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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
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//    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
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//    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"
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// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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package org.objectweb.asm.util;

import org.objectweb.asm.AnnotationVisitor;
import org.objectweb.asm.Attribute;
import org.objectweb.asm.FieldVisitor;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.TypePath;
import org.objectweb.asm.TypeReference;

/**
 * A {@link FieldVisitor} that checks that its methods are properly used.
 *
 * @author Eric Bruneton
 */
public class CheckFieldAdapter extends FieldVisitor {

  /** Whether the {@link #visitEnd} method has been called. */
  private boolean visitEndCalled;

  /**
   * Constructs a new {@link CheckFieldAdapter}. Subclasses must not use this constructor.
   * Instead, they must use the {@link #CheckFieldAdapter(int, FieldVisitor)} version.
   *
   * @param fieldVisitor the field visitor to which this adapter must delegate calls.
   * @throws IllegalStateException If a subclass calls this constructor.
   */
  public CheckFieldAdapter(final FieldVisitor fieldVisitor) {
    this(Opcodes.ASM7, fieldVisitor);
    if (getClass() != CheckFieldAdapter.class) {
      throw new IllegalStateException();
    }
  }

  /**
   * Constructs a new {@link CheckFieldAdapter}.
   *
   * @param api the ASM API version implemented by this visitor. Must be one of {@link
   *     Opcodes#ASM4}, {@link Opcodes#ASM5}, {@link Opcodes#ASM6} or {@link Opcodes#ASM7}.
   * @param fieldVisitor the field visitor to which this adapter must delegate calls.
   */
  protected CheckFieldAdapter(final int api, final FieldVisitor fieldVisitor) {
    super(api, fieldVisitor);
  }

  @Override
  public AnnotationVisitor visitAnnotation(final String descriptor, final boolean visible) {
    checkVisitEndNotCalled();
    // Annotations can only appear in V1_5 or more classes.
    CheckMethodAdapter.checkDescriptor(Opcodes.V1_5, descriptor, false);
    return new CheckAnnotationAdapter(super.visitAnnotation(descriptor, visible));
  }

  @Override
  public AnnotationVisitor visitTypeAnnotation(
      final int typeRef, final TypePath typePath, final String descriptor, final boolean visible) {
    checkVisitEndNotCalled();
    int sort = new TypeReference(typeRef).getSort();
    if (sort != TypeReference.FIELD) {
      throw new IllegalArgumentException(
          "Invalid type reference sort 0x" + Integer.toHexString(sort));
    }
    CheckClassAdapter.checkTypeRef(typeRef);
    CheckMethodAdapter.checkDescriptor(Opcodes.V1_5, descriptor, false);
    return new CheckAnnotationAdapter(
        super.visitTypeAnnotation(typeRef, typePath, descriptor, visible));
  }

  @Override
  public void visitAttribute(final Attribute attribute) {
    checkVisitEndNotCalled();
    if (attribute == null) {
      throw new IllegalArgumentException("Invalid attribute (must not be null)");
    }
    super.visitAttribute(attribute);
  }

  @Override
  public void visitEnd() {
    checkVisitEndNotCalled();
    visitEndCalled = true;
    super.visitEnd();
  }

  private void checkVisitEndNotCalled() {
    if (visitEndCalled) {
      throw new IllegalStateException("Cannot call a visit method after visitEnd has been called");
    }
  }
}