package net.sf.saxon.style;

import net.sf.saxon.expr.Expression;
import net.sf.saxon.expr.instruct.Executable;
import net.sf.saxon.expr.instruct.NextMatch;
import net.sf.saxon.om.AttributeCollection;
import net.sf.saxon.om.Axis;
import net.sf.saxon.om.NodeInfo;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.tree.iter.AxisIterator;
import net.sf.saxon.type.Type;
import net.sf.saxon.value.Whitespace;

/**
* An xsl:next-match element in the stylesheet
*/

public class XSLNextMatch extends StyleElement {

    private boolean useTailRecursion = false;

    /**
    * 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 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(Declaration decl) throws XPathException {
        AxisIterator kids = iterateAxis(Axis.CHILD);
        while (true) {
            NodeInfo child = kids.next();
            if (child == null) {
                break;
            }
            if (child instanceof XSLWithParam || child instanceof XSLFallback) {
                // OK;
            } else if (child.getNodeKind() == Type.TEXT) {
                    // with xml:space=preserve, white space nodes may still be there
                if (!Whitespace.isWhite(child.getStringValueCS())) {
                    compileError("No character data is allowed within xsl:next-match", "XTSE0010");
                }
            } else {
                compileError("Child element " + child.getDisplayName() +
                        " is not allowed as a child of xsl:next-match", "XTSE0010");
            }
        }

    }


    /**
     * Mark tail-recursive calls on templates and functions.
     * For most instructions, this does nothing.
     */

    protected boolean markTailCalls() {
        useTailRecursion = true;
        return true;
    }

    /*@NotNull*/ public Expression compile(Executable exec, Declaration decl) throws XPathException {
        NextMatch inst = new NextMatch(useTailRecursion);
        inst.setActualParameters(getWithParamInstructions(exec, decl, false, inst),
                                 getWithParamInstructions(exec, decl, true, inst));
        return inst;
    }

}

//
// The contents of this file are subject to the Mozilla Public License Version 1.0 (the "License");
// you may not use this file except in compliance with the License. You may obtain a copy of the
// License at http://www.mozilla.org/MPL/
//
// Software distributed under the License is distributed on an "AS IS" basis,
// WITHOUT WARRANTY OF ANY KIND, either express or implied.
// See the License for the specific language governing rights and limitations under the License.
//
// The Original Code is: all this file
//
// The Initial Developer of the Original Code is Saxonica Limited.
// Portions created by ___ are Copyright (C) ___. All rights reserved.
//
// Contributor(s):
//