HPACK substitution & header table pruning

I'm attempting to implement HTTP/2.0 for
OkHttp<http://square.github.io/okhttp/>,
Square's HTTP client for Android and Java.

I'd like to clarify how header table pruning works with
replacement-by-index. The doc
says<http://http2.github.io/compression-spec/compression-spec.html#rfc.section.3.2.3>
:

When the modification of the header table is the replacement of an existing
entry, the replaced entry is the one indicated in the literal
representation before any entry is removed from the header table. *If the
entry to be replaced is removed* from the header table when performing the
size adjustment, the replacement entry is inserted at the beginning of the
header table.

Is the entry to be replaced removed before pruning-from-0 begins? Or does
all pruning happen, and then the replacement happens?

Here‘s an example situation where the order of these operations is
relevant. Suppose I’ve got a headers table containing 4 entries, each 1024
bytes. The max size of this table is 4096.

   0  A: <value> (entry size: 1024)
   1  B: <value> (entry size: 1024)
   2  C: <value> (entry size: 1024)
   3  D: <value> (entry size: 1024)

At this point I receive a literal header with substitution indexing “E” at
index 2 and entry size 2048. This will replace C.

If I prune first, I remove A and B. Substituting yields this new headers
table:

   0  E: <value> (entry size: 2048)
   1  D: <value> (entry size: 1024)

If I remove the replaced entry C first, I get a different result:

   0  B: <value> (entry size: 1024)
   1  E: <value> (entry size: 2048)
   2  D: <value> (entry size: 1024)

Another way to look at it is whether I'm pruning until currentSize +
size(E) <= max or until currentSize - size(C) + size(E) <= max.

Thanks!