groovy-core/src/main/groovy/lang/Script.java

/*
 $Id$

 Copyright 2003 (C) James Strachan and Bob Mcwhirter. All Rights Reserved.

 Redistribution and use of this software and associated documentation
 ("Software"), with or without modification, are permitted provided
 that the following conditions are met:

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    copy of this document.

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    above copyright notice, this list of conditions and the
    following disclaimer in the documentation and/or other
    materials provided with the distribution.

 3. The name "groovy" must not be used to endorse or promote
    products derived from this Software without prior written
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    please contact info@codehaus.org.

 4. Products derived from this Software may not be called "groovy"
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    trademark of The Codehaus.

 5. Due credit should be given to The Codehaus -
    http://groovy.codehaus.org/

 THIS SOFTWARE IS PROVIDED BY THE CODEHAUS AND CONTRIBUTORS
 ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
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 */
package groovy.lang;

import org.codehaus.groovy.ast.expr.ArgumentListExpression;
import org.codehaus.groovy.control.CompilationFailedException;
import org.codehaus.groovy.runtime.DefaultGroovyMethods;
import org.codehaus.groovy.runtime.InvokerHelper;

import java.io.File;
import java.io.IOException;

/**
 * This object represents a Groovy script
 *
 * @author <a href="mailto:james@coredevelopers.net">James Strachan</a>
 * @author Guillaume Laforge
 * @version $Revision$
 */
public abstract class Script extends GroovyObjectSupport {
    private Binding binding = new Binding();

    protected Script() {
    }

    protected Script(Binding binding) {
        this.binding = binding;
    }

    public Binding getBinding() {
        return binding;
    }

    public void setBinding(Binding binding) {
        this.binding = binding;
    }

    public Object getProperty(String property) {
        try {
            return binding.getVariable(property);
        } catch (MissingPropertyException e) {
            return super.getProperty(property);
        }
    }

    public void setProperty(String property, Object newValue) {
        if ("binding".equals(property))
            setBinding((Binding) newValue);
        else
            binding.setVariable(property, newValue);
    }

    /**
     * Invoke a method (or closure in the binding) defined.
     *
     * @param name method to call
     * @param args arguments to pass to the method
     * @return value
     */
    public Object invokeMethod(String name, Object args) {
        try {
            return super.invokeMethod(name, args);
        }
                // if the method was not found in the current scope (the script's methods)
                // let's try to see if there's a method closure with the same name in the binding
        catch (MissingMethodException mme) {
            try {
                if (name.equals(mme.getMethod())) {
                    Object boundClosure = binding.getVariable(name);
                    if (boundClosure != null && boundClosure instanceof Closure) {
                        return ((Closure) boundClosure).call((Object[])args);
                    } else {
                        throw mme;
                    }
                } else {
                    throw mme;
                }
            } catch (MissingPropertyException mpe) {
                throw mme;
            }
        }
    }

    /**
     * The main instance method of a script which has variables in scope
     * as defined by the current {@link Binding} instance.
     */
    public abstract Object run();

    // println helper methods

    /**
     * Prints a newline to the current 'out' variable which should be a PrintWriter
     * or at least have a println() method defined on it.
     * If there is no 'out' property then print to standard out.
     */
    public void println() {
        Object object;

        try {
            object = getProperty("out");
        } catch (MissingPropertyException e) {
            System.out.println();
            return;
        }

        InvokerHelper.invokeMethod(object, "println", ArgumentListExpression.EMPTY_ARRAY);
    }

    /**
     * Prints the value to the current 'out' variable which should be a PrintWriter
     * or at least have a print() method defined on it.
     * If there is no 'out' property then print to standard out.
     */
    public void print(Object value) {
        Object object;

        try {
            object = getProperty("out");
        } catch (MissingPropertyException e) {
            DefaultGroovyMethods.print(System.out,value);
            return;
        }

        InvokerHelper.invokeMethod(object, "print", new Object[]{value});
    }

    /**
     * Prints the value and a newline to the current 'out' variable which should be a PrintWriter
     * or at least have a println() method defined on it.
     * If there is no 'out' property then print to standard out.
     */
    public void println(Object value) {
        Object object;

        try {
            object = getProperty("out");
        } catch (MissingPropertyException e) {
            DefaultGroovyMethods.println(System.out,value);
            return;
        }

        InvokerHelper.invokeMethod(object, "println", new Object[]{value});
    }

    /**
     * A helper method to allow the dynamic evaluation of groovy expressions using this
     * scripts binding as the variable scope
     *
     * @param expression is the Groovy script expression to evaluate
     */
    public Object evaluate(String expression) throws CompilationFailedException, IOException {
        GroovyShell shell = new GroovyShell(binding);
        return shell.evaluate(expression);
    }

    /**
     * A helper method to allow the dynamic evaluation of groovy expressions using this
     * scripts binding as the variable scope
     *
     * @param file is the Groovy script to evaluate
     */
    public Object evaluate(File file) throws CompilationFailedException, IOException {
        GroovyShell shell = new GroovyShell(binding);
        return shell.evaluate(file);
    }

    /**
     * A helper method to allow scripts to be run taking command line arguments
     */
    public void run(File file, String[] arguments) throws CompilationFailedException, IOException {
        GroovyShell shell = new GroovyShell(binding);
        shell.run(file, arguments);
    }
}