util._matcher: speed up regexp matching.
In 4babaa52badf, Benoit made a change that substantially slows matching
when a big .hgignore file is in play, because it calls into the regexp
matching engine potentially hundreds of times per file to be matched.
I've partly rolled back his change, so that we only call into the matcher
once per file, but preserved the ability to report a meaningful error
message if there's a syntax error in the regexp.
#!/bin/sh
mkdir t
cd t
hg init
echo import > port
hg add port
hg commit -m 0 -u spam -d '0 0'
echo export >> port
hg commit -m 1 -u eggs -d '1 0'
echo export > port
echo vaportight >> port
echo 'import/export' >> port
hg commit -m 2 -u spam -d '2 0'
echo 'import/export' >> port
hg commit -m 3 -u eggs -d '3 0'
head -n 3 port > port1
mv port1 port
hg commit -m 4 -u spam -d '4 0'
echo % simple
hg grep port port
echo % all
hg grep --all -nu port port
echo % other
hg grep import port
hg cp port port2
hg commit -m 4 -u spam -d '5 0'
echo '% follow'
hg grep -f 'import$' port2
echo deport >> port2
hg commit -m 5 -u eggs -d '6 0'
hg grep -f --all -nu port port2
cd ..
hg init t2
cd t2
hg grep foobar foo
hg grep foobar
echo blue >> color
echo black >> color
hg add color
hg ci -m 0 -d '0 0'
echo orange >> color
hg ci -m 1 -d '0 0'
echo black > color
hg ci -m 2 -d '0 0'
echo orange >> color
echo blue >> color
hg ci -m 3 -d '0 0'
hg grep orange
hg grep --all orange