templates: add filter to reverse list
The filter supports only lists because for lists, it’s straightforward to
implement. Reversing text doesn’t seem very useful and is hard to implement.
Reversing the bytes would break multi-bytes encodings. Reversing the code
points would break characters consisting of multiple code points. Reversing
graphemes is non-trivial without using a library not included in the standard
library.
#!/usr/bin/env python3
#
# Dumps output generated by Mercurial's command server in a formatted style to a
# given file or stderr if '-' is specified. Output is also written in its raw
# format to stdout.
#
# $ ./hg serve --cmds pipe | ./contrib/debugcmdserver.py -
# o, 52 -> 'capabilities: getencoding runcommand\nencoding: UTF-8'
import struct
import sys
if len(sys.argv) != 2:
print('usage: debugcmdserver.py FILE')
sys.exit(1)
outputfmt = '>cI'
outputfmtsize = struct.calcsize(outputfmt)
if sys.argv[1] == '-':
log = sys.stderr
else:
log = open(sys.argv[1], 'a')
def read(size):
data = sys.stdin.read(size)
if not data:
raise EOFError
sys.stdout.write(data)
sys.stdout.flush()
return data
try:
while True:
header = read(outputfmtsize)
channel, length = struct.unpack(outputfmt, header)
log.write('%s, %-4d' % (channel, length))
if channel in 'IL':
log.write(' -> waiting for input\n')
else:
data = read(length)
log.write(' -> %r\n' % data)
log.flush()
except EOFError:
pass
finally:
if log != sys.stderr:
log.close()