# HG changeset patch
# User Gregory Szorc <gregory.szorc@gmail.com>
# Date 2016-11-11 07:34:15
# Node ID c3944ab1443a0a8872a5e9ca48b21ea973cf6f90
# Parent  71b368e3b590b5fb130eb549123afba64e829439

exchange: obtain compression engines from the registrar

util.compengines has knowledge of all registered compression engines
and the metadata that associates them with various bundle types.

This patch removes the now redundant declaration of this metadata from
exchange.py and obtains it from the new source.

The effect of this patch is that once a new compression engine is
registered with util.compengines, `hg bundle -t <engine>` will just
work.

diff --git a/mercurial/exchange.py b/mercurial/exchange.py
--- a/mercurial/exchange.py
+++ b/mercurial/exchange.py
@@ -37,12 +37,6 @@ from . import (
 urlerr = util.urlerr
 urlreq = util.urlreq
 
-# Maps bundle compression human names to internal representation.
-_bundlespeccompressions = {'none': None,
-                           'bzip2': 'BZ',
-                           'gzip': 'GZ',
-                          }
-
 # Maps bundle version human names to changegroup versions.
 _bundlespeccgversions = {'v1': '01',
                          'v2': '02',
@@ -114,7 +108,7 @@ def parsebundlespec(repo, spec, strict=T
     if '-' in spec:
         compression, version = spec.split('-', 1)
 
-        if compression not in _bundlespeccompressions:
+        if compression not in util.compengines.supportedbundlenames:
             raise error.UnsupportedBundleSpecification(
                     _('%s compression is not supported') % compression)
 
@@ -130,7 +124,7 @@ def parsebundlespec(repo, spec, strict=T
 
         spec, params = parseparams(spec)
 
-        if spec in _bundlespeccompressions:
+        if spec in util.compengines.supportedbundlenames:
             compression = spec
             version = 'v1'
             if 'generaldelta' in repo.requirements:
@@ -157,7 +151,8 @@ def parsebundlespec(repo, spec, strict=T
                       ', '.join(sorted(missingreqs)))
 
     if not externalnames:
-        compression = _bundlespeccompressions[compression]
+        engine = util.compengines.forbundlename(compression)
+        compression = engine.bundletype()[1]
         version = _bundlespeccgversions[version]
     return compression, version, params
 
@@ -196,10 +191,10 @@ def getbundlespec(ui, fh):
     restored.
     """
     def speccompression(alg):
-        for k, v in _bundlespeccompressions.items():
-            if v == alg:
-                return k
-        return None
+        try:
+            return util.compengines.forbundletype(alg).bundletype()[0]
+        except KeyError:
+            return None
 
     b = readbundle(ui, fh, None)
     if isinstance(b, changegroup.cg1unpacker):