TypeVariableName.java 文件源码

/**
 * Make a TypeVariableName for the given TypeMirror. This form is used internally to avoid
 * infinite recursion in cases like {@code Enum<E extends Enum<E>>}. When we encounter such a
 * thing, we will make a TypeVariableName without bounds and add that to the {@code typeVariables}
 * map before looking up the bounds. Then if we encounter this TypeVariable again while
 * constructing the bounds, we can just return it from the map. And, the code that put the entry
 * in {@code variables} will make sure that the bounds are filled in before returning.
 */
static TypeVariableName get(
    TypeVariable mirror, Map<TypeParameterElement, TypeVariableName> typeVariables) {
  TypeParameterElement element = (TypeParameterElement) mirror.asElement();
  TypeVariableName typeVariableName = typeVariables.get(element);
  if (typeVariableName == null) {
    // Since the bounds field is public, we need to make it an unmodifiableList. But we control
    // the List that that wraps, which means we can change it before returning.
    List<TypeName> bounds = new ArrayList<>();
    List<TypeName> visibleBounds = Collections.unmodifiableList(bounds);
    typeVariableName = new TypeVariableName(element.getSimpleName().toString(), visibleBounds);
    typeVariables.put(element, typeVariableName);
    for (TypeMirror typeMirror : element.getBounds()) {
      bounds.add(TypeName.get(typeMirror, typeVariables));
    }
    bounds.remove(OBJECT);
  }
  return typeVariableName;
}