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////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2018-2022 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.style;

import net.sf.saxon.expr.Expression;
import net.sf.saxon.expr.instruct.WherePopulated;
import net.sf.saxon.om.AttributeInfo;
import net.sf.saxon.om.NodeName;
import net.sf.saxon.trans.XPathException;


/**
 * An xsl:where-populated element in the stylesheet.
 */

public final class XSLWherePopulated extends StyleElement {

    private Expression select;

    /**
     * Determine whether this node is an instruction.
     *
     * @return true - it is an instruction
     */

    @Override
    public boolean isInstruction() {
        return true;
    }

    /**
     * Determine whether this type of element is allowed to contain a sequence constructor
     *
     * @return in XSLT 2.0, false. In XSLT 3.0 true: yes, it may contain a sequence constructor
     */

    @Override
    protected boolean mayContainSequenceConstructor() {
        return true;
    }

    /**
     * Determine whether this type of element is allowed to contain an xsl:fallback
     * instruction
     */

    @Override
    protected boolean mayContainFallback() {
        return true;
    }

    @Override
    protected void prepareAttributes() {

        for (AttributeInfo att : attributes()) {
            NodeName attName = att.getNodeName();
            String f = attName.getDisplayName();
            checkUnknownAttribute(attName);
        }
    }

    @Override
    public void validate(ComponentDeclaration decl) throws XPathException {
        // no action
    }

    /*@Nullable*/
    @Override
    public Expression compile(Compilation exec, ComponentDeclaration decl) throws XPathException {
        if (select == null) {
            select = compileSequenceConstructor(exec, decl, false);
        }
        return new WherePopulated(select);
    }

}