com.sun.el.lang.ExpressionBuilder Maven / Gradle / Ivy
/*
* Copyright (c) 1997, 2018 Oracle and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v. 2.0, which is available at
* http://www.eclipse.org/legal/epl-2.0.
*
* This Source Code may also be made available under the following Secondary
* Licenses when the conditions for such availability set forth in the
* Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
* version 2 with the GNU Classpath Exception, which is available at
* https://www.gnu.org/software/classpath/license.html.
*
* SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
*/
package com.sun.el.lang;
import java.io.StringReader;
import java.lang.ref.ReferenceQueue;
import java.lang.ref.SoftReference;
import java.lang.reflect.Method;
import java.util.concurrent.ConcurrentHashMap;
import jakarta.el.ELContext;
import jakarta.el.ELException;
import jakarta.el.FunctionMapper;
import jakarta.el.MethodExpression;
import jakarta.el.ValueExpression;
import jakarta.el.VariableMapper;
import com.sun.el.MethodExpressionImpl;
import com.sun.el.MethodExpressionLiteral;
import com.sun.el.ValueExpressionImpl;
import com.sun.el.parser.AstCompositeExpression;
import com.sun.el.parser.AstDeferredExpression;
import com.sun.el.parser.AstDynamicExpression;
import com.sun.el.parser.AstFunction;
import com.sun.el.parser.AstIdentifier;
import com.sun.el.parser.AstLiteralExpression;
import com.sun.el.parser.AstMethodArguments;
import com.sun.el.parser.AstValue;
import com.sun.el.parser.ELParser;
import com.sun.el.parser.Node;
import com.sun.el.parser.NodeVisitor;
import com.sun.el.parser.ParseException;
import com.sun.el.util.MessageFactory;
/**
* @author Jacob Hookom [[email protected]]
* @author Kin-man Chung // EL cache
* @version $Change: 181177 $$DateTime: 2001/06/26 08:45:09 $$Author: kchung $
*/
public final class ExpressionBuilder implements NodeVisitor {
static private class NodeSoftReference extends SoftReference {
final String key;
NodeSoftReference(String key, Node node, ReferenceQueue refQ) {
super(node, refQ);
this.key = key;
}
}
static private class SoftConcurrentHashMap extends ConcurrentHashMap {
private static final int CACHE_INIT_SIZE = 256;
private ConcurrentHashMap map = new ConcurrentHashMap(CACHE_INIT_SIZE);
private ReferenceQueue refQ = new ReferenceQueue();
// Remove map entries that have been placed on the queue by GC.
private void cleanup() {
NodeSoftReference nodeRef = null;
while ((nodeRef = (NodeSoftReference) refQ.poll()) != null) {
map.remove(nodeRef.key);
}
}
@Override
public Node put(String key, Node value) {
cleanup();
NodeSoftReference prev = map.put(key, new NodeSoftReference(key, value, refQ));
return prev == null ? null : prev.get();
}
@Override
public Node putIfAbsent(String key, Node value) {
cleanup();
NodeSoftReference prev = map.putIfAbsent(key, new NodeSoftReference(key, value, refQ));
return prev == null ? null : prev.get();
}
@Override
public Node get(Object key) {
cleanup();
NodeSoftReference nodeRef = map.get(key);
if (nodeRef == null) {
return null;
}
if (nodeRef.get() == null) {
// value has been garbage collected, remove entry in map
map.remove(key);
return null;
}
return nodeRef.get();
}
}
private static final SoftConcurrentHashMap cache = new SoftConcurrentHashMap();
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 static Node createNode(String expr) throws ELException {
Node n = createNodeInternal(expr);
return n;
}
private 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 com.sun.el.parser.ELParserTokenManager(new com.sun.el.parser.SimpleCharStream(new StringReader(expr), 1, 1, expr.length() + 1))))
.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.putIfAbsent(expr, n);
} catch (ParseException pe) {
throw new ELException("Error Parsing: " + expr, pe);
}
}
return n;
}
/**
* Scan the expression nodes and captures the functions and variables used in this expression. This ensures that any
* changes to the functions or variables mappings during the expression will not affect the evaluation of this
* expression, as the functions and variables are bound and resolved at parse time, as specified in the spec.
*/
private void prepare(Node node) throws ELException {
node.accept(this);
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)
*/
@Override
public void visit(Node node) throws ELException {
if (node instanceof AstFunction) {
AstFunction funcNode = (AstFunction) node;
if ((funcNode.getPrefix().length() == 0)
&& (this.fnMapper == null || fnMapper.resolveFunction(funcNode.getPrefix(), funcNode.getLocalName()) == null)) {
// This can be a call to a LambdaExpression. The target
// of the call is a bean or an Jakarta Expression variable. Capture
// the variable name in the variable mapper if it is an
// variable. The decision to invoke the static method or
// the LambdaExpression will be made at runtime.
if (this.varMapper != null) {
this.varMapper.resolveVariable(funcNode.getLocalName());
}
return;
}
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 pcnt = m.getParameterTypes().length;
int acnt = ((AstMethodArguments) node.jjtGetChild(0)).getParameterCount();
if (acnt != pcnt) {
throw new ELException(MessageFactory.get("error.fnMapper.paramcount", funcNode.getOutputName(), "" + pcnt, "" + acnt));
}
} 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);
}
}
}
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