package net.sf.saxon.pull;

import net.sf.saxon.event.PipelineConfiguration;
import net.sf.saxon.om.AttributeCollection;
import net.sf.saxon.om.NamespaceDeclarations;
import net.sf.saxon.om.NamePool;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.value.AtomicValue;

import javax.xml.transform.SourceLocator;
import java.util.List;

/**
 * PullFilter is a pass-through filter class that links one PullProvider to another PullProvider
 * in a pipeline. This class passes all events through completely unchanged. The class is designed
 * so that subclasses can modify this behavior by altering some of the events.
*/

public class PullFilter implements PullProvider {

    private PullProvider base;
    private PipelineConfiguration pipe;
    protected int currentEvent;

    /**
     * Create a PullFilter
     * @param base the PullProvider to which requests are to be passed
     */

    public PullFilter(PullProvider base) {
        this.base = base;
        if (base.getPipelineConfiguration() != null) {
            setPipelineConfiguration(base.getPipelineConfiguration());
        }
    }

    /**
     * Set configuration information. This must only be called before any events
     * have been read.
     */

    public void setPipelineConfiguration(PipelineConfiguration pipe) {
        this.pipe = pipe;
        base.setPipelineConfiguration(pipe);
    }

    /**
     * Get configuration information.
     */

    public PipelineConfiguration getPipelineConfiguration() {
        return pipe;
    }

    /**
     * Helper method to get the current namePool
     * @return the NamePool
     */

    public final NamePool getNamePool() {
        return getPipelineConfiguration().getConfiguration().getNamePool();
    }

    /**
     * Get the underlying PullProvider
     * @return  the underlying PullProvider
     */

    public PullProvider getUnderlyingProvider() {
        return base;
    }

    /**
     * Get the next event.
     *
     * <p>Note that a subclass that overrides this method is responsible for ensuring
     * that current() works properly. This can be achieved by setting the field
     * currentEvent to the event returned by any call on next().</p>
     *
     * @return an integer code indicating the type of event. The code
     *         {@link #END_OF_INPUT} is returned at the end of the sequence.
     */

    public int next() throws XPathException {
        return base.next();
    }

    /**
     * Get the event most recently returned by next(), or by other calls that change
     * the position, for example getStringValue() and skipToMatchingEnd(). This
     * method does not change the position of the PullProvider.
     *
     * @return the current event
     */

    public int current() {
        return currentEvent;
    }

    /**
     * Get the attributes associated with the current element. This method must
     * be called only after a START_ELEMENT event has been notified. The contents
     * of the returned AttributeCollection are guaranteed to remain unchanged
     * until the next START_ELEMENT event, but may be modified thereafter. The object
     * should not be modified by the client.
     * <p/>
     * <p>Attributes may be read before or after reading the namespaces of an element,
     * but must not be read after the first child node has been read, or after calling
     * one of the methods skipToEnd(), getStringValue(), or getTypedValue().</p>
     *
     * @return an AttributeCollection representing the attributes of the element
     *         that has just been notified.
     */

    public AttributeCollection getAttributes() throws XPathException {
        return base.getAttributes();
    }

    /**
     * Get the namespace declarations associated with the current element. This method must
     * be called only after a START_ELEMENT event has been notified. In the case of a top-level
     * START_ELEMENT event (that is, an element that either has no parent node, or whose parent
     * is not included in the sequence being read), the NamespaceDeclarations object returned
     * will contain a namespace declaration for each namespace that is in-scope for this element
     * node. In the case of a non-top-level element, the NamespaceDeclarations will contain
     * a set of namespace declarations and undeclarations, representing the differences between
     * this element and its parent.
     * <p/>
     * <p>It is permissible for this method to return namespace declarations that are redundant.</p>
     * <p/>
     * <p>The NamespaceDeclarations object is guaranteed to remain unchanged until the next START_ELEMENT
     * event, but may then be overwritten. The object should not be modified by the client.</p>
     * <p/>
     * <p>Namespaces may be read before or after reading the attributes of an element,
     * but must not be read after the first child node has been read, or after calling
     * one of the methods skipToEnd(), getStringValue(), or getTypedValue().</p>*
     */

    public NamespaceDeclarations getNamespaceDeclarations() throws XPathException {
        return base.getNamespaceDeclarations();
    }

    /**
     * Skip the current subtree. This method may be called only immediately after
     * a START_DOCUMENT or START_ELEMENT event. This call returns the matching
     * END_DOCUMENT or END_ELEMENT event; the next call on next() will return
     * the event following the END_DOCUMENT or END_ELEMENT.
     */

    public int skipToMatchingEnd() throws XPathException {
        return base.skipToMatchingEnd();
    }

    /**
     * Close the event reader. This indicates that no further events are required.
     * It is not necessary to close an event reader after {@link #END_OF_INPUT} has
     * been reported, but it is recommended to close it if reading terminates
     * prematurely. Once an event reader has been closed, the effect of further
     * calls on next() is undefined.
     */

    public void close() {
        base.close();
    }

    /**
     * Get the nameCode identifying the name of the current node. This method
     * can be used after the {@link #START_ELEMENT}, {@link #PROCESSING_INSTRUCTION},
     * {@link #ATTRIBUTE}, or {@link #NAMESPACE} events. With some PullProvider implementations,
     * it can also be used after {@link #END_ELEMENT}, but this is not guaranteed: a client who
     * requires the information at that point (for example, to do serialization) should insert an
     * {@link ElementNameTracker} into the pipeline.
     * If called at other times, the result is undefined and may result in an IllegalStateException.
     * If called when the current node is an unnamed namespace node (a node representing the default namespace)
     * the returned value is -1.
     *
     * @return the nameCode. The nameCode can be used to obtain the prefix, local name,
     *         and namespace URI from the name pool.
     */

    public int getNameCode() {
        return base.getNameCode();
    }

    /**
     * Get the fingerprint of the name of the element. This is similar to the nameCode, except that
     * it does not contain any information about the prefix: so two elements with the same fingerprint
     * have the same name, excluding prefix. This method
     * can be used after the {@link #START_ELEMENT}, {@link #END_ELEMENT}, {@link #PROCESSING_INSTRUCTION},
     * {@link #ATTRIBUTE}, or {@link #NAMESPACE} events.
     * If called at other times, the result is undefined and may result in an IllegalStateException.
     * If called when the current node is an unnamed namespace node (a node representing the default namespace)
     * the returned value is -1.
     *
     * @return the fingerprint. The fingerprint can be used to obtain the local name
     *         and namespace URI from the name pool.
     */

    public int getFingerprint() {
        return base.getFingerprint();
    }

    /**
     * Get the string value of the current element, text node, processing-instruction,
     * or top-level attribute or namespace node, or atomic value.
     * <p/>
     * <p>In other situations the result is undefined and may result in an IllegalStateException.</p>
     * <p/>
     * <p>If the most recent event was a {@link #START_ELEMENT}, this method causes the content
     * of the element to be read. The next event notified will be the corresponding {@link #END_ELEMENT}.</p>
     *
     * @return the String Value of the node in question, defined according to the rules in the
     *         XPath data model.
     */

    public CharSequence getStringValue() throws XPathException {
        return base.getStringValue();
    }

    /**
     * Get an atomic value. This call may be used only when the last event reported was
     * ATOMIC_VALUE. This indicates that the PullProvider is reading a sequence that contains
     * a free-standing atomic value; it is never used when reading the content of a node.
     */

    public AtomicValue getAtomicValue() {
        return base.getAtomicValue();
    }

    /**
     * Get the type annotation of the current attribute or element node, or atomic value.
     * The result of this method is undefined unless the most recent event was START_ELEMENT,
     * ATTRIBUTE, or ATOMIC_VALUE.
     *
     * @return the type annotation. This code is the fingerprint of a type name, which may be
     *         resolved to a {@link net.sf.saxon.type.SchemaType} by access to the Configuration.
     */

    public int getTypeAnnotation() {
        return base.getTypeAnnotation();
    }

    /**
     * Get the location of the current event.
     * For an event stream representing a real document, the location information
     * should identify the location in the lexical XML source. For a constructed document, it should
     * identify the location in the query or stylesheet that caused the node to be created.
     * A value of null can be returned if no location information is available.
     */

    public SourceLocator getSourceLocator() {
        return base.getSourceLocator();
    }

    /**
     * Get a list of unparsed entities.
     *
     * @return a list of unparsed entities, or null if the information is not available, or
     *         an empty list if there are no unparsed entities.
     */

    public List getUnparsedEntities() {
        return base.getUnparsedEntities();
    }
}

//
// The contents of this file are subject to the Mozilla Public License Version 1.0 (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.mozilla.org/MPL/
//
// Software distributed under the License is distributed on an "AS IS" basis,
// WITHOUT WARRANTY OF ANY KIND, either express or implied.
// See the License for the specific language governing rights and limitations under the License.
//
// The Original Code is: all this file.
//
// The Initial Developer of the Original Code is Michael H. Kay.
//
// Portions created by (your name) are Copyright (C) (your legal entity). All Rights Reserved.
//
// Contributor(s): none.
//
