final Iterator attrs = this.attributes.keySet().iterator();

                    while (attrs.hasNext()) {
                        final Object key = attrs.next();
                        final Object attributeNamespaceURI = this.attributeNamespaces.get(key);

                        if (attributeNamespaceURI != null) {
                            attributesWithNamespaces.put(getTagFor(attributeNamespaceURI, current, pending, namespaceMap, namespaceTagHints, newTags, builder) +
                                    "$" + key, attributesWithNamespaces.remove(key));
                        }
                    }

                    builder.getProperty(getTagFor(this.namespaceURI, current, pending, namespaceMap, namespaceTagHints, newTags, builder));
                    builder.invokeMethod(this.name, new Object[]{attributesWithNamespaces, rest});
                }

                // remove the new tags we had to define for this element
                if (!newTags.isEmpty()) {
                    final Iterator iter = newTags.iterator();

                    do {
                        pending.remove(iter.next());
                    } while (iter.hasNext());
                }
            }
        } else {
            ((ReplacementNode) this.replacementNodeStack.peek()).build(builder, namespaceMap, namespaceTagHints);
        }
    }

    private static String getTagFor(final Object namespaceURI, final Map current,
                                    final Map pending, final Map local, final Map tagHints,
                                    final List newTags, final GroovyObject builder) {
        String tag = findNamespaceTag(pending, namespaceURI); // look in the namespaces whose declaration has already been emitted
        if (tag == null) {
            tag = findNamespaceTag(current, namespaceURI);  // look in the namespaces who will be declared at the next element

            if (tag == null) {
                // we have to declare the namespace - choose a tag
                tag = findNamespaceTag(local, namespaceURI);  // If the namespace has been declared in the GPath expression use that tag

                if (tag == null || tag.length() == 0) {
                    tag = findNamespaceTag(tagHints, namespaceURI);  // If the namespace has been used in the parse document use that tag
                }

                if (tag == null || tag.length() == 0) { // otherwise make up a new tag and check it has not been used before
                    int suffix = 0;

                    do {
                        final String possibleTag = "tag" + suffix++;

                        if (!pending.containsKey(possibleTag) && !current.containsKey(possibleTag) && !local.containsKey(possibleTag)) {
                            tag = possibleTag;
                        }
                    } while (tag == null);
                }

                final Map newNamespace = new HashMap();
                newNamespace.put(tag, namespaceURI);
                builder.getProperty("mkp");
                builder.invokeMethod("declareNamespace", new Object[]{newNamespace});
                newTags.add(tag);
            }
        }
        return tag;
    }

    private static String findNamespaceTag(final Map tagMap, final Object namespaceURI) {
        if (tagMap.containsValue(namespaceURI)) {
            final Iterator entries = tagMap.entrySet().iterator();
            while (entries.hasNext()) {
                final Map.Entry entry = (Map.Entry) entries.next();
                if (namespaceURI.equals(entry.getValue())) {
                    return (String) entry.getKey();
                }
            }
        }
        return null;
    }

    private void buildChildren(final GroovyObject builder, final Map namespaceMap, final Map<String, String> namespaceTagHints) {
        final Iterator iter = this.children.iterator();
        while (iter.hasNext()) {
            final Object child = iter.next();
            if (child instanceof Node) {
                ((Node) child).build(builder, namespaceMap, namespaceTagHints);
            } else if (child instanceof Buildable) {
                ((Buildable) child).build(builder);
            } else {
                builder.getProperty("mkp");
                builder.invokeMethod("yield", new Object[]{child});
            }
        }
    }
}