/*
* Copyright 2003-2013 the original author or authors.
*
* 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 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.
* <p>
* 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:
* <pre>
* assert 10 == Eval.me(' 2 * 4 + 2')
* assert 10 == Eval.x(2, ' x * 4 + 2')
* </pre>
*
* @see GroovyShell
* @author Dierk Koenig
*/
public class Eval {
/**
* Evaluates the specified String expression and returns the result. For example:
* <pre>
* assert 10 == Eval.me(' 2 * 4 + 2')
* </pre>
* @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:
* <pre>
* assert 10 == Eval.me('x', 2, ' x * 4 + 2')
* </pre>
* @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:
* <pre>
* assert 10 == Eval.x(2, ' x * 4 + 2')
* </pre>
* @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:
* <pre>
* assert 10 == Eval.xy(2, 4, ' x * y + 2')
* </pre>
* @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:
* <pre>
* assert 10 == Eval.xyz(2, 4, 2, ' x * y + z')
* </pre>
* @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);
}
}