/*
* 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.el.lang;
import java.io.StringReader;
import java.lang.reflect.Method;
import java.security.AccessController;
import java.security.PrivilegedAction;
import javax.el.ELContext;
import javax.el.ELException;
import javax.el.FunctionMapper;
import javax.el.MethodExpression;
import javax.el.ValueExpression;
import javax.el.VariableMapper;
import org.apache.el.MethodExpressionImpl;
import org.apache.el.MethodExpressionLiteral;
import org.apache.el.ValueExpressionImpl;
import org.apache.el.parser.AstCompositeExpression;
import org.apache.el.parser.AstDeferredExpression;
import org.apache.el.parser.AstDynamicExpression;
import org.apache.el.parser.AstFunction;
import org.apache.el.parser.AstIdentifier;
import org.apache.el.parser.AstLiteralExpression;
import org.apache.el.parser.AstValue;
import org.apache.el.parser.ELParser;
import org.apache.el.parser.Node;
import org.apache.el.parser.NodeVisitor;
import org.apache.el.util.ConcurrentCache;
import org.apache.el.util.MessageFactory;
/**
* @author Jacob Hookom [jacob@hookom.net]
*
*/
public final class ExpressionBuilder implements NodeVisitor {
private static final int CACHE_SIZE;
private static final String CACHE_SIZE_PROP =
"org.apache.el.ExpressionBuilder.CACHE_SIZE";
static {
if (System.getSecurityManager() == null) {
CACHE_SIZE = Integer.parseInt(
System.getProperty(CACHE_SIZE_PROP, "5000"));
} else {
CACHE_SIZE = AccessController.doPrivileged(
new PrivilegedAction<Integer>() {
public Integer run() {
return Integer.valueOf(
System.getProperty(CACHE_SIZE_PROP, "5000"));
}
}).intValue();
}
}
private static final ConcurrentCache<String, Node> cache =
new ConcurrentCache<String, Node>(CACHE_SIZE);
private FunctionMapper fnMapper;
private VariableMapper varMapper;
private String expression;
/**
*
*/
public ExpressionBuilder(String expression, ELContext ctx)
throws ELException {
this.expression = expression;
FunctionMapper ctxFn = ctx.getFunctionMapper();
VariableMapper ctxVar = ctx.getVariableMapper();
if (ctxFn != null) {
this.fnMapper = new FunctionMapperFactory(ctxFn);
}
if (ctxVar != null) {
this.varMapper = new VariableMapperFactory(ctxVar);
}
}
public final static Node createNode(String expr) throws ELException {
Node n = createNodeInternal(expr);
return n;
}
private final static Node createNodeInternal(String expr)
throws ELException {
if (expr == null) {
throw new ELException(MessageFactory.get("error.null"));
}
Node n = cache.get(expr);
if (n == null) {
try {
n = (new ELParser(new StringReader(expr)))
.CompositeExpression();
// validate composite expression
if (n instanceof AstCompositeExpression) {
int numChildren = n.jjtGetNumChildren();
if (numChildren == 1) {
n = n.jjtGetChild(0);
} else {
Class type = null;
Node child = null;
for (int i = 0; i < numChildren; i++) {
child = n.jjtGetChild(i);
if (child instanceof AstLiteralExpression)
continue;
if (type == null)
type = child.getClass();
else {
if (!type.equals(child.getClass())) {
throw new ELException(MessageFactory.get(
"error.mixed", expr));
}
}
}
}
}
if (n instanceof AstDeferredExpression
|| n instanceof AstDynamicExpression) {
n = n.jjtGetChild(0);
}
cache.put(expr, n);
} catch (Exception e) {
throw new ELException(
MessageFactory.get("error.parseFail", expr), e);
}
}
return n;
}
private void prepare(Node node) throws ELException {
try {
node.accept(this);
} catch (Exception e) {
if (e instanceof ELException) {
throw (ELException) e;
} else {
throw (new ELException(e));
}
}
if (this.fnMapper instanceof FunctionMapperFactory) {
this.fnMapper = ((FunctionMapperFactory) this.fnMapper).create();
}
if (this.varMapper instanceof VariableMapperFactory) {
this.varMapper = ((VariableMapperFactory) this.varMapper).create();
}
}
private Node build() throws ELException {
Node n = createNodeInternal(this.expression);
this.prepare(n);
if (n instanceof AstDeferredExpression
|| n instanceof AstDynamicExpression) {
n = n.jjtGetChild(0);
}
return n;
}
/*
* (non-Javadoc)
*
* @see com.sun.el.parser.NodeVisitor#visit(com.sun.el.parser.Node)
*/
public void visit(Node node) throws ELException {
if (node instanceof AstFunction) {
AstFunction funcNode = (AstFunction) node;
if (this.fnMapper == null) {
throw new ELException(MessageFactory.get("error.fnMapper.null"));
}
Method m = fnMapper.resolveFunction(funcNode.getPrefix(), funcNode
.getLocalName());
if (m == null) {
throw new ELException(MessageFactory.get(
"error.fnMapper.method", funcNode.getOutputName()));
}
int methodParameterCount = m.getParameterTypes().length;
int inputParameterCount = node.jjtGetNumChildren();
if (m.isVarArgs() && inputParameterCount < methodParameterCount - 1 ||
!m.isVarArgs() && inputParameterCount != methodParameterCount) {
throw new ELException(MessageFactory.get(
"error.fnMapper.paramcount", funcNode.getOutputName(),
"" + methodParameterCount, "" + node.jjtGetNumChildren()));
}
} else if (node instanceof AstIdentifier && this.varMapper != null) {
String variable = ((AstIdentifier) node).getImage();
// simply capture it
this.varMapper.resolveVariable(variable);
}
}
public ValueExpression createValueExpression(Class expectedType)
throws ELException {
Node n = this.build();
return new ValueExpressionImpl(this.expression, n, this.fnMapper,
this.varMapper, expectedType);
}
public MethodExpression createMethodExpression(Class expectedReturnType,
Class[] expectedParamTypes) throws ELException {
Node n = this.build();
if (n instanceof AstValue || n instanceof AstIdentifier) {
return new MethodExpressionImpl(expression, n, this.fnMapper,
this.varMapper, expectedReturnType, expectedParamTypes);
} else if (n instanceof AstLiteralExpression) {
return new MethodExpressionLiteral(expression, expectedReturnType,
expectedParamTypes);
} else {
throw new ELException("Not a Valid Method Expression: "
+ expression);
}
}
}