1 /*
2 * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package jdk.nashorn.internal.objects;
27
28 import static jdk.nashorn.internal.runtime.ECMAErrors.typeError;
29 import static jdk.nashorn.internal.runtime.ScriptRuntime.UNDEFINED;
30
31 import java.lang.invoke.MethodHandles;
32 import java.lang.reflect.Array;
33 import java.util.Collection;
34 import java.util.Deque;
35 import java.util.List;
36 import java.util.Map;
37 import java.util.Queue;
38 import jdk.internal.dynalink.beans.StaticClass;
39 import jdk.internal.dynalink.support.TypeUtilities;
40 import jdk.nashorn.api.scripting.JSObject;
41 import jdk.nashorn.api.scripting.ScriptObjectMirror;
42 import jdk.nashorn.internal.objects.annotations.Attribute;
43 import jdk.nashorn.internal.objects.annotations.Function;
44 import jdk.nashorn.internal.objects.annotations.ScriptClass;
45 import jdk.nashorn.internal.objects.annotations.Where;
46 import jdk.nashorn.internal.runtime.Context;
47 import jdk.nashorn.internal.runtime.JSType;
48 import jdk.nashorn.internal.runtime.ListAdapter;
49 import jdk.nashorn.internal.runtime.PropertyMap;
50 import jdk.nashorn.internal.runtime.ScriptFunction;
51 import jdk.nashorn.internal.runtime.ScriptObject;
52 import jdk.nashorn.internal.runtime.ScriptRuntime;
53 import jdk.nashorn.internal.runtime.linker.Bootstrap;
54 import jdk.nashorn.internal.runtime.linker.JavaAdapterFactory;
55
56 /**
57 * This class is the implementation for the {@code Java} global object exposed to programs running under Nashorn. This
58 * object acts as the API entry point to Java platform specific functionality, dealing with creating new instances of
59 * Java classes, subclassing Java classes, implementing Java interfaces, converting between Java arrays and ECMAScript
60 * arrays, and so forth.
61 */
62 @ScriptClass("Java")
63 public final class NativeJava {
64
65 // initialized by nasgen
66 @SuppressWarnings("unused")
67 private static PropertyMap $nasgenmap$;
68
69 private NativeJava() {
70 // don't create me
71 throw new UnsupportedOperationException();
72 }
73
74 /**
75 * Returns true if the specified object is a Java type object, that is an instance of {@link StaticClass}.
76 * @param self not used
77 * @param type the object that is checked if it is a type object or not
78 * @return tells whether given object is a Java type object or not.
79 * @see #type(Object, Object)
80 */
81 @Function(attributes = Attribute.NOT_ENUMERABLE, where = Where.CONSTRUCTOR)
82 public static boolean isType(final Object self, final Object type) {
83 return type instanceof StaticClass;
84 }
85
86 /**
87 * Returns synchronized wrapper version of the given ECMAScript function.
88 * @param self not used
89 * @param func the ECMAScript function whose synchronized version is returned.
90 * @param obj the object (i.e, lock) on which the function synchronizes.
91 * @return synchronized wrapper version of the given ECMAScript function.
92 */
93 @Function(name="synchronized", attributes = Attribute.NOT_ENUMERABLE, where = Where.CONSTRUCTOR)
94 public static Object synchronizedFunc(final Object self, final Object func, final Object obj) {
95 if (func instanceof ScriptFunction) {
96 return ((ScriptFunction)func).makeSynchronizedFunction(obj);
97 }
98
99 throw typeError("not.a.function", ScriptRuntime.safeToString(func));
100 }
101
102 /**
103 * Returns true if the specified object is a Java method.
104 * @param self not used
105 * @param obj the object that is checked if it is a Java method object or not
106 * @return tells whether given object is a Java method object or not.
107 */
108 @Function(attributes = Attribute.NOT_ENUMERABLE, where = Where.CONSTRUCTOR)
109 public static boolean isJavaMethod(final Object self, final Object obj) {
110 return Bootstrap.isDynamicMethod(obj);
111 }
112
113 /**
114 * Returns true if the specified object is a java function (but not script function)
115 * @param self not used
116 * @param obj the object that is checked if it is a Java function or not
117 * @return tells whether given object is a Java function or not
118 */
119 @Function(attributes = Attribute.NOT_ENUMERABLE, where = Where.CONSTRUCTOR)
120 public static boolean isJavaFunction(final Object self, final Object obj) {
121 return Bootstrap.isCallable(obj) && !(obj instanceof ScriptFunction);
122 }
123
124 /**
125 * Returns true if the specified object is a Java object but not a script object
126 * @param self not used
127 * @param obj the object that is checked
128 * @return tells whether given object is a Java object but not a script object
129 */
130 @Function(attributes = Attribute.NOT_ENUMERABLE, where = Where.CONSTRUCTOR)
131 public static boolean isJavaObject(final Object self, final Object obj) {
132 return obj != null && !(obj instanceof ScriptObject);
133 }
134
135 /**
136 * Returns true if the specified object is a ECMAScript object, that is an instance of {@link ScriptObject}.
137 * @param self not used
138 * @param obj the object that is checked if it is a ECMAScript object or not
139 * @return tells whether given object is a ECMAScript object or not.
140 */
141 @Function(attributes = Attribute.NOT_ENUMERABLE, where = Where.CONSTRUCTOR)
142 public static boolean isScriptObject(final Object self, final Object obj) {
143 return obj instanceof ScriptObject;
144 }
145
146 /**
147 * Returns true if the specified object is a ECMAScript function, that is an instance of {@link ScriptFunction}.
148 * @param self not used
149 * @param obj the object that is checked if it is a ECMAScript function or not
150 * @return tells whether given object is a ECMAScript function or not.
151 */
152 @Function(attributes = Attribute.NOT_ENUMERABLE, where = Where.CONSTRUCTOR)
153 public static boolean isScriptFunction(final Object self, final Object obj) {
154 return obj instanceof ScriptFunction;
155 }
156
157 /**
158 * <p>
159 * Given a name of a Java type, returns an object representing that type in Nashorn. The Java class of the objects
160 * used to represent Java types in Nashorn is not {@link java.lang.Class} but rather {@link StaticClass}. They are
161 * the objects that you can use with the {@code new} operator to create new instances of the class as well as to
162 * access static members of the class. In Nashorn, {@code Class} objects are just regular Java objects that aren't
163 * treated specially. Instead of them, {@link StaticClass} instances - which we sometimes refer to as "Java type
164 * objects" are used as constructors with the {@code new} operator, and they expose static fields, properties, and
165 * methods. While this might seem confusing at first, it actually closely matches the Java language: you use a
166 * different expression (e.g. {@code java.io.File}) as an argument in "new" and to address statics, and it is
167 * distinct from the {@code Class} object (e.g. {@code java.io.File.class}). Below we cover in details the
168 * properties of the type objects.
169 * </p>
170 * <p><b>Constructing Java objects</b></p>
171 * Examples:
172 * <pre>
173 * var arrayListType = Java.type("java.util.ArrayList")
174 * var intType = Java.type("int")
175 * var stringArrayType = Java.type("java.lang.String[]")
176 * var int2DArrayType = Java.type("int[][]")
177 * </pre>
178 * Note that the name of the type is always a string for a fully qualified name. You can use any of these types to
179 * create new instances, e.g.:
180 * <pre>
181 * var anArrayList = new Java.type("java.util.ArrayList")
182 * </pre>
183 * or
184 * <pre>
185 * var ArrayList = Java.type("java.util.ArrayList")
186 * var anArrayList = new ArrayList
187 * var anArrayListWithSize = new ArrayList(16)
188 * </pre>
189 * In the special case of inner classes, you can either use the JVM fully qualified name, meaning using {@code $}
190 * sign in the class name, or you can use the dot:
191 * <pre>
192 * var ftype = Java.type("java.awt.geom.Arc2D$Float")
193 * </pre>
194 * and
195 * <pre>
196 * var ftype = Java.type("java.awt.geom.Arc2D.Float")
197 * </pre>
198 * both work. Note however that using the dollar sign is faster, as Java.type first tries to resolve the class name
199 * as it is originally specified, and the internal JVM names for inner classes use the dollar sign. If you use the
200 * dot, Java.type will internally get a ClassNotFoundException and subsequently retry by changing the last dot to
201 * dollar sign. As a matter of fact, it'll keep replacing dots with dollar signs until it either successfully loads
202 * the class or runs out of all dots in the name. This way it can correctly resolve and load even multiply nested
203 * inner classes with the dot notation. Again, this will be slower than using the dollar signs in the name. An
204 * alternative way to access the inner class is as a property of the outer class:
205 * <pre>
206 * var arctype = Java.type("java.awt.geom.Arc2D")
207 * var ftype = arctype.Float
208 * </pre>
209 * <p>
210 * You can access both static and non-static inner classes. If you want to create an instance of a non-static
211 * inner class, remember to pass an instance of its outer class as the first argument to the constructor.
212 * </p>
213 * <p>
214 * If the type is abstract, you can instantiate an anonymous subclass of it using an argument list that is
215 * applicable to any of its public or protected constructors, but inserting a JavaScript object with functions
216 * properties that provide JavaScript implementations of the abstract methods. If method names are overloaded, the
217 * JavaScript function will provide implementation for all overloads. E.g.:
218 * </p>
219 * <pre>
220 * var TimerTask = Java.type("java.util.TimerTask")
221 * var task = new TimerTask({ run: function() { print("Hello World!") } })
222 * </pre>
223 * <p>
224 * Nashorn supports a syntactic extension where a "new" expression followed by an argument is identical to
225 * invoking the constructor and passing the argument to it, so you can write the above example also as:
226 * </p>
227 * <pre>
228 * var task = new TimerTask {
229 * run: function() {
230 * print("Hello World!")
231 * }
232 * }
233 * </pre>
234 * <p>
235 * which is very similar to Java anonymous inner class definition. On the other hand, if the type is an abstract
236 * type with a single abstract method (commonly referred to as a "SAM type") or all abstract methods it has share
237 * the same overloaded name), then instead of an object, you can just pass a function, so the above example can
238 * become even more simplified to:
239 * </p>
240 * <pre>
241 * var task = new TimerTask(function() { print("Hello World!") })
242 * </pre>
243 * <p>
244 * Note that in every one of these cases if you are trying to instantiate an abstract class that has constructors
245 * that take some arguments, you can invoke those simply by specifying the arguments after the initial
246 * implementation object or function.
247 * </p>
248 * <p>The use of functions can be taken even further; if you are invoking a Java method that takes a SAM type,
249 * you can just pass in a function object, and Nashorn will know what you meant:
250 * </p>
251 * <pre>
252 * var timer = new Java.type("java.util.Timer")
253 * timer.schedule(function() { print("Hello World!") })
254 * </pre>
255 * <p>
256 * Here, {@code Timer.schedule()} expects a {@code TimerTask} as its argument, so Nashorn creates an instance of a
257 * {@code TimerTask} subclass and uses the passed function to implement its only abstract method, {@code run()}. In
258 * this usage though, you can't use non-default constructors; the type must be either an interface, or must have a
259 * protected or public no-arg constructor.
260 * </p>
261 * <p>
262 * You can also subclass non-abstract classes; for that you will need to use the {@link #extend(Object, Object...)}
263 * method.
264 * </p>
265 * <p><b>Accessing static members</b></p>
266 * Examples:
267 * <pre>
268 * var File = Java.type("java.io.File")
269 * var pathSep = File.pathSeparator
270 * var tmpFile1 = File.createTempFile("abcdefg", ".tmp")
271 * var tmpFile2 = File.createTempFile("abcdefg", ".tmp", new File("/tmp"))
272 * </pre>
273 * Actually, you can even assign static methods to variables, so the above example can be rewritten as:
274 * <pre>
275 * var File = Java.type("java.io.File")
276 * var createTempFile = File.createTempFile
277 * var tmpFile1 = createTempFile("abcdefg", ".tmp")
278 * var tmpFile2 = createTempFile("abcdefg", ".tmp", new File("/tmp"))
279 * </pre>
280 * If you need to access the actual {@code java.lang.Class} object for the type, you can use the {@code class}
281 * property on the object representing the type:
282 * <pre>
283 * var File = Java.type("java.io.File")
284 * var someFile = new File("blah")
285 * print(File.class === someFile.getClass()) // prints true
286 * </pre>
287 * Of course, you can also use the {@code getClass()} method or its equivalent {@code class} property on any
288 * instance of the class. Other way round, you can use the synthetic {@code static} property on any
289 * {@code java.lang.Class} object to retrieve its type-representing object:
290 * <pre>
291 * var File = Java.type("java.io.File")
292 * print(File.class.static === File) // prints true
293 * </pre>
294 * <p><b>{@code instanceof} operator</b></p>
295 * The standard ECMAScript {@code instanceof} operator is extended to recognize Java objects and their type objects:
296 * <pre>
297 * var File = Java.type("java.io.File")
298 * var aFile = new File("foo")
299 * print(aFile instanceof File) // prints true
300 * print(aFile instanceof File.class) // prints false - Class objects aren't type objects.
301 * </pre>
302 * @param self not used
303 * @param objTypeName the object whose JS string value represents the type name. You can use names of primitive Java
304 * types to obtain representations of them, and you can use trailing square brackets to represent Java array types.
305 * @return the object representing the named type
306 * @throws ClassNotFoundException if the class is not found
307 */
308 @Function(attributes = Attribute.NOT_ENUMERABLE, where = Where.CONSTRUCTOR)
309 public static Object type(final Object self, final Object objTypeName) throws ClassNotFoundException {
310 return type(objTypeName);
311 }
312
313 private static StaticClass type(final Object objTypeName) throws ClassNotFoundException {
314 return StaticClass.forClass(type(JSType.toString(objTypeName)));
315 }
316
317 private static Class<?> type(final String typeName) throws ClassNotFoundException {
318 if (typeName.endsWith("[]")) {
319 return arrayType(typeName);
320 }
321
322 return simpleType(typeName);
323 }
324
325 /**
326 * Returns name of a java type {@link StaticClass}.
327 * @param self not used
328 * @param type the type whose name is returned
329 * @return name of the given type
330 */
331 @Function(attributes = Attribute.NOT_ENUMERABLE, where = Where.CONSTRUCTOR)
332 public static Object typeName(final Object self, final Object type) {
333 if (type instanceof StaticClass) {
334 return ((StaticClass)type).getRepresentedClass().getName();
335 } else if (type instanceof Class) {
336 return ((Class<?>)type).getName();
337 } else {
338 return UNDEFINED;
339 }
340 }
341
342 /**
343 * Given a script object and a Java type, converts the script object into the desired Java type. Currently it
344 * performs shallow creation of Java arrays, as well as wrapping of objects in Lists, Dequeues, Queues,
345 * and Collections. Example:
346 * <pre>
347 * var anArray = [1, "13", false]
348 * var javaIntArray = Java.to(anArray, "int[]")
349 * print(javaIntArray[0]) // prints 1
350 * print(javaIntArray[1]) // prints 13, as string "13" was converted to number 13 as per ECMAScript ToNumber conversion
351 * print(javaIntArray[2]) // prints 0, as boolean false was converted to number 0 as per ECMAScript ToNumber conversion
352 * </pre>
353 * @param self not used
354 * @param obj the script object. Can be null.
355 * @param objType either a {@link #type(Object, Object) type object} or a String describing the type of the Java
356 * object to create. Can not be null. If undefined, a "default" conversion is presumed (allowing the argument to be
357 * omitted).
358 * @return a Java object whose value corresponds to the original script object's value. Specifically, for array
359 * target types, returns a Java array of the same type with contents converted to the array's component type.
360 * Converts recursively when the target type is multidimensional array. For {@link List}, {@link Deque},
361 * {@link Queue}, or {@link Collection}, returns a live wrapper around the object, see {@link ListAdapter} for
362 * details. Returns null if obj is null.
363 * @throws ClassNotFoundException if the class described by objType is not found
364 */
365 @Function(attributes = Attribute.NOT_ENUMERABLE, where = Where.CONSTRUCTOR)
366 public static Object to(final Object self, final Object obj, final Object objType) throws ClassNotFoundException {
367 if (obj == null) {
368 return null;
369 }
370
371 if (!(obj instanceof ScriptObject) && !(obj instanceof JSObject)) {
372 throw typeError("not.an.object", ScriptRuntime.safeToString(obj));
373 }
374
375 final Class<?> targetClass;
376 if(objType == UNDEFINED) {
377 targetClass = Object[].class;
378 } else {
379 final StaticClass targetType;
380 if(objType instanceof StaticClass) {
381 targetType = (StaticClass)objType;
382 } else {
383 targetType = type(objType);
384 }
385 targetClass = targetType.getRepresentedClass();
386 }
387
388 if(targetClass.isArray()) {
389 return JSType.toJavaArray(obj, targetClass.getComponentType());
390 }
391
392 if (targetClass == List.class || targetClass == Deque.class || targetClass == Queue.class || targetClass == Collection.class) {
393 return ListAdapter.create(obj);
394 }
395
396 throw typeError("unsupported.java.to.type", targetClass.getName());
397 }
398
399 /**
400 * Given a Java array or {@link Collection}, returns a JavaScript array with a shallow copy of its contents. Note
401 * that in most cases, you can use Java arrays and lists natively in Nashorn; in cases where for some reason you
402 * need to have an actual JavaScript native array (e.g. to work with the array comprehensions functions), you will
403 * want to use this method. Example:
404 * <pre>
405 * var File = Java.type("java.io.File")
406 * var listHomeDir = new File("~").listFiles()
407 * var jsListHome = Java.from(listHomeDir)
408 * var jpegModifiedDates = jsListHome
409 * .filter(function(val) { return val.getName().endsWith(".jpg") })
410 * .map(function(val) { return val.lastModified() })
411 * </pre>
412 * @param self not used
413 * @param objArray the java array or collection. Can be null.
414 * @return a JavaScript array with the copy of Java array's or collection's contents. Returns null if objArray is
415 * null.
416 */
417 @Function(attributes = Attribute.NOT_ENUMERABLE, where = Where.CONSTRUCTOR)
418 public static NativeArray from(final Object self, final Object objArray) {
419 if (objArray == null) {
420 return null;
421 } else if (objArray instanceof Collection) {
422 return new NativeArray(((Collection<?>)objArray).toArray());
423 } else if (objArray instanceof Object[]) {
424 return new NativeArray(((Object[])objArray).clone());
425 } else if (objArray instanceof int[]) {
426 return new NativeArray(((int[])objArray).clone());
427 } else if (objArray instanceof double[]) {
428 return new NativeArray(((double[])objArray).clone());
429 } else if (objArray instanceof long[]) {
430 return new NativeArray(((long[])objArray).clone());
431 } else if (objArray instanceof byte[]) {
432 return new NativeArray(copyArray((byte[])objArray));
433 } else if (objArray instanceof short[]) {
434 return new NativeArray(copyArray((short[])objArray));
435 } else if (objArray instanceof char[]) {
436 return new NativeArray(copyArray((char[])objArray));
437 } else if (objArray instanceof float[]) {
438 return new NativeArray(copyArray((float[])objArray));
439 } else if (objArray instanceof boolean[]) {
440 return new NativeArray(copyArray((boolean[])objArray));
441 }
442
443 throw typeError("cant.convert.to.javascript.array", objArray.getClass().getName());
444 }
445
446 private static int[] copyArray(final byte[] in) {
447 final int[] out = new int[in.length];
448 for(int i = 0; i < in.length; ++i) {
449 out[i] = in[i];
450 }
451 return out;
452 }
453
454 private static int[] copyArray(final short[] in) {
455 final int[] out = new int[in.length];
456 for(int i = 0; i < in.length; ++i) {
457 out[i] = in[i];
458 }
459 return out;
460 }
461
462 private static int[] copyArray(final char[] in) {
463 final int[] out = new int[in.length];
464 for(int i = 0; i < in.length; ++i) {
465 out[i] = in[i];
466 }
467 return out;
468 }
469
470 private static double[] copyArray(final float[] in) {
471 final double[] out = new double[in.length];
472 for(int i = 0; i < in.length; ++i) {
473 out[i] = in[i];
474 }
475 return out;
476 }
477
478 private static Object[] copyArray(final boolean[] in) {
479 final Object[] out = new Object[in.length];
480 for(int i = 0; i < in.length; ++i) {
481 out[i] = in[i];
482 }
483 return out;
484 }
485
486 private static Class<?> simpleType(final String typeName) throws ClassNotFoundException {
487 final Class<?> primClass = TypeUtilities.getPrimitiveTypeByName(typeName);
488 if(primClass != null) {
489 return primClass;
490 }
491 final Context ctx = Global.getThisContext();
492 try {
493 return ctx.findClass(typeName);
494 } catch(final ClassNotFoundException e) {
495 // The logic below compensates for a frequent user error - when people use dot notation to separate inner
496 // class names, i.e. "java.lang.Character.UnicodeBlock" vs."java.lang.Character$UnicodeBlock". The logic
497 // below will try alternative class names, replacing dots at the end of the name with dollar signs.
498 final StringBuilder nextName = new StringBuilder(typeName);
499 int lastDot = nextName.length();
500 for(;;) {
501 lastDot = nextName.lastIndexOf(".", lastDot - 1);
502 if(lastDot == -1) {
503 // Exhausted the search space, class not found - rethrow the original exception.
504 throw e;
505 }
506 nextName.setCharAt(lastDot, '$');
507 try {
508 return ctx.findClass(nextName.toString());
509 } catch(final ClassNotFoundException cnfe) {
510 // Intentionally ignored, so the loop retries with the next name
511 }
512 }
513 }
514
515 }
516
517 private static Class<?> arrayType(final String typeName) throws ClassNotFoundException {
518 return Array.newInstance(type(typeName.substring(0, typeName.length() - 2)), 0).getClass();
519 }
520
521 /**
522 * Returns a type object for a subclass of the specified Java class (or implementation of the specified interface)
523 * that acts as a script-to-Java adapter for it. See {@link #type(Object, Object)} for a discussion of type objects,
524 * and see {@link JavaAdapterFactory} for details on script-to-Java adapters. Note that you can also implement
525 * interfaces and subclass abstract classes using {@code new} operator on a type object for an interface or abstract
526 * class. However, to extend a non-abstract class, you will have to use this method. Example:
527 * <pre>
528 * var ArrayList = Java.type("java.util.ArrayList")
529 * var ArrayListExtender = Java.extend(ArrayList)
530 * var printSizeInvokedArrayList = new ArrayListExtender() {
531 * size: function() { print("size invoked!"); }
532 * }
533 * var printAddInvokedArrayList = new ArrayListExtender() {
534 * add: function(x, y) {
535 * if(typeof(y) === "undefined") {
536 * print("add(e) invoked!");
537 * } else {
538 * print("add(i, e) invoked!");
539 * }
540 * }
541 * </pre>
542 * We can see several important concepts in the above example:
543 * <ul>
544 * <li>Every specified list of Java types will have one extender subclass in Nashorn per caller protection domain -
545 * repeated invocations of {@code extend} for the same list of types for scripts same protection domain will yield
546 * the same extender type. It's a generic adapter that delegates to whatever JavaScript functions its implementation
547 * object has on a per-instance basis.</li>
548 * <li>If the Java method is overloaded (as in the above example {@code List.add()}), then your JavaScript adapter
549 * must be prepared to deal with all overloads.</li>
550 * <li>To invoke super methods from adapters, call them on the adapter instance prefixing them with {@code super$},
551 * or use the special {@link #_super(Object, Object) super-adapter}.</li>
552 * <li>It is also possible to specify an ordinary JavaScript object as the last argument to {@code extend}. In that
553 * case, it is treated as a class-level override. {@code extend} will return an extender class where all instances
554 * will have the methods implemented by functions on that object, just as if that object were passed as the last
555 * argument to their constructor. Example:
556 * <pre>
557 * var Runnable = Java.type("java.lang.Runnable")
558 * var R1 = Java.extend(Runnable, {
559 * run: function() {
560 * print("R1.run() invoked!")
561 * }
562 * })
563 * var r1 = new R1
564 * var t = new java.lang.Thread(r1)
565 * t.start()
566 * t.join()
567 * </pre>
568 * As you can see, you don't have to pass any object when you create a new instance of {@code R1} as its
569 * {@code run()} function was defined already when extending the class. If you also want to add instance-level
570 * overrides on these objects, you will have to repeatedly use {@code extend()} to subclass the class-level adapter.
571 * For such adapters, the order of precedence is instance-level method, class-level method, superclass method, or
572 * {@code UnsupportedOperationException} if the superclass method is abstract. If we continue our previous example:
573 * <pre>
574 * var R2 = Java.extend(R1);
575 * var r2 = new R2(function() { print("r2.run() invoked!") })
576 * r2.run()
577 * </pre>
578 * We'll see it'll print {@code "r2.run() invoked!"}, thus overriding on instance-level the class-level behavior.
579 * Note that you must use {@code Java.extend} to explicitly create an instance-override adapter class from a
580 * class-override adapter class, as the class-override adapter class is no longer abstract.
581 * </li>
582 * </ul>
583 * @param self not used
584 * @param types the original types. The caller must pass at least one Java type object of class {@link StaticClass}
585 * representing either a public interface or a non-final public class with at least one public or protected
586 * constructor. If more than one type is specified, at most one can be a class and the rest have to be interfaces.
587 * Invoking the method twice with exactly the same types in the same order - in absence of class-level overrides -
588 * will return the same adapter class, any reordering of types or even addition or removal of redundant types (i.e.
589 * interfaces that other types in the list already implement/extend, or {@code java.lang.Object} in a list of types
590 * consisting purely of interfaces) will result in a different adapter class, even though those adapter classes are
591 * functionally identical; we deliberately don't want to incur the additional processing cost of canonicalizing type
592 * lists. As a special case, the last argument can be a {@code ScriptObject} instead of a type. In this case, a
593 * separate adapter class is generated - new one for each invocation - that will use the passed script object as its
594 * implementation for all instances. Instances of such adapter classes can then be created without passing another
595 * script object in the constructor, as the class has a class-level behavior defined by the script object. However,
596 * you can still pass a script object (or if it's a SAM type, a function) to the constructor to provide further
597 * instance-level overrides.
598 *
599 * @return a new {@link StaticClass} that represents the adapter for the original types.
600 */
601 @Function(attributes = Attribute.NOT_ENUMERABLE, where = Where.CONSTRUCTOR)
602 public static Object extend(final Object self, final Object... types) {
603 if(types == null || types.length == 0) {
604 throw typeError("extend.expects.at.least.one.argument");
605 }
606 final int l = types.length;
607 final int typesLen;
608 final ScriptObject classOverrides;
609 if(types[l - 1] instanceof ScriptObject) {
610 classOverrides = (ScriptObject)types[l - 1];
611 typesLen = l - 1;
612 if(typesLen == 0) {
613 throw typeError("extend.expects.at.least.one.type.argument");
614 }
615 } else {
616 classOverrides = null;
617 typesLen = l;
618 }
619 final Class<?>[] stypes = new Class<?>[typesLen];
620 try {
621 for(int i = 0; i < typesLen; ++i) {
622 stypes[i] = ((StaticClass)types[i]).getRepresentedClass();
623 }
624 } catch(final ClassCastException e) {
625 throw typeError("extend.expects.java.types");
626 }
627 // Note that while the public API documentation claims self is not used, we actually use it.
628 // ScriptFunction.findCallMethod will bind the lookup object into it, and we can then use that lookup when
629 // requesting the adapter class. Note that if Java.extend is invoked with no lookup object, it'll pass the
630 // public lookup which'll result in generation of a no-permissions adapter. A typical situation this can happen
631 // is when the extend function is bound.
632 final MethodHandles.Lookup lookup;
633 if(self instanceof MethodHandles.Lookup) {
634 lookup = (MethodHandles.Lookup)self;
635 } else {
636 lookup = MethodHandles.publicLookup();
637 }
638 return JavaAdapterFactory.getAdapterClassFor(stypes, classOverrides, lookup);
639 }
640
641 /**
642 * When given an object created using {@code Java.extend()} or equivalent mechanism (that is, any JavaScript-to-Java
643 * adapter), returns an object that can be used to invoke superclass methods on that object. E.g.:
644 * <pre>
645 * var cw = new FilterWriterAdapter(sw) {
646 * write: function(s, off, len) {
647 * s = capitalize(s, off, len)
648 * cw_super.write(s, 0, s.length())
649 * }
650 * }
651 * var cw_super = Java.super(cw)
652 * </pre>
653 * @param self the {@code Java} object itself - not used.
654 * @param adapter the original Java adapter instance for which the super adapter is created.
655 * @return a super adapter for the original adapter
656 */
657 @Function(attributes = Attribute.NOT_ENUMERABLE, where = Where.CONSTRUCTOR, name="super")
658 public static Object _super(final Object self, final Object adapter) {
659 return Bootstrap.createSuperAdapter(adapter);
660 }
661
662 /**
663 * Returns an object that is compatible with Java JSON libraries expectations; namely, that if it itself, or any
664 * object transitively reachable through it is a JavaScript array, then such objects will be exposed as
665 * {@link JSObject} that also implements the {@link List} interface for exposing the array elements. An explicit
666 * API is required as otherwise Nashorn exposes all objects externally as {@link JSObject}s that also implement the
667 * {@link Map} interface instead. By using this method, arrays will be exposed as {@link List}s and all other
668 * objects as {@link Map}s.
669 * @param self not used
670 * @param obj the object to be exposed in a Java JSON library compatible manner.
671 * @return a wrapper around the object that will enforce Java JSON library compatible exposure.
672 */
673 @Function(attributes = Attribute.NOT_ENUMERABLE, where = Where.CONSTRUCTOR)
674 public static Object asJSONCompatible(final Object self, final Object obj) {
675 return ScriptObjectMirror.wrapAsJSONCompatible(obj, Context.getGlobal());
676 }
677 }