nashorn/src/jdk.scripting.nashorn/share/classes/module-info.java
changeset 43017 88c78d6617f4
parent 42380 180839e7d68a
child 43742 abd8bc4c4c9d
--- a/nashorn/src/jdk.scripting.nashorn/share/classes/module-info.java	Tue Jan 03 22:14:41 2017 +0530
+++ b/nashorn/src/jdk.scripting.nashorn/share/classes/module-info.java	Wed Jan 04 18:47:35 2017 +0530
@@ -24,7 +24,71 @@
  */
 
 /**
- * Nashorn
+<p>
+Nashorn is a runtime environment for programs written in ECMAScript 5.1.
+</p>
+<h1>Usage</h1>
+The recommended way to use Nashorn is through the <a href="http://jcp.org/en/jsr/detail?id=223" target="_top">JSR-223
+"Scripting for the Java Platform"</a> APIs found in the {@link javax.script} package. Usually, you'll obtain a
+{@link javax.script.ScriptEngine} instance for Nashorn using:
+<pre>
+import javax.script.*;
+...
+ScriptEngine nashornEngine = new ScriptEngineManager().getEngineByName("nashorn");
+</pre>
+and then use it just as you would any other JSR-223 script engine. See
+<a href="jdk/nashorn/api/scripting/package-summary.html">{@code jdk.nashorn.api.scripting}</a> package
+for details.
+<h1>Compatibility</h1>
+Nashorn is 100% compliant with the <a href="http://www.ecma-international.org/publications/standards/Ecma-262.htm"
+target="_top">ECMA-262 Standard, Edition 5.1</a>. It requires a Java Virtual Machine that implements the
+<a href="http://jcp.org/en/jsr/detail?id=292" target="_top">JSR-292 "Supporting Dynamically Typed Languages on the Java
+Platform"</a> specification (often referred to as "invokedynamic"), as well as the already mentioned JSR-223.
+<h1>Interoperability with the Java platform</h1>
+In addition to being a 100% ECMAScript 5.1 runtime, Nashorn provides features for interoperability of the ECMAScript
+programs with the Java platform. In general, any Java object put into the script engine's context will be visible from
+the script. In terms of the standard, such Java objects are not considered "native objects", but rather "host objects",
+as defined in section 4.3.8. This distinction allows certain semantical differences in handling them compared to native
+objects. For most purposes, Java objects behave just as native objects do: you can invoke their methods, get and set
+their properties. In most cases, though, you can't add arbitrary properties to them, nor can you remove existing
+properties.
+<h2>Java collection handling</h2>
+Native Java arrays and {@link java.util.List}s support indexed access to their elements through the property accessors,
+and {@link java.util.Map}s support both property and element access through both dot and square-bracket property
+accessors, with the difference being that dot operator gives precedence to object properties (its fields and properties
+defined as {@code getXxx} and {@code setXxx} methods) while the square bracket operator gives precedence to map
+elements. Native Java arrays expose the {@code length} property.
+<h2>ECMAScript primitive types</h2>
+ECMAScript primitive types for number, string, and boolean are represented with {@link java.lang.Number},
+{@link java.lang.CharSequence}, and {@link java.lang.Boolean} objects. While the most often used number type is
+{@link java.lang.Double} and the most often used string type is {@link java.lang.String}, don't rely on it as various
+internal optimizations cause other subclasses of {@code Number} and internal implementations of {@code CharSequence} to
+be used.
+<h2>Type conversions</h2>
+When a method on a Java object is invoked, the arguments are converted to the formal parameter types of the Java method
+using all allowed ECMAScript conversions. This can be surprising, as in general, conversions from string to number will
+succeed according to Standard's section 9.3 "ToNumber" and so on; string to boolean, number to boolean, Object to
+number, Object to string all work. Note that if the Java method's declared parameter type is {@code java.lang.Object},
+Nashorn objects are passed without any conversion whatsoever; specifically if the JavaScript value being passed is of
+primitive string type, you can only rely on it being a {@code java.lang.CharSequence}, and if the value is a number, you
+can only rely on it being a {@code java.lang.Number}. If the Java method declared parameter type is more specific (e.g.
+{@code java.lang.String} or {@code java.lang.Double}), then Nashorn will of course ensure the required type is passed.
+<h2>SAM types</h2>
+As a special extension when invoking Java methods, ECMAScript function objects can be passed in place of an argument
+whose Java type is so-called "single abstract method" or "SAM" type. While this name usually covers single-method
+interfaces, Nashorn is a bit more versatile, and it recognizes a type as a SAM type if all its abstract methods are
+overloads of the same name, and it is either an interface, or it is an abstract class with
+a no-arg constructor. The type itself must be public, while the constructor and the methods can be either public or
+protected. If there are multiple abstract overloads of the same name, the single function will serve as the shared
+implementation for all of them, <em>and additionally it will also override any non-abstract methods of the same name</em>.
+This is done to be consistent with the fact that ECMAScript does not have the concept of overloaded methods.
+<h2>The {@code Java} object</h2>
+Nashorn exposes a non-standard global object named {@code Java} that is the primary API entry point into Java
+platform-specific functionality. You can use it to create instances of Java classes, convert from Java arrays to native
+arrays and back, and so on.
+<h2>Other non-standard built-in objects</h2>
+In addition to {@code Java}, Nashorn also exposes some other non-standard built-in objects:
+{@code JSAdapter}, {@code JavaImporter}, {@code Packages}
  */
 module jdk.scripting.nashorn {
     requires java.logging;
@@ -47,4 +111,3 @@
     provides jdk.dynalink.linker.GuardingDynamicLinkerExporter
         with jdk.nashorn.api.linker.NashornLinkerExporter;
 }
-