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Truffle is a multi-language framework for executing dynamic languages
that achieves high performance when combined with Graal.
/*
* Copyright (c) 2018, 2020, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* The Universal Permissive License (UPL), Version 1.0
*
* Subject to the condition set forth below, permission is hereby granted to any
* person obtaining a copy of this software, associated documentation and/or
* data (collectively the "Software"), free of charge and under any and all
* copyright rights in the Software, and any and all patent rights owned or
* freely licensable by each licensor hereunder covering either (i) the
* unmodified Software as contributed to or provided by such licensor, or (ii)
* the Larger Works (as defined below), to deal in both
*
* (a) the Software, and
*
* (b) any piece of software and/or hardware listed in the lrgrwrks.txt file if
* one is included with the Software each a "Larger Work" to which the Software
* is contributed by such licensors),
*
* without restriction, including without limitation the rights to copy, create
* derivative works of, display, perform, and distribute the Software and make,
* use, sell, offer for sale, import, export, have made, and have sold the
* Software and the Larger Work(s), and to sublicense the foregoing rights on
* either these or other terms.
*
* This license is subject to the following condition:
*
* The above copyright notice and either this complete permission notice or at a
* minimum a reference to the UPL must be included in all copies or substantial
* portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
package com.oracle.truffle.api.library;
import java.lang.annotation.ElementType;
import java.lang.annotation.Repeatable;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import com.oracle.truffle.api.nodes.EncapsulatingNodeReference;
/**
* Libraries are specified with public and abstract Java classes that
* extend the {@linkplain Library} class and are annotated by @GenerateLibrary. A
* library consists of a set of messages, that are specified using public Java methods. The methods
* may be abstract or use default implementations. The first parameter of every library message is
* the receiver parameter, which must be a non-primitive type and consistent across all messages of
* a library. There are no restrictions on the return type or argument types of a message. Every
* method that specifies a message must have a name that is unique per library. Final or private
* methods will always be ignored by the generator. Parameter type overloading is currently not
* supported for messages, therefore every public method must have a unique name per library.
* Generic type arguments local to messages are generally supported, but generic type arguments on
* the library type are not yet supported.
*
*
*
Basic Usage
*
* The following example specifies a basic library for arrays:
*
*
* @GenerateLibrary
* public abstract class ArrayLibrary extends Library {
*
* public boolean isArray(Object receiver) {
* return false;
* }
*
* public abstract int read(Object receiver, int index);
* }
*
*
* Messages that are not implemented and have no default implementation throw an
* {@link AbstractMethodError}. The {@link Abstract} annotation can be used, to provide a default
* implementation for receiver types but at the same time make the message abstract.
*
* A library class may also specify {@link DefaultExport default exports} that can be used to
* dispatch to receiver types that don't export the library. Since the receiver type for default
* exports can be specified explicitly, it can be used to provide a default implementation for
* receiver types of third parties or the JDK. For example the Truffle interop library has default
* exports for most {@link Number} types, {@link String} and {@link Boolean} type.
*
* @see DefaultExport to specify default exports.
* @see Abstract to make messages abstract if they have a default implemetnation
* @since 19.0
*/
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE})
public @interface GenerateLibrary {
/**
* Specifies an assertion wrapper class that can be used to verify pre and post conditions of a
* library. Assertion wrappers are only inserted when assertions (-ea) are enabled. It is
* required that assertion wrappers don't introduce additional side-effects and call the
* delegate methods exactly once. If assertions are disabled no library wrapper will be inserted
* therefore not performing any checks when library messages are invoked.
*
*
* Example Usage:
*
*
* @GenerateLibrary(assertions = ArrayAssertions.class)
* public abstract class ArrayLibrary extends Library {
*
* public boolean isArray(Object receiver) {
* return false;
* }
*
* public int read(Object receiver, int index) {
* throw new UnsupportedOperationException();
* }
*
* static class ArrayAssertions extends ArrayLibrary {
*
* @Child private ArrayLibrary delegate;
*
* ArrayAssertions(ArrayLibrary delegate) {
* this.delegate = delegate;
* }
*
* @Override
* public boolean isArray(Object receiver) {
* return delegate.isArray(receiver);
* }
*
* @Override
* public int read(Object receiver, int index) {
* int result = super.read(receiver, index);
* assert delegate.isArray(receiver) : "if a read was successful the receiver must be an array";
* return result;
* }
*
* @Override
* public boolean accepts(Object receiver) {
* return delegate.accepts(receiver);
* }
* }
* }
*
*
*
* @since 19.0
*/
Class assertions() default Library.class;
/**
* Restricts the receiver type for exports that implement this library. This allows to have
* different receiver type in message methods, but require export receiver types to implement or
* extend a declared class. Default exports are not affected by this restriction and can
* therefore export the library for any receiver type the message methods first parameter is
* compatible with.
*
* @since 19.0
*/
Class receiverType() default Object.class;
/**
*
* Specifies {@link GenerateLibrary library} implementations provided by default as a fallback.
* May only be used on classes annotated with Library.
*
* @since 19.0
*/
@Retention(RetentionPolicy.CLASS)
@Target({ElementType.TYPE})
@Repeatable(DefaultExport.Repeat.class)
public @interface DefaultExport {
/**
* @since 19.0
*/
Class value();
/**
* @since 19.0
*/
@Retention(RetentionPolicy.CLASS)
@Target({ElementType.TYPE})
public @interface Repeat {
/**
* @since 19.0
*/
DefaultExport[] value();
}
}
/**
* Makes a library message abstract, but allows to keep a default implementation. By default,
* abstract messages throw an {@link AbstractMethodError} if they are not exported for a given
* receiver type. To customize this behavior the library message can specify a method body and
* annotate it with {@link Abstract} to keep requiring an implementation from exports.
*
* For example:
*
*
* @GenerateLibrary
* public abstract class ArrayLibrary extends Library {
*
* @Abstract(ifExported = "read")
* public boolean isArray(Object receiver) {
* return false;
* }
*
* @Abstract(ifExported = "isArray")
* public int read(Object receiver, int index) {
* throw new UnsupportedOperationException();
* }
* }
*
*
* In this example a receiver that does not export the ArrayLibrary will return
* false for isArray and throw an
* {@linkplain UnsupportedOperationException} for read calls. A message may be made
* conditionally abstract by specifying the {@link Abstract#ifExported()} attribute.
*
* @see #ifExported()
* @since 19.0
*/
@Retention(RetentionPolicy.CLASS)
@Target({ElementType.METHOD})
public @interface Abstract {
/**
* Specifies a message to be abstract only if another message is implemented. Multiple other
* messages can be specified.
*
* For example:
*
*
* @GenerateLibrary
* public abstract class ArrayLibrary extends Library {
*
* @Abstract(ifExported = "read")
* public boolean isArray(Object receiver) {
* return false;
* }
*
* @Abstract(ifExported = "isArray")
* public int read(Object receiver, int index) {
* throw new UnsupportedOperationException();
* }
* }
*
*
* In this example the isArray message only needs to be exported if the read message is
* exported and vice-versa.
*
* @since 19.0
*/
String[] ifExported() default {};
}
/**
* Allows the library to lookup additional default exports using a service provider interface.
* {@link ExportLibrary Exports} for this library with explicit receiver type will automatically
* be interpreted as additional default exports. External default exports may specify with the
* {@link ExportLibrary#priority() priority} whether they are looked up before or after existing
* default exports specified for the library. Default exports always have a lower priority than
* explicit exports on the receiver type or exports that use dynamic dispatch.
*
* @see ExportLibrary#priority()
* @since 20.1
*/
boolean defaultExportLookupEnabled() default false;
/**
* Allows the use of {@link DynamicDispatchLibrary} with this library. By default dynamic
* dispatch is enabled. If this flag is set to false then the
* {@link DynamicDispatchLibrary#dispatch(Object) dispatch} method will not be used for this
* library. Only default exports and exports declared with the receiver type will be used
* instead for this library.
*
* @since 20.1
*/
boolean dynamicDispatchEnabled() default true;
/**
* Enables push and pop of the encapsulating node when a library transitions from cached to
* uncached. The current encapsulating node is needed for correct stack trace location when
* library exports perform guest language calls. If a library is known to never need correct
* stack trace information, e.g. if all exports are known to not perform guest language calls,
* then pushing and popping of encapsulating nodes can be disabled. By default pushing and
* popping of encapsulating nodes is enabled.
*
* @see EncapsulatingNodeReference
* @since 20.3
*/
boolean pushEncapsulatingNode() default true;
}