JDK14/Java14源码在线阅读
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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* published by the Free Software Foundation. Oracle designates this
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*
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* 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).
*
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* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
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package jdk.jshell.spi;
import java.io.Serializable;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.ServiceLoader;
import java.util.Set;
/**
* 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.
*
* @since 9
*/
public interface ExecutionControl extends AutoCloseable {
/**
* 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;
/**
* 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.
*/
@Override
void close();
/**
* Search for a provider, then create and return the
* {@code ExecutionControl} instance.
*
* @param env the execution environment (provided by JShell)
* @param name the name of provider
* @param parameters the parameter map.
* @return the execution engine
* @throws Throwable an exception that occurred attempting to find or create
* the execution engine.
* @throws IllegalArgumentException if no ExecutionControlProvider has the
* specified {@code name} and {@code parameters}.
*/
static ExecutionControl generate(ExecutionEnv env, String name, Map<String, String> parameters)
throws Throwable {
Set<String> keys = parameters == null
? Collections.emptySet()
: parameters.keySet();
for (ExecutionControlProvider p : ServiceLoader.load(ExecutionControlProvider.class)) {
if (p.name().equals(name)
&& p.defaultParameters().keySet().containsAll(keys)) {
return p.generate(env, parameters);
}
}
throw new IllegalArgumentException("No ExecutionControlProvider with name '"
+ name + "' and parameter keys: " + keys.toString());
}
/**
* Search for a provider, then create and return the
* {@code ExecutionControl} instance.
*
* @param env the execution environment (provided by JShell)
* @param spec the {@code ExecutionControl} spec, which is described in
* the documentation of this
* {@linkplain jdk.jshell.spi package documentation}.
* @return the execution engine
* @throws Throwable an exception that occurred attempting to find or create
* the execution engine.
* @throws IllegalArgumentException if no ExecutionControlProvider has the
* specified {@code name} and {@code parameters}.
* @throws IllegalArgumentException if {@code spec} is malformed
*/
static ExecutionControl generate(ExecutionEnv env, String spec)
throws Throwable {
class SpecReader {
int len = spec.length();
int i = -1;
char ch;
SpecReader() {
next();
}
boolean more() {
return i < len;
}
char current() {
return ch;
}
final boolean next() {
++i;
if (i < len) {
ch = spec.charAt(i);
return true;
}
i = len;
return false;
}
void skipWhite() {
while (more() && Character.isWhitespace(ch)) {
next();
}
}
String readId() {
skipWhite();
StringBuilder sb = new StringBuilder();
while (more() && Character.isJavaIdentifierPart(ch)) {
sb.append(ch);
next();
}
skipWhite();
String id = sb.toString();
if (id.isEmpty()) {
throw new IllegalArgumentException("Expected identifier in " + spec);
}
return id;
}
void expect(char exp) {
skipWhite();
if (!more() || ch != exp) {
throw new IllegalArgumentException("Expected '" + exp + "' in " + spec);
}
next();
skipWhite();
}
String readValue() {
expect('(');
int parenDepth = 1;
StringBuilder sb = new StringBuilder();
while (more()) {
if (ch == ')') {
--parenDepth;
if (parenDepth == 0) {
break;
}
} else if (ch == '(') {
++parenDepth;
}
sb.append(ch);
next();
}
expect(')');
return sb.toString();
}
}
Map<String, String> parameters = new HashMap<>();
SpecReader sr = new SpecReader();
String name = sr.readId();
if (sr.more()) {
sr.expect(':');
while (sr.more()) {
String key = sr.readId();
String value = sr.readValue();
parameters.put(key, value);
if (sr.more()) {
sr.expect(',');
}
}
}
return generate(env, name, parameters);
}
/**
* 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>
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