Is Expr::Classification gone in the latest version of SVN code

From the, we can found a subclass

"Classification" in "Expr" class, and a function "Classify" which
classifies each expression to corresponding type. However, this can
not be found in the latest version of the SVN code, has it gone or has
it been substituted by some stuff else where?

It's alive and happy. Check your svn status to see if you have a locally
modified version.