ELFunctionMapper.java
/*
* 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.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import jakarta.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 each call to EL evaluator, thus avoiding the prefix overlapping and redefinition issues.
*
* @author Kin-man Chung
*/
public class ELFunctionMapper {
private int currFunc = 0;
private StringBuilder ds; // Contains codes to initialize the functions mappers.
private StringBuilder ss; // Contains declarations of the functions mappers.
/**
* Creates the functions mappers for all EL expressions in the JSP page.
*
* @param page The current compilation unit.
*
* @throws JasperException EL error
*/
public static void map(Node.Nodes page) throws JasperException {
ELFunctionMapper map = new ELFunctionMapper();
map.ds = new StringBuilder();
map.ss = new StringBuilder();
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();
@SuppressWarnings("unused")
Node unused = new Node.Declaration(map.ss.toString(), null, root);
unused = 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.
*/
private class ELFunctionVisitor extends Node.Visitor {
/**
* Use a global name map to facilitate reuse of function maps. The key used is prefix:function:uri.
*/
private final Map<String,String> gMap = new HashMap<>();
@Override
public void visit(Node.ParamAction n) throws JasperException {
doMap(n.getValue());
visitBody(n);
}
@Override
public void visit(Node.IncludeAction n) throws JasperException {
doMap(n.getPage());
visitBody(n);
}
@Override
public void visit(Node.ForwardAction n) throws JasperException {
doMap(n.getPage());
visitBody(n);
}
@Override
public void visit(Node.SetProperty n) throws JasperException {
doMap(n.getValue());
visitBody(n);
}
@Override
public void visit(Node.UseBean n) throws JasperException {
doMap(n.getBeanName());
visitBody(n);
}
@Override
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);
}
@Override
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);
}
@Override
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);
}
@Override
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 {
private final List<ELNode.Function> funcs = new ArrayList<>();
private final Set<String> keySet = new HashSet<>();
@Override
public void visit(ELNode.Function n) throws JasperException {
String key = n.getPrefix() + ":" + n.getName();
if (keySet.add(key)) {
funcs.add(n);
}
}
}
if (el == null) {
return;
}
// First locate all unique functions in this EL
Fvisitor fv = new Fvisitor();
el.visit(fv);
List<ELNode.Function> 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("private static 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 (ELNode.Function f : functions) {
FunctionInfo funcInfo = f.getFunctionInfo();
String fnQName = f.getPrefix() + ":" + f.getName();
if (funcInfo == null) {
// Added via Lambda or ImportHandler. EL will expect a
// function mapper even if one isn't used so just pass null
ds.append(funcMethod + "(null, null, null, null);\n");
} else {
ds.append(funcMethod + "(\"" + fnQName + "\", " + getCanonicalName(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(fnQName + ':' + 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 A List 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(List<ELNode.Function> functions) {
String mapName = null;
for (ELNode.Function f : functions) {
String temName = 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 A unique name for a function mapper.
*/
private String getMapName() {
return "_jspx_fnmap_" + currFunc++;
}
/**
* Convert a binary class name into a canonical one that can be used when generating Java source code.
*
* @param className Binary class name
*
* @return Canonical equivalent
*/
private String getCanonicalName(String className) throws JasperException {
Class<?> clazz;
ClassLoader tccl = Thread.currentThread().getContextClassLoader();
try {
clazz = Class.forName(className, false, tccl);
} catch (ClassNotFoundException e) {
throw new JasperException(e);
}
return clazz.getCanonicalName();
}
}
}