////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2013 Saxonica Limited.
// This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
// If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
// This Source Code Form is "Incompatible With Secondary Licenses", as defined by the Mozilla Public License, v. 2.0.
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

package net.sf.saxon.pattern;

import net.sf.saxon.Configuration;
import net.sf.saxon.om.Item;
import net.sf.saxon.om.NodeInfo;
import net.sf.saxon.om.NodeName;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.tree.tiny.TinyTree;
import net.sf.saxon.type.ItemType;
import net.sf.saxon.type.SchemaComponentVisitor;
import net.sf.saxon.type.Type;

/**
  * NodeTest is an interface that enables a test of whether a node has a particular
  * name and type. An EmptySequenceTest matches no nodes or atomic values: it corresponds to the
  * type empty-sequence().
  *
  * @author Michael H. Kay
  */

public final class EmptySequenceTest extends NodeTest {

    private static EmptySequenceTest THE_INSTANCE = new EmptySequenceTest();

    /**
    * Get a NoNodeTest instance
    */

    public static EmptySequenceTest getInstance() {
        return THE_INSTANCE;
    }

    /**
     * Private constructor
     */ 

    private EmptySequenceTest() {}

	public final int getPrimitiveType() {
		return Type.EMPTY;
	}

    /**
     * Get the primitive item type corresponding to this item type. For item(),
     * this is Type.ITEM. For node(), it is Type.NODE. For specific node kinds,
     * it is the value representing the node kind, for example Type.ELEMENT.
     * For anyAtomicValue it is Type.ATOMIC_VALUE. For numeric it is Type.NUMBER.
     * For other atomic types it is the primitive type as defined in XML Schema,
     * except that INTEGER is considered to be a primitive type.
     */

    /*@NotNull*/
    public ItemType getPrimitiveItemType() {
        return this;
    }

    /**
     * Test whether a given item conforms to this type
     * @param item The item to be tested
     * @param allowURIPromotion
     * @param config
     * @return true if the item is an instance of this type; false otherwise
    */

    public boolean matchesItem(Item item, boolean allowURIPromotion, Configuration config) {
        return false;
    }


    /**
     * Test whether this node test is satisfied by a given node. This method is only
     * fully supported for a subset of NodeTests, because it doesn't provide all the information
     * needed to evaluate all node tests. In particular (a) it can't be used to evaluate a node
     * test of the form element(N,T) or schema-element(E) where it is necessary to know whether the
     * node is nilled, and (b) it can't be used to evaluate a node test of the form
     * document-node(element(X)). This in practice means that it is used (a) to evaluate the
     * simple node tests found in the XPath 1.0 subset used in XML Schema, and (b) to evaluate
     * node tests where the node kind is known to be an attribute.
     *
     * @param nodeKind   The kind of node to be matched
     * @param name       identifies the expanded name of the node to be matched.
     *                   The value should be null for a node with no name.
     * @param annotation The actual content type of the node
     */
    @Override
    public boolean matches(int nodeKind, NodeName name, int annotation) {
        return false;
    }

    /**
     * Test whether this node test is satisfied by a given node on a TinyTree. The node
     * must be a document, element, text, comment, or processing instruction node.
     * This method is provided
     * so that when navigating a TinyTree a node can be rejected without
     * actually instantiating a NodeInfo object.
     *
     * @param tree   the TinyTree containing the node
     * @param nodeNr the number of the node within the TinyTree
     * @return true if the node matches the NodeTest, otherwise false
     */

    public boolean matches(TinyTree tree, int nodeNr) {
        return false;
    }

    /**
     * Test whether this node test is satisfied by a given node. This alternative
     * method is used in the case of nodes where calculating the fingerprint is expensive,
     * for example DOM or JDOM nodes.
     * @param node the node to be matched
     */

    public boolean matches(NodeInfo node) {
        return false;
    }


    /**
    * Determine the default priority of this node test when used on its own as a Pattern
    */

    public final double getDefaultPriority() {
    	return -0.5;
    }

    /**
     * Get a mask indicating which kinds of nodes this NodeTest can match. This is a combination
     * of bits: 1<<Type.ELEMENT for element nodes, 1<<Type.TEXT for text nodes, and so on.
     */

    public int getNodeKindMask() {
        return 0;
    }

    /**
     * Visit all the schema components used in this ItemType definition
     * @param visitor the visitor class to be called when each component is visited
     */

    public void visitNamedSchemaComponents(SchemaComponentVisitor visitor) throws XPathException {
        // no action
    }

    /*@NotNull*/ public String toString() {
        return "empty-sequence()";
    }

    /**
      * Returns a hash code value for the object.
      */

     public int hashCode() {
         return "NoNodeTest".hashCode();
     }




}

