/*
* Copyright (c) 2016, 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
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*/
package jdk.jshell.spi;
import java.io.Serializable;
/**
* This interface specifies the functionality that must provided to implement a
* pluggable JShell execution engine.
* <p>
* The audience for this Service Provider Interface is engineers wishing to
* implement their own version of the execution engine in support of the JShell
* API.
* <p>
* A Snippet is compiled into code wrapped in a 'wrapper class'. The execution
* engine is used by the core JShell implementation to load and, for executable
* Snippets, execute the Snippet.
* <p>
* Methods defined in this interface should only be called by the core JShell
* implementation.
* <p>
* To install an {@code ExecutionControl}, its {@code Generator} is passed to
* {@link jdk.jshell.JShell.Builder#executionEngine(ExecutionControl.Generator) }.
*/
public interface ExecutionControl extends AutoCloseable {
/**
* Defines a functional interface for creating {@link ExecutionControl}
* instances.
*/
@FunctionalInterface
public interface Generator {
/**
* Generates an execution engine, given an execution environment.
*
* @param env the context in which the {@link ExecutionControl} is to
* be created
* @return the created instance
* @throws Throwable if problems occurred
*/
ExecutionControl generate(ExecutionEnv env) throws Throwable;
}
/**
* Attempts to load new classes.
*
* @param cbcs the class name and bytecodes to load
* @throws ClassInstallException exception occurred loading the classes,
* some or all were not loaded
* @throws NotImplementedException if not implemented
* @throws EngineTerminationException the execution engine has terminated
*/
void load(ClassBytecodes[] cbcs)
throws ClassInstallException, NotImplementedException, EngineTerminationException;
/**
* Attempts to redefine previously loaded classes.
*
* @param cbcs the class name and bytecodes to redefine
* @throws ClassInstallException exception occurred redefining the classes,
* some or all were not redefined
* @throws NotImplementedException if not implemented
* @throws EngineTerminationException the execution engine has terminated
*/
void redefine(ClassBytecodes[] cbcs)
throws ClassInstallException, NotImplementedException, EngineTerminationException;
/**
* Invokes an executable Snippet by calling a method on the specified
* wrapper class. The method must have no arguments and return String.
*
* @param className the class whose method should be invoked
* @param methodName the name of method to invoke
* @return the result of the execution or null if no result
* @throws UserException the invoke raised a user exception
* @throws ResolutionException the invoke attempted to directly or
* indirectly invoke an unresolved snippet
* @throws StoppedException if the {@code invoke()} was canceled by
* {@link ExecutionControl#stop}
* @throws EngineTerminationException the execution engine has terminated
* @throws InternalException an internal problem occurred
*/
String invoke(String className, String methodName)
throws RunException, EngineTerminationException, InternalException;
/**
* Returns the value of a variable.
*
* @param className the name of the wrapper class of the variable
* @param varName the name of the variable
* @return the value of the variable
* @throws UserException formatting the value raised a user exception
* @throws ResolutionException formatting the value attempted to directly or
* indirectly invoke an unresolved snippet
* @throws StoppedException if the formatting the value was canceled by
* {@link ExecutionControl#stop}
* @throws EngineTerminationException the execution engine has terminated
* @throws InternalException an internal problem occurred
*/
String varValue(String className, String varName)
throws RunException, EngineTerminationException, InternalException;
/**
* Adds the path to the execution class path.
*
* @param path the path to add
* @throws EngineTerminationException the execution engine has terminated
* @throws InternalException an internal problem occurred
*/
void addToClasspath(String path)
throws EngineTerminationException, InternalException;
/**
* Sets the execution class path to the specified path.
*
* @param path the path to add
* @throws EngineTerminationException the execution engine has terminated
* @throws InternalException an internal problem occurred
*/
void setClasspath(String path)
throws EngineTerminationException, InternalException;
/**
* Interrupts a running invoke.
*
* @throws EngineTerminationException the execution engine has terminated
* @throws InternalException an internal problem occurred
*/
void stop()
throws EngineTerminationException, InternalException;
/**
* Run a non-standard command (or a standard command from a newer version).
*
* @param command the non-standard command
* @param arg the commands argument
* @return the commands return value
* @throws UserException the command raised a user exception
* @throws ResolutionException the command attempted to directly or
* indirectly invoke an unresolved snippet
* @throws StoppedException if the command was canceled by
* {@link ExecutionControl#stop}
* @throws EngineTerminationException the execution engine has terminated
* @throws NotImplementedException if not implemented
* @throws InternalException an internal problem occurred
*/
Object extensionCommand(String command, Object arg)
throws RunException, EngineTerminationException, InternalException;
/**
* Shuts down this execution engine. Implementation should free all
* resources held by this execution engine.
* <p>
* No calls to methods on this interface should be made after close.
*/
void close();
/**
* Bundles class name with class bytecodes.
*/
public static final class ClassBytecodes implements Serializable {
private static final long serialVersionUID = 0xC1A55B47EC0DE5L;
private final String name;
private final byte[] bytecodes;
/**
* Creates a name/bytecode pair.
* @param name the class name
* @param bytecodes the class bytecodes
*/
public ClassBytecodes(String name, byte[] bytecodes) {
this.name = name;
this.bytecodes = bytecodes;
}
/**
* The bytecodes for the class.
*
* @return the bytecodes
*/
public byte[] bytecodes() {
return bytecodes;
}
/**
* The class name.
*
* @return the class name
*/
public String name() {
return name;
}
}
/**
* The abstract base of all {@code ExecutionControl} exceptions.
*/
public static abstract class ExecutionControlException extends Exception {
private static final long serialVersionUID = 1L;
public ExecutionControlException(String message) {
super(message);
}
}
/**
* Unbidden execution engine termination has occurred.
*/
public static class EngineTerminationException extends ExecutionControlException {
private static final long serialVersionUID = 1L;
public EngineTerminationException(String message) {
super(message);
}
}
/**
* The command is not implemented.
*/
public static class NotImplementedException extends InternalException {
private static final long serialVersionUID = 1L;
public NotImplementedException(String message) {
super(message);
}
}
/**
* An internal problem has occurred.
*/
public static class InternalException extends ExecutionControlException {
private static final long serialVersionUID = 1L;
public InternalException(String message) {
super(message);
}
}
/**
* A class install (load or redefine) encountered a problem.
*/
public static class ClassInstallException extends ExecutionControlException {
private static final long serialVersionUID = 1L;
private final boolean[] installed;
public ClassInstallException(String message, boolean[] installed) {
super(message);
this.installed = installed;
}
/**
* Indicates which of the passed classes were successfully
* loaded/redefined.
* @return a one-to-one array with the {@link ClassBytecodes}{@code[]}
* array -- {@code true} if installed
*/
public boolean[] installed() {
return installed;
}
}
/**
* The abstract base of of exceptions specific to running user code.
*/
public static abstract class RunException extends ExecutionControlException {
private static final long serialVersionUID = 1L;
private RunException(String message) {
super(message);
}
}
/**
* A 'normal' user exception occurred.
*/
public static class UserException extends RunException {
private static final long serialVersionUID = 1L;
private final String causeExceptionClass;
public UserException(String message, String causeExceptionClass, StackTraceElement[] stackElements) {
super(message);
this.causeExceptionClass = causeExceptionClass;
this.setStackTrace(stackElements);
}
/**
* Returns the class of the user exception.
* @return the name of the user exception class
*/
public String causeExceptionClass() {
return causeExceptionClass;
}
}
/**
* An exception indicating that a {@code DeclarationSnippet} with unresolved
* references has been encountered.
* <p>
* Contrast this with the initiating {@link SPIResolutionException}
* (a {@code RuntimeException}) which is embedded in generated corralled
* code. Also, contrast this with
* {@link jdk.jshell.UnresolvedReferenceException} the high-level
* exception (with {@code DeclarationSnippet} reference) provided in the
* main API.
*/
public static class ResolutionException extends RunException {
private static final long serialVersionUID = 1L;
private final int id;
/**
* Constructs an exception indicating that a {@code DeclarationSnippet}
* with unresolved references has been encountered.
*
* @param id An internal identifier of the specific method
* @param stackElements the stack trace
*/
public ResolutionException(int id, StackTraceElement[] stackElements) {
super("resolution exception: " + id);
this.id = id;
this.setStackTrace(stackElements);
}
/**
* Retrieves the internal identifier of the unresolved identifier.
*
* @return the internal identifier
*/
public int id() {
return id;
}
}
/**
* An exception indicating that an
* {@link ExecutionControl#invoke(java.lang.String, java.lang.String) }
* (or theoretically a
* {@link ExecutionControl#varValue(java.lang.String, java.lang.String) })
* has been interrupted by a {@link ExecutionControl#stop() }.
*/
public static class StoppedException extends RunException {
private static final long serialVersionUID = 1L;
public StoppedException() {
super("stopped by stop()");
}
}
}