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An OSGi bundle for Saxon-HE
There is a newer version: 10.5
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// 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.expr;




import net.sf.saxon.event.SequenceReceiver;
import net.sf.saxon.expr.instruct.Block;
import net.sf.saxon.expr.instruct.Choose;
import net.sf.saxon.expr.instruct.ValueOf;
import net.sf.saxon.expr.parser.ExpressionVisitor;
import net.sf.saxon.om.AtomicSequence;
import net.sf.saxon.om.Item;
import net.sf.saxon.om.NodeInfo;
import net.sf.saxon.om.SequenceIterator;
import net.sf.saxon.pattern.NodeKindTest;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.tree.iter.AdjacentTextNodeMergingIterator;
import net.sf.saxon.tree.util.FastStringBuffer;
import net.sf.saxon.type.ItemType;
import net.sf.saxon.type.Type;
import net.sf.saxon.type.TypeHierarchy;
import net.sf.saxon.value.AtomicValue;
import net.sf.saxon.value.Cardinality;

import java.util.List;



/**
 * This class performs the first phase of processing in "constructing simple content":
 * it takes an input sequence, eliminates empty text nodes, and combines adjacent text nodes
 * into one.
 * @since 9.3
 */
public class AdjacentTextNodeMerger extends UnaryExpression {

    public AdjacentTextNodeMerger(Expression p0) {
        super(p0);
    }

    /**
     * Make an AdjacentTextNodeMerger expression with a given operand, or a simpler equivalent expression if appropriate
     * @param base the operand expression
     * @return an AdjacentTextNodeMerger or equivalent expression
     */

    public static Expression makeAdjacentTextNodeMerger(Expression base) {
        if (base instanceof Literal && ((Literal)base).getValue() instanceof AtomicSequence) {
            return base;
        } else {
            return new AdjacentTextNodeMerger(base);
        }
    }

    @Override
    public Expression simplify(ExpressionVisitor visitor) throws XPathException {
        if (operand instanceof Literal && ((Literal)operand).getValue() instanceof AtomicValue) {
            return operand;
        } else {
            return super.simplify(visitor);
        }
    }

    /*@NotNull*/
    @Override
    public Expression typeCheck(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) throws XPathException {
        Expression e = super.typeCheck(visitor, contextItemType);
        if (e != this) {
            return e;
        }
        // This wrapper expression is unnecessary if the base expression cannot return text nodes,
        // or if it can return at most one item
        TypeHierarchy th = visitor.getConfiguration().getTypeHierarchy();
        if (th.relationship(getBaseExpression().getItemType(th), NodeKindTest.TEXT) == TypeHierarchy.DISJOINT) {
            return getBaseExpression();
        }
        if (!Cardinality.allowsMany(getBaseExpression().getCardinality())) {
            return getBaseExpression();
        }
        // In a choose expression, we can push the wrapper down to the action branches (whence it may disappear)
        if (getBaseExpression() instanceof Choose) {
            Choose choose = (Choose) getBaseExpression();
            Expression[] actions = choose.getActions();
            for (int i=0; i 0) {
                    fsb.append(s);
                    prevText = true;
                }

            } else {
                if (prevText) {
                    out.characters(fsb, locationId, options);
                }
                prevText = false;
                fsb.setLength(0);
                out.append(item, locationId, options);
            }
        }
        if (prevText) {
            out.characters(fsb, locationId, options);
        }
    }


    @Override
    public String getExpressionName() {
        return "mergeAdjacentText";
    }

    /**
     * Ask whether an item is a text node
     * @param item the item in question
     * @return true if the item is a node of kind text
     */

    public static boolean isTextNode(Item item) {
        return item instanceof NodeInfo && ((NodeInfo)item).getNodeKind() == Type.TEXT;
    }

}