1 /*
2 * Copyright (c) 2012, 2024, 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 *
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24 */
25
26 package java.lang.invoke;
27
28 import java.io.Serializable;
29 import java.util.Arrays;
30 import java.lang.reflect.Array;
31 import java.util.Objects;
32
33 /**
34 * <p>Methods to facilitate the creation of simple "function objects" that
35 * implement one or more interfaces by delegation to a provided {@link MethodHandle},
36 * possibly after type adaptation and partial evaluation of arguments. These
37 * methods are typically used as <em>bootstrap methods</em> for {@code invokedynamic}
38 * call sites, to support the <em>lambda expression</em> and <em>method
39 * reference expression</em> features of the Java Programming Language.
40 *
41 * <p>Indirect access to the behavior specified by the provided {@code MethodHandle}
42 * proceeds in order through three phases:
43 * <ul>
44 * <li><p><em>Linkage</em> occurs when the methods in this class are invoked.
45 * They take as arguments an interface to be implemented (typically a
46 * <em>functional interface</em>, one with a single abstract method), a
47 * name and signature of a method from that interface to be implemented, a
48 * {@linkplain MethodHandleInfo direct method handle} describing the desired
49 * implementation behavior for that method, and possibly other additional
50 * metadata, and produce a {@link CallSite} whose target can be used to
51 * create suitable function objects.
52 *
53 * <p>Linkage may involve dynamically loading a new class that implements
54 * the target interface, or re-using a suitable existing class.
55 *
56 * <p>The {@code CallSite} can be considered a "factory" for function
57 * objects and so these linkage methods are referred to as
58 * "metafactories".</li>
59 *
60 * <li><p><em>Capture</em> occurs when the {@code CallSite}'s target is
61 * invoked, typically through an {@code invokedynamic} call site,
62 * producing a function object. This may occur many times for
63 * a single factory {@code CallSite}.
64 *
65 * <p>If the behavior {@code MethodHandle} has additional parameters beyond
66 * those of the specified interface method, these are referred to as
67 * <em>captured parameters</em>, which must be provided as arguments to the
68 * {@code CallSite} target. The expected number and types of captured
69 * parameters are determined during linkage.
70 *
71 * <p>Capture may involve allocation of a new function object, or may return
72 * a suitable existing function object. The identity of a function object
73 * produced by capture is unpredictable, and therefore identity-sensitive
74 * operations (such as reference equality, object locking, and {@code
75 * System.identityHashCode()}) may produce different results in different
76 * implementations, or even upon different invocations in the same
77 * implementation.</li>
78 *
79 * <li><p><em>Invocation</em> occurs when an implemented interface method is
80 * invoked on a function object. This may occur many times for a single
81 * function object. The method referenced by the implementation
82 * {@code MethodHandle} is invoked, passing to it the captured arguments and
83 * the invocation arguments. The result of the method is returned.
84 * </li>
85 * </ul>
86 *
87 * <p>It is sometimes useful to restrict the set of inputs or results permitted
88 * at invocation. For example, when the generic interface {@code Predicate<T>}
89 * is parameterized as {@code Predicate<String>}, the input must be a
90 * {@code String}, even though the method to implement allows any {@code Object}.
91 * At linkage time, an additional {@link MethodType} parameter describes the
92 * "dynamic" method type; on invocation, the arguments and eventual result
93 * are checked against this {@code MethodType}.
94 *
95 * <p>This class provides two forms of linkage methods: a standard version
96 * ({@link #metafactory(MethodHandles.Lookup, String, MethodType, MethodType, MethodHandle, MethodType)})
97 * using an optimized protocol, and an alternate version
98 * {@link #altMetafactory(MethodHandles.Lookup, String, MethodType, Object...)}).
99 * The alternate version is a generalization of the standard version, providing
100 * additional control over the behavior of the generated function objects via
101 * flags and additional arguments. The alternate version adds the ability to
102 * manage the following attributes of function objects:
103 *
104 * <ul>
105 * <li><em>Multiple methods.</em> It is sometimes useful to implement multiple
106 * variations of the method signature, involving argument or return type
107 * adaptation. This occurs when multiple distinct VM signatures for a method
108 * are logically considered to be the same method by the language. The
109 * flag {@code FLAG_BRIDGES} indicates that a list of additional
110 * {@code MethodType}s will be provided, each of which will be implemented
111 * by the resulting function object. These methods will share the same
112 * name and instantiated type.</li>
113 *
114 * <li><em>Multiple interfaces.</em> If needed, more than one interface
115 * can be implemented by the function object. (These additional interfaces
116 * are typically marker interfaces with no methods.) The flag {@code FLAG_MARKERS}
117 * indicates that a list of additional interfaces will be provided, each of
118 * which should be implemented by the resulting function object.</li>
119 *
120 * <li><em>Serializability.</em> The generated function objects do not
121 * generally support serialization. If desired, {@code FLAG_SERIALIZABLE}
122 * can be used to indicate that the function objects should be serializable.
123 * Serializable function objects will use, as their serialized form,
124 * instances of the class {@code SerializedLambda}, which requires additional
125 * assistance from the capturing class (the class described by the
126 * {@link MethodHandles.Lookup} parameter {@code caller}); see
127 * {@link SerializedLambda} for details.</li>
128 * </ul>
129 *
130 * <p>Assume the linkage arguments are as follows:
131 * <ul>
132 * <li>{@code factoryType} (describing the {@code CallSite} signature) has
133 * K parameters of types (D1..Dk) and return type Rd;</li>
134 * <li>{@code interfaceMethodType} (describing the implemented method type) has N
135 * parameters, of types (U1..Un) and return type Ru;</li>
136 * <li>{@code implementation} (the {@code MethodHandle} providing the
137 * implementation) has M parameters, of types (A1..Am) and return type Ra
138 * (if the method describes an instance method, the method type of this
139 * method handle already includes an extra first argument corresponding to
140 * the receiver);</li>
141 * <li>{@code dynamicMethodType} (allowing restrictions on invocation)
142 * has N parameters, of types (T1..Tn) and return type Rt.</li>
143 * </ul>
144 *
145 * <p>Then the following linkage invariants must hold:
146 * <ul>
147 * <li>{@code interfaceMethodType} and {@code dynamicMethodType} have the same
148 * arity N, and for i=1..N, Ti and Ui are the same type, or Ti and Ui are
149 * both reference types and Ti is a subtype of Ui</li>
150 * <li>Either Rt and Ru are the same type, or both are reference types and
151 * Rt is a subtype of Ru</li>
152 * <li>K + N = M</li>
153 * <li>For i=1..K, Di = Ai</li>
154 * <li>For i=1..N, Ti is adaptable to Aj, where j=i+k</li>
155 * <li>The return type Rt is void, or the return type Ra is not void and is
156 * adaptable to Rt</li>
157 * </ul>
158 *
159 * <p>Further, at capture time, if {@code implementation} corresponds to an instance
160 * method, and there are any capture arguments ({@code K > 0}), then the first
161 * capture argument (corresponding to the receiver) must be non-null.
162 *
163 * <p>A type Q is considered adaptable to S as follows:
164 * <table class="striped">
165 * <caption style="display:none">adaptable types</caption>
166 * <thead>
167 * <tr><th scope="col">Q</th><th scope="col">S</th><th scope="col">Link-time checks</th><th scope="col">Invocation-time checks</th></tr>
168 * </thead>
169 * <tbody>
170 * <tr>
171 * <th scope="row">Primitive</th><th scope="row">Primitive</th>
172 * <td>Q can be converted to S via a primitive widening conversion</td>
173 * <td>None</td>
174 * </tr>
175 * <tr>
176 * <th scope="row">Primitive</th><th scope="row">Reference</th>
177 * <td>S is a supertype of the Wrapper(Q)</td>
178 * <td>Cast from Wrapper(Q) to S</td>
179 * </tr>
180 * <tr>
181 * <th scope="row">Reference</th><th scope="row">Primitive</th>
182 * <td>for parameter types: Q is a primitive wrapper and Primitive(Q)
183 * can be widened to S
184 * <br>for return types: If Q is a primitive wrapper, check that
185 * Primitive(Q) can be widened to S</td>
186 * <td>If Q is not a primitive wrapper, cast Q to the base Wrapper(S);
187 * for example Number for numeric types</td>
188 * </tr>
189 * <tr>
190 * <th scope="row">Reference</th><th scope="row">Reference</th>
191 * <td>for parameter types: S is a supertype of Q
192 * <br>for return types: none</td>
193 * <td>Cast from Q to S</td>
194 * </tr>
195 * </tbody>
196 * </table>
197 *
198 * @apiNote These linkage methods are designed to support the evaluation
199 * of <em>lambda expressions</em> and <em>method references</em> in the Java
200 * Language. For every lambda expressions or method reference in the source code,
201 * there is a target type which is a functional interface. Evaluating a lambda
202 * expression produces an object of its target type. The recommended mechanism
203 * for evaluating lambda expressions is to desugar the lambda body to a method,
204 * invoke an invokedynamic call site whose static argument list describes the
205 * sole method of the functional interface and the desugared implementation
206 * method, and returns an object (the lambda object) that implements the target
207 * type. (For method references, the implementation method is simply the
208 * referenced method; no desugaring is needed.)
209 *
210 * <p>The argument list of the implementation method and the argument list of
211 * the interface method(s) may differ in several ways. The implementation
212 * methods may have additional arguments to accommodate arguments captured by
213 * the lambda expression; there may also be differences resulting from permitted
214 * adaptations of arguments, such as casting, boxing, unboxing, and primitive
215 * widening. (Varargs adaptations are not handled by the metafactories; these are
216 * expected to be handled by the caller.)
217 *
218 * <p>Invokedynamic call sites have two argument lists: a static argument list
219 * and a dynamic argument list. The static argument list is stored in the
220 * constant pool; the dynamic argument is pushed on the operand stack at capture
221 * time. The bootstrap method has access to the entire static argument list
222 * (which in this case, includes information describing the implementation method,
223 * the target interface, and the target interface method(s)), as well as a
224 * method signature describing the number and static types (but not the values)
225 * of the dynamic arguments and the static return type of the invokedynamic site.
226 *
227 * <p>The implementation method is described with a direct method handle
228 * referencing a method or constructor. In theory, any method handle could be
229 * used, but this is not compatible with some implementation techniques and
230 * would complicate the work implementations must do.
231 *
232 * <p>Uses besides evaluation of lambda expressions and method references are
233 * unintended. These linkage methods may change their unspecified behaviors at
234 * any time to better suit the Java language features they were designed to
235 * support, and such changes may impact unintended uses. Unintended uses of
236 * these linkage methods may lead to resource leaks, or other unspecified
237 * negative effects.
238 *
239 * @implNote In the reference implementation, the classes implementing the created
240 * function objects are strongly reachable from the defining class loader of the
241 * caller, like classes and interfaces in Java source code. This technique
242 * reduces heap memory use, but as a consequence, the implementation classes can
243 * be unloaded only if the caller class can be unloaded. In particular, if the
244 * caller is a {@linkplain MethodHandles.Lookup.ClassOption#STRONG weak hidden
245 * class}, the implementation class, a strong hidden class, may not be unloaded
246 * even if the caller may be unloaded.
247 *
248 * @since 1.8
249 */
250 public final class LambdaMetafactory {
251
252 private LambdaMetafactory() {}
253
254 /** Flag for {@link #altMetafactory} indicating the lambda object
255 * must be serializable */
256 public static final int FLAG_SERIALIZABLE = 1 << 0;
257
258 /**
259 * Flag for {@link #altMetafactory} indicating the lambda object implements
260 * other interfaces besides {@code Serializable}
261 */
262 public static final int FLAG_MARKERS = 1 << 1;
263
264 /**
265 * Flag for alternate metafactories indicating the lambda object requires
266 * additional methods that invoke the {@code implementation}
267 */
268 public static final int FLAG_BRIDGES = 1 << 2;
269
270 /** Flag for {@link #altMetafactory} indicating the lambda object
271 * must be a {@code Quotable} object, inspectable using code reflection. */
272 public static final int FLAG_QUOTABLE = 1 << 3;
273
274 private static final Class<?>[] EMPTY_CLASS_ARRAY = new Class<?>[0];
275 private static final MethodType[] EMPTY_MT_ARRAY = new MethodType[0];
276
277 // LambdaMetafactory bootstrap methods are startup sensitive, and may be
278 // special cased in java.lang.invoke.BootstrapMethodInvoker to ensure
279 // methods are invoked with exact type information to avoid generating
280 // code for runtime checks. Take care any changes or additions here are
281 // reflected there as appropriate.
282
283 /**
284 * Facilitates the creation of simple "function objects" that implement one
285 * or more interfaces by delegation to a provided {@link MethodHandle},
286 * after appropriate type adaptation and partial evaluation of arguments.
287 * Typically used as a <em>bootstrap method</em> for {@code invokedynamic}
288 * call sites, to support the <em>lambda expression</em> and <em>method
289 * reference expression</em> features of the Java Programming Language.
290 *
291 * <p>This is the standard, streamlined metafactory; additional flexibility
292 * is provided by {@link #altMetafactory(MethodHandles.Lookup, String, MethodType, Object...)}.
293 * A general description of the behavior of this method is provided
294 * {@link LambdaMetafactory above}.
295 *
296 * <p>When the target of the {@code CallSite} returned from this method is
297 * invoked, the resulting function objects are instances of a class which
298 * implements the interface named by the return type of {@code factoryType},
299 * declares a method with the name given by {@code interfaceMethodName} and the
300 * signature given by {@code interfaceMethodType}. It may also override additional
301 * methods from {@code Object}.
302 *
303 * @param caller Represents a lookup context with the accessibility
304 * privileges of the caller. Specifically, the lookup context
305 * must have {@linkplain MethodHandles.Lookup#hasFullPrivilegeAccess()
306 * full privilege access}.
307 * When used with {@code invokedynamic}, this is stacked
308 * automatically by the VM.
309 * @param interfaceMethodName The name of the method to implement. When used with
310 * {@code invokedynamic}, this is provided by the
311 * {@code NameAndType} of the {@code InvokeDynamic}
312 * structure and is stacked automatically by the VM.
313 * @param factoryType The expected signature of the {@code CallSite}. The
314 * parameter types represent the types of capture variables;
315 * the return type is the interface to implement. When
316 * used with {@code invokedynamic}, this is provided by
317 * the {@code NameAndType} of the {@code InvokeDynamic}
318 * structure and is stacked automatically by the VM.
319 * @param interfaceMethodType Signature and return type of method to be
320 * implemented by the function object.
321 * @param implementation A direct method handle describing the implementation
322 * method which should be called (with suitable adaptation
323 * of argument types and return types, and with captured
324 * arguments prepended to the invocation arguments) at
325 * invocation time.
326 * @param dynamicMethodType The signature and return type that should
327 * be enforced dynamically at invocation time.
328 * In simple use cases this is the same as
329 * {@code interfaceMethodType}.
330 * @return a CallSite whose target can be used to perform capture, generating
331 * instances of the interface named by {@code factoryType}
332 * @throws LambdaConversionException If {@code caller} does not have full privilege
333 * access, or if {@code interfaceMethodName} is not a valid JVM
334 * method name, or if the return type of {@code factoryType} is not
335 * an interface, or if {@code implementation} is not a direct method
336 * handle referencing a method or constructor, or if the linkage
337 * invariants are violated, as defined {@link LambdaMetafactory above}.
338 * @throws NullPointerException If any argument is {@code null}.
339 */
340 public static CallSite metafactory(MethodHandles.Lookup caller,
341 String interfaceMethodName,
342 MethodType factoryType,
343 MethodType interfaceMethodType,
344 MethodHandle implementation,
345 MethodType dynamicMethodType)
346 throws LambdaConversionException {
347 AbstractValidatingLambdaMetafactory mf;
348 mf = new InnerClassLambdaMetafactory(Objects.requireNonNull(caller),
349 Objects.requireNonNull(factoryType),
350 Objects.requireNonNull(interfaceMethodName),
351 Objects.requireNonNull(interfaceMethodType),
352 Objects.requireNonNull(implementation),
353 Objects.requireNonNull(dynamicMethodType),
354 false,
355 EMPTY_CLASS_ARRAY,
356 EMPTY_MT_ARRAY,
357 null);
358 mf.validateMetafactoryArgs();
359 return mf.buildCallSite();
360 }
361
362 /**
363 * Facilitates the creation of simple "function objects" that implement one
364 * or more interfaces by delegation to a provided {@link MethodHandle},
365 * after appropriate type adaptation and partial evaluation of arguments.
366 * Typically used as a <em>bootstrap method</em> for {@code invokedynamic}
367 * call sites, to support the <em>lambda expression</em> and <em>method
368 * reference expression</em> features of the Java Programming Language.
369 *
370 * <p>This is the general, more flexible metafactory; a streamlined version
371 * is provided by {@link #metafactory(java.lang.invoke.MethodHandles.Lookup,
372 * String, MethodType, MethodType, MethodHandle, MethodType)}.
373 * A general description of the behavior of this method is provided
374 * {@link LambdaMetafactory above}.
375 *
376 * <p>The argument list for this method includes three fixed parameters,
377 * corresponding to the parameters automatically stacked by the VM for the
378 * bootstrap method in an {@code invokedynamic} invocation, and an {@code Object[]}
379 * parameter that contains additional parameters. The declared argument
380 * list for this method is:
381 *
382 * <pre>{@code
383 * CallSite altMetafactory(MethodHandles.Lookup caller,
384 * String interfaceMethodName,
385 * MethodType factoryType,
386 * Object... args)
387 * }</pre>
388 *
389 * <p>but it behaves as if the argument list is as follows:
390 *
391 * <pre>{@code
392 * CallSite altMetafactory(MethodHandles.Lookup caller,
393 * String interfaceMethodName,
394 * MethodType factoryType,
395 * MethodType interfaceMethodType,
396 * MethodHandle implementation,
397 * MethodType dynamicMethodType,
398 * int flags,
399 * int altInterfaceCount, // IF flags has MARKERS set
400 * Class... altInterfaces, // IF flags has MARKERS set
401 * int altMethodCount, // IF flags has BRIDGES set
402 * MethodType... altMethods // IF flags has BRIDGES set
403 * MethodHandle quotableField // IF flags has QUOTABLE set
404 * )
405 * }</pre>
406 *
407 * <p>Arguments that appear in the argument list for
408 * {@link #metafactory(MethodHandles.Lookup, String, MethodType, MethodType, MethodHandle, MethodType)}
409 * have the same specification as in that method. The additional arguments
410 * are interpreted as follows:
411 * <ul>
412 * <li>{@code flags} indicates additional options; this is a bitwise
413 * OR of desired flags. Defined flags are {@link #FLAG_BRIDGES},
414 * {@link #FLAG_MARKERS}, and {@link #FLAG_SERIALIZABLE}.</li>
415 * <li>{@code altInterfaceCount} is the number of additional interfaces
416 * the function object should implement, and is present if and only if the
417 * {@code FLAG_MARKERS} flag is set.</li>
418 * <li>{@code altInterfaces} is a variable-length list of additional
419 * interfaces to implement, whose length equals {@code altInterfaceCount},
420 * and is present if and only if the {@code FLAG_MARKERS} flag is set.</li>
421 * <li>{@code altMethodCount} is the number of additional method signatures
422 * the function object should implement, and is present if and only if
423 * the {@code FLAG_BRIDGES} flag is set.</li>
424 * <li>{@code altMethods} is a variable-length list of additional
425 * methods signatures to implement, whose length equals {@code altMethodCount},
426 * and is present if and only if the {@code FLAG_BRIDGES} flag is set.</li>
427 * <li>{@code quotableField} is a
428 * {@linkplain MethodHandles.Lookup#findGetter(Class, String, Class) getter} method handle
429 * that is used to retrieve the string representation of the quotable lambda's associated
430 * intermediate representation.</li>
431 * </ul>
432 *
433 * <p>Each class named by {@code altInterfaces} is subject to the same
434 * restrictions as {@code Rd}, the return type of {@code factoryType},
435 * as described {@link LambdaMetafactory above}. Each {@code MethodType}
436 * named by {@code altMethods} is subject to the same restrictions as
437 * {@code interfaceMethodType}, as described {@link LambdaMetafactory above}.
438 *
439 * <p>When FLAG_SERIALIZABLE is set in {@code flags}, the function objects
440 * will implement {@code Serializable}, and will have a {@code writeReplace}
441 * method that returns an appropriate {@link SerializedLambda}. The
442 * {@code caller} class must have an appropriate {@code $deserializeLambda$}
443 * method, as described in {@link SerializedLambda}.
444 *
445 * <p>When FLAG_QUOTABLE is set in {@code flags}, the function objects
446 * will implement {@code Quotable}.
447 *
448 * <p>When the target of the {@code CallSite} returned from this method is
449 * invoked, the resulting function objects are instances of a class with
450 * the following properties:
451 * <ul>
452 * <li>The class implements the interface named by the return type
453 * of {@code factoryType} and any interfaces named by {@code altInterfaces}</li>
454 * <li>The class declares methods with the name given by {@code interfaceMethodName},
455 * and the signature given by {@code interfaceMethodType} and additional signatures
456 * given by {@code altMethods}</li>
457 * <li>The class may override methods from {@code Object}, and may
458 * implement methods related to serialization.</li>
459 * </ul>
460 *
461 * @param caller Represents a lookup context with the accessibility
462 * privileges of the caller. Specifically, the lookup context
463 * must have {@linkplain MethodHandles.Lookup#hasFullPrivilegeAccess()
464 * full privilege access}.
465 * When used with {@code invokedynamic}, this is stacked
466 * automatically by the VM.
467 * @param interfaceMethodName The name of the method to implement. When used with
468 * {@code invokedynamic}, this is provided by the
469 * {@code NameAndType} of the {@code InvokeDynamic}
470 * structure and is stacked automatically by the VM.
471 * @param factoryType The expected signature of the {@code CallSite}. The
472 * parameter types represent the types of capture variables;
473 * the return type is the interface to implement. When
474 * used with {@code invokedynamic}, this is provided by
475 * the {@code NameAndType} of the {@code InvokeDynamic}
476 * structure and is stacked automatically by the VM.
477 * @param args An array of {@code Object} containing the required
478 * arguments {@code interfaceMethodType}, {@code implementation},
479 * {@code dynamicMethodType}, {@code flags}, and any
480 * optional arguments, as described above
481 * @return a CallSite whose target can be used to perform capture, generating
482 * instances of the interface named by {@code factoryType}
483 * @throws LambdaConversionException If {@code caller} does not have full privilege
484 * access, or if {@code interfaceMethodName} is not a valid JVM
485 * method name, or if the return type of {@code factoryType} is not
486 * an interface, or if any of {@code altInterfaces} is not an
487 * interface, or if {@code implementation} is not a direct method
488 * handle referencing a method or constructor, or if the linkage
489 * invariants are violated, as defined {@link LambdaMetafactory above}.
490 * @throws NullPointerException If any argument, or any component of {@code args},
491 * is {@code null}.
492 * @throws IllegalArgumentException If the number or types of the components
493 * of {@code args} do not follow the above rules, or if
494 * {@code altInterfaceCount} or {@code altMethodCount} are negative
495 * integers.
496 */
497 public static CallSite altMetafactory(MethodHandles.Lookup caller,
498 String interfaceMethodName,
499 MethodType factoryType,
500 Object... args)
501 throws LambdaConversionException {
502 Objects.requireNonNull(caller);
503 Objects.requireNonNull(interfaceMethodName);
504 Objects.requireNonNull(factoryType);
505 Objects.requireNonNull(args);
506 int argIndex = 0;
507 MethodType interfaceMethodType = extractArg(args, argIndex++, MethodType.class);
508 MethodHandle implementation = extractArg(args, argIndex++, MethodHandle.class);
509 MethodType dynamicMethodType = extractArg(args, argIndex++, MethodType.class);
510 int flags = extractArg(args, argIndex++, Integer.class);
511 Class<?>[] altInterfaces = EMPTY_CLASS_ARRAY;
512 MethodType[] altMethods = EMPTY_MT_ARRAY;
513 // Getter that returns the op of a Quotable instance
514 MethodHandle quotableOpGetter = null;
515 if ((flags & FLAG_MARKERS) != 0) {
516 int altInterfaceCount = extractArg(args, argIndex++, Integer.class);
517 if (altInterfaceCount < 0) {
518 throw new IllegalArgumentException("negative argument count");
519 }
520 if (altInterfaceCount > 0) {
521 altInterfaces = extractArgs(args, argIndex, Class.class, altInterfaceCount);
522 argIndex += altInterfaceCount;
523 }
524 }
525 if ((flags & FLAG_BRIDGES) != 0) {
526 int altMethodCount = extractArg(args, argIndex++, Integer.class);
527 if (altMethodCount < 0) {
528 throw new IllegalArgumentException("negative argument count");
529 }
530 if (altMethodCount > 0) {
531 altMethods = extractArgs(args, argIndex, MethodType.class, altMethodCount);
532 argIndex += altMethodCount;
533 }
534 }
535 if ((flags & FLAG_QUOTABLE) != 0) {
536 quotableOpGetter = extractArg(args, argIndex++, MethodHandle.class);
537 altInterfaces = Arrays.copyOf(altInterfaces, altInterfaces.length + 1);
538 altInterfaces[altInterfaces.length-1] = InnerClassLambdaMetafactory.CodeReflectionSupport.QUOTABLE_CLASS;
539 }
540 if (argIndex < args.length) {
541 throw new IllegalArgumentException("too many arguments");
542 }
543
544 boolean isSerializable = ((flags & FLAG_SERIALIZABLE) != 0);
545 if (isSerializable) {
546 boolean foundSerializableSupertype = Serializable.class.isAssignableFrom(factoryType.returnType());
547 for (Class<?> c : altInterfaces)
548 foundSerializableSupertype |= Serializable.class.isAssignableFrom(c);
549 if (!foundSerializableSupertype) {
550 altInterfaces = Arrays.copyOf(altInterfaces, altInterfaces.length + 1);
551 altInterfaces[altInterfaces.length-1] = Serializable.class;
552 }
553 }
554
555 AbstractValidatingLambdaMetafactory mf
556 = new InnerClassLambdaMetafactory(caller,
557 factoryType,
558 interfaceMethodName,
559 interfaceMethodType,
560 implementation,
561 dynamicMethodType,
562 isSerializable,
563 altInterfaces,
564 altMethods,
565 quotableOpGetter);
566 mf.validateMetafactoryArgs();
567 return mf.buildCallSite();
568 }
569
570 private static <T> T extractArg(Object[] args, int index, Class<T> type) {
571 if (index >= args.length) {
572 throw new IllegalArgumentException("missing argument");
573 }
574 Object result = Objects.requireNonNull(args[index]);
575 if (!type.isInstance(result)) {
576 throw new IllegalArgumentException("argument has wrong type");
577 }
578 return type.cast(result);
579 }
580
581 private static <T> T[] extractArgs(Object[] args, int index, Class<T> type, int count) {
582 @SuppressWarnings("unchecked")
583 T[] result = (T[]) Array.newInstance(type, count);
584 for (int i = 0; i < count; i++) {
585 result[i] = extractArg(args, index + i, type);
586 }
587 return result;
588 }
589
590 }