Class LocalVariablesSorter

src/jvm/clojure/asm/commons/LocalVariablesSorter.java:48–351

A MethodVisitor that renumbers local variables in their order of appearance. This adapter allows one to easily add new local variables to a method. It may be used by inheriting from this class, but the preferred way of using it is via delegation: the next visitor in the chain can indeed add

 * @author Eric Bruneton
 */
public class LocalVariablesSorter extends MethodVisitor {

  /** The type of the java.lang.Object class. */
  private static final Type OBJECT_TYPE = Type.getObjectType("java/lang/Object");

  /**
   * The mapping from old to new local variable indices. A local variable at index i of size 1 is
   * remapped to 'mapping[2*i]', while a local variable at index i of size 2 is remapped to
   * 'mapping[2*i+1]'.
   */
  private int[] remappedVariableIndices = new int[40];

  /**
   * The local variable types after remapping. The format of this array is the same as in {@link
   * MethodVisitor#visitFrame}, except that long and double types use two slots.
   */
  private Object[] remappedLocalTypes = new Object[20];

  /** The index of the first local variable, after formal parameters. */
  protected final int firstLocal;

  /** The index of the next local variable to be created by {@link #newLocal}. */
  protected int nextLocal;

  /**
   * Constructs a new {@link LocalVariablesSorter}. <i>Subclasses must not use this constructor</i>.
   * Instead, they must use the {@link #LocalVariablesSorter(int, int, String, MethodVisitor)}
   * version.
   *
   * @param access access flags of the adapted method.
   * @param descriptor the method's descriptor (see {@link Type}).
   * @param methodVisitor the method visitor to which this adapter delegates calls.
   * @throws IllegalStateException if a subclass calls this constructor.
   */
  public LocalVariablesSorter(
      final int access, final String descriptor, final MethodVisitor methodVisitor) {
    this(Opcodes.ASM6, access, descriptor, methodVisitor);
    if (getClass() != LocalVariablesSorter.class) {
      throw new IllegalStateException();
    }
  }

  /**
   * Constructs a new {@link LocalVariablesSorter}.
   *
   * @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_EXPERIMENTAL}.
   * @param access access flags of the adapted method.
   * @param descriptor the method's descriptor (see {@link Type}).
   * @param methodVisitor the method visitor to which this adapter delegates calls.
   */
  protected LocalVariablesSorter(
      final int api, final int access, final String descriptor, final MethodVisitor methodVisitor) {
    super(api, methodVisitor);
    nextLocal = (Opcodes.ACC_STATIC & access) == 0 ? 1 : 0;
    for (Type argumentType : Type.getArgumentTypes(descriptor)) {
      nextLocal += argumentType.getSize();
    }