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view truffle/com.oracle.truffle.api.interop/src/com/oracle/truffle/api/interop/Message.java @ 22548:6b76a24fffbd default tip
Use all variables: a, b, u,v and x, y
author | Jaroslav Tulach <jaroslav.tulach@oracle.com> |
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date | Thu, 14 Jan 2016 14:20:57 +0100 |
parents | 6af6ca6c848e |
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/* * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package com.oracle.truffle.api.interop; import com.oracle.truffle.api.TruffleLanguage.Env; import com.oracle.truffle.api.frame.VirtualFrame; import com.oracle.truffle.api.interop.ForeignAccess.Factory; import com.oracle.truffle.api.nodes.Node; /** * Inter-operability is based on sending messages. Standard messages are defined as as constants * like {@link #IS_NULL} or factory methods in this class, but one can always define their own, * specialized messages. */ public abstract class Message { /** * One can define their own extended message by subclassing. The expectation is that the * subclass will have public constructor and its {@link #equals(java.lang.Object)} and * {@link #hashCode()} methods will operate on the class equivalence. Only then the subclass * will work properly with {@link #valueOf(java.lang.String)} and * {@link #toString(com.oracle.truffle.api.interop.Message)} methods. */ protected Message() { } /** * Message to read an object field. The * {@link Factory#access(com.oracle.truffle.api.interop.Message) target} created for this * message accepts (in addition to a * {@link ForeignAccess#getReceiver(com.oracle.truffle.api.frame.Frame) receiver}) a single * {@link ForeignAccess#getArguments(com.oracle.truffle.api.frame.Frame) argument} identifying a * field to read - e.g. either {@link String} or an {@link Integer} - if access to an array at * particular index is requested. The code that wants to send this message should use: * * <pre> * {@link ForeignAccess}.{@link ForeignAccess#execute(com.oracle.truffle.api.nodes.Node, com.oracle.truffle.api.frame.VirtualFrame, com.oracle.truffle.api.interop.TruffleObject, java.lang.Object...) execute}( * {@link Message#READ}.{@link Message#createNode()}, {@link VirtualFrame currentFrame}, receiver, nameOfTheField * ); * </pre> * * Where <code>receiver</code> is the {@link TruffleObject foreign object} to access and * <code>nameOfTheField</code> is the name (or index) of its field. * <p> * To achieve good performance it is essential to cache/keep reference to the * {@link Message#createNode() created node}. */ public static final Message READ = Read.INSTANCE; /** * Converts {@link TruffleObject truffle value} to Java primitive type. Primitive types are * subclasses of {@link Number}, {@link Boolean}, {@link Character} and {@link String}. Before * sending the {@link #UNBOX} message, it is desirable to send the {@link #IS_BOXED} one and * verify that the object can really be unboxed. To unbox an object, use: * * <pre> * {@link ForeignAccess}.{@link ForeignAccess#execute(com.oracle.truffle.api.nodes.Node, com.oracle.truffle.api.frame.VirtualFrame, com.oracle.truffle.api.interop.TruffleObject, java.lang.Object...) execute}( * {@link Message#UNBOX}.{@link Message#createNode()}, {@link VirtualFrame currentFrame}, objectToUnbox * ); * </pre> * * The returned value should be subclass of {@link Number}, {@link Boolean}, {@link Character} * or {@link String}. * <p> * To achieve good performance it is essential to cache/keep reference to the * {@link Message#createNode() created node}. */ public static final Message UNBOX = Unbox.INSTANCE; /** * Message to write a field. The {@link Factory#access(com.oracle.truffle.api.interop.Message) * target} created for this message accepts the object to modify as a * {@link ForeignAccess#getReceiver(com.oracle.truffle.api.frame.Frame) receiver} and two * {@link ForeignAccess#getArguments(com.oracle.truffle.api.frame.Frame) arguments}. The first * one identifies a field to read - e.g. either {@link String} or an {@link Integer} - if access * to an array at particular index is requested. The second one is the value to assign to such * field. Use following style to construct field modification message: * * <pre> * {@link ForeignAccess}.{@link ForeignAccess#execute(com.oracle.truffle.api.nodes.Node, com.oracle.truffle.api.frame.VirtualFrame, com.oracle.truffle.api.interop.TruffleObject, java.lang.Object...) execute}( * {@link Message#WRITE}.{@link Message#createNode()}, {@link VirtualFrame currentFrame}, receiver, nameOfTheField, newValue * ); * </pre> * * Where <code>receiver</code> is the {@link TruffleObject foreign object} to access, * <code>nameOfTheField</code> is the name (or index) of its field and <code>newValue</code> is * the value to assign to the receiver's field. * <p> * To achieve good performance it is essential to cache/keep reference to the * {@link Message#createNode() created node}. */ public static Message WRITE = Write.INSTANCE; /** * Creates a non-object oriented execution message. In contrast to {@link #createInvoke(int)} * messages, which are more suitable for dealing with object oriented style of programming, * messages created by this method are more suitable for execution where one can explicitly * control all passed in arguments. * <p> * To inter-operate with a non-OOP language like <em>C</em> - for example to execute its * function: * * <pre> * <b>double</b> add(<b>double</b> a, <b>double</b> b) { * <b>return</b> a + b; * } * </pre> * * One can obtain reference to the <em>add</em> function (for example by * {@link Env#importSymbol(java.lang.String) importing it as a global symbol}) and store it into * variable <code>addFunction</code>. Then it's time to check the object is executable by * sending it the {@link #IS_EXECUTABLE} message. If the answer is <code>true</code> one can: * * <pre> * {@link ForeignAccess}.{@link ForeignAccess#execute(com.oracle.truffle.api.nodes.Node, com.oracle.truffle.api.frame.VirtualFrame, com.oracle.truffle.api.interop.TruffleObject, java.lang.Object...) execute}( * {@link Message#createExecute(int) Message.createExecute}(2).{@link Message#createNode()}, {@link VirtualFrame currentFrame}, addFunction, valueOfA, valueOfB * ); * </pre> * * The <code>valueOfA</code> and <code>valueOfB</code> should be <code>double</code> or * {@link Double} or at least be {@link #UNBOX unboxable} to such type. * <p> * One can use this method to talk to object oriented language as well, however one needs to pay * attention to provide all necessary arguments manually - usually an OOP language requires the * first argument to represent <code>this</code> or <code>self</code> and only then pass in the * additional arguments. It may be easier to use {@link #createInvoke(int)} message which is * more suitable for object oriented languages and handles (if supported) the arguments * manipulation automatically. * <p> * * * <p> * All messages created by this method are {@link Object#equals(java.lang.Object) equal} to each * other regardless of the value of <code>argumentsLength</code>. * * @param argumentsLength number of parameters to pass to the target * @return execute message */ public static Message createExecute(int argumentsLength) { return Execute.create(Execute.EXECUTE, argumentsLength); } /** * Message to check executability of a * {@link ForeignAccess#getReceiver(com.oracle.truffle.api.frame.Frame) foreign object}. * <p> * Calling {@link Factory#access(com.oracle.truffle.api.interop.Message) the target} created for * this message accepts {@link ForeignAccess#getArguments(com.oracle.truffle.api.frame.Frame) no * arguments} and a single non-null * {@link ForeignAccess#getReceiver(com.oracle.truffle.api.frame.Frame) receiver}. The call * should yield value of {@link Boolean}. Either {@link Boolean#TRUE} if the receiver can be * executed (e.g. accepts {@link #createExecute(int)} message, or {@link Boolean#FALSE} * otherwise. This is the way to send the <code>IS_EXECUTABLE</code> message: * * <pre> * {@link Boolean} canBeExecuted = ({@link Boolean}) {@link ForeignAccess}.execute( * {@link Message#IS_EXECUTABLE}.{@link Message#createNode()}, {@link VirtualFrame currentFrame}, receiver * ); * </pre> * <p> * To achieve good performance it is essential to cache/keep reference to the * {@link Message#createNode() created node}. */ public static final Message IS_EXECUTABLE = IsExecutable.INSTANCE; /** * Creates an object oriented execute message. Unlike {@link #createExecute(int)} the receiver * of the message isn't the actual function to invoke, but an object. The object has the * function as a field, or as a field of its class, or whatever is appropriate for an object * oriented language. * <p> * Languages that don't support object oriented semantics do not and should not implement this * message. When the invoke message isn't supported, the caller is expected to fall back into * following basic operations: * <ul> * <li>sending {@link #READ} message to access the field</li> * <li>verify the result {@link #IS_EXECUTABLE}, if so continue by</li> * <li>sending {@link #createExecute(int) execute message}</li> * </ul> * <p> * The last step is problematic, as it is not clear whether to pass just the execution * arguments, or prefix them with the original receiver (aka <code>this</code> or * <code>self</code>). Object oriented languages would in general welcome obtaining the * receiving object as first argument, non-object languages like <em>C</em> would get confused * by doing so. However it is not possible for the caller to find out what language one is * sending message to - only the set of supported messages is known. As a result it is * recommended for object oriented languages to support the {@link #createInvoke(int)} message * and handle the semantics the way it is natural to them. Languages like <em>C</em> shouldn't * implement {@link #createInvoke(int)} and just support primitive operations like * {@link #createExecute(int)} and {@link #READ}. * <p> * When accessing a method of an object in an object oriented manner, one is supposed to send * the {@link #createInvoke(int)} message first. Only when that fails, fallback to non-object * oriented workflow with {@link #createExecute(int)}. Imagine there is a <em>Java</em> class * with <code>add</code> method and its instance: * * <pre> * <b>public class</b> Arith { * <b>public double</b> add(double a, double b) { * <b>return</b> a + b; * } * } * Arith obj = <b>new</b> Arith(); * </pre> * * To access <code>obj</code>'s <code>add</code> method one should use: * * <pre> * <b>try</b> { * {@link ForeignAccess}.{@link ForeignAccess#execute(com.oracle.truffle.api.nodes.Node, com.oracle.truffle.api.frame.VirtualFrame, com.oracle.truffle.api.interop.TruffleObject, java.lang.Object...) execute}( * {@link Message#createInvoke(int) Message.createInvoke}(2).{@link Message#createNode()}, {@link VirtualFrame currentFrame}, obj, "add", valueOfA, valueOfB * ); * } <b>catch</b> ({@link IllegalArgumentException} ex) { * // access the language via {@link #createExecute(int)} * } * </pre> * * The <code>valueOfA</code> and <code>valueOfB</code> should be <code>double</code> or * {@link Double} or at least be {@link #UNBOX unboxable} to such type. * <p> * All messages created by this method are {@link Object#equals(java.lang.Object) equal} to each * other regardless of the value of <code>argumentsLength</code>. The expected behavior of this * message is to perform {@link #READ} first and on the result invoke * {@link #createExecute(int)}. * * @param argumentsLength number of parameters to pass to the target * @return message combining read & execute messages tailored for use with object oriented * languages */ public static Message createInvoke(int argumentsLength) { return Execute.create(Execute.INVOKE, argumentsLength); } /** * Creates an allocation message. All messages created by this method are * {@link Object#equals(java.lang.Object) equal} to each other regardless of the value of * <code>argumentsLength</code>. The expected behavior of this message is to allocate a new * instance of the {@link ForeignAccess#getReceiver(com.oracle.truffle.api.frame.Frame) * receiver} and then perform its constructor with appropriate number of arguments. * * @param argumentsLength number of parameters to pass to the target * @return new instance message */ public static Message createNew(int argumentsLength) { return Execute.create(Execute.NEW, argumentsLength); } /** * Check for <code>null</code> message. The Truffle languages are suggested to have their own * object representing <code>null</code> like values in their languages. For purposes of * inter-operability it is essential to canonicalize such values from time to time - sending * this message is a way to recognize such <code>null</code> representing values: * * <pre> * {@link Boolean} isNull = ({@link Boolean}) {@link ForeignAccess}.execute( * {@link Message#IS_NULL}.{@link Message#createNode()}, {@link VirtualFrame currentFrame}, objectToCheckForNull * ); * </pre> * * <p> * Calling {@link Factory#access(com.oracle.truffle.api.interop.Message) the target} created for * this message should yield value of {@link Boolean}. * <p> * To achieve good performance it is essential to cache/keep reference to the * {@link Message#createNode() created node}. */ public static final Message IS_NULL = IsNull.INSTANCE; /** * Message to check for having a size. * <p> * Calling {@link Factory#access(com.oracle.truffle.api.interop.Message) the target} created for * this message should yield value of {@link Boolean}. */ public static final Message HAS_SIZE = HasSize.INSTANCE; /** * Getter of the size. If {@link #HAS_SIZE supported}, this message allows to obtain a size (of * an array). * <p> * Calling {@link Factory#access(com.oracle.truffle.api.interop.Message) the target} created for * this message should yield value of {@link Integer}. */ public static final Message GET_SIZE = GetSize.INSTANCE; /** * Check for value being boxed. Can the {@link TruffleObject foreign object} be converted to one * of the basic Java types? Many languages have a special representation for types like number, * string, etc. To ensure inter-operability, these types should support unboxing - if they do, * they should handle this message and return {@link Boolean#TRUE}. The way to check whether an * object is boxed is: * * <pre> * {@link Boolean} isBoxed = ({@link Boolean}) {@link ForeignAccess}.execute( * {@link Message#IS_BOXED}.{@link Message#createNode()}, {@link VirtualFrame currentFrame}, objectToCheck * ); * </pre> * * Calling {@link Factory#accessMessage(com.oracle.truffle.api.interop.Message) the target} * created for this message should yield value of {@link Boolean}. If the object responds with * {@link Boolean#TRUE}, it is safe to continue by sending it {@link #UNBOX} message. */ public static final Message IS_BOXED = IsBoxed.INSTANCE; /** * Compares types of two messages. Messages are encouraged to implement this method. All * standard ones ({@link #IS_NULL}, {@link #READ}, etc.) do so. Messages obtained via the same * {@link #createExecute(int) method} are equal, messages obtained by different methods or * fields are not. * * @param message the object to compare to * @return true, if the structure of the message is that same as of <code>this</code> one. */ @Override public abstract boolean equals(Object message); /** * When re-implementing {@link #equals(java.lang.Object)}, it is generally recommended to also * implement <code>hashCode()</code>. * * @return hash code */ @Override public abstract int hashCode(); /** * Creates an AST node for this message. The node can be inserted into AST of your language and * will handle communication with the foreign language. * * @return node to be inserted into your AST and passed back to * {@link ForeignAccess#execute(com.oracle.truffle.api.nodes.Node, com.oracle.truffle.api.frame.VirtualFrame, com.oracle.truffle.api.interop.TruffleObject, java.lang.Object[])} * method. */ public final Node createNode() { return new ForeignObjectAccessHeadNode(this); } /** * Converts the message into canonical string representation. The converted string can be * stored, persisted, transfered and later passed to {@link #valueOf(java.lang.String)} to * construct the message again. * * @param message the message to convert * @return canonical string representation */ public static String toString(Message message) { if (Message.READ == message) { return "READ"; // NOI18N } if (Message.WRITE == message) { return "WRITE"; // NOI18N } if (Message.UNBOX == message) { return "UNBOX"; // NOI18N } if (Message.GET_SIZE == message) { return "GET_SIZE"; // NOI18N } if (Message.HAS_SIZE == message) { return "HAS_SIZE"; // NOI18N } if (Message.IS_NULL == message) { return "IS_NULL"; // NOI18N } if (Message.IS_BOXED == message) { return "IS_BOXED"; // NOI18N } if (Message.IS_EXECUTABLE == message) { return "IS_EXECUTABLE"; // NOI18N } if (message instanceof Execute) { return ((Execute) message).name(); } return message.getClass().getName(); } /** * Converts string representation into real message. If the string was obtained by * {@link #toString(com.oracle.truffle.api.interop.Message)} method, it is guaranteed to be * successfully recognized (if the classpath of the system remains the same). * * @param message canonical string representation of a message * @return the message * @throws IllegalArgumentException if the string does not represent known message */ public static Message valueOf(String message) { try { return (Message) Message.class.getField(message).get(null); } catch (Exception ex) { try { String factory = "create" + message.charAt(0) + message.substring(1).toLowerCase(); return (Message) Message.class.getMethod(factory, int.class).invoke(null, 0); } catch (Exception ex2) { try { ClassLoader l = Message.class.getClassLoader(); if (l == null) { l = ClassLoader.getSystemClassLoader(); } return (Message) Class.forName(message, false, l).newInstance(); } catch (Exception ex1) { throw new IllegalArgumentException("Cannot find message for " + message, ex); } } } } }