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Groovy: A powerful, dynamic language for the JVM
/**
* 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 groovy.util;
import org.codehaus.groovy.control.CompilationFailedException;
import groovy.lang.Binding;
import groovy.lang.GroovyShell;
/**
* Allow easy integration from Groovy into Java through convenience methods.
*
* This class is a simple helper on top of GroovyShell. You can use it to evaluate small
* Groovy scripts that don't need large Binding objects. For example, this script
* executes with no errors:
*
* assert 10 == Eval.me(' 2 * 4 + 2')
* assert 10 == Eval.x(2, ' x * 4 + 2')
*
*
* @see GroovyShell
* @author Dierk Koenig
*/
public class Eval {
/**
* Evaluates the specified String expression and returns the result. For example:
*
* assert 10 == Eval.me(' 2 * 4 + 2')
*
* @param expression the Groovy expression to evaluate
* @return the result of the expression
* @throws CompilationFailedException if expression is not valid Groovy
*/
public static Object me(final String expression) throws CompilationFailedException {
return me(null, null, expression);
}
/**
* Evaluates the specified String expression and makes the parameter available inside
* the script, returning the result. For example, this code binds the 'x' variable:
*
* assert 10 == Eval.me('x', 2, ' x * 4 + 2')
*
* @param expression the Groovy expression to evaluate
* @return the result of the expression
* @throws CompilationFailedException if expression is not valid Groovy
*/
public static Object me(final String symbol, final Object object, final String expression) throws CompilationFailedException {
Binding b = new Binding();
b.setVariable(symbol, object);
GroovyShell sh = new GroovyShell(b);
return sh.evaluate(expression);
}
/**
* Evaluates the specified String expression and makes the parameter available inside
* the script bound to a variable named 'x', returning the result. For example, this
* code executes without failure:
*
* assert 10 == Eval.x(2, ' x * 4 + 2')
*
* @param expression the Groovy expression to evaluate
* @return the result of the expression
* @throws CompilationFailedException if expression is not valid Groovy
*/
public static Object x(final Object x, final String expression) throws CompilationFailedException {
return me("x", x, expression);
}
/**
* Evaluates the specified String expression and makes the first two parameters available inside
* the script bound to variables named 'x' and 'y' respectively, returning the result. For example,
* this code executes without failure:
*
* assert 10 == Eval.xy(2, 4, ' x * y + 2')
*
* @param expression the Groovy expression to evaluate
* @return the result of the expression
* @throws CompilationFailedException if expression is not valid Groovy
*/
public static Object xy(final Object x, final Object y, final String expression) throws CompilationFailedException {
Binding b = new Binding();
b.setVariable("x", x);
b.setVariable("y", y);
GroovyShell sh = new GroovyShell(b);
return sh.evaluate(expression);
}
/**
* Evaluates the specified String expression and makes the first three parameters available inside
* the script bound to variables named 'x', 'y', and 'z' respectively, returning the result. For
* example, this code executes without failure:
*
* assert 10 == Eval.xyz(2, 4, 2, ' x * y + z')
*
* @param expression the Groovy expression to evaluate
* @return the result of the expression
* @throws CompilationFailedException if expression is not valid Groovy
*/
public static Object xyz(final Object x, final Object y, final Object z, final String expression) throws CompilationFailedException {
Binding b = new Binding();
b.setVariable("x", x);
b.setVariable("y", y);
b.setVariable("z", z);
GroovyShell sh = new GroovyShell(b);
return sh.evaluate(expression);
}
}