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package com.sun.el.lang;
import java.io.StringReader;
import java.lang.reflect.Method;
import java.lang.ref.SoftReference;
import java.util.Map;
import java.util.Collections;
import java.util.concurrent.ConcurrentHashMap;
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 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.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 [jacob@hookom.net]
* @version $Change: 181177 $$DateTime: 2001/06/26 08:45:09 $$Author: tcfujii $
*/
public final class ExpressionBuilder implements NodeVisitor {
private static final int CACHE_INIT_SIZE = 256;
private static final ConcurrentHashMap cache =
new ConcurrentHashMap(CACHE_INIT_SIZE) {
@Override
public Object put(Object key, Object value) {
SoftReference ref = new SoftReference(value);
SoftReference prev = (SoftReference)super.put(key, ref);
return prev == null? null: prev.get();
}
@Override
public Object putIfAbsent(Object key, Object value) {
SoftReference ref = new SoftReference(value);
SoftReference prev = (SoftReference)super.putIfAbsent(key, ref);
return prev == null? null: prev.get();
}
@Override
public Object get(Object key) {
SoftReference ref = (SoftReference)super.get(key);
if (ref != null && ref.get() == null) {
remove(key);
}
return ref != null ? ref.get() : null;
}
};
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 = (Node) 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.putIfAbsent(expr, n);
} catch (ParseException pe) {
throw new ELException("Error Parsing: " + expr, pe);
}
}
return n;
}
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)
*/
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 pcnt = m.getParameterTypes().length;
if (node.jjtGetNumChildren() != pcnt) {
throw new ELException(MessageFactory.get(
"error.fnMapper.paramcount", funcNode.getOutputName(),
"" + pcnt, "" + 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);
}
}
}
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