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////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// 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.tree.tiny;

import net.sf.saxon.om.NodeInfo;
import net.sf.saxon.pattern.NodeTest;
import net.sf.saxon.tree.iter.AxisIterator;
import net.sf.saxon.tree.iter.AxisIteratorImpl;

/**
* Enumerate all the nodes on the preceding axis from a given start node.
* The calling code ensures that the start node is not a root, attribute,
* or namespace node. As well as the standard XPath preceding axis, this
* class also implements a Saxon-specific "preceding-or-ancestor" axis
* which returns ancestor nodes as well as preceding nodes. This is used
* when performing xsl:number level="any".
*/

final class PrecedingEnumeration extends AxisIteratorImpl {

    private TinyTree tree;
    private TinyNodeImpl startNode;
    private NodeTest test;
    private int nextAncestorDepth;
    private boolean includeAncestors;

    public PrecedingEnumeration(/*@NotNull*/ TinyTree doc, /*@NotNull*/ TinyNodeImpl node,
                                NodeTest nodeTest, boolean includeAncestors) {

        this.includeAncestors = includeAncestors;
        test = nodeTest;
        tree = doc;
        startNode = node;
        current = startNode;
        nextAncestorDepth = doc.depth[node.nodeNr] - 1;
    }

    /*@Nullable*/ public NodeInfo next() {
        if (current == null) {
            return null;
        }
        int nextNodeNr = ((TinyNodeImpl)current).nodeNr;
        while (true) {
            if (!includeAncestors) {
                nextNodeNr--;
                // skip over ancestor elements
                while (nextAncestorDepth >= 0 && tree.depth[nextNodeNr] == nextAncestorDepth) {
                    if (nextAncestorDepth-- <= 0) {  // bug 1121528
                        current = null;
                        position = -1;
                        return null;
                    }
                    nextNodeNr--;
                }
            } else {
                if (tree.depth[nextNodeNr] == 0) {
                    current = null;
                    position = -1;
                    return null;
                } else {
                    nextNodeNr--;
                }
            }
            if (test.matches(tree, nextNodeNr)) {
                position++;
                current = tree.getNode(nextNodeNr);
                return current;
            }
            if (tree.depth[nextNodeNr] == 0) {
                current = null;
                position = -1;
                return null;
            }
        }
    }

    /**
    * Get another enumeration of the same nodes
    */

    /*@NotNull*/ public AxisIterator getAnother() {
        return new PrecedingEnumeration(tree, startNode, test, includeAncestors);
    }
}