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| |
| /** |
| <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} |
| |
| @since 9 |
| */ |
| module jdk.scripting.nashorn { |
| requires java.logging; |
| requires transitive java.scripting; |
| requires jdk.dynalink; |
| |
| exports jdk.nashorn.api.scripting; |
| exports jdk.nashorn.api.tree; |
| |
| exports jdk.nashorn.internal.runtime to |
| jdk.scripting.nashorn.shell; |
| exports jdk.nashorn.internal.objects to |
| jdk.scripting.nashorn.shell; |
| exports jdk.nashorn.tools to |
| jdk.scripting.nashorn.shell; |
| |
| provides javax.script.ScriptEngineFactory |
| with jdk.nashorn.api.scripting.NashornScriptEngineFactory; |
| |
| provides jdk.dynalink.linker.GuardingDynamicLinkerExporter |
| with jdk.nashorn.api.linker.NashornLinkerExporter; |
| } |