methodcallexpression.java

大名鼎鼎的java动态脚本语言。已经通过了sun的认证

/*
 $Id: MethodCallExpression.java,v 1.10 2006/01/19 00:06:51 blackdrag Exp $

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

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 ("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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    products derived from this Software without prior written
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    please contact [e-mail].

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    permission of The Codehaus. "groovy" is a registered
    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
 NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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 HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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 */
package org.codehaus.groovy.ast.expr;

import groovy.lang.MetaMethod;

import org.codehaus.groovy.ast.ClassHelper;
import org.codehaus.groovy.ast.GroovyCodeVisitor;

/**
 * A method call on an object or class
 * 
 * @author <a href="mailto:[e-mail]">James Strachan</a>
 * @version $Revision: 1.10 $
 */
public class MethodCallExpression extends Expression {

    private Expression objectExpression;
    private String method;
    private Expression arguments;
    private boolean spreadSafe = false;
    private boolean safe = false;
    private boolean implicitThis;

    public MetaMethod getMetaMethod() {
        return metaMethod;
    }

    private MetaMethod metaMethod = null;

    public MethodCallExpression(Expression objectExpression, String method, Expression arguments) {
        this.objectExpression = objectExpression;
        this.method = method;
        this.arguments = arguments;
        //TODO: set correct type here
        // if setting type and a methodcall is the last expresssion in a method,
        // then the method will return null if the method itself is not void too!
        // (in bytecode after call: aconst_null, areturn)
        this.setType(ClassHelper.DYNAMIC_TYPE);
    }

    public void visit(GroovyCodeVisitor visitor) {
        visitor.visitMethodCallExpression(this);
    }

    public Expression transformExpression(ExpressionTransformer transformer) {
        MethodCallExpression answer =
            new MethodCallExpression(transformer.transform(objectExpression), method, transformer.transform(arguments));
        answer.setSafe(safe);
        answer.setSourcePosition(this);
        return answer;
    }

    public Expression getArguments() {
        return arguments;
    }

    public String getMethod() {
        return method;
    }

    public Expression getObjectExpression() {
        return objectExpression;
    }

    public String getText() {
        return objectExpression.getText() + "." + method + arguments.getText();
    }

    /**
     * @return is this a safe method call, i.e. if true then if the source object is null
     * then this method call will return null rather than throwing a null pointer exception
     */
    public boolean isSafe() {
        return safe;
    }

    public void setSafe(boolean safe) {
        this.safe = safe;
    }

    public boolean isSpreadSafe() {
        return spreadSafe;
    }

    public void setSpreadSafe(boolean value) {
        spreadSafe = value;
    }

    /**
     * @return true if no object expression was specified otherwise if 
     * some expression was specified for the object on which to evaluate
     * the method then return false
     */
    public boolean isImplicitThis() {
        return implicitThis;
    }

    public void setImplicitThis(boolean implicitThis) {
        this.implicitThis = implicitThis;
    }

    public String toString() {
        return super.toString()
            + "[object: "
            + objectExpression
            + " method: "
            + method
            + " arguments: "
            + arguments
            + "]";
    }

    public static boolean isSuperMethodCall(MethodCallExpression call) {
        Expression expression = call.getObjectExpression();
        if (expression instanceof VariableExpression) {
            VariableExpression varExp = (VariableExpression) expression;
            String variable = varExp.getName();
            return variable.equals("super");
        }
        return false;
    }

    public void setMethod(MetaMethod mmeth) {
        this.metaMethod = mmeth;
        super.setType(ClassHelper.make(mmeth.getReturnType()));
    }
}