add annotation validation to validate API

[neetopia]

Annotation argument values are left out for check for now.

[ting-yuan]

Should have noticed previously: Since this visitor extends KSDefaultVisitor, why not delegating to it? I.e., replace calls to validateAnnotations(), validateTypeParameters(), validateDeclarations() and validateDeclaration() with a single return super.validateClassDeclaration(). Then you don't need private fun validateBlabla; Just put them in visitBlabla(). For example,

override fun visitClassDeclaration(c: KSClassDeclaration, parent: KSNode) {
  if (predicate(parent, c) == false)
    return true
  // Only validate super types here
  if ( c.superTypes.any { it.accept(this, c) } == false )
    return false
  // This in turn calls visitDeclaration and visitDeclarationContainer
  return super.visitClassDeclaration()
}

override fun visitDeclaration(decl: KSDeclaration) {
  if (predicate(parent, c) == false)
    return true
  if (decl.typeParameters.any { it.accept(this, decl) } == false)
    return false
  return super.visitDeclaration()
}

override fun visitTypeParameter() {
  if (predicate(parent, c) == false)
    return true
  // validate a type parameter.
}

override fun visitDeclarationContainer(container: KSDeclarationContainer, ...) {
  if (predicate(parent, c) == false)
    return true
  return container.declarations.all { it.accept(this, container) }
}

and so on.

[ting-yuan]

Actually d050c49 looks better. May I know the reason why you decided to go with the latter approach? Besides the default handler.

[neetopia]

Actually d050c49 looks better. May I know the reason why you decided to go with the latter approach? Besides the default handler.

Because if we simply delegate to super, there is no control for us to let super return our desired result, all return result will be from defaultHandler and things will break, like the call to common logic won't affect the return result of super.visitClassDeclaration()