path: root/asm/src/main/java/org/objectweb/asm/FieldWriter.java

// ASM: a very small and fast Java bytecode manipulation framework
// Copyright (c) 2000-2011 INRIA, France Telecom
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package org.objectweb.asm;

/**
 * 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. */
  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 {@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. */
  private final int nameIndex;

  /** 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.
   */
  private int signatureIndex;

  /**
   * 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
   * {@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
   * {@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 {@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 {@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 {@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 {@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(/* latest api = */ Opcodes.ASM9);
    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) {
    if (visible) {
      return lastRuntimeVisibleAnnotation =
          AnnotationWriter.create(symbolTable, descriptor, lastRuntimeVisibleAnnotation);
    } else {
      return lastRuntimeInvisibleAnnotation =
          AnnotationWriter.create(symbolTable, descriptor, lastRuntimeInvisibleAnnotation);
    }
  }

  @Override
  public 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 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.
   *
   * @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;
    }
    size += Attribute.computeAttributesSize(symbolTable, accessFlags, signatureIndex);
    size +=
        AnnotationWriter.computeAnnotationsSize(
            lastRuntimeVisibleAnnotation,
            lastRuntimeInvisibleAnnotation,
            lastRuntimeVisibleTypeAnnotation,
            lastRuntimeInvisibleTypeAnnotation);
    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.
   *
   * @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);
    }
    Attribute.putAttributes(symbolTable, accessFlags, signatureIndex, output);
    AnnotationWriter.putAnnotations(
        symbolTable,
        lastRuntimeVisibleAnnotation,
        lastRuntimeInvisibleAnnotation,
        lastRuntimeVisibleTypeAnnotation,
        lastRuntimeInvisibleTypeAnnotation,
        output);
    if (firstAttribute != null) {
      firstAttribute.putAttributes(symbolTable, output);
    }
  }

  /**
   * 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);
  }
}