shelve: make shelvestate use simplekeyvaluefile
Currently shelvestate uses line ordering to differentiate fields. This
makes it hard for extensions to wrap shelve, since if two alternative
versions of code add a new line, correct merging is going to be problematic.
simplekeyvaluefile was introduced fot this purpose specifically.
After this patch:
- shelve will always write a simplekeyvaluefile
- unshelve will check the first line of the file for a version, and if the
version is 1, will read it in a position-based way, if the version is 2,
will read it in a key-value way
As discussed with Yuya previously, this will be able to handle old-style
shelvedstate files, but old Mercurial versions will fail on the attempt to
read shelvedstate file of version 2 with a self-explanatory message:
'abort: this version of shelve is incompatible with the version used
in this repo'
from __future__ import absolute_import, print_function
import sys
globalvars = {}
lines = sys.stdin.readlines()
while lines:
l = lines.pop(0)
if l.startswith('SALT'):
print(l[:-1])
elif l.startswith('>>> '):
snippet = l[4:]
while lines and lines[0].startswith('... '):
l = lines.pop(0)
snippet += l[4:]
c = compile(snippet, '<heredoc>', 'single')
try:
exec(c, globalvars)
except Exception as inst:
print(repr(inst))