util: add a stream compression API to compression engines
It is a common pattern throughout the code to perform compression
on an iterator of chunks, yielding an iterator of compressed chunks.
Let's formalize that as part of the compression engine API.
The zlib and bzip2 implementations allow an optional "level" option
to control the compression level. The default values are the same as
what the Python modules use. This option will be used in subsequent
patches.
# RelaxNG schema for "xml" log style
# Inspired by Subversion's XML log format.
start = log
node.type = xsd:string {minLength = "40" maxLength = "40"}
log = element log { logentry+ }
logentry = element logentry {
logentry.attlist,
branch*, tag*, hgparent*,
author, date,
msg, paths?, copies?, extra*
}
logentry.attlist =
attribute revision {xsd:nonNegativeInteger}
& attribute node {node.type}
branch = element branch { text }
tag = element tag { text }
hgparent = element parent {hgparent.attlist, text}
hgparent.attlist =
attribute revision {xsd:integer {minInclusive = "-1"} }
& attribute node {node.type}
author = element author { author.attlist, text }
author.attlist =
attribute email {text}
date = element date {xsd:dateTime}
msg = element msg {msg.attlist, text}
msg.attlist =
attribute xml:space {"preserve"}
paths = element paths { path* }
path = element path { path.attlist, text }
path.attlist =
# Action: (A)dd, (M)odify, (R)emove
attribute action {"A"|"M"|"R"}
copies = element copies { copy+ }
copy = element copy { copy.attlist, text }
copy.attlist =
attribute source {text}
extra = element extra {extra.attlist, text}
extra.attlist =
attribute key {text}