contrib/xml.rnc

templatekw: make negrev return empty for wdir() and nullrev

I considered just returning the same output that {rev} returns here,
but {rev} also returns essentially gibberish: either an INT_MAX-kind
of variable for wdir() or -1 for null. Since these are numbers that
are intended to be used for calculations, and since the numbers for
wdir() and -1 are not really very helpful for calculation (and worse,
when used as a revision number -1 is equal to unhidden tip), I figured
the most reasonable thing to do here is to just return nothing for
negrev.

This could potentially break scripts that are expecting to parse a
nonempty integer out of a {negrev}, but that seems like a very remote
concern at this juncture.

# 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}