bug#46761: 28.0.50; Speed up json.el encoding

[Basil L. Contovounesios]

Severity: wishlist
Tags: patch

The attached patch speeds up json-encode by inserting into a buffer
rather than concatenating strings.  It does so backward compatibly by
creating a new json--print-* namespace that mirrors the existing
json-encode-* namespace, cleaning it up a bit and reducing code
duplication in the process.

Using my usual benchmark from bug#40693#89:

  canada.json
  old (1.412693239 96 0.736882091)
  new (1.154423962 32 0.248241551)

  citm_catalog.json
  old (0.676292855 68 0.5285956769999993)
  new (0.306573098 12 0.0965493740000003)

  twitter.json
  old (0.353447016 40 0.28536439900000055)
  new (0.142140227  8 0.05943713899999992)

Note that one of the unit tests depends on the patch to map.el in
bug#46754 in order to pass.

WDYT?

Thanks,

-- 
Basil

0001-Speed-up-json.el-encoding.patch
Description: Text Data