net.sf.saxon.expr.elab.SimpleNodePushElaborator Maven / Gradle / Ivy

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////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2023 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.elab;

import net.sf.saxon.Configuration;
import net.sf.saxon.expr.instruct.SimpleNodeConstructor;
import net.sf.saxon.expr.parser.ExpressionTool;
import net.sf.saxon.om.Item;
import net.sf.saxon.str.EmptyUnicodeString;
import net.sf.saxon.str.UnicodeString;
import net.sf.saxon.tree.iter.SingletonIterator;
import net.sf.saxon.tree.util.Orphan;

/**
 * Abstract elaborator for expressions that evaluate simple nodes (text nodes, comments, attributes, etc) in push mode.
 * The concrete subclass must supply an {@link #elaborateForPush()} method.
 */
public abstract class SimpleNodePushElaborator extends Elaborator {

    @Override
    public SequenceEvaluator eagerly() {
        ItemEvaluator itemEval = elaborateForItem();
        return new OptionalItemEvaluator(itemEval);
    }

    @Override
    public PullEvaluator elaborateForPull() {
        ItemEvaluator itemEval = elaborateForItem();
        return context -> SingletonIterator.makeIterator(itemEval.eval(context));
    }

    @Override
    public PushEvaluator elaborateForPush() {
        // Must be implemented in a subclass
        throw new UnsupportedOperationException();
    }

    @Override
    public ItemEvaluator elaborateForItem() {
        final SimpleNodeConstructor instr = (SimpleNodeConstructor) getExpression();
        final ItemEvaluator select = instr.getSelect().makeElaborator().elaborateForItem();
        final short kind = (short)instr.getItemType().getPrimitiveType();
        final Configuration config = getConfiguration();
        return context -> {
            Item contentItem = select.eval(context);
            UnicodeString content;
            if (contentItem == null) {
                content = EmptyUnicodeString.getInstance();
            } else {
                content = contentItem.getUnicodeStringValue();
                content = instr.checkContent(content, context);
            }
            Orphan o = new Orphan(config);
            o.setNodeKind(kind);
            o.setStringValue(content);
            o.setNodeName(instr.evaluateNodeName(context));   // TODO elaborate this
            return o;
        };
    }

    public BooleanEvaluator elaborateForBoolean() {
        ItemEvaluator ie = elaborateForItem();
        return context -> ExpressionTool.effectiveBooleanValue(ie.eval(context));
    }

    @Override
    public UnicodeStringEvaluator elaborateForUnicodeString(boolean zeroLengthWhenAbsent) {
        ItemEvaluator ie = elaborateForItem();
        return context -> {
            Item item = ie.eval(context);
            return item == null ? handleNullUnicodeString(zeroLengthWhenAbsent) : item.getUnicodeStringValue();
        };
    }


}