8172183: Provide a javadoc description for jdk.dynalink module
Reviewed-by: attila, jlaskey
This commit is contained in:
Athijegannathan Sundararajan
parent
f8ccef1982
commit
fe1956e041
nashorn
@ -24,33 +24,33 @@ and downlaoded using
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You can clone Nashorn Mercurial forest using this command:
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hg fclone http://hg.openjdk.java.net/nashorn/jdk8 nashorn~jdk8
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hg fclone http://hg.openjdk.java.net/nashorn/jdk9 nashorn~jdk9
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To update your copy of the forest (fwith the latest code:
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(cd nashorn~jdk8 ; hg fpull)
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(cd nashorn~jdk9 ; hg fpull)
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Or just the nashorn subdirectory with
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(cd nashorn~jdk8/nashorn ; hg pull -u)
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(cd nashorn~jdk9/nashorn ; hg pull -u)
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To learn about Mercurial in detail, please visit http://hgbook.red-bean.com.
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- How to build?
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To build Nashorn, you need to install JDK 8. You may use the Nashorn
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To build Nashorn, you need to install JDK 9. You may use the Nashorn
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forest build (recommended) or down load from java.net. You will need to
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set JAVA_HOME environmental variable to point to your JDK installation
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directory.
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cd nashorn~jdk8/nashorn/make
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cd nashorn~jdk9/nashorn/make
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ant clean; ant
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- How to run?
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Use the jjs script (see RELESE_README):
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cd nashorn~jdk8/nashorn
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cd nashorn~jdk9/nashorn
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sh bin/jjs <your .js file>
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Nashorn supports javax.script API. It is possible to drop nashorn.jar in
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@ -64,7 +64,7 @@ Look for samples under the directory test/src/jdk/nashorn/api/scripting/.
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Comprehensive development documentation is found in the Nashorn JavaDoc. You can
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build it using:
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cd nashorn~jdk8/nashorn/make
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cd nashorn~jdk9/nashorn/make
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ant javadoc
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after which you can view the generated documentation at dist/javadoc/index.html.
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@ -90,7 +90,7 @@ Alternatively, you can check it out elsewhere and make
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test/script/external/test262 a symbolic link to that directory. After
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you've done this, you can run the ECMA-262 tests using:
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cd nashorn~jdk8/nashorn/make
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cd nashorn~jdk9/nashorn/make
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ant test262
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Ant target to get/update external test suites:
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@ -101,7 +101,7 @@ Ant target to get/update external test suites:
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These tests take time, so we have a parallelized runner for them that
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takes advantage of all processor cores on the computer:
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cd nashorn~jdk8/nashorn/make
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cd nashorn~jdk9/nashorn/make
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ant test262parallel
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- How to write your own test?
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@ -1,20 +0,0 @@
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The Nashorn repo is in the process of being migrated to OpenJDK and as such is
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incomplete in several areas.
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- The build system is not fully integrated. When complete, Nashorn will be
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installed in its proper location in the JRE.
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- Once integrated, the correct version of the JDK will be wrapped around
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Nashorn. In the meantime, ensure you use JDK8 b68 or later.
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- The jjs tool has not been implemented in binary form yet. Use "sh bin/jjs"
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(or bin/jjs.bat on windows) in the interm.
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- The Dynalink component is not fully integrated into Nashorn as yet, but will
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be when details are finalized.
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- And, finally Nashorn is still in development. To stay up to date, subscribe
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to nashorn-dev@openjdk.java.net at
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http://mail.openjdk.java.net/mailman/listinfo/nashorn-dev.
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@ -82,197 +82,6 @@
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*/
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/**
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* <p>
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* Dynalink is a library for dynamic linking of high-level operations on objects.
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* These operations include "read a property",
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* "write a property", "invoke a function" and so on. Dynalink is primarily
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* useful for implementing programming languages where at least some expressions
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* have dynamic types (that is, types that can not be decided statically), and
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* the operations on dynamic types are expressed as
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* {@link java.lang.invoke.CallSite call sites}. These call sites will be
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* linked to appropriate target {@link java.lang.invoke.MethodHandle method handles}
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* at run time based on actual types of the values the expressions evaluated to.
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* These can change between invocations, necessitating relinking the call site
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* multiple times to accommodate new types; Dynalink handles all that and more.
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* <p>
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* Dynalink supports implementation of programming languages with object models
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* that differ (even radically) from the JVM's class-based model and have their
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* custom type conversions.
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* <p>
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* Dynalink is closely related to, and relies on, the {@link java.lang.invoke}
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* package.
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* <p>
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*
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* While {@link java.lang.invoke} provides a low level API for dynamic linking
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* of {@code invokedynamic} call sites, it does not provide a way to express
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* higher level operations on objects, nor methods that implement them. These
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* operations are the usual ones in object-oriented environments: property
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* access, access of elements of collections, invocation of methods and
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* constructors (potentially with multiple dispatch, e.g. link- and run-time
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* equivalents of Java overloaded method resolution). These are all functions
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* that are normally desired in a language on the JVM. If a language is
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* statically typed and its type system matches that of the JVM, it can
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* accomplish this with use of the usual invocation, field access, etc.
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* instructions (e.g. {@code invokevirtual}, {@code getfield}). However, if the
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* language is dynamic (hence, types of some expressions are not known until
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* evaluated at run time), or its object model or type system don't match
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* closely that of the JVM, then it should use {@code invokedynamic} call sites
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* instead and let Dynalink manage them.
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* <h2>Example</h2>
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* Dynalink is probably best explained by an example showing its use. Let's
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* suppose you have a program in a language where you don't have to declare the
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* type of an object and you want to access a property on it:
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* <pre>
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* var color = obj.color;
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* </pre>
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* If you generated a Java class to represent the above one-line program, its
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* bytecode would look something like this:
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* <pre>
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* aload 2 // load "obj" on stack
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* invokedynamic "GET:PROPERTY:color"(Object)Object // invoke property getter on object of unknown type
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* astore 3 // store the return value into local variable "color"
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* </pre>
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* In order to link the {@code invokedynamic} instruction, we need a bootstrap
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* method. A minimalist bootstrap method with Dynalink could look like this:
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* <pre>
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* import java.lang.invoke.*;
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* import jdk.dynalink.*;
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* import jdk.dynalink.support.*;
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*
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* class MyLanguageRuntime {
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* private static final DynamicLinker dynamicLinker = new DynamicLinkerFactory().createLinker();
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*
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* public static CallSite bootstrap(MethodHandles.Lookup lookup, String name, MethodType type) {
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* return dynamicLinker.link(
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* new SimpleRelinkableCallSite(
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* new CallSiteDescriptor(lookup, parseOperation(name), type)));
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* }
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*
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* private static Operation parseOperation(String name) {
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* ...
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* }
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* }
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* </pre>
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* There are several objects of significance in the above code snippet:
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* <ul>
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* <li>{@link jdk.dynalink.DynamicLinker} is the main object in Dynalink, it
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* coordinates the linking of call sites to method handles that implement the
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* operations named in them. It is configured and created using a
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* {@link jdk.dynalink.DynamicLinkerFactory}.</li>
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* <li>When the bootstrap method is invoked, it needs to create a
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* {@link java.lang.invoke.CallSite} object. In Dynalink, these call sites need
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* to additionally implement the {@link jdk.dynalink.RelinkableCallSite}
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* interface. "Relinkable" here alludes to the fact that if the call site
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* encounters objects of different types at run time, its target will be changed
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* to a method handle that can perform the operation on the newly encountered
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* type. {@link jdk.dynalink.support.SimpleRelinkableCallSite} and
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* {@link jdk.dynalink.support.ChainedCallSite} (not used in the above example)
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* are two implementations already provided by the library.</li>
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* <li>Dynalink uses {@link jdk.dynalink.CallSiteDescriptor} objects to
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* preserve the parameters to the bootstrap method: the lookup and the method type,
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* as it will need them whenever it needs to relink a call site.</li>
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* <li>Dynalink uses {@link jdk.dynalink.Operation} objects to express
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* dynamic operations. It does not prescribe how would you encode the operations
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* in your call site, though. That is why in the above example the
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* {@code parseOperation} function is left empty, and you would be expected to
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* provide the code to parse the string {@code "GET:PROPERTY:color"}
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* in the call site's name into a named property getter operation object as
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* {@code StandardOperation.GET.withNamespace(StandardNamespace.PROPERTY).named("color")}.
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* </ul>
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* <p>What can you already do with the above setup? {@code DynamicLinkerFactory}
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* by default creates a {@code DynamicLinker} that can link Java objects with the
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* usual Java semantics. If you have these three simple classes:
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* <pre>
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* public class A {
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* public String color;
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* public A(String color) { this.color = color; }
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* }
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*
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* public class B {
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* private String color;
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* public B(String color) { this.color = color; }
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* public String getColor() { return color; }
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* }
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*
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* public class C {
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* private int color;
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* public C(int color) { this.color = color; }
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* public int getColor() { return color; }
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* }
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* </pre>
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* and you somehow create their instances and pass them to your call site in your
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* programming language:
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* <pre>
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* for each(var obj in [new A("red"), new B("green"), new C(0x0000ff)]) {
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* print(obj.color);
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* }
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* </pre>
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* then on first invocation, Dynalink will link the {@code .color} getter
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* operation to a field getter for {@code A.color}, on second invocation it will
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* relink it to {@code B.getColor()} returning a {@code String}, and finally on
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* third invocation it will relink it to {@code C.getColor()} returning an {@code int}.
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* The {@code SimpleRelinkableCallSite} we used above only remembers the linkage
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* for the last encountered type (it implements what is known as a <i>monomorphic
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* inline cache</i>). Another already provided implementation,
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* {@link jdk.dynalink.support.ChainedCallSite} will remember linkages for
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* several different types (it is a <i>polymorphic inline cache</i>) and is
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* probably a better choice in serious applications.
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* <h2>Dynalink and bytecode creation</h2>
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* {@code CallSite} objects are usually created as part of bootstrapping
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* {@code invokedynamic} instructions in bytecode. Hence, Dynalink is typically
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* used as part of language runtimes that compile programs into Java
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* {@code .class} bytecode format. Dynalink does not address the aspects of
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* either creating bytecode classes or loading them into the JVM. That said,
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* Dynalink can also be used without bytecode compilation (e.g. in language
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* interpreters) by creating {@code CallSite} objects explicitly and associating
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* them with representations of dynamic operations in the interpreted program
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* (e.g. a typical representation would be some node objects in a syntax tree).
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* <h2>Available operations</h2>
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* Dynalink defines several standard operations in its
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* {@link jdk.dynalink.StandardOperation} class. The linker for Java
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* objects can link all of these operations, and you are encouraged to at
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* minimum support and use these operations in your language too. The
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* standard operations {@code GET} and {@code SET} need to be combined with
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* at least one {@link jdk.dynalink.Namespace} to be useful, e.g. to express a
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* property getter, you'd use {@code StandardOperation.GET.withNamespace(StandardNamespace.PROPERTY)}.
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* Dynalink defines three standard namespaces in the {@link jdk.dynalink.StandardNamespace} class.
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* To associate a fixed name with an operation, you can use
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* {@link jdk.dynalink.NamedOperation} as in the previous example:
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* {@code StandardOperation.GET.withNamespace(StandardNamespace.PROPERTY).named("color")}
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* expresses a getter for the property named "color".
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* <h2>Operations on multiple namespaces</h2>
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* Some languages might not have separate namespaces on objects for
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* properties, elements, and methods, and a source language construct might
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* address several of them at once. Dynalink supports specifying multiple
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* {@link jdk.dynalink.Namespace} objects with {@link jdk.dynalink.NamespaceOperation}.
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* <h2>Language-specific linkers</h2>
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* Languages that define their own object model different than the JVM
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* class-based model and/or use their own type conversions will need to create
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* their own language-specific linkers. See the {@link jdk.dynalink.linker}
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* package and specifically the {@link jdk.dynalink.linker.GuardingDynamicLinker}
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* interface to get started.
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* <h2>Dynalink and Java objects</h2>
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* The {@code DynamicLinker} objects created by {@code DynamicLinkerFactory} by
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* default contain an internal instance of
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* {@code BeansLinker}, which is a language-specific linker
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* that implements the usual Java semantics for all of the above operations and
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* can link any Java object that no other language-specific linker has managed
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* to link. This way, all language runtimes have built-in interoperability with
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* ordinary Java objects. See {@link jdk.dynalink.beans.BeansLinker} for details
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* on how it links the various operations.
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* <h2>Cross-language interoperability</h2>
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* A {@code DynamicLinkerFactory} can be configured with a
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* {@link jdk.dynalink.DynamicLinkerFactory#setClassLoader(ClassLoader) class
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* loader}. It will try to instantiate all
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* {@link jdk.dynalink.linker.GuardingDynamicLinkerExporter} classes visible to
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* that class loader and compose the linkers they provide into the
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* {@code DynamicLinker} it creates. This allows for interoperability between
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* languages: if you have two language runtimes A and B deployed in your JVM and
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* they export their linkers through the above mechanism, language runtime A
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* will have a language-specific linker instance from B and vice versa inside
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* their {@code DynamicLinker} objects. This means that if an object from
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* language runtime B gets passed to code from language runtime A, the linker
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* from B will get a chance to link the call site in A when it encounters the
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* object from B.
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* Contains interfaces and classes that are used to link an {@code invokedynamic} call site.
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*/
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package jdk.dynalink;
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@ -24,7 +24,198 @@
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*/
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/**
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* Dynalink
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* <p>
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* Dynalink is a library for dynamic linking of high-level operations on objects.
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* These operations include "read a property",
|
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* "write a property", "invoke a function" and so on. Dynalink is primarily
|
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* useful for implementing programming languages where at least some expressions
|
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* have dynamic types (that is, types that can not be decided statically), and
|
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* the operations on dynamic types are expressed as
|
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* {@link java.lang.invoke.CallSite call sites}. These call sites will be
|
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* linked to appropriate target {@link java.lang.invoke.MethodHandle method handles}
|
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* at run time based on actual types of the values the expressions evaluated to.
|
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* These can change between invocations, necessitating relinking the call site
|
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* multiple times to accommodate new types; Dynalink handles all that and more.
|
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* <p>
|
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* Dynalink supports implementation of programming languages with object models
|
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* that differ (even radically) from the JVM's class-based model and have their
|
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* custom type conversions.
|
||||
* <p>
|
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* Dynalink is closely related to, and relies on, the {@link java.lang.invoke}
|
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* package.
|
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* <p>
|
||||
*
|
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* While {@link java.lang.invoke} provides a low level API for dynamic linking
|
||||
* of {@code invokedynamic} call sites, it does not provide a way to express
|
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* higher level operations on objects, nor methods that implement them. These
|
||||
* operations are the usual ones in object-oriented environments: property
|
||||
* access, access of elements of collections, invocation of methods and
|
||||
* constructors (potentially with multiple dispatch, e.g. link- and run-time
|
||||
* equivalents of Java overloaded method resolution). These are all functions
|
||||
* that are normally desired in a language on the JVM. If a language is
|
||||
* statically typed and its type system matches that of the JVM, it can
|
||||
* accomplish this with use of the usual invocation, field access, etc.
|
||||
* instructions (e.g. {@code invokevirtual}, {@code getfield}). However, if the
|
||||
* language is dynamic (hence, types of some expressions are not known until
|
||||
* evaluated at run time), or its object model or type system don't match
|
||||
* closely that of the JVM, then it should use {@code invokedynamic} call sites
|
||||
* instead and let Dynalink manage them.
|
||||
* <h2>Example</h2>
|
||||
* Dynalink is probably best explained by an example showing its use. Let's
|
||||
* suppose you have a program in a language where you don't have to declare the
|
||||
* type of an object and you want to access a property on it:
|
||||
* <pre>
|
||||
* var color = obj.color;
|
||||
* </pre>
|
||||
* If you generated a Java class to represent the above one-line program, its
|
||||
* bytecode would look something like this:
|
||||
* <pre>
|
||||
* aload 2 // load "obj" on stack
|
||||
* invokedynamic "GET:PROPERTY:color"(Object)Object // invoke property getter on object of unknown type
|
||||
* astore 3 // store the return value into local variable "color"
|
||||
* </pre>
|
||||
* In order to link the {@code invokedynamic} instruction, we need a bootstrap
|
||||
* method. A minimalist bootstrap method with Dynalink could look like this:
|
||||
* <pre>
|
||||
* import java.lang.invoke.*;
|
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* import jdk.dynalink.*;
|
||||
* import jdk.dynalink.support.*;
|
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*
|
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* class MyLanguageRuntime {
|
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* private static final DynamicLinker dynamicLinker = new DynamicLinkerFactory().createLinker();
|
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*
|
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* public static CallSite bootstrap(MethodHandles.Lookup lookup, String name, MethodType type) {
|
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* return dynamicLinker.link(
|
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* new SimpleRelinkableCallSite(
|
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* new CallSiteDescriptor(lookup, parseOperation(name), type)));
|
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* }
|
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*
|
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* private static Operation parseOperation(String name) {
|
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* ...
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* }
|
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* }
|
||||
* </pre>
|
||||
* There are several objects of significance in the above code snippet:
|
||||
* <ul>
|
||||
* <li>{@link jdk.dynalink.DynamicLinker} is the main object in Dynalink, it
|
||||
* coordinates the linking of call sites to method handles that implement the
|
||||
* operations named in them. It is configured and created using a
|
||||
* {@link jdk.dynalink.DynamicLinkerFactory}.</li>
|
||||
* <li>When the bootstrap method is invoked, it needs to create a
|
||||
* {@link java.lang.invoke.CallSite} object. In Dynalink, these call sites need
|
||||
* to additionally implement the {@link jdk.dynalink.RelinkableCallSite}
|
||||
* interface. "Relinkable" here alludes to the fact that if the call site
|
||||
* encounters objects of different types at run time, its target will be changed
|
||||
* to a method handle that can perform the operation on the newly encountered
|
||||
* type. {@link jdk.dynalink.support.SimpleRelinkableCallSite} and
|
||||
* {@link jdk.dynalink.support.ChainedCallSite} (not used in the above example)
|
||||
* are two implementations already provided by the library.</li>
|
||||
* <li>Dynalink uses {@link jdk.dynalink.CallSiteDescriptor} objects to
|
||||
* preserve the parameters to the bootstrap method: the lookup and the method type,
|
||||
* as it will need them whenever it needs to relink a call site.</li>
|
||||
* <li>Dynalink uses {@link jdk.dynalink.Operation} objects to express
|
||||
* dynamic operations. It does not prescribe how would you encode the operations
|
||||
* in your call site, though. That is why in the above example the
|
||||
* {@code parseOperation} function is left empty, and you would be expected to
|
||||
* provide the code to parse the string {@code "GET:PROPERTY:color"}
|
||||
* in the call site's name into a named property getter operation object as
|
||||
* {@code StandardOperation.GET.withNamespace(StandardNamespace.PROPERTY).named("color")}.
|
||||
* </ul>
|
||||
* <p>What can you already do with the above setup? {@code DynamicLinkerFactory}
|
||||
* by default creates a {@code DynamicLinker} that can link Java objects with the
|
||||
* usual Java semantics. If you have these three simple classes:
|
||||
* <pre>
|
||||
* public class A {
|
||||
* public String color;
|
||||
* public A(String color) { this.color = color; }
|
||||
* }
|
||||
*
|
||||
* public class B {
|
||||
* private String color;
|
||||
* public B(String color) { this.color = color; }
|
||||
* public String getColor() { return color; }
|
||||
* }
|
||||
*
|
||||
* public class C {
|
||||
* private int color;
|
||||
* public C(int color) { this.color = color; }
|
||||
* public int getColor() { return color; }
|
||||
* }
|
||||
* </pre>
|
||||
* and you somehow create their instances and pass them to your call site in your
|
||||
* programming language:
|
||||
* <pre>
|
||||
* for each(var obj in [new A("red"), new B("green"), new C(0x0000ff)]) {
|
||||
* print(obj.color);
|
||||
* }
|
||||
* </pre>
|
||||
* then on first invocation, Dynalink will link the {@code .color} getter
|
||||
* operation to a field getter for {@code A.color}, on second invocation it will
|
||||
* relink it to {@code B.getColor()} returning a {@code String}, and finally on
|
||||
* third invocation it will relink it to {@code C.getColor()} returning an {@code int}.
|
||||
* The {@code SimpleRelinkableCallSite} we used above only remembers the linkage
|
||||
* for the last encountered type (it implements what is known as a <i>monomorphic
|
||||
* inline cache</i>). Another already provided implementation,
|
||||
* {@link jdk.dynalink.support.ChainedCallSite} will remember linkages for
|
||||
* several different types (it is a <i>polymorphic inline cache</i>) and is
|
||||
* probably a better choice in serious applications.
|
||||
* <h2>Dynalink and bytecode creation</h2>
|
||||
* {@code CallSite} objects are usually created as part of bootstrapping
|
||||
* {@code invokedynamic} instructions in bytecode. Hence, Dynalink is typically
|
||||
* used as part of language runtimes that compile programs into Java
|
||||
* {@code .class} bytecode format. Dynalink does not address the aspects of
|
||||
* either creating bytecode classes or loading them into the JVM. That said,
|
||||
* Dynalink can also be used without bytecode compilation (e.g. in language
|
||||
* interpreters) by creating {@code CallSite} objects explicitly and associating
|
||||
* them with representations of dynamic operations in the interpreted program
|
||||
* (e.g. a typical representation would be some node objects in a syntax tree).
|
||||
* <h2>Available operations</h2>
|
||||
* Dynalink defines several standard operations in its
|
||||
* {@link jdk.dynalink.StandardOperation} class. The linker for Java
|
||||
* objects can link all of these operations, and you are encouraged to at
|
||||
* minimum support and use these operations in your language too. The
|
||||
* standard operations {@code GET} and {@code SET} need to be combined with
|
||||
* at least one {@link jdk.dynalink.Namespace} to be useful, e.g. to express a
|
||||
* property getter, you'd use {@code StandardOperation.GET.withNamespace(StandardNamespace.PROPERTY)}.
|
||||
* Dynalink defines three standard namespaces in the {@link jdk.dynalink.StandardNamespace} class.
|
||||
* To associate a fixed name with an operation, you can use
|
||||
* {@link jdk.dynalink.NamedOperation} as in the previous example:
|
||||
* {@code StandardOperation.GET.withNamespace(StandardNamespace.PROPERTY).named("color")}
|
||||
* expresses a getter for the property named "color".
|
||||
* <h2>Operations on multiple namespaces</h2>
|
||||
* Some languages might not have separate namespaces on objects for
|
||||
* properties, elements, and methods, and a source language construct might
|
||||
* address several of them at once. Dynalink supports specifying multiple
|
||||
* {@link jdk.dynalink.Namespace} objects with {@link jdk.dynalink.NamespaceOperation}.
|
||||
* <h2>Language-specific linkers</h2>
|
||||
* Languages that define their own object model different than the JVM
|
||||
* class-based model and/or use their own type conversions will need to create
|
||||
* their own language-specific linkers. See the {@link jdk.dynalink.linker}
|
||||
* package and specifically the {@link jdk.dynalink.linker.GuardingDynamicLinker}
|
||||
* interface to get started.
|
||||
* <h2>Dynalink and Java objects</h2>
|
||||
* The {@code DynamicLinker} objects created by {@code DynamicLinkerFactory} by
|
||||
* default contain an internal instance of
|
||||
* {@code BeansLinker}, which is a language-specific linker
|
||||
* that implements the usual Java semantics for all of the above operations and
|
||||
* can link any Java object that no other language-specific linker has managed
|
||||
* to link. This way, all language runtimes have built-in interoperability with
|
||||
* ordinary Java objects. See {@link jdk.dynalink.beans.BeansLinker} for details
|
||||
* on how it links the various operations.
|
||||
* <h2>Cross-language interoperability</h2>
|
||||
* A {@code DynamicLinkerFactory} can be configured with a
|
||||
* {@link jdk.dynalink.DynamicLinkerFactory#setClassLoader(ClassLoader) class
|
||||
* loader}. It will try to instantiate all
|
||||
* {@link jdk.dynalink.linker.GuardingDynamicLinkerExporter} classes visible to
|
||||
* that class loader and compose the linkers they provide into the
|
||||
* {@code DynamicLinker} it creates. This allows for interoperability between
|
||||
* languages: if you have two language runtimes A and B deployed in your JVM and
|
||||
* they export their linkers through the above mechanism, language runtime A
|
||||
* will have a language-specific linker instance from B and vice versa inside
|
||||
* their {@code DynamicLinker} objects. This means that if an object from
|
||||
* language runtime B gets passed to code from language runtime A, the linker
|
||||
* from B will get a chance to link the call site in A when it encounters the
|
||||
* object from B.
|
||||
*/
|
||||
module jdk.dynalink {
|
||||
requires java.logging;
|
||||
|
||||
Loading…
x
Reference in New Issue
Block a user