camundafeel.de.odysseus.el.tree.impl.Builder Maven / Gradle / Ivy
/*
* Copyright 2006-2009 Odysseus Software GmbH
*
* Licensed 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 de.odysseus.el.tree.impl;
import java.io.PrintWriter;
import java.util.EnumSet;
import javax.el.ELContext;
import javax.el.ELException;
import javax.el.ELResolver;
import javax.el.ExpressionFactory;
import javax.el.FunctionMapper;
import javax.el.VariableMapper;
import de.odysseus.el.tree.Bindings;
import de.odysseus.el.tree.NodePrinter;
import de.odysseus.el.tree.Tree;
import de.odysseus.el.tree.TreeBuilder;
import de.odysseus.el.tree.TreeBuilderException;
import de.odysseus.el.tree.impl.Parser.ParseException;
import de.odysseus.el.tree.impl.Scanner.ScanException;
/**
* Tree builder.
*
* @author Christoph Beck
*/
public class Builder implements TreeBuilder {
private static final long serialVersionUID = 1L;
/**
* Feature enumeration type.
*/
public static enum Feature {
/**
* Method invocations as in ${foo.bar(1)} as specified in JSR 245,
* maintenance release 2.
* The method to be invoked is resolved at evaluation time by calling
* {@link ELResolver#invoke(javax.el.ELContext, Object, Object, Class[], Object[])}.
*/
METHOD_INVOCATIONS,
/**
* For some reason we don't understand, the specification does not allow to resolve
* null property values. E.g. ${map[key]} will always
* return null if key evaluates to null.
* Enabling this feature will allow JUEL to pass null to
* the property resolvers just like any other property value.
*/
NULL_PROPERTIES,
/**
* Allow for use of Java 5 varargs in function calls.
*/
VARARGS,
/**
* Do not verify that a method's return type matches the expected return type passed to
* {@link ExpressionFactory#createMethodExpression(ELContext, String, Class, Class[])}.
*/
IGNORE_RETURN_TYPE
}
protected final EnumSet features;
public Builder() {
this.features = EnumSet.noneOf(Feature.class);
}
public Builder(Feature... features) {
if (features == null || features.length == 0) {
this.features = EnumSet.noneOf(Feature.class);
} else if (features.length == 1) {
this.features = EnumSet.of(features[0]);
} else {
Feature[] rest = new Feature[features.length-1];
for (int i = 1; i < features.length; i++) {
rest[i-1] = features[i];
}
this.features = EnumSet.of(features[0], rest);
}
}
/**
* @return true iff the specified feature is supported.
*/
public boolean isEnabled(Feature feature) {
return features.contains(feature);
}
/**
* Parse expression.
*/
public Tree build(String expression) throws TreeBuilderException {
try {
return createParser(expression).tree();
} catch (ScanException e) {
throw new TreeBuilderException(expression, e.position, e.encountered, e.expected, e.getMessage());
} catch (ParseException e) {
throw new TreeBuilderException(expression, e.position, e.encountered, e.expected, e.getMessage());
}
}
protected Parser createParser(String expression) {
return new Parser(this, expression);
}
@Override
public boolean equals(Object obj) {
if (obj == null || obj.getClass() != getClass()) {
return false;
}
return features.equals(((Builder)obj).features);
}
@Override
public int hashCode() {
return getClass().hashCode();
}
/**
* Dump out abstract syntax tree for a given expression
*
* @param args array with one element, containing the expression string
*/
public static void main(String[] args) {
if (args.length != 1) {
System.err.println("usage: java " + Builder.class.getName() + " ");
System.exit(1);
}
PrintWriter out = new PrintWriter(System.out);
Tree tree = null;
try {
tree = new Builder(Feature.METHOD_INVOCATIONS).build(args[0]);
} catch (TreeBuilderException e) {
System.out.println(e.getMessage());
System.exit(0);
}
NodePrinter.dump(out, tree.getRoot());
if (!tree.getFunctionNodes().iterator().hasNext() && !tree.getIdentifierNodes().iterator().hasNext()) {
ELContext context = new ELContext() {
@Override
public VariableMapper getVariableMapper() {
return null;
}
@Override
public FunctionMapper getFunctionMapper() {
return null;
}
@Override
public ELResolver getELResolver() {
return null;
}
};
out.print(">> ");
try {
out.println(tree.getRoot().getValue(new Bindings(null, null), context, null));
} catch (ELException e) {
out.println(e.getMessage());
}
}
out.flush();
}
}