https://github.com/spring-projects/spring-framework: Spring Core (Spring IO)
  • Juergen Hoeller 
// ASM: a very small and fast Java bytecode manipulation framework
// Copyright (c) 2000-2011 INRIA, France Telecom
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package org.springframework.asm;


A FieldVisitor that generates a corresponding 'field_info' structure, as defined in the Java Virtual Machine Specification (JVMS). 
Author:Eric Bruneton
See Also:
/**
 * A {@link FieldVisitor} that generates a corresponding 'field_info' structure, as defined in the
 * Java Virtual Machine Specification (JVMS).
 *
 * @see <a href="https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-4.html#jvms-4.5">JVMS
 *     4.5</a>
 * @author Eric Bruneton
 */
final class FieldWriter extends FieldVisitor {

  
Where the constants used in this FieldWriter must be stored. 
/** Where the constants used in this FieldWriter must be stored. */
  private final SymbolTable symbolTable;

  // Note: fields are ordered as in the field_info structure, and those related to attributes are
  // ordered as in Section 4.7 of the JVMS.

  
The access_flags field of the field_info JVMS structure. This field can contain ASM specific access flags, such as Opcodes.ACC_DEPRECATED, which are removed when generating the ClassFile structure. 
/**
   * The access_flags field of the field_info JVMS structure. This field can contain ASM specific
   * access flags, such as {@link Opcodes#ACC_DEPRECATED}, which are removed when generating the
   * ClassFile structure.
   */
  private final int accessFlags;

  
The name_index field of the field_info JVMS structure. 
/** The name_index field of the field_info JVMS structure. */
  private final int nameIndex;

  
The descriptor_index field of the field_info JVMS structure. 
/** The descriptor_index field of the field_info JVMS structure. */
  private final int descriptorIndex;

  
The signature_index field of the Signature attribute of this field_info, or 0 if there is no
Signature attribute.

/**
   * The signature_index field of the Signature attribute of this field_info, or 0 if there is no
   * Signature attribute.
   */
  private int signatureIndex;

  
The constantvalue_index field of the ConstantValue attribute of this field_info, or 0 if there
is no ConstantValue attribute.

/**
   * The constantvalue_index field of the ConstantValue attribute of this field_info, or 0 if there
   * is no ConstantValue attribute.
   */
  private int constantValueIndex;

  
The last runtime visible annotation of this field. The previous ones can be accessed with the AnnotationWriter.previousAnnotation field. May be null. 
/**
   * The last runtime visible annotation of this field. 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 field. The previous ones can be accessed with the AnnotationWriter.previousAnnotation field. May be null. 
/**
   * The last runtime invisible annotation of this field. 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 field. The previous ones can be accessed with the AnnotationWriter.previousAnnotation field. May be null. 
/**
   * The last runtime visible type annotation of this field. 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 field. The previous ones can be accessed with the AnnotationWriter.previousAnnotation field. May be null. 
/**
   * The last runtime invisible type annotation of this field. The previous ones can be accessed
   * with the {@link AnnotationWriter#previousAnnotation} field. May be {@literal null}.
   */
  private AnnotationWriter lastRuntimeInvisibleTypeAnnotation;

  
The first non standard attribute of this field. The next ones can be accessed with the Attribute.nextAttribute field. May be null. 
WARNING: this list stores the attributes in the reverse order of their visit. firstAttribute is actually the last attribute visited in visitAttribute. The putFieldInfo method writes the attributes in the order defined by this list, i.e. in the reverse order specified by the user. 
/**
   * The first non standard attribute of this field. The next ones can be accessed with the {@link
   * Attribute#nextAttribute} field. May be {@literal null}.
   *
   * <p><b>WARNING</b>: this list stores the attributes in the <i>reverse</i> order of their visit.
   * firstAttribute is actually the last attribute visited in {@link #visitAttribute}. The {@link
   * #putFieldInfo} method writes the attributes in the order defined by this list, i.e. in the
   * reverse order specified by the user.
   */
  private Attribute firstAttribute;

  // -----------------------------------------------------------------------------------------------
  // Constructor
  // -----------------------------------------------------------------------------------------------

  
Constructs a new FieldWriter. 
Params:
  • symbolTable – where the constants used in this FieldWriter must be stored.
  • access – the field's access flags (see Opcodes).
  • name – the field's name.
  • descriptor – the field's descriptor (see Type).
  • signature – the field's signature. May be null.
  • constantValue – the field's constant value. May be null.
/**
   * Constructs a new {@link FieldWriter}.
   *
   * @param symbolTable where the constants used in this FieldWriter must be stored.
   * @param access the field's access flags (see {@link Opcodes}).
   * @param name the field's name.
   * @param descriptor the field's descriptor (see {@link Type}).
   * @param signature the field's signature. May be {@literal null}.
   * @param constantValue the field's constant value. May be {@literal null}.
   */
  FieldWriter(
      final SymbolTable symbolTable,
      final int access,
      final String name,
      final String descriptor,
      final String signature,
      final Object constantValue) {
    super(Opcodes.ASM7);
    this.symbolTable = symbolTable;
    this.accessFlags = access;
    this.nameIndex = symbolTable.addConstantUtf8(name);
    this.descriptorIndex = symbolTable.addConstantUtf8(descriptor);
    if (signature != null) {
      this.signatureIndex = symbolTable.addConstantUtf8(signature);
    }
    if (constantValue != null) {
      this.constantValueIndex = symbolTable.addConstant(constantValue).index;
    }
  }

  // -----------------------------------------------------------------------------------------------
  // Implementation of the FieldVisitor abstract class
  // -----------------------------------------------------------------------------------------------

  @Override
  public AnnotationVisitor visitAnnotation(final String descriptor, final boolean visible) {
    // Create a ByteVector to hold an 'annotation' JVMS structure.
    // See https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-4.html#jvms-4.7.16.
    ByteVector annotation = new ByteVector();
    // Write type_index and reserve space for num_element_value_pairs.
    annotation.putShort(symbolTable.addConstantUtf8(descriptor)).putShort(0);
    if (visible) {
      return lastRuntimeVisibleAnnotation =
          new AnnotationWriter(symbolTable, annotation, lastRuntimeVisibleAnnotation);
    } else {
      return lastRuntimeInvisibleAnnotation =
          new AnnotationWriter(symbolTable, annotation, lastRuntimeInvisibleAnnotation);
    }
  }

  @Override
  public AnnotationVisitor visitTypeAnnotation(
      final int typeRef, final TypePath typePath, final String descriptor, final boolean visible) {
    // Create a ByteVector to hold a 'type_annotation' JVMS structure.
    // See https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-4.html#jvms-4.7.20.
    ByteVector typeAnnotation = new ByteVector();
    // Write target_type, target_info, and target_path.
    TypeReference.putTarget(typeRef, typeAnnotation);
    TypePath.put(typePath, typeAnnotation);
    // Write type_index and reserve space for num_element_value_pairs.
    typeAnnotation.putShort(symbolTable.addConstantUtf8(descriptor)).putShort(0);
    if (visible) {
      return lastRuntimeVisibleTypeAnnotation =
          new AnnotationWriter(symbolTable, typeAnnotation, lastRuntimeVisibleTypeAnnotation);
    } else {
      return lastRuntimeInvisibleTypeAnnotation =
          new AnnotationWriter(symbolTable, typeAnnotation, lastRuntimeInvisibleTypeAnnotation);
    }
  }

  @Override
  public void visitAttribute(final Attribute attribute) {
    // Store the attributes in the <i>reverse</i> order of their visit by this method.
    attribute.nextAttribute = firstAttribute;
    firstAttribute = attribute;
  }

  @Override
  public void visitEnd() {
    // Nothing to do.
  }

  // -----------------------------------------------------------------------------------------------
  // Utility methods
  // -----------------------------------------------------------------------------------------------

  
Returns the size of the field_info JVMS structure generated by this FieldWriter. Also adds the
names of the attributes of this field in the constant pool.

Returns:the size in bytes of the field_info JVMS structure.
/**
   * Returns the size of the field_info JVMS structure generated by this FieldWriter. Also adds the
   * names of the attributes of this field in the constant pool.
   *
   * @return the size in bytes of the field_info JVMS structure.
   */
  int computeFieldInfoSize() {
    // The access_flags, name_index, descriptor_index and attributes_count fields use 8 bytes.
    int size = 8;
    // For ease of reference, we use here the same attribute order as in Section 4.7 of the JVMS.
    if (constantValueIndex != 0) {
      // ConstantValue attributes always use 8 bytes.
      symbolTable.addConstantUtf8(Constants.CONSTANT_VALUE);
      size += 8;
    }
    // Before Java 1.5, synthetic fields are represented with a Synthetic attribute.
    if ((accessFlags & Opcodes.ACC_SYNTHETIC) != 0
        && symbolTable.getMajorVersion() < Opcodes.V1_5) {
      // Synthetic attributes always use 6 bytes.
      symbolTable.addConstantUtf8(Constants.SYNTHETIC);
      size += 6;
    }
    if (signatureIndex != 0) {
      // Signature attributes always use 8 bytes.
      symbolTable.addConstantUtf8(Constants.SIGNATURE);
      size += 8;
    }
    // ACC_DEPRECATED is ASM specific, the ClassFile format uses a Deprecated attribute instead.
    if ((accessFlags & Opcodes.ACC_DEPRECATED) != 0) {
      // Deprecated attributes always use 6 bytes.
      symbolTable.addConstantUtf8(Constants.DEPRECATED);
      size += 6;
    }
    if (lastRuntimeVisibleAnnotation != null) {
      size +=
          lastRuntimeVisibleAnnotation.computeAnnotationsSize(
              Constants.RUNTIME_VISIBLE_ANNOTATIONS);
    }
    if (lastRuntimeInvisibleAnnotation != null) {
      size +=
          lastRuntimeInvisibleAnnotation.computeAnnotationsSize(
              Constants.RUNTIME_INVISIBLE_ANNOTATIONS);
    }
    if (lastRuntimeVisibleTypeAnnotation != null) {
      size +=
          lastRuntimeVisibleTypeAnnotation.computeAnnotationsSize(
              Constants.RUNTIME_VISIBLE_TYPE_ANNOTATIONS);
    }
    if (lastRuntimeInvisibleTypeAnnotation != null) {
      size +=
          lastRuntimeInvisibleTypeAnnotation.computeAnnotationsSize(
              Constants.RUNTIME_INVISIBLE_TYPE_ANNOTATIONS);
    }
    if (firstAttribute != null) {
      size += firstAttribute.computeAttributesSize(symbolTable);
    }
    return size;
  }

  
Puts the content of the field_info JVMS structure generated by this FieldWriter into the given
ByteVector.

Params:
  • output – where the field_info structure must be put.
/**
   * Puts the content of the field_info JVMS structure generated by this FieldWriter into the given
   * ByteVector.
   *
   * @param output where the field_info structure must be put.
   */
  void putFieldInfo(final ByteVector output) {
    boolean useSyntheticAttribute = symbolTable.getMajorVersion() < Opcodes.V1_5;
    // Put the access_flags, name_index and descriptor_index fields.
    int mask = useSyntheticAttribute ? Opcodes.ACC_SYNTHETIC : 0;
    output.putShort(accessFlags & ~mask).putShort(nameIndex).putShort(descriptorIndex);
    // Compute and put the attributes_count field.
    // For ease of reference, we use here the same attribute order as in Section 4.7 of the JVMS.
    int attributesCount = 0;
    if (constantValueIndex != 0) {
      ++attributesCount;
    }
    if ((accessFlags & Opcodes.ACC_SYNTHETIC) != 0 && useSyntheticAttribute) {
      ++attributesCount;
    }
    if (signatureIndex != 0) {
      ++attributesCount;
    }
    if ((accessFlags & Opcodes.ACC_DEPRECATED) != 0) {
      ++attributesCount;
    }
    if (lastRuntimeVisibleAnnotation != null) {
      ++attributesCount;
    }
    if (lastRuntimeInvisibleAnnotation != null) {
      ++attributesCount;
    }
    if (lastRuntimeVisibleTypeAnnotation != null) {
      ++attributesCount;
    }
    if (lastRuntimeInvisibleTypeAnnotation != null) {
      ++attributesCount;
    }
    if (firstAttribute != null) {
      attributesCount += firstAttribute.getAttributeCount();
    }
    output.putShort(attributesCount);
    // Put the field_info attributes.
    // For ease of reference, we use here the same attribute order as in Section 4.7 of the JVMS.
    if (constantValueIndex != 0) {
      output
          .putShort(symbolTable.addConstantUtf8(Constants.CONSTANT_VALUE))
          .putInt(2)
          .putShort(constantValueIndex);
    }
    if ((accessFlags & Opcodes.ACC_SYNTHETIC) != 0 && useSyntheticAttribute) {
      output.putShort(symbolTable.addConstantUtf8(Constants.SYNTHETIC)).putInt(0);
    }
    if (signatureIndex != 0) {
      output
          .putShort(symbolTable.addConstantUtf8(Constants.SIGNATURE))
          .putInt(2)
          .putShort(signatureIndex);
    }
    if ((accessFlags & Opcodes.ACC_DEPRECATED) != 0) {
      output.putShort(symbolTable.addConstantUtf8(Constants.DEPRECATED)).putInt(0);
    }
    if (lastRuntimeVisibleAnnotation != null) {
      lastRuntimeVisibleAnnotation.putAnnotations(
          symbolTable.addConstantUtf8(Constants.RUNTIME_VISIBLE_ANNOTATIONS), output);
    }
    if (lastRuntimeInvisibleAnnotation != null) {
      lastRuntimeInvisibleAnnotation.putAnnotations(
          symbolTable.addConstantUtf8(Constants.RUNTIME_INVISIBLE_ANNOTATIONS), output);
    }
    if (lastRuntimeVisibleTypeAnnotation != null) {
      lastRuntimeVisibleTypeAnnotation.putAnnotations(
          symbolTable.addConstantUtf8(Constants.RUNTIME_VISIBLE_TYPE_ANNOTATIONS), output);
    }
    if (lastRuntimeInvisibleTypeAnnotation != null) {
      lastRuntimeInvisibleTypeAnnotation.putAnnotations(
          symbolTable.addConstantUtf8(Constants.RUNTIME_INVISIBLE_TYPE_ANNOTATIONS), output);
    }
    if (firstAttribute != null) {
      firstAttribute.putAttributes(symbolTable, output);
    }
  }

  
Collects the attributes of this field into the given set of attribute prototypes.

Params:
  • attributePrototypes – a set of attribute prototypes.
/**
   * Collects the attributes of this field into the given set of attribute prototypes.
   *
   * @param attributePrototypes a set of attribute prototypes.
   */
  final void collectAttributePrototypes(final Attribute.Set attributePrototypes) {
    attributePrototypes.addAttributes(firstAttribute);
  }
}