code: // ASM: a very small and fast Java bytecode manipulation framework
  // Copyright (c) 2000-2011 INRIA, France Telecom
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  // THE POSSIBILITY OF SUCH DAMAGE.
  package clojure.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 <tt>null</tt>.
     */
    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 <tt>null</tt>.
     */
    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 <tt>null</tt>.
     */
    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 <tt>null</tt>.
     */
    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 <tt>null</tt>.
     *
     * <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 <tt>null</tt>.
     * @param constantValue the field's constant value. May be <tt>null</tt>.
     */
    FieldWriter(
        final SymbolTable symbolTable,
        final int access,
        final String name,
        final String descriptor,
        final String signature,
        final Object constantValue) {
      super(Opcodes.ASM6);
      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.
     *
     * @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.
     *
     * @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.
     *
     * @param attributePrototypes a set of attribute prototypes.
     */
    final void collectAttributePrototypes(final Attribute.Set attributePrototypes) {
      attributePrototypes.addAttributes(firstAttribute);
    }
  }
  