saxoncontext.java

bpel执行引擎用来执行bpel业务流程

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.ode.bpel.elang.xpath20.compiler;

import net.sf.saxon.xpath.StandaloneContext;
import net.sf.saxon.xpath.XPathFunctionLibrary;
import net.sf.saxon.trans.Variable;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.trans.StaticError;
import net.sf.saxon.om.QNameException;
import net.sf.saxon.om.NameChecker;
import net.sf.saxon.Configuration;
import net.sf.saxon.functions.FunctionLibraryList;
import net.sf.saxon.functions.FunctionLibrary;
import net.sf.saxon.expr.VariableReference;

import javax.xml.namespace.QName;

import org.apache.ode.utils.Namespaces;

import java.util.List;

/**
 * Hooks on Saxon StandaloneContext to be notified when the compilation
 * finds some variables and functions. This allows us to prepare the
 * OXpathExpression with variable references and all the things needed
 * at runtime.
 * @author mriou <mriou at apache dot org>
 */
public class SaxonContext extends StandaloneContext {

    private JaxpVariableResolver _varResolver;
    private JaxpFunctionResolver _funcResolver;

    public SaxonContext(Configuration config, JaxpVariableResolver varResolver,
                        JaxpFunctionResolver funcResolver) {
        super(config);

        // We need to remove the default XPathFunctionLibrary to replace it
        // with our own
        List libList = ((FunctionLibraryList)getFunctionLibrary()).libraryList;
        XPathFunctionLibrary xpathLib = null;
        for (Object lib : libList) {
            FunctionLibrary flib = (FunctionLibrary) lib;
            if (flib instanceof XPathFunctionLibrary) xpathLib = (XPathFunctionLibrary) flib;
        }
        if (xpathLib != null) libList.remove(xpathLib);
        OdeXPathFunctionLibrary oxpfl = new OdeXPathFunctionLibrary(funcResolver);
        oxpfl.setXPathFunctionResolver(funcResolver);

        oxpfl.setXPathFunctionResolver(_funcResolver);
        ((FunctionLibraryList)getFunctionLibrary()).addFunctionLibrary(oxpfl);

        _varResolver = varResolver;
        _funcResolver = funcResolver;
    }

    public Variable declareVariable(String qname, Object initialValue) throws XPathException {
        String prefix;
        String localName;
        final NameChecker checker = getConfiguration().getNameChecker();
        try {
            String[] parts = checker.getQNameParts(qname);
            prefix = parts[0];
            localName = parts[1];
        } catch (QNameException err) {
            throw new StaticError("Invalid QName for variable: " + qname);
        }
        String uri = "";
        if (!("".equals(prefix))) {
            uri = getURIForPrefix(prefix);
        }

        _varResolver.resolveVariable(new QName(uri, localName, prefix));

        return super.declareVariable(qname, initialValue);
    }

    public VariableReference bindVariable(int fingerprint) throws StaticError {
        String localName = getNamePool().getLocalName(fingerprint);
        String prefix = getNamePool().getPrefix(fingerprint);
        String ns = getNamePool().getURI(fingerprint);
        // The prefix is lost by compilation, hardcoding it from the ns.
        if (Namespaces.ODE_EXTENSION_NS.equals(ns)) prefix = "ode";
        if (prefix != null && prefix.length() > 0) prefix = prefix + ":";
        try {
            declareVariable(prefix + localName, null);
        } catch (XPathException e) {
            throw new StaticError(e);
        }
        return super.bindVariable(fingerprint);
    }


}