Message8932

This has recently come up as an issue in #jython. I took at look at lib-python/2.7/json, and it looks like we just need to implement the following functions from _json:

c_make_scanner, c_scanstring, c_encode_basestring_ascii, c_make_encoder 

The only one that's slightly involved is the last, and even then the code in python it's replacing is pretty minimal - couple pages maybe of c-like python.

Note that we can selectively choose which functions to implement - json will fallback to pure Python if a function is not present.