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Tomcat example source code file (ELFunctionMapper.java)

This example Tomcat source code file (ELFunctionMapper.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Tomcat tags/keywords

contains, elfunctionmapper, elfunctionvisitor, functioninfo, fvisitor, hashmap, hashmap, jasperexception, jasperexception, jsp, node, servlet, string, string, stringbuffer, stringbuffer, util

The Tomcat ELFunctionMapper.java source code

/*
 * 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.jasper.compiler;

import java.util.*;
import javax.servlet.jsp.tagext.FunctionInfo;
import org.apache.jasper.JasperException;

/**
 * This class generates functions mappers for the EL expressions in the page.
 * Instead of a global mapper, a mapper is used for ecah call to EL
 * evaluator, thus avoiding the prefix overlapping and redefinition
 * issues.
 *
 * @author Kin-man Chung
 */

public class ELFunctionMapper {
    private int currFunc = 0;
    StringBuffer ds;  // Contains codes to initialize the functions mappers.
    StringBuffer ss;  // Contains declarations of the functions mappers.

    /**
     * Creates the functions mappers for all EL expressions in the JSP page.
     *
     * @param compiler Current compiler, mainly for accessing error dispatcher.
     * @param page The current compilation unit.
     */
    public static void map(Compiler compiler, Node.Nodes page) 
                throws JasperException {

        ELFunctionMapper map = new ELFunctionMapper();
        map.ds = new StringBuffer();
        map.ss = new StringBuffer();

        page.visit(map.new ELFunctionVisitor());

        // Append the declarations to the root node
        String ds = map.ds.toString();
        if (ds.length() > 0) {
            Node root = page.getRoot();
            new Node.Declaration(map.ss.toString(), null, root);
            new Node.Declaration("static {\n" + ds + "}\n", null, root);
        }
    }

    /**
     * A visitor for the page.  The places where EL is allowed are scanned
     * for functions, and if found functions mappers are created.
     */
    class ELFunctionVisitor extends Node.Visitor {
        
        /**
         * Use a global name map to facilitate reuse of function maps.
         * The key used is prefix:function:uri.
         */
        private HashMap<String, String> gMap = new HashMap();

        public void visit(Node.ParamAction n) throws JasperException {
            doMap(n.getValue());
            visitBody(n);
        }

        public void visit(Node.IncludeAction n) throws JasperException {
            doMap(n.getPage());
            visitBody(n);
        }

        public void visit(Node.ForwardAction n) throws JasperException {
            doMap(n.getPage());
            visitBody(n);
        }

        public void visit(Node.SetProperty n) throws JasperException {
            doMap(n.getValue());
            visitBody(n);
        }

        public void visit(Node.UseBean n) throws JasperException {
            doMap(n.getBeanName());
            visitBody(n);
        }

        public void visit(Node.PlugIn n) throws JasperException {
            doMap(n.getHeight());
            doMap(n.getWidth());
            visitBody(n);
        }

        public void visit(Node.JspElement n) throws JasperException {

            Node.JspAttribute[] attrs = n.getJspAttributes();
            for (int i = 0; attrs != null && i < attrs.length; i++) {
                doMap(attrs[i]);
            }
            doMap(n.getNameAttribute());
            visitBody(n);
        }

        public void visit(Node.UninterpretedTag n) throws JasperException {

            Node.JspAttribute[] attrs = n.getJspAttributes();
            for (int i = 0; attrs != null && i < attrs.length; i++) {
                doMap(attrs[i]);
            }
            visitBody(n);
        }

        public void visit(Node.CustomTag n) throws JasperException {
            Node.JspAttribute[] attrs = n.getJspAttributes();
            for (int i = 0; attrs != null && i < attrs.length; i++) {
                doMap(attrs[i]);
            }
            visitBody(n);
        }

        public void visit(Node.ELExpression n) throws JasperException {
            doMap(n.getEL());
        }

        private void doMap(Node.JspAttribute attr) 
                throws JasperException {
            if (attr != null) {
                doMap(attr.getEL());
            }
        }

        /**
         * Creates function mappers, if needed, from ELNodes
         */
        private void doMap(ELNode.Nodes el) 
                throws JasperException {

            // Only care about functions in ELNode's
            class Fvisitor extends ELNode.Visitor {
                ArrayList<ELNode.Function> funcs =
                    new ArrayList<ELNode.Function>();
                HashMap<String, String> keyMap = new HashMap();
                public void visit(ELNode.Function n) throws JasperException {
                    String key = n.getPrefix() + ":" + n.getName();
                    if (! keyMap.containsKey(key)) {
                        keyMap.put(key,"");
                        funcs.add(n);
                    }
                }
            }

            if (el == null) {
                return;
            }

            // First locate all unique functions in this EL
            Fvisitor fv = new Fvisitor();
            el.visit(fv);
            ArrayList functions = fv.funcs;

            if (functions.size() == 0) {
                return;
            }

            // Reuse a previous map if possible
            String decName = matchMap(functions);
            if (decName != null) {
                el.setMapName(decName);
                return;
            }
        
            // Generate declaration for the map statically
            decName = getMapName();
            ss.append("static private org.apache.jasper.runtime.ProtectedFunctionMapper " + decName + ";\n");

            ds.append("  " + decName + "= ");
            ds.append("org.apache.jasper.runtime.ProtectedFunctionMapper");

            // Special case if there is only one function in the map
            String funcMethod = null;
            if (functions.size() == 1) {
                funcMethod = ".getMapForFunction";
            } else {
                ds.append(".getInstance();\n");
                funcMethod = "  " + decName + ".mapFunction";
            }

            // Setup arguments for either getMapForFunction or mapFunction
            for (int i = 0; i < functions.size(); i++) {
                ELNode.Function f = (ELNode.Function)functions.get(i);
                FunctionInfo funcInfo = f.getFunctionInfo();
                String key = f.getPrefix()+ ":" + f.getName();
                ds.append(funcMethod + "(\"" + key + "\", " +
                        funcInfo.getFunctionClass() + ".class, " +
                        '\"' + f.getMethodName() + "\", " +
                        "new Class[] {");
                String params[] = f.getParameters();
                for (int k = 0; k < params.length; k++) {
                    if (k != 0) {
                        ds.append(", ");
                    }
                    int iArray = params[k].indexOf('[');
                    if (iArray < 0) {
                        ds.append(params[k] + ".class");
                    }
                    else {
                        String baseType = params[k].substring(0, iArray);
                        ds.append("java.lang.reflect.Array.newInstance(");
                        ds.append(baseType);
                        ds.append(".class,");

                        // Count the number of array dimension
                        int aCount = 0;
                        for (int jj = iArray; jj < params[k].length(); jj++ ) {
                            if (params[k].charAt(jj) == '[') {
                                aCount++;
                            }
                        }
                        if (aCount == 1) {
                            ds.append("0).getClass()");
                        } else {
                            ds.append("new int[" + aCount + "]).getClass()");
                        }
                    }
                }
                ds.append("});\n");
                // Put the current name in the global function map
                gMap.put(f.getPrefix() + ':' + f.getName() + ':' + f.getUri(),
                         decName);
            }
            el.setMapName(decName);
        }

        /**
         * Find the name of the function mapper for an EL.  Reuse a
         * previously generated one if possible.
         * @param functions An ArrayList of ELNode.Function instances that
         *                  represents the functions in an EL
         * @return A previous generated function mapper name that can be used
         *         by this EL; null if none found.
         */
        private String matchMap(ArrayList functions) {

            String mapName = null;
            for (int i = 0; i < functions.size(); i++) {
                ELNode.Function f = (ELNode.Function)functions.get(i);
                String temName = (String) gMap.get(f.getPrefix() + ':' +
                                        f.getName() + ':' + f.getUri());
                if (temName == null) {
                    return null;
                }
                if (mapName == null) {
                    mapName = temName;
                } else if (!temName.equals(mapName)) {
                    // If not all in the previous match, then no match.
                    return null;
                }
            }
            return mapName;
        }

        /*
         * @return An unique name for a function mapper.
         */
        private String getMapName() {
            return "_jspx_fnmap_" + currFunc++;
        }
    }
}

Other Tomcat examples (source code examples)

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