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// ASM: a very small and fast Java bytecode manipulation framework
// Copyright (c) 2000-2011 INRIA, France Telecom
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// 1. Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
// 3. Neither the name of the copyright holders nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
// THE POSSIBILITY OF SUCH DAMAGE.
package org.objectweb.asm;
/**
* A {@link ClassVisitor} that generates a corresponding ClassFile structure, as defined in the Java
* Virtual Machine Specification (JVMS). It can be used alone, to generate a Java class "from
* scratch", or with one or more {@link ClassReader} and adapter {@link ClassVisitor} to generate a
* modified class from one or more existing Java classes.
*
* @see JVMS 4
* @author Eric Bruneton
*/
public class ClassWriter extends ClassVisitor {
/**
* A flag to automatically compute the maximum stack size and the maximum number of local
* variables of methods. If this flag is set, then the arguments of the {@link
* MethodVisitor#visitMaxs} method of the {@link MethodVisitor} returned by the {@link
* #visitMethod} method will be ignored, and computed automatically from the signature and the
* bytecode of each method.
*
* Note: for classes whose version is {@link Opcodes#V1_7} of more, this option requires
* valid stack map frames. The maximum stack size is then computed from these frames, and from the
* bytecode instructions in between. If stack map frames are not present or must be recomputed,
* used {@link #COMPUTE_FRAMES} instead.
*
* @see #ClassWriter(int)
*/
public static final int COMPUTE_MAXS = 1;
/**
* A flag to automatically compute the stack map frames of methods from scratch. If this flag is
* set, then the calls to the {@link MethodVisitor#visitFrame} method are ignored, and the stack
* map frames are recomputed from the methods bytecode. The arguments of the {@link
* MethodVisitor#visitMaxs} method are also ignored and recomputed from the bytecode. In other
* words, {@link #COMPUTE_FRAMES} implies {@link #COMPUTE_MAXS}.
*
* @see #ClassWriter(int)
*/
public static final int COMPUTE_FRAMES = 2;
/**
* The flags passed to the constructor. Must be zero or more of {@link #COMPUTE_MAXS} and {@link
* #COMPUTE_FRAMES}.
*/
private final int flags;
// Note: fields are ordered as in the ClassFile structure, and those related to attributes are
// ordered as in Section 4.7 of the JVMS.
/**
* The minor_version and major_version fields of the JVMS ClassFile structure. minor_version is
* stored in the 16 most significant bits, and major_version in the 16 least significant bits.
*/
private int version;
/** The symbol table for this class (contains the constant_pool and the BootstrapMethods). */
private final SymbolTable symbolTable;
/**
* The access_flags field of the JVMS ClassFile structure. This field can contain ASM specific
* access flags, such as {@link Opcodes#ACC_DEPRECATED} or {@link Opcodes#ACC_RECORD}, which are
* removed when generating the ClassFile structure.
*/
private int accessFlags;
/** The this_class field of the JVMS ClassFile structure. */
private int thisClass;
/** The super_class field of the JVMS ClassFile structure. */
private int superClass;
/** The interface_count field of the JVMS ClassFile structure. */
private int interfaceCount;
/** The 'interfaces' array of the JVMS ClassFile structure. */
private int[] interfaces;
/**
* The fields of this class, stored in a linked list of {@link FieldWriter} linked via their
* {@link FieldWriter#fv} field. This field stores the first element of this list.
*/
private FieldWriter firstField;
/**
* The fields of this class, stored in a linked list of {@link FieldWriter} linked via their
* {@link FieldWriter#fv} field. This field stores the last element of this list.
*/
private FieldWriter lastField;
/**
* The methods of this class, stored in a linked list of {@link MethodWriter} linked via their
* {@link MethodWriter#mv} field. This field stores the first element of this list.
*/
private MethodWriter firstMethod;
/**
* The methods of this class, stored in a linked list of {@link MethodWriter} linked via their
* {@link MethodWriter#mv} field. This field stores the last element of this list.
*/
private MethodWriter lastMethod;
/** The number_of_classes field of the InnerClasses attribute, or 0. */
private int numberOfInnerClasses;
/** The 'classes' array of the InnerClasses attribute, or {@literal null}. */
private ByteVector innerClasses;
/** The class_index field of the EnclosingMethod attribute, or 0. */
private int enclosingClassIndex;
/** The method_index field of the EnclosingMethod attribute. */
private int enclosingMethodIndex;
/** The signature_index field of the Signature attribute, or 0. */
private int signatureIndex;
/** The source_file_index field of the SourceFile attribute, or 0. */
private int sourceFileIndex;
/** The debug_extension field of the SourceDebugExtension attribute, or {@literal null}. */
private ByteVector debugExtension;
/**
* The last runtime visible annotation of this class. The previous ones can be accessed with the
* {@link AnnotationWriter#previousAnnotation} field. May be {@literal null}.
*/
private AnnotationWriter lastRuntimeVisibleAnnotation;
/**
* The last runtime invisible annotation of this class. The previous ones can be accessed with the
* {@link AnnotationWriter#previousAnnotation} field. May be {@literal null}.
*/
private AnnotationWriter lastRuntimeInvisibleAnnotation;
/**
* The last runtime visible type annotation of this class. The previous ones can be accessed with
* the {@link AnnotationWriter#previousAnnotation} field. May be {@literal null}.
*/
private AnnotationWriter lastRuntimeVisibleTypeAnnotation;
/**
* The last runtime invisible type annotation of this class. The previous ones can be accessed
* with the {@link AnnotationWriter#previousAnnotation} field. May be {@literal null}.
*/
private AnnotationWriter lastRuntimeInvisibleTypeAnnotation;
/** The Module attribute of this class, or {@literal null}. */
private ModuleWriter moduleWriter;
/** The host_class_index field of the NestHost attribute, or 0. */
private int nestHostClassIndex;
/** The number_of_classes field of the NestMembers attribute, or 0. */
private int numberOfNestMemberClasses;
/** The 'classes' array of the NestMembers attribute, or {@literal null}. */
private ByteVector nestMemberClasses;
/** The number_of_classes field of the PermittedSubclasses attribute, or 0. */
private int numberOfPermittedSubclasses;
/** The 'classes' array of the PermittedSubclasses attribute, or {@literal null}. */
private ByteVector permittedSubclasses;
/**
* The record components of this class, stored in a linked list of {@link RecordComponentWriter}
* linked via their {@link RecordComponentWriter#delegate} field. This field stores the first
* element of this list.
*/
private RecordComponentWriter firstRecordComponent;
/**
* The record components of this class, stored in a linked list of {@link RecordComponentWriter}
* linked via their {@link RecordComponentWriter#delegate} field. This field stores the last
* element of this list.
*/
private RecordComponentWriter lastRecordComponent;
/**
* The first non standard attribute of this class. The next ones can be accessed with the {@link
* Attribute#nextAttribute} field. May be {@literal null}.
*
*
WARNING: this list stores the attributes in the reverse order of their visit.
* firstAttribute is actually the last attribute visited in {@link #visitAttribute}. The {@link
* #toByteArray} method writes the attributes in the order defined by this list, i.e. in the
* reverse order specified by the user.
*/
private Attribute firstAttribute;
/**
* Indicates what must be automatically computed in {@link MethodWriter}. Must be one of {@link
* MethodWriter#COMPUTE_NOTHING}, {@link MethodWriter#COMPUTE_MAX_STACK_AND_LOCAL}, {@link
* MethodWriter#COMPUTE_MAX_STACK_AND_LOCAL_FROM_FRAMES}, {@link
* MethodWriter#COMPUTE_INSERTED_FRAMES}, or {@link MethodWriter#COMPUTE_ALL_FRAMES}.
*/
private int compute;
// -----------------------------------------------------------------------------------------------
// Constructor
// -----------------------------------------------------------------------------------------------
/**
* Constructs a new {@link ClassWriter} object.
*
* @param flags option flags that can be used to modify the default behavior of this class. Must
* be zero or more of {@link #COMPUTE_MAXS} and {@link #COMPUTE_FRAMES}.
*/
public ClassWriter(final int flags) {
this(null, flags);
}
/**
* Constructs a new {@link ClassWriter} object and enables optimizations for "mostly add" bytecode
* transformations. These optimizations are the following:
*
*
* - The constant pool and bootstrap methods from the original class are copied as is in the
* new class, which saves time. New constant pool entries and new bootstrap methods will be
* added at the end if necessary, but unused constant pool entries or bootstrap methods
* won't be removed.
*
- Methods that are not transformed are copied as is in the new class, directly from the
* original class bytecode (i.e. without emitting visit events for all the method
* instructions), which saves a lot of time. Untransformed methods are detected by
* the fact that the {@link ClassReader} receives {@link MethodVisitor} objects that come
* from a {@link ClassWriter} (and not from any other {@link ClassVisitor} instance).
*
*
* @param classReader the {@link ClassReader} used to read the original class. It will be used to
* copy the entire constant pool and bootstrap methods from the original class and also to
* copy other fragments of original bytecode where applicable.
* @param flags option flags that can be used to modify the default behavior of this class. Must
* be zero or more of {@link #COMPUTE_MAXS} and {@link #COMPUTE_FRAMES}. These option flags
* do not affect methods that are copied as is in the new class. This means that neither the
* maximum stack size nor the stack frames will be computed for these methods.
*/
public ClassWriter(final ClassReader classReader, final int flags) {
super(/* latest api = */ Opcodes.ASM9);
this.flags = flags;
symbolTable = classReader == null ? new SymbolTable(this) : new SymbolTable(this, classReader);
if ((flags & COMPUTE_FRAMES) != 0) {
compute = MethodWriter.COMPUTE_ALL_FRAMES;
} else if ((flags & COMPUTE_MAXS) != 0) {
compute = MethodWriter.COMPUTE_MAX_STACK_AND_LOCAL;
} else {
compute = MethodWriter.COMPUTE_NOTHING;
}
}
// -----------------------------------------------------------------------------------------------
// Accessors
// -----------------------------------------------------------------------------------------------
/**
* Returns true if all the given flags were passed to the constructor.
*
* @param flags some option flags. Must be zero or more of {@link #COMPUTE_MAXS} and {@link
* #COMPUTE_FRAMES}.
* @return true if all the given flags, or more, were passed to the constructor.
*/
public boolean hasFlags(final int flags) {
return (this.flags & flags) == flags;
}
// -----------------------------------------------------------------------------------------------
// Implementation of the ClassVisitor abstract class
// -----------------------------------------------------------------------------------------------
@Override
public final void visit(
final int version,
final int access,
final String name,
final String signature,
final String superName,
final String[] interfaces) {
this.version = version;
this.accessFlags = access;
this.thisClass = symbolTable.setMajorVersionAndClassName(version & 0xFFFF, name);
if (signature != null) {
this.signatureIndex = symbolTable.addConstantUtf8(signature);
}
this.superClass = superName == null ? 0 : symbolTable.addConstantClass(superName).index;
if (interfaces != null && interfaces.length > 0) {
interfaceCount = interfaces.length;
this.interfaces = new int[interfaceCount];
for (int i = 0; i < interfaceCount; ++i) {
this.interfaces[i] = symbolTable.addConstantClass(interfaces[i]).index;
}
}
if (compute == MethodWriter.COMPUTE_MAX_STACK_AND_LOCAL && (version & 0xFFFF) >= Opcodes.V1_7) {
compute = MethodWriter.COMPUTE_MAX_STACK_AND_LOCAL_FROM_FRAMES;
}
}
@Override
public final void visitSource(final String file, final String debug) {
if (file != null) {
sourceFileIndex = symbolTable.addConstantUtf8(file);
}
if (debug != null) {
debugExtension = new ByteVector().encodeUtf8(debug, 0, Integer.MAX_VALUE);
}
}
@Override
public final ModuleVisitor visitModule(
final String name, final int access, final String version) {
return moduleWriter =
new ModuleWriter(
symbolTable,
symbolTable.addConstantModule(name).index,
access,
version == null ? 0 : symbolTable.addConstantUtf8(version));
}
@Override
public final void visitNestHost(final String nestHost) {
nestHostClassIndex = symbolTable.addConstantClass(nestHost).index;
}
@Override
public final void visitOuterClass(
final String owner, final String name, final String descriptor) {
enclosingClassIndex = symbolTable.addConstantClass(owner).index;
if (name != null && descriptor != null) {
enclosingMethodIndex = symbolTable.addConstantNameAndType(name, descriptor);
}
}
@Override
public final AnnotationVisitor visitAnnotation(final String descriptor, final boolean visible) {
if (visible) {
return lastRuntimeVisibleAnnotation =
AnnotationWriter.create(symbolTable, descriptor, lastRuntimeVisibleAnnotation);
} else {
return lastRuntimeInvisibleAnnotation =
AnnotationWriter.create(symbolTable, descriptor, lastRuntimeInvisibleAnnotation);
}
}
@Override
public final AnnotationVisitor visitTypeAnnotation(
final int typeRef, final TypePath typePath, final String descriptor, final boolean visible) {
if (visible) {
return lastRuntimeVisibleTypeAnnotation =
AnnotationWriter.create(
symbolTable, typeRef, typePath, descriptor, lastRuntimeVisibleTypeAnnotation);
} else {
return lastRuntimeInvisibleTypeAnnotation =
AnnotationWriter.create(
symbolTable, typeRef, typePath, descriptor, lastRuntimeInvisibleTypeAnnotation);
}
}
@Override
public final void visitAttribute(final Attribute attribute) {
// Store the attributes in the reverse order of their visit by this method.
attribute.nextAttribute = firstAttribute;
firstAttribute = attribute;
}
@Override
public final void visitNestMember(final String nestMember) {
if (nestMemberClasses == null) {
nestMemberClasses = new ByteVector();
}
++numberOfNestMemberClasses;
nestMemberClasses.putShort(symbolTable.addConstantClass(nestMember).index);
}
@Override
public final void visitPermittedSubclass(final String permittedSubclass) {
if (permittedSubclasses == null) {
permittedSubclasses = new ByteVector();
}
++numberOfPermittedSubclasses;
permittedSubclasses.putShort(symbolTable.addConstantClass(permittedSubclass).index);
}
@Override
public final void visitInnerClass(
final String name, final String outerName, final String innerName, final int access) {
if (innerClasses == null) {
innerClasses = new ByteVector();
}
// Section 4.7.6 of the JVMS states "Every CONSTANT_Class_info entry in the constant_pool table
// which represents a class or interface C that is not a package member must have exactly one
// corresponding entry in the classes array". To avoid duplicates we keep track in the info
// field of the Symbol of each CONSTANT_Class_info entry C whether an inner class entry has
// already been added for C. If so, we store the index of this inner class entry (plus one) in
// the info field. This trick allows duplicate detection in O(1) time.
Symbol nameSymbol = symbolTable.addConstantClass(name);
if (nameSymbol.info == 0) {
++numberOfInnerClasses;
innerClasses.putShort(nameSymbol.index);
innerClasses.putShort(outerName == null ? 0 : symbolTable.addConstantClass(outerName).index);
innerClasses.putShort(innerName == null ? 0 : symbolTable.addConstantUtf8(innerName));
innerClasses.putShort(access);
nameSymbol.info = numberOfInnerClasses;
}
// Else, compare the inner classes entry nameSymbol.info - 1 with the arguments of this method
// and throw an exception if there is a difference?
}
@Override
public final RecordComponentVisitor visitRecordComponent(
final String name, final String descriptor, final String signature) {
RecordComponentWriter recordComponentWriter =
new RecordComponentWriter(symbolTable, name, descriptor, signature);
if (firstRecordComponent == null) {
firstRecordComponent = recordComponentWriter;
} else {
lastRecordComponent.delegate = recordComponentWriter;
}
return lastRecordComponent = recordComponentWriter;
}
@Override
public final FieldVisitor visitField(
final int access,
final String name,
final String descriptor,
final String signature,
final Object value) {
FieldWriter fieldWriter =
new FieldWriter(symbolTable, access, name, descriptor, signature, value);
if (firstField == null) {
firstField = fieldWriter;
} else {
lastField.fv = fieldWriter;
}
return lastField = fieldWriter;
}
@Override
public final MethodVisitor visitMethod(
final int access,
final String name,
final String descriptor,
final String signature,
final String[] exceptions) {
MethodWriter methodWriter =
new MethodWriter(symbolTable, access, name, descriptor, signature, exceptions, compute);
if (firstMethod == null) {
firstMethod = methodWriter;
} else {
lastMethod.mv = methodWriter;
}
return lastMethod = methodWriter;
}
@Override
public final void visitEnd() {
// Nothing to do.
}
// -----------------------------------------------------------------------------------------------
// Other public methods
// -----------------------------------------------------------------------------------------------
/**
* Returns the content of the class file that was built by this ClassWriter.
*
* @return the binary content of the JVMS ClassFile structure that was built by this ClassWriter.
* @throws ClassTooLargeException if the constant pool of the class is too large.
* @throws MethodTooLargeException if the Code attribute of a method is too large.
*/
public byte[] toByteArray() {
// First step: compute the size in bytes of the ClassFile structure.
// The magic field uses 4 bytes, 10 mandatory fields (minor_version, major_version,
// constant_pool_count, access_flags, this_class, super_class, interfaces_count, fields_count,
// methods_count and attributes_count) use 2 bytes each, and each interface uses 2 bytes too.
int size = 24 + 2 * interfaceCount;
int fieldsCount = 0;
FieldWriter fieldWriter = firstField;
while (fieldWriter != null) {
++fieldsCount;
size += fieldWriter.computeFieldInfoSize();
fieldWriter = (FieldWriter) fieldWriter.fv;
}
int methodsCount = 0;
MethodWriter methodWriter = firstMethod;
while (methodWriter != null) {
++methodsCount;
size += methodWriter.computeMethodInfoSize();
methodWriter = (MethodWriter) methodWriter.mv;
}
// For ease of reference, we use here the same attribute order as in Section 4.7 of the JVMS.
int attributesCount = 0;
if (innerClasses != null) {
++attributesCount;
size += 8 + innerClasses.length;
symbolTable.addConstantUtf8(Constants.INNER_CLASSES);
}
if (enclosingClassIndex != 0) {
++attributesCount;
size += 10;
symbolTable.addConstantUtf8(Constants.ENCLOSING_METHOD);
}
if ((accessFlags & Opcodes.ACC_SYNTHETIC) != 0 && (version & 0xFFFF) < Opcodes.V1_5) {
++attributesCount;
size += 6;
symbolTable.addConstantUtf8(Constants.SYNTHETIC);
}
if (signatureIndex != 0) {
++attributesCount;
size += 8;
symbolTable.addConstantUtf8(Constants.SIGNATURE);
}
if (sourceFileIndex != 0) {
++attributesCount;
size += 8;
symbolTable.addConstantUtf8(Constants.SOURCE_FILE);
}
if (debugExtension != null) {
++attributesCount;
size += 6 + debugExtension.length;
symbolTable.addConstantUtf8(Constants.SOURCE_DEBUG_EXTENSION);
}
if ((accessFlags & Opcodes.ACC_DEPRECATED) != 0) {
++attributesCount;
size += 6;
symbolTable.addConstantUtf8(Constants.DEPRECATED);
}
if (lastRuntimeVisibleAnnotation != null) {
++attributesCount;
size +=
lastRuntimeVisibleAnnotation.computeAnnotationsSize(
Constants.RUNTIME_VISIBLE_ANNOTATIONS);
}
if (lastRuntimeInvisibleAnnotation != null) {
++attributesCount;
size +=
lastRuntimeInvisibleAnnotation.computeAnnotationsSize(
Constants.RUNTIME_INVISIBLE_ANNOTATIONS);
}
if (lastRuntimeVisibleTypeAnnotation != null) {
++attributesCount;
size +=
lastRuntimeVisibleTypeAnnotation.computeAnnotationsSize(
Constants.RUNTIME_VISIBLE_TYPE_ANNOTATIONS);
}
if (lastRuntimeInvisibleTypeAnnotation != null) {
++attributesCount;
size +=
lastRuntimeInvisibleTypeAnnotation.computeAnnotationsSize(
Constants.RUNTIME_INVISIBLE_TYPE_ANNOTATIONS);
}
if (symbolTable.computeBootstrapMethodsSize() > 0) {
++attributesCount;
size += symbolTable.computeBootstrapMethodsSize();
}
if (moduleWriter != null) {
attributesCount += moduleWriter.getAttributeCount();
size += moduleWriter.computeAttributesSize();
}
if (nestHostClassIndex != 0) {
++attributesCount;
size += 8;
symbolTable.addConstantUtf8(Constants.NEST_HOST);
}
if (nestMemberClasses != null) {
++attributesCount;
size += 8 + nestMemberClasses.length;
symbolTable.addConstantUtf8(Constants.NEST_MEMBERS);
}
if (permittedSubclasses != null) {
++attributesCount;
size += 8 + permittedSubclasses.length;
symbolTable.addConstantUtf8(Constants.PERMITTED_SUBCLASSES);
}
int recordComponentCount = 0;
int recordSize = 0;
if ((accessFlags & Opcodes.ACC_RECORD) != 0 || firstRecordComponent != null) {
RecordComponentWriter recordComponentWriter = firstRecordComponent;
while (recordComponentWriter != null) {
++recordComponentCount;
recordSize += recordComponentWriter.computeRecordComponentInfoSize();
recordComponentWriter = (RecordComponentWriter) recordComponentWriter.delegate;
}
++attributesCount;
size += 8 + recordSize;
symbolTable.addConstantUtf8(Constants.RECORD);
}
if (firstAttribute != null) {
attributesCount += firstAttribute.getAttributeCount();
size += firstAttribute.computeAttributesSize(symbolTable);
}
// IMPORTANT: this must be the last part of the ClassFile size computation, because the previous
// statements can add attribute names to the constant pool, thereby changing its size!
size += symbolTable.getConstantPoolLength();
int constantPoolCount = symbolTable.getConstantPoolCount();
if (constantPoolCount > 0xFFFF) {
throw new ClassTooLargeException(symbolTable.getClassName(), constantPoolCount);
}
// Second step: allocate a ByteVector of the correct size (in order to avoid any array copy in
// dynamic resizes) and fill it with the ClassFile content.
ByteVector result = new ByteVector(size);
result.putInt(0xCAFEBABE).putInt(version);
symbolTable.putConstantPool(result);
int mask = (version & 0xFFFF) < Opcodes.V1_5 ? Opcodes.ACC_SYNTHETIC : 0;
result.putShort(accessFlags & ~mask).putShort(thisClass).putShort(superClass);
result.putShort(interfaceCount);
for (int i = 0; i < interfaceCount; ++i) {
result.putShort(interfaces[i]);
}
result.putShort(fieldsCount);
fieldWriter = firstField;
while (fieldWriter != null) {
fieldWriter.putFieldInfo(result);
fieldWriter = (FieldWriter) fieldWriter.fv;
}
result.putShort(methodsCount);
boolean hasFrames = false;
boolean hasAsmInstructions = false;
methodWriter = firstMethod;
while (methodWriter != null) {
hasFrames |= methodWriter.hasFrames();
hasAsmInstructions |= methodWriter.hasAsmInstructions();
methodWriter.putMethodInfo(result);
methodWriter = (MethodWriter) methodWriter.mv;
}
// For ease of reference, we use here the same attribute order as in Section 4.7 of the JVMS.
result.putShort(attributesCount);
if (innerClasses != null) {
result
.putShort(symbolTable.addConstantUtf8(Constants.INNER_CLASSES))
.putInt(innerClasses.length + 2)
.putShort(numberOfInnerClasses)
.putByteArray(innerClasses.data, 0, innerClasses.length);
}
if (enclosingClassIndex != 0) {
result
.putShort(symbolTable.addConstantUtf8(Constants.ENCLOSING_METHOD))
.putInt(4)
.putShort(enclosingClassIndex)
.putShort(enclosingMethodIndex);
}
if ((accessFlags & Opcodes.ACC_SYNTHETIC) != 0 && (version & 0xFFFF) < Opcodes.V1_5) {
result.putShort(symbolTable.addConstantUtf8(Constants.SYNTHETIC)).putInt(0);
}
if (signatureIndex != 0) {
result
.putShort(symbolTable.addConstantUtf8(Constants.SIGNATURE))
.putInt(2)
.putShort(signatureIndex);
}
if (sourceFileIndex != 0) {
result
.putShort(symbolTable.addConstantUtf8(Constants.SOURCE_FILE))
.putInt(2)
.putShort(sourceFileIndex);
}
if (debugExtension != null) {
int length = debugExtension.length;
result
.putShort(symbolTable.addConstantUtf8(Constants.SOURCE_DEBUG_EXTENSION))
.putInt(length)
.putByteArray(debugExtension.data, 0, length);
}
if ((accessFlags & Opcodes.ACC_DEPRECATED) != 0) {
result.putShort(symbolTable.addConstantUtf8(Constants.DEPRECATED)).putInt(0);
}
AnnotationWriter.putAnnotations(
symbolTable,
lastRuntimeVisibleAnnotation,
lastRuntimeInvisibleAnnotation,
lastRuntimeVisibleTypeAnnotation,
lastRuntimeInvisibleTypeAnnotation,
result);
symbolTable.putBootstrapMethods(result);
if (moduleWriter != null) {
moduleWriter.putAttributes(result);
}
if (nestHostClassIndex != 0) {
result
.putShort(symbolTable.addConstantUtf8(Constants.NEST_HOST))
.putInt(2)
.putShort(nestHostClassIndex);
}
if (nestMemberClasses != null) {
result
.putShort(symbolTable.addConstantUtf8(Constants.NEST_MEMBERS))
.putInt(nestMemberClasses.length + 2)
.putShort(numberOfNestMemberClasses)
.putByteArray(nestMemberClasses.data, 0, nestMemberClasses.length);
}
if (permittedSubclasses != null) {
result
.putShort(symbolTable.addConstantUtf8(Constants.PERMITTED_SUBCLASSES))
.putInt(permittedSubclasses.length + 2)
.putShort(numberOfPermittedSubclasses)
.putByteArray(permittedSubclasses.data, 0, permittedSubclasses.length);
}
if ((accessFlags & Opcodes.ACC_RECORD) != 0 || firstRecordComponent != null) {
result
.putShort(symbolTable.addConstantUtf8(Constants.RECORD))
.putInt(recordSize + 2)
.putShort(recordComponentCount);
RecordComponentWriter recordComponentWriter = firstRecordComponent;
while (recordComponentWriter != null) {
recordComponentWriter.putRecordComponentInfo(result);
recordComponentWriter = (RecordComponentWriter) recordComponentWriter.delegate;
}
}
if (firstAttribute != null) {
firstAttribute.putAttributes(symbolTable, result);
}
// Third step: replace the ASM specific instructions, if any.
if (hasAsmInstructions) {
return replaceAsmInstructions(result.data, hasFrames);
} else {
return result.data;
}
}
/**
* Returns the equivalent of the given class file, with the ASM specific instructions replaced
* with standard ones. This is done with a ClassReader -> ClassWriter round trip.
*
* @param classFile a class file containing ASM specific instructions, generated by this
* ClassWriter.
* @param hasFrames whether there is at least one stack map frames in 'classFile'.
* @return an equivalent of 'classFile', with the ASM specific instructions replaced with standard
* ones.
*/
private byte[] replaceAsmInstructions(final byte[] classFile, final boolean hasFrames) {
final Attribute[] attributes = getAttributePrototypes();
firstField = null;
lastField = null;
firstMethod = null;
lastMethod = null;
lastRuntimeVisibleAnnotation = null;
lastRuntimeInvisibleAnnotation = null;
lastRuntimeVisibleTypeAnnotation = null;
lastRuntimeInvisibleTypeAnnotation = null;
moduleWriter = null;
nestHostClassIndex = 0;
numberOfNestMemberClasses = 0;
nestMemberClasses = null;
numberOfPermittedSubclasses = 0;
permittedSubclasses = null;
firstRecordComponent = null;
lastRecordComponent = null;
firstAttribute = null;
compute = hasFrames ? MethodWriter.COMPUTE_INSERTED_FRAMES : MethodWriter.COMPUTE_NOTHING;
new ClassReader(classFile, 0, /* checkClassVersion= */ false)
.accept(
this,
attributes,
(hasFrames ? ClassReader.EXPAND_FRAMES : 0) | ClassReader.EXPAND_ASM_INSNS);
return toByteArray();
}
/**
* Returns the prototypes of the attributes used by this class, its fields and its methods.
*
* @return the prototypes of the attributes used by this class, its fields and its methods.
*/
private Attribute[] getAttributePrototypes() {
Attribute.Set attributePrototypes = new Attribute.Set();
attributePrototypes.addAttributes(firstAttribute);
FieldWriter fieldWriter = firstField;
while (fieldWriter != null) {
fieldWriter.collectAttributePrototypes(attributePrototypes);
fieldWriter = (FieldWriter) fieldWriter.fv;
}
MethodWriter methodWriter = firstMethod;
while (methodWriter != null) {
methodWriter.collectAttributePrototypes(attributePrototypes);
methodWriter = (MethodWriter) methodWriter.mv;
}
RecordComponentWriter recordComponentWriter = firstRecordComponent;
while (recordComponentWriter != null) {
recordComponentWriter.collectAttributePrototypes(attributePrototypes);
recordComponentWriter = (RecordComponentWriter) recordComponentWriter.delegate;
}
return attributePrototypes.toArray();
}
// -----------------------------------------------------------------------------------------------
// Utility methods: constant pool management for Attribute sub classes
// -----------------------------------------------------------------------------------------------
/**
* Adds a number or string constant to the constant pool of the class being build. Does nothing if
* the constant pool already contains a similar item. This method is intended for {@link
* Attribute} sub classes, and is normally not needed by class generators or adapters.
*
* @param value the value of the constant to be added to the constant pool. This parameter must be
* an {@link Integer}, a {@link Float}, a {@link Long}, a {@link Double} or a {@link String}.
* @return the index of a new or already existing constant item with the given value.
*/
public int newConst(final Object value) {
return symbolTable.addConstant(value).index;
}
/**
* Adds an UTF8 string to the constant pool of the class being build. Does nothing if the constant
* pool already contains a similar item. This method is intended for {@link Attribute} sub
* classes, and is normally not needed by class generators or adapters.
*
* @param value the String value.
* @return the index of a new or already existing UTF8 item.
*/
// DontCheck(AbbreviationAsWordInName): can't be renamed (for backward binary compatibility).
public int newUTF8(final String value) {
return symbolTable.addConstantUtf8(value);
}
/**
* Adds a class reference to the constant pool of the class being build. Does nothing if the
* constant pool already contains a similar item. This method is intended for {@link Attribute}
* sub classes, and is normally not needed by class generators or adapters.
*
* @param value the internal name of the class (see {@link Type#getInternalName()}).
* @return the index of a new or already existing class reference item.
*/
public int newClass(final String value) {
return symbolTable.addConstantClass(value).index;
}
/**
* Adds a method type reference to the constant pool of the class being build. Does nothing if the
* constant pool already contains a similar item. This method is intended for {@link Attribute}
* sub classes, and is normally not needed by class generators or adapters.
*
* @param methodDescriptor method descriptor of the method type.
* @return the index of a new or already existing method type reference item.
*/
public int newMethodType(final String methodDescriptor) {
return symbolTable.addConstantMethodType(methodDescriptor).index;
}
/**
* Adds a module reference to the constant pool of the class being build. Does nothing if the
* constant pool already contains a similar item. This method is intended for {@link Attribute}
* sub classes, and is normally not needed by class generators or adapters.
*
* @param moduleName name of the module.
* @return the index of a new or already existing module reference item.
*/
public int newModule(final String moduleName) {
return symbolTable.addConstantModule(moduleName).index;
}
/**
* Adds a package reference to the constant pool of the class being build. Does nothing if the
* constant pool already contains a similar item. This method is intended for {@link Attribute}
* sub classes, and is normally not needed by class generators or adapters.
*
* @param packageName name of the package in its internal form.
* @return the index of a new or already existing module reference item.
*/
public int newPackage(final String packageName) {
return symbolTable.addConstantPackage(packageName).index;
}
/**
* Adds a handle to the constant pool of the class being build. Does nothing if the constant pool
* already contains a similar item. This method is intended for {@link Attribute} sub classes,
* and is normally not needed by class generators or adapters.
*
* @param tag the kind of this handle. Must be {@link Opcodes#H_GETFIELD}, {@link
* Opcodes#H_GETSTATIC}, {@link Opcodes#H_PUTFIELD}, {@link Opcodes#H_PUTSTATIC}, {@link
* Opcodes#H_INVOKEVIRTUAL}, {@link Opcodes#H_INVOKESTATIC}, {@link Opcodes#H_INVOKESPECIAL},
* {@link Opcodes#H_NEWINVOKESPECIAL} or {@link Opcodes#H_INVOKEINTERFACE}.
* @param owner the internal name of the field or method owner class (see {@link
* Type#getInternalName()}).
* @param name the name of the field or method.
* @param descriptor the descriptor of the field or method.
* @return the index of a new or already existing method type reference item.
* @deprecated this method is superseded by {@link #newHandle(int, String, String, String,
* boolean)}.
*/
@Deprecated
public int newHandle(
final int tag, final String owner, final String name, final String descriptor) {
return newHandle(tag, owner, name, descriptor, tag == Opcodes.H_INVOKEINTERFACE);
}
/**
* Adds a handle to the constant pool of the class being build. Does nothing if the constant pool
* already contains a similar item. This method is intended for {@link Attribute} sub classes,
* and is normally not needed by class generators or adapters.
*
* @param tag the kind of this handle. Must be {@link Opcodes#H_GETFIELD}, {@link
* Opcodes#H_GETSTATIC}, {@link Opcodes#H_PUTFIELD}, {@link Opcodes#H_PUTSTATIC}, {@link
* Opcodes#H_INVOKEVIRTUAL}, {@link Opcodes#H_INVOKESTATIC}, {@link Opcodes#H_INVOKESPECIAL},
* {@link Opcodes#H_NEWINVOKESPECIAL} or {@link Opcodes#H_INVOKEINTERFACE}.
* @param owner the internal name of the field or method owner class (see {@link
* Type#getInternalName()}).
* @param name the name of the field or method.
* @param descriptor the descriptor of the field or method.
* @param isInterface true if the owner is an interface.
* @return the index of a new or already existing method type reference item.
*/
public int newHandle(
final int tag,
final String owner,
final String name,
final String descriptor,
final boolean isInterface) {
return symbolTable.addConstantMethodHandle(tag, owner, name, descriptor, isInterface).index;
}
/**
* Adds a dynamic constant reference to the constant pool of the class being build. Does nothing
* if the constant pool already contains a similar item. This method is intended for {@link
* Attribute} sub classes, and is normally not needed by class generators or adapters.
*
* @param name name of the invoked method.
* @param descriptor field descriptor of the constant type.
* @param bootstrapMethodHandle the bootstrap method.
* @param bootstrapMethodArguments the bootstrap method constant arguments.
* @return the index of a new or already existing dynamic constant reference item.
*/
public int newConstantDynamic(
final String name,
final String descriptor,
final Handle bootstrapMethodHandle,
final Object... bootstrapMethodArguments) {
return symbolTable.addConstantDynamic(
name, descriptor, bootstrapMethodHandle, bootstrapMethodArguments)
.index;
}
/**
* Adds an invokedynamic reference to the constant pool of the class being build. Does nothing if
* the constant pool already contains a similar item. This method is intended for {@link
* Attribute} sub classes, and is normally not needed by class generators or adapters.
*
* @param name name of the invoked method.
* @param descriptor descriptor of the invoke method.
* @param bootstrapMethodHandle the bootstrap method.
* @param bootstrapMethodArguments the bootstrap method constant arguments.
* @return the index of a new or already existing invokedynamic reference item.
*/
public int newInvokeDynamic(
final String name,
final String descriptor,
final Handle bootstrapMethodHandle,
final Object... bootstrapMethodArguments) {
return symbolTable.addConstantInvokeDynamic(
name, descriptor, bootstrapMethodHandle, bootstrapMethodArguments)
.index;
}
/**
* Adds a field reference to the constant pool of the class being build. Does nothing if the
* constant pool already contains a similar item. This method is intended for {@link Attribute}
* sub classes, and is normally not needed by class generators or adapters.
*
* @param owner the internal name of the field's owner class (see {@link Type#getInternalName()}).
* @param name the field's name.
* @param descriptor the field's descriptor.
* @return the index of a new or already existing field reference item.
*/
public int newField(final String owner, final String name, final String descriptor) {
return symbolTable.addConstantFieldref(owner, name, descriptor).index;
}
/**
* Adds a method reference to the constant pool of the class being build. Does nothing if the
* constant pool already contains a similar item. This method is intended for {@link Attribute}
* sub classes, and is normally not needed by class generators or adapters.
*
* @param owner the internal name of the method's owner class (see {@link
* Type#getInternalName()}).
* @param name the method's name.
* @param descriptor the method's descriptor.
* @param isInterface {@literal true} if {@code owner} is an interface.
* @return the index of a new or already existing method reference item.
*/
public int newMethod(
final String owner, final String name, final String descriptor, final boolean isInterface) {
return symbolTable.addConstantMethodref(owner, name, descriptor, isInterface).index;
}
/**
* Adds a name and type to the constant pool of the class being build. Does nothing if the
* constant pool already contains a similar item. This method is intended for {@link Attribute}
* sub classes, and is normally not needed by class generators or adapters.
*
* @param name a name.
* @param descriptor a type descriptor.
* @return the index of a new or already existing name and type item.
*/
public int newNameType(final String name, final String descriptor) {
return symbolTable.addConstantNameAndType(name, descriptor);
}
// -----------------------------------------------------------------------------------------------
// Default method to compute common super classes when computing stack map frames
// -----------------------------------------------------------------------------------------------
/**
* Returns the common super type of the two given types. The default implementation of this method
* loads the two given classes and uses the java.lang.Class methods to find the common
* super class. It can be overridden to compute this common super type in other ways, in
* particular without actually loading any class, or to take into account the class that is
* currently being generated by this ClassWriter, which can of course not be loaded since it is
* under construction.
*
* @param type1 the internal name of a class (see {@link Type#getInternalName()}).
* @param type2 the internal name of another class (see {@link Type#getInternalName()}).
* @return the internal name of the common super class of the two given classes (see {@link
* Type#getInternalName()}).
*/
protected String getCommonSuperClass(final String type1, final String type2) {
ClassLoader classLoader = getClassLoader();
Class class1;
try {
class1 = Class.forName(type1.replace('/', '.'), false, classLoader);
} catch (ClassNotFoundException e) {
throw new TypeNotPresentException(type1, e);
}
Class class2;
try {
class2 = Class.forName(type2.replace('/', '.'), false, classLoader);
} catch (ClassNotFoundException e) {
throw new TypeNotPresentException(type2, e);
}
if (class1.isAssignableFrom(class2)) {
return type1;
}
if (class2.isAssignableFrom(class1)) {
return type2;
}
if (class1.isInterface() || class2.isInterface()) {
return "java/lang/Object";
} else {
do {
class1 = class1.getSuperclass();
} while (!class1.isAssignableFrom(class2));
return class1.getName().replace('.', '/');
}
}
/**
* Returns the {@link ClassLoader} to be used by the default implementation of {@link
* #getCommonSuperClass(String, String)}, that of this {@link ClassWriter}'s runtime type by
* default.
*
* @return ClassLoader
*/
protected ClassLoader getClassLoader() {
return getClass().getClassLoader();
}
}
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