contrib/packagelib.sh

encoding: add fast path of jsonescape() (issue5533)

This isn't highly optimized as it copies characters one by one, but seems
reasonably simple and not slow.

  (with mercurial repo)
  $ export HGRCPATH=/dev/null HGPLAIN=
  $ hg log --time --config experimental.stabilization=all -Tjson > /dev/null

  (original)
  time: real 6.830 secs (user 6.740+0.000 sys 0.080+0.000)
  time: real 6.690 secs (user 6.650+0.000 sys 0.040+0.000)
  time: real 6.700 secs (user 6.640+0.000 sys 0.060+0.000)

  (this patch)
  time: real 5.630 secs (user 5.550+0.000 sys 0.070+0.000)
  time: real 5.700 secs (user 5.650+0.000 sys 0.050+0.000)
  time: real 5.690 secs (user 5.640+0.000 sys 0.050+0.000)

# Extract version number into 4 parts, some of which may be empty:
#
# version: the numeric part of the most recent tag. Will always look like 1.3.
#
# type: if an rc build, "rc", otherwise empty
#
# distance: the distance from the nearest tag, or empty if built from a tag
#
# node: the node|short hg was built from, or empty if built from a tag
gethgversion() {
    make cleanbutpackages
    make local || make local PURE=--pure
    HG="$PWD/hg"

    $HG version > /dev/null || { echo 'abort: hg version failed!'; exit 1 ; }

    hgversion=`LANGUAGE=C $HG version | sed -ne 's/.*(version \(.*\))$/\1/p'`

    if echo $hgversion | grep + > /dev/null 2>&1 ; then
        tmp=`echo $hgversion | cut -d+ -f 2`
        hgversion=`echo $hgversion | cut -d+ -f 1`
        distance=`echo $tmp | cut -d- -f 1`
        node=`echo $tmp | cut -d- -f 2`
    else
        distance=''
        node=''
    fi
    if echo $hgversion | grep -- '-' > /dev/null 2>&1; then
        version=`echo $hgversion | cut -d- -f1`
        type=`echo $hgversion | cut -d- -f2`
    else
        version=$hgversion
        type=''
    fi
}