1 /*
2 * Copyright (c) 2022, 2025, 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 /**
27 * <h2>Provides classfile parsing, generation, and transformation library.</h2>
28 * The {@code java.lang.classfile} package contains API models for reading,
29 * writing, and modifying Java class files, as specified in Chapter {@jvms 4} of
30 * the <cite>Java Virtual Machine Specification</cite>. This package, {@link
31 * java.lang.classfile.attribute}, {@link java.lang.classfile.constantpool},
32 * and {@link java.lang.classfile.instruction} form the Class-File API.
33 *
34 * <h2>Reading classfiles</h2>
35 * The main class for reading classfiles is {@link ClassModel}; we
36 * convert bytes into a {@link ClassModel} with {@link
37 * ClassFile#parse(byte[])}:
38 *
39 * {@snippet lang=java :
40 * ClassModel cm = ClassFile.of().parse(bytes);
41 * }
42 *
43 * There are several additional overloads of {@code parse} that let you specify
44 * various processing options.
45 * <p>
46 * A {@link ClassModel} is an immutable description of a class
47 * file. It provides accessor methods to get at class metadata (e.g., {@link
48 * ClassModel#thisClass()}, {@link ClassModel#flags()}),
49 * as well as subordinate classfile entities ({@link ClassModel#fields()},
50 * {@link ClassModel#attributes()}). A {@link
51 * ClassModel} is inflated lazily; most parts of the classfile are
52 * not parsed until they are actually needed. Due to the laziness, these models
53 * may not be thread safe. Additionally, invocations to accessor methods on
54 * models may lead to {@link IllegalArgumentException} due to malformed {@code
55 * class} file format, as parsing happens lazily.
56 * <p>
57 * We can enumerate the names of the fields and methods in a class by:
58 * {@snippet lang="java" class="PackageSnippets" region="enumerateFieldsMethods1"}
59 * <p>
60 * When we enumerate the methods, we get a {@link MethodModel} for each method; like a
61 * {@code ClassModel}, it gives us access to method metadata and
62 * the ability to descend into subordinate entities such as the bytecodes of the
63 * method body. In this way, a {@code ClassModel} is the root of a
64 * tree, with children for fields, methods, and attributes, and {@code MethodModel} in
65 * turn has its own children (attributes, {@code CodeModel}, etc.)
66 * <p>
67 * Methods like {@link ClassModel#methods} allows us to traverse the class structure
68 * explicitly, going straight to the parts we are interested in. This is useful
69 * for certain kinds of analysis, but if we wanted to process the whole
70 * classfile, we may want something more organized. A {@link
71 * ClassModel} also provides us with a view of the classfile as a
72 * series of class <em>elements</em>, which may include methods, fields, attributes,
73 * and more, and which can be distinguished with pattern matching. We could
74 * rewrite the above example as:
75 * {@snippet lang="java" class="PackageSnippets" region="enumerateFieldsMethods2"}
76 * <p>
77 * The models returned as elements from traversing {@code ClassModel} can in
78 * turn be sources of elements. If we wanted to
79 * traverse a classfile and enumerate all the classes for which we access fields
80 * and methods, we can pick out the class elements that describe methods, then
81 * in turn pick out the method elements that describe the code attribute, and
82 * finally pick out the code elements that describe field access and invocation
83 * instructions:
84 * {@snippet lang="java" class="PackageSnippets" region="gatherDependencies1"}
85 * <p>
86 * This same query could alternately be processed as a stream pipeline over
87 * class elements:
88 * {@snippet lang="java" class="PackageSnippets" region="gatherDependencies2"}
89 *
90 * <h3>Models and elements</h3>
91 * The view of classfiles presented by this API is framed in terms of
92 * <em>models</em> and <em>elements</em>. Models represent complex structures,
93 * such as classes, methods, fields, record elements, or the code body of a
94 * method. Models can be explored either via random-access navigation (such as
95 * the {@link ClassModel#methods()} accessor) or as a linear
96 * sequence of <em>elements</em>. (Elements can in turn also be models; a {@link
97 * FieldModel} is also an element of a class.) For each model type
98 * (e.g., {@link MethodModel}), there is a corresponding element
99 * type ({@link MethodElement}). Models and elements are immutable
100 * and are inflated lazily so creating a model does not necessarily require
101 * processing its entire content.
102 *
103 * <h3>The constant pool</h3>
104 * Much of the interesting content in a classfile lives in the <em>constant
105 * pool</em>. {@link ClassModel} provides a lazily-inflated,
106 * read-only view of the constant pool via {@link ClassModel#constantPool()}.
107 * Descriptions of classfile content is often exposed in the form of various
108 * subtypes of {@link PoolEntry}, such as {@link
109 * ClassEntry} or {@link Utf8Entry}.
110 * <p>
111 * Constant pool entries are also exposed through models and elements; in the
112 * above traversal example, the {@link InvokeInstruction}
113 * element exposed a method for {@code owner} that corresponds to a {@code
114 * Constant_Class_info} entry in the constant pool.
115 *
116 * <h3>Attributes</h3>
117 * Much of the contents of a classfile is stored in attributes; attributes are
118 * found on classes, methods, fields, record components, and on the {@code Code}
119 * attribute. Most attributes are surfaced as elements; for example, {@link
120 * SignatureAttribute} is a {@link
121 * ClassElement}, {@link MethodElement}, and {@link
122 * FieldElement} since it can appear in all of those places, and is
123 * included when iterating the elements of the corresponding model.
124 * <p>
125 * Some attributes are not surfaced as elements; these are attributes that are
126 * tightly coupled to -- and logically part of -- other parts of the class file.
127 * These include the {@code BootstrapMethods}, {@code LineNumberTable}, {@code
128 * StackMapTable}, {@code LocalVariableTable}, and {@code
129 * LocalVariableTypeTable} attributes. These are processed by the library and
130 * treated as part of the structure they are coupled to (the entries of the
131 * {@code BootstrapMethods} attribute are treated as part of the constant pool;
132 * line numbers and local variable metadata are modeled as elements of {@link
133 * CodeModel}.)
134 * <p>
135 * The {@code Code} attribute, in addition to being modeled as a {@link
136 * MethodElement}, is also a model in its own right ({@link
137 * CodeModel}) due to its complex structure.
138 * <p>
139 * Each standard attribute has an interface (in {@code java.lang.classfile.attribute})
140 * which exposes the contents of the attribute and provides factories to
141 * construct the attribute. For example, the {@code Signature} attribute is
142 * defined by the {@link SignatureAttribute} class, and
143 * provides accessors for {@link SignatureAttribute#signature()}
144 * as well as factories taking {@link Utf8Entry} or
145 * {@link String}.
146 *
147 * <h3>Custom attributes</h3>
148 * Attributes are converted between their classfile form and their corresponding
149 * object form via an {@link AttributeMapper}. An {@code
150 * AttributeMapper} provides the
151 * {@link AttributeMapper#readAttribute(AttributedElement,
152 * ClassReader, int)} method for mapping from the classfile format
153 * to an attribute instance, and the
154 * {@link AttributeMapper#writeAttribute(BufWriter,
155 * Attribute)} method for mapping back to the classfile format. It also
156 * contains metadata including the attribute name, the set of classfile entities
157 * where the attribute is applicable, and whether multiple attributes of the
158 * same kind are allowed on a single entity.
159 * <p>
160 * There are built-in attribute mappers (in {@link Attributes}) for
161 * each of the attribute types defined in section {@jvms 4.7} of <cite>The Java Virtual
162 * Machine Specification</cite>, as well as several common nonstandard attributes used by the
163 * JDK such as {@code CharacterRangeTable}.
164 * <p>
165 * Unrecognized attributes are delivered as elements of type {@link
166 * UnknownAttribute}, which provide access only to the
167 * {@code byte[]} contents of the attribute.
168 * <p>
169 * For nonstandard attributes, user-provided attribute mappers can be specified
170 * through the use of the {@link
171 * ClassFile.AttributeMapperOption#of(Function)}}
172 * classfile option. Implementations of custom attributes should extend {@link
173 * CustomAttribute}.
174 *
175 * <h3 id="options">Options</h3>
176 * <p>
177 * {@link ClassFile#of(ClassFile.Option[])}
178 * accepts a list of options. {@link ClassFile.Option} is a base interface
179 * for some statically enumerated options, as well as factories for more complex options,
180 * including:
181 * <ul>
182 * <li>{@link ClassFile.AttributeMapperOption#of(Function)}
183 * -- specify format of custom attributes</li>
184 * <li>{@link ClassFile.AttributesProcessingOption}
185 * -- unrecognized or problematic original attributes (default is {@code PASS_ALL_ATTRIBUTES})</li>
186 * <li>{@link ClassFile.ClassHierarchyResolverOption#of(ClassHierarchyResolver)}
187 * -- specify a custom class hierarchy resolver used by stack map generation</li>
188 * <li>{@link ClassFile.ConstantPoolSharingOption}}
189 * -- share constant pool when transforming (default is {@code SHARED_POOL})</li>
190 * <li>{@link ClassFile.DeadCodeOption}}
191 * -- patch out unreachable code (default is {@code PATCH_DEAD_CODE})</li>
192 * <li>{@link ClassFile.DeadLabelsOption}}
193 * -- filter unresolved labels (default is {@code FAIL_ON_DEAD_LABELS})</li>
194 * <li>{@link ClassFile.DebugElementsOption}
195 * -- processing of debug information, such as local variable metadata (default is {@code PASS_DEBUG}) </li>
196 * <li>{@link ClassFile.LineNumbersOption}
197 * -- processing of line numbers (default is {@code PASS_LINE_NUMBERS}) </li>
198 * <li>{@link ClassFile.ShortJumpsOption}
199 * -- automatically rewrite short jumps to long when necessary (default is {@code FIX_SHORT_JUMPS})</li>
200 * <li>{@link ClassFile.StackMapsOption}
201 * -- generate stackmaps (default is {@code STACK_MAPS_WHEN_REQUIRED})</li>
202 * </ul>
203 * <p>
204 * {@link ClassFile.AttributeMapperOption} and {@link ClassFile.ClassHierarchyResolverOption}
205 * are critical to the correctness of {@code class} file parsing and generation.
206 * The attribute mapper is required to parse custom attributes. A correct
207 * resolver is required to generate {@code class} files that refer to classes
208 * not available to the system class loader in its bytecode, or in corner cases,
209 * when generation wishes to avoid loading system classes, such as in agents.
210 * <p>
211 * Most options allow you to request that certain parts of the classfile be
212 * skipped during traversal, such as debug information or unrecognized
213 * attributes. Some options allow you to suppress generation of portions of the
214 * classfile, such as stack maps. Many of these options are to access
215 * performance tradeoffs; processing debug information and line numbers has a
216 * cost (both in writing and reading.) If you don't need this information, you
217 * can suppress it with options to gain some performance.
218 *
219 * <h2>Writing classfiles</h2>
220 * ClassFile generation is accomplished through <em>builders</em>. For each
221 * entity type that has a model, there is also a corresponding builder type;
222 * classes are built through {@link ClassBuilder}, methods through
223 * {@link MethodBuilder}, etc.
224 * <p>
225 * Rather than creating builders directly, builders are provided as an argument
226 * to a user-provided lambda. To generate the familiar "hello world" program,
227 * we ask for a class builder, and use that class builder to create method
228 * builders for the constructor and {@code main} method, and in turn use the
229 * method builders to create a {@code Code} attribute and use the code builders
230 * to generate the instructions:
231 * {@snippet lang="java" class="PackageSnippets" region="helloWorld1"}
232 * <p>
233 * The convenience methods {@code ClassBuilder.buildMethodBody} allows us to ask
234 * {@link ClassBuilder} to create code builders to build method bodies directly,
235 * skipping the method builder custom lambda:
236 * {@snippet lang="java" class="PackageSnippets" region="helloWorld2"}
237 * <p>
238 * Builders often support multiple ways of expressing the same entity at
239 * different levels of abstraction. For example, the {@code invokevirtual}
240 * instruction invoking {@code println} could have been generated with {@link
241 * CodeBuilder#invokevirtual(ClassDesc,
242 * String, MethodTypeDesc) CodeBuilder.invokevirtual}, {@link
243 * CodeBuilder#invoke(Opcode,
244 * ClassDesc, String, MethodTypeDesc,
245 * boolean) CodeBuilder.invoke}, or {@link
246 * CodeBuilder#with(ClassFileElement)
247 * CodeBuilder.with}.
248 * <p>
249 * The convenience method {@code CodeBuilder.invokevirtual} behaves as if it calls
250 * the convenience method {@code CodeBuilder.invoke}, which in turn behaves
251 * as if it calls method {@code CodeBuilder.with}. This composing of method calls on the
252 * builder enables the composing of transforms (as described later).
253 * <p>
254 * Unless otherwise noted, passing a {@code null} argument to a constructor
255 * or method of any Class-File API class or interface will cause a {@link
256 * NullPointerException} to be thrown. Additionally,
257 * invoking a method with an array or collection containing a {@code null} element
258 * will cause a {@code NullPointerException}, unless otherwise specified. </p>
259 *
260 * <h3>Symbolic information</h3>
261 * To describe symbolic information for classes and types, the API uses the
262 * nominal descriptor abstractions from {@link java.lang.constant} such as {@link
263 * ClassDesc} and {@link MethodTypeDesc},
264 * which is less error-prone than using raw strings.
265 * <p>
266 * If a constant pool entry has a nominal representation then it provides a
267 * method returning the corresponding nominal descriptor type e.g.
268 * method {@link ClassEntry#asSymbol} returns
269 * {@code ClassDesc}.
270 * <p>
271 * Where appropriate builders provide two methods for building an element with
272 * symbolic information, one accepting nominal descriptors, and the other
273 * accepting constant pool entries.
274 *
275 * <h3>Consistency checks, syntax checks and verification</h3>
276 * No consistency checks are performed while building or transforming classfiles
277 * (except for null arguments checks). All builders and classfile elements factory
278 * methods accepts the provided information without implicit validation.
279 * However, fatal inconsistencies (like for example invalid code sequence or
280 * unresolved labels) affects internal tools and may cause exceptions later in
281 * the classfile building process. These fatal exceptions are thrown as
282 * {@link IllegalArgumentException}.
283 * <p>
284 * Using nominal descriptors assures the right serial form is applied by the
285 * ClassFile API library based on the actual context. Also these nominal
286 * descriptors are validated during their construction, so it is not possible to
287 * create them with invalid content by mistake. Following example pass class
288 * name to the {@link ClassDesc#of} method for validation
289 * and the library performs automatic conversion to the right internal form of
290 * the class name when serialized in the constant pool as a class entry.
291 * {@snippet lang=java :
292 * var validClassEntry = constantPoolBuilder.classEntry(ClassDesc.of("mypackage.MyClass"));
293 * }
294 * <p>
295 * On the other hand it is possible to use builders methods and factories accepting
296 * constant pool entries directly. Constant pool entries can be constructed also
297 * directly from raw values, with no additional conversions or validations.
298 * Following example uses intentionally wrong class name form and it is applied
299 * without any validation or conversion.
300 * {@snippet lang=java :
301 * var invalidClassEntry = constantPoolBuilder.classEntry(
302 * constantPoolBuilder.utf8Entry("mypackage.MyClass"));
303 * }
304 * <p>
305 * More complex verification of a classfile can be achieved by invocation of
306 * {@link ClassFile#verify}.
307 *
308 * <h2>Transforming classfiles</h2>
309 * ClassFile Processing APIs are most frequently used to combine reading and
310 * writing into transformation, where a classfile is read, localized changes are
311 * made, but much of the classfile is passed through unchanged. For each kind
312 * of builder, {@code XxxBuilder} has a method {@code with(XxxElement)} so that
313 * elements that we wish to pass through unchanged can be handed directly back
314 * to the builder.
315 * <p>
316 * If we wanted to strip out methods whose names starts with "debug", we could
317 * get an existing {@link ClassModel}, build a new classfile that
318 * provides a {@link ClassBuilder}, iterate the elements of the
319 * original {@link ClassModel}, and pass through all of them to
320 * the builder except the methods we want to drop:
321 * {@snippet lang="java" class="PackageSnippets" region="stripDebugMethods1"}
322 * <p>
323 * This hands every class element, except for those corresponding to methods
324 * whose names start with {@code debug}, back to the builder. Transformations
325 * can of course be more complicated, diving into method bodies and instructions
326 * and transforming those as well, but the same structure is repeated at every
327 * level, since every entity has corresponding model, builder, and element
328 * abstractions.
329 * <p>
330 * Transformation can be viewed as a "flatMap" operation on the sequence of
331 * elements; for every element, we could pass it through unchanged, drop it, or
332 * replace it with one or more elements. Because transformation is such a
333 * common operation on classfiles, each model type has a corresponding {@code
334 * XxxTransform} type (which describes a transform on a sequence of {@code
335 * XxxElement}) and each builder type has {@code transformYyy} methods for transforming
336 * its child models. A transform is simply a functional interface that takes a
337 * builder and an element, and an implementation "flatMap"s elements
338 * into the builder. We could express the above as:
339 * {@snippet lang="java" class="PackageSnippets" region="stripDebugMethods2"}
340 * <p>
341 * {@code ClassTransform.dropping} convenience method allow us to simplify the same
342 * transformation construction and express the above as:
343 * {@snippet lang="java" class="PackageSnippets" region="stripDebugMethods3"}
344 *
345 * <h3>Lifting transforms</h3>
346 * While the example using transformations are only slightly shorter, the
347 * advantage of expressing transformation in this way is that the transform
348 * operations can be more easily combined. Suppose we want to redirect
349 * invocations of static methods on {@code Foo} to the corresponding method on
350 * {@code Bar} instead. We could express this as a transformation on {@link
351 * CodeElement}:
352 * {@snippet lang="java" class="PackageSnippets" region="fooToBarTransform"}
353 * <p>
354 * We can then <em>lift</em> this transformation on code elements into a
355 * transformation on method elements. This intercepts method elements that
356 * correspond to a {@code Code} attribute, dives into its code elements, and
357 * applies the code transform to them, and passes other method elements through
358 * unchanged:
359 * {@snippet lang=java :
360 * MethodTransform mt = MethodTransform.transformingCode(fooToBar);
361 * }
362 * <p>
363 * and further lift the transform on method elements into one on class
364 * elements:
365 * {@snippet lang=java :
366 * ClassTransform ct = ClassTransform.transformingMethods(mt);
367 * }
368 * <p>
369 * or lift the code transform into the class transform directly:
370 * {@snippet lang=java :
371 * ClassTransform ct = ClassTransform.transformingMethodBodies(fooToBar);
372 * }
373 * <p>
374 * and then transform the classfile:
375 * {@snippet lang=java :
376 * var cc = ClassFile.of();
377 * byte[] newBytes = cc.transformClass(cc.parse(bytes), ct);
378 * }
379 * <p>
380 * This is much more concise (and less error-prone) than the equivalent
381 * expressed by traversing the classfile structure directly:
382 * {@snippet lang="java" class="PackageSnippets" region="fooToBarUnrolled"}
383 *
384 * <h3>Composing transforms</h3>
385 * Transforms on the same type of element can be composed in sequence, where the
386 * output of the first is fed to the input of the second. Suppose we want to
387 * instrument all method calls, where we print the name of a method before
388 * calling it:
389 * {@snippet lang="java" class="PackageSnippets" region="instrumentCallsTransform"}
390 * <p>
391 * Then we can compose {@code fooToBar} and {@code instrumentCalls} with {@link
392 * CodeTransform#andThen(CodeTransform)}:
393 *
394 * {@snippet lang=java :
395 * var cc = ClassFile.of();
396 * byte[] newBytes = cc.transformClass(cc.parse(bytes),
397 * ClassTransform.transformingMethods(
398 * MethodTransform.transformingCode(
399 * fooToBar.andThen(instrumentCalls))));
400 * }
401 *
402 * Transform {@code instrumentCalls} will receive all code elements produced by
403 * transform {@code forToBar}, either those code elements from the original classfile
404 * or replacements (replacing static invocations to {@code Foo} with those to {@code Bar}).
405 *
406 * <h3>Constant pool sharing</h3>
407 * Transformation doesn't merely handle the logistics of reading, transforming
408 * elements, and writing. Most of the time when we are transforming a
409 * classfile, we are making relatively minor changes. To optimize such cases,
410 * transformation seeds the new classfile with a copy of the constant pool from
411 * the original classfile; this enables significant optimizations (methods and
412 * attributes that are not transformed can be processed by bulk-copying their
413 * bytes, rather than parsing them and regenerating their contents.) If
414 * constant pool sharing is not desired it can be suppressed
415 * with the {@link ClassFile.ConstantPoolSharingOption} option.
416 * Such suppression may be beneficial when transformation removes many elements,
417 * resulting in many unreferenced constant pool entries.
418 *
419 * <h3>Transformation handling of unknown classfile elements</h3>
420 * Custom classfile transformations might be unaware of classfile elements
421 * introduced by future JDK releases. To achieve deterministic stability,
422 * classfile transforms interested in consuming all classfile elements should be
423 * implemented strictly to throw exceptions if running on a newer JDK, if the
424 * transformed class file is a newer version, or if a new and unknown classfile
425 * element appears. As for example in the following strict compatibility-checking
426 * transformation snippets:
427 * {@snippet lang="java" class="PackageSnippets" region="strictTransform1"}
428 * {@snippet lang="java" class="PackageSnippets" region="strictTransform2"}
429 * {@snippet lang="java" class="PackageSnippets" region="strictTransform3"}
430 * <p>
431 * Conversely, classfile transforms that are only interested in consuming a portion
432 * of classfile elements do not need to concern with new and unknown classfile
433 * elements and may pass them through. Following example shows such future-proof
434 * code transformation:
435 * {@snippet lang="java" class="PackageSnippets" region="benevolentTransform"}
436 *
437 * <h2>API conventions</h2>
438 * <p>
439 * The API is largely derived from a <a href="#data_model"><em>data model</em></a>
440 * for the classfile format, which defines each element kind (which includes models and
441 * attributes) and its properties. For each element kind, there is a
442 * corresponding interface to describe that element, and factory methods to
443 * create that element. Some element kinds also have convenience methods on the
444 * corresponding builder (e.g., {@link
445 * CodeBuilder#invokevirtual(ClassDesc,
446 * String, MethodTypeDesc)}).
447 * <p>
448 * Most symbolic information in elements is represented by constant pool entries
449 * (for example, the owner of a field is represented by a {@link
450 * ClassEntry}.) Factories and builders also
451 * accept nominal descriptors from {@link java.lang.constant} (e.g., {@link
452 * ClassDesc}.)
453 *
454 * <h2><a id="data_model"></a>Data model</h2>
455 * We define each kind of element by its name, an optional arity indicator (zero
456 * or more, zero or one, exactly one), and a list of components. The elements
457 * of a class are fields, methods, and the attributes that can appear on
458 * classes:
459 *
460 * {@snippet lang="text" :
461 * ClassElement =
462 * FieldModel*(UtfEntry name, Utf8Entry descriptor)
463 * | MethodModel*(UtfEntry name, Utf8Entry descriptor)
464 * | ModuleAttribute?(int flags, ModuleEntry moduleName, UtfEntry moduleVersion,
465 * List<ModuleRequireInfo> requires, List<ModuleOpenInfo> opens,
466 * List<ModuleExportInfo> exports, List<ModuleProvidesInfo> provides,
467 * List<ClassEntry> uses)
468 * | ModulePackagesAttribute?(List<PackageEntry> packages)
469 * | ModuleTargetAttribute?(Utf8Entry targetPlatform)
470 * | ModuleHashesAttribute?(Utf8Entry algorithm, List<HashInfo> hashes)
471 * | ModuleResolutionAttribute?(int resolutionFlags)
472 * | SourceFileAttribute?(Utf8Entry sourceFile)
473 * | SourceDebugExtensionsAttribute?(byte[] contents)
474 * | CompilationIDAttribute?(Utf8Entry compilationId)
475 * | SourceIDAttribute?(Utf8Entry sourceId)
476 * | NestHostAttribute?(ClassEntry nestHost)
477 * | NestMembersAttribute?(List<ClassEntry> nestMembers)
478 * | RecordAttribute?(List<RecordComponent> components)
479 * | EnclosingMethodAttribute?(ClassEntry className, NameAndTypeEntry method)
480 * | InnerClassesAttribute?(List<InnerClassInfo> classes)
481 * | PermittedSubclassesAttribute?(List<ClassEntry> permittedSubclasses)
482 * | DeclarationElement*
483 * }
484 *
485 * where {@code DeclarationElement} are the elements that are common to all declarations
486 * (classes, methods, fields) and so are factored out:
487 *
488 * {@snippet lang="text" :
489 * DeclarationElement =
490 * SignatureAttribute?(Utf8Entry signature)
491 * | SyntheticAttribute?()
492 * | DeprecatedAttribute?()
493 * | RuntimeInvisibleAnnotationsAttribute?(List<Annotation> annotations)
494 * | RuntimeVisibleAnnotationsAttribute?(List<Annotation> annotations)
495 * | CustomAttribute*
496 * | UnknownAttribute*
497 * }
498 *
499 * Fields and methods are models with their own elements. The elements of fields
500 * and methods are fairly simple; most of the complexity of methods lives in the
501 * {@link CodeModel} (which models the {@code Code} attribute
502 * along with the code-related attributes: stack map table, local variable table,
503 * line number table, etc.)
504 *
505 * {@snippet lang="text" :
506 * FieldElement =
507 * DeclarationElement
508 * | ConstantValueAttribute?(ConstantValueEntry constant)
509 *
510 * MethodElement =
511 * DeclarationElement
512 * | CodeModel?()
513 * | AnnotationDefaultAttribute?(ElementValue defaultValue)
514 * | MethodParametersAttribute?(List<MethodParameterInfo> parameters)
515 * | ExceptionsAttribute?(List<ClassEntry> exceptions)
516 * }
517 *
518 * {@link CodeModel} is unique in that its elements are <em>ordered</em>.
519 * Elements of {@code Code} include ordinary bytecodes, as well as a number of pseudo-instructions
520 * representing branch targets, line number metadata, local variable metadata, and
521 * catch blocks.
522 *
523 * {@snippet lang="text" :
524 * CodeElement = Instruction | PseudoInstruction
525 *
526 * Instruction =
527 * LoadInstruction(TypeKind type, int slot)
528 * | StoreInstruction(TypeKind type, int slot)
529 * | IncrementInstruction(int slot, int constant)
530 * | BranchInstruction(Opcode opcode, Label target)
531 * | LookupSwitchInstruction(Label defaultTarget, List<SwitchCase> cases)
532 * | TableSwitchInstruction(Label defaultTarget, int low, int high,
533 * List<SwitchCase> cases)
534 * | ReturnInstruction(TypeKind kind)
535 * | ThrowInstruction()
536 * | FieldInstruction(Opcode opcode, FieldRefEntry field)
537 * | InvokeInstruction(Opcode opcode, MemberRefEntry method, boolean isInterface)
538 * | InvokeDynamicInstruction(InvokeDynamicEntry invokedynamic)
539 * | NewObjectInstruction(ClassEntry className)
540 * | NewReferenceArrayInstruction(ClassEntry componentType)
541 * | NewPrimitiveArrayInstruction(TypeKind typeKind)
542 * | NewMultiArrayInstruction(ClassEntry componentType, int dims)
543 * | ArrayLoadInstruction(Opcode opcode)
544 * | ArrayStoreInstruction(Opcode opcode)
545 * | TypeCheckInstruction(Opcode opcode, ClassEntry className)
546 * | ConvertInstruction(TypeKind from, TypeKind to)
547 * | OperatorInstruction(Opcode opcode)
548 * | ConstantInstruction(ConstantDesc constant)
549 * | StackInstruction(Opcode opcode)
550 * | MonitorInstruction(Opcode opcode)
551 * | NopInstruction()
552 *
553 * PseudoInstruction =
554 * | LabelTarget(Label label)
555 * | LineNumber(int line)
556 * | ExceptionCatch(Label tryStart, Label tryEnd, Label handler, ClassEntry exception)
557 * | LocalVariable(int slot, UtfEntry name, Utf8Entry type, Label startScope, Label endScope)
558 * | LocalVariableType(int slot, Utf8Entry name, Utf8Entry type, Label startScope, Label endScope)
559 * | CharacterRange(int rangeStart, int rangeEnd, int flags, Label startScope, Label endScope)
560 * }
561 *
562 * @since 24
563 */
564 package java.lang.classfile;
565
566 import java.lang.classfile.attribute.SignatureAttribute;
567 import java.lang.classfile.attribute.UnknownAttribute;
568 import java.lang.classfile.constantpool.ClassEntry;
569 import java.lang.classfile.constantpool.PoolEntry;
570 import java.lang.classfile.constantpool.Utf8Entry;
571 import java.lang.classfile.instruction.InvokeInstruction;
572 import java.lang.constant.ClassDesc;
573 import java.lang.constant.MethodTypeDesc;
574 import java.util.function.Function;