package mockit.asm.methods;
   
   import edu.umd.cs.findbugs.annotations.NonNull;
   import edu.umd.cs.findbugs.annotations.Nullable;
   
   import mockit.asm.constantPool.AttributeWriter;
   import mockit.asm.constantPool.ConstantPoolGeneration;
   import mockit.asm.controlFlow.Label;
   import mockit.asm.util.ByteVector;
  
  import org.checkerframework.checker.index.qual.NonNegative;
  
  /**
   * Writes the bytecode for the "LineNumberTable" method code attribute.
   */
  final class LineNumberTableWriter extends AttributeWriter {
      /**
       * Number of entries in the <code>LineNumberTable</code> attribute.
       */
      @NonNegative
      private int lineNumberCount;
  
      /**
       * The <code>LineNumberTable</code> attribute.
       */
      @Nullable
      private ByteVector lineNumbers;
  
      LineNumberTableWriter(@NonNull ConstantPoolGeneration cp) {
          super(cp);
      }
  
      void addLineNumber(@NonNegative int line, @NonNull Label start) {
          if (lineNumbers == null) {
              setAttribute("LineNumberTable");
              lineNumbers = new ByteVector();
          }
  
          lineNumberCount++;
          lineNumbers.putShort(start.position);
          lineNumbers.putShort(line);
      }
  
      boolean hasLineNumbers() {
          return lineNumbers != null;
      }
  
      @NonNegative
      @Override
      public int getSize() {
          return lineNumbers == null ? 0 : 8 + lineNumbers.getLength();
      }
  
      @Override
      public void put(@NonNull ByteVector out) {
          if (lineNumbers != null) {
              put(out, 2 + lineNumbers.getLength());
              out.putShort(lineNumberCount);
              out.putByteVector(lineNumbers);
          }
      }
  }