////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2018 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.AttributeCollection;
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
     */

    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
     */

    public boolean mayContainSequenceConstructor() {
        return true;
    }

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

    public boolean mayContainFallback() {
        return true;
    }

    public void prepareAttributes() throws XPathException {

        AttributeCollection atts = getAttributeList();

        for (int a = 0; a < atts.getLength(); a++) {
            checkUnknownAttribute(atts.getNodeName(a));
        }
    }

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

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

}
