checker/src/main/java/org/checkerframework/checker/nullness/NullnessAnnotatedTypeFormatter.java

package org.checkerframework.checker.nullness;

import java.util.Set;
import org.checkerframework.checker.nullness.qual.Nullable;
import org.checkerframework.framework.type.AnnotatedTypeMirror;
import org.checkerframework.framework.type.AnnotatedTypeMirror.AnnotatedNullType;
import org.checkerframework.framework.type.DefaultAnnotatedTypeFormatter;
import org.checkerframework.framework.util.AnnotationFormatter;
import org.checkerframework.framework.util.DefaultAnnotationFormatter;

/** A DefaultAnnotatedTypeFormatter that prints null literals without their annotations. */
public class NullnessAnnotatedTypeFormatter extends DefaultAnnotatedTypeFormatter {
  public NullnessAnnotatedTypeFormatter(
      boolean printVerboseGenerics, boolean printInvisibleQualifiers) {
    super(
        new NullnessFormattingVisitor(
            new DefaultAnnotationFormatter(), printVerboseGenerics, printInvisibleQualifiers));
  }

  protected static class NullnessFormattingVisitor extends FormattingVisitor {

    public NullnessFormattingVisitor(
        AnnotationFormatter annoFormatter,
        boolean printVerboseGenerics,
        boolean defaultInvisiblesSetting) {
      super(annoFormatter, printVerboseGenerics, defaultInvisiblesSetting);
    }

    @Override
    public String visitNull(AnnotatedNullType type, Set<AnnotatedTypeMirror> visiting) {
      if (type.getAnnotation(Nullable.class) != null) {
        // The null type will be understood as nullable by readers (I hope), therefore omit the
        // annotations if they are @Nullable.
        // Note: The visitTypeVariable will still print lower bounds with Null kind as "Void"
        if (!currentPrintInvisibleSetting) {
          return "null (NullType)";
        }
      }

      return super.visitNull(type, visiting);
    }
  }
}