ConstructorFunctionLibrary.java

package client.net.sf.saxon.ce.functions;

import client.net.sf.saxon.ce.expr.CastExpression;
import client.net.sf.saxon.ce.expr.Container;
import client.net.sf.saxon.ce.expr.Expression;
import client.net.sf.saxon.ce.expr.StaticContext;
import client.net.sf.saxon.ce.lib.NamespaceConstant;
import client.net.sf.saxon.ce.om.StandardNames;
import client.net.sf.saxon.ce.om.StructuredQName;
import client.net.sf.saxon.ce.trans.XPathException;
import client.net.sf.saxon.ce.type.AtomicType;
import client.net.sf.saxon.ce.type.BuiltInType;
import client.net.sf.saxon.ce.type.Type;

/**
 * The ConstructorFunctionLibrary represents the collection of constructor functions for atomic types. These
 * are provided for the built-in types such as xs:integer and xs:date, and also for user-defined atomic types.
 */

public class ConstructorFunctionLibrary implements FunctionLibrary {

    public static ConstructorFunctionLibrary THE_INSTANCE = new ConstructorFunctionLibrary();

    public static ConstructorFunctionLibrary getInstance() {
        return THE_INSTANCE;
    }

    /**
     * Create a ConstructorFunctionLibrary
     */

    private ConstructorFunctionLibrary() {
    }

    /**
     * Test whether a system function with a given name and arity is available, and return its signature. This supports
     * the function-available() function in XSLT. This method may be called either at compile time
     * or at run time.
     * @param functionName the name of the function
     * @param arity The number of arguments. This is set to -1 in the case of the single-argument
     * @return if a function of this name and arity is available for calling, then the type signature of the
     * function, as an array of sequence types in which the zeroth entry represents the return type; otherwise null
     */

    public boolean hasFunctionSignature(StructuredQName functionName, int arity) {
        if (arity != 1 && arity != -1) {
            return false;
        }
        String uri = functionName.getNamespaceURI();
        String local = functionName.getLocalName();
        return BuiltInType.getSchemaType(StandardNames.getFingerprint(uri, local)) != null;
    }

    /**
     * Bind an extension function, given the URI and local parts of the function name,
     * and the list of expressions supplied as arguments. This method is called at compile
     * time.
     * @param functionName
     * @param arguments  The expressions supplied statically in the function call. The intention is
     * that the static type of the arguments (obtainable via getItemType() and getCardinality() may
     * be used as part of the binding algorithm.
     * @param env
     * @param container
     * @return An object representing the extension function to be called, if one is found;
     * null if no extension function was found matching the required name and arity.
     * @throws client.net.sf.saxon.ce.trans.XPathException if a function is found with the required name and arity, but
     * the implementation of the function cannot be loaded or used; or if an error occurs
     * while searching for the function; or if this function library "owns" the namespace containing
     * the function call, but no function was found.
     */

    public Expression bind(StructuredQName functionName, Expression[] arguments, StaticContext env, Container container)
            throws XPathException {
        final String uri = functionName.getNamespaceURI();
        final String localName = functionName.getLocalName();
        if (uri.equals(NamespaceConstant.SCHEMA)) {
            // it's a constructor function: treat it as shorthand for a cast expression
            if (arguments.length != 1) {
                throw new XPathException("A constructor function must have exactly one argument");
            }
            AtomicType type = (AtomicType)Type.getBuiltInItemType(uri, localName);
            if (type==null || type.getFingerprint() == StandardNames.XS_ANY_ATOMIC_TYPE) {
                XPathException err = new XPathException("Unknown constructor function: {" + uri + '}' + localName);
                err.setErrorCode("XPST0017");
                err.setIsStaticError(true);
                throw err;
            }

            Expression cast = new CastExpression(arguments[0], type, true);
            cast.setContainer(container);
            return cast;
        }
        return null;
    }

}
// 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.