I'm attempting to write a lens for the LVM config file. One of the fun things
about the file is that within a given section (contained within { }) is that
the closing curly brace is not necessarily preceded by a newline. e.g.:
config { myoption = "test"}
is perfectly valid as is
config { myoption = "test"
}
I'm having a really hard time getting augeas to properly deal with that
optional newline. Here's a simplified version of my lens so far. For now I'm
ignoring the section name and just focusing on the block itself excluding the
curly brackets:
module Lvm =
let eol = Util.eol
let empty = Util.empty
let comment = Util.comment
let indent = del /[ \t]*/ ""
let eq = del /=/ "="
let opt_nl = del /\n?/ "\n"
let lns1 =
[ indent . key /[a-zA-Z][a-zA-Z0-9_]+/ . indent . eq . indent . store
/[0-9]+/ . opt_nl]
let empty_generic_re = /\n[ \t]*#?[ \t]*/
let empty2 =
[ del empty_generic_re "\n" . Util.del_str "\n" ]
let lns =
empty* . (( lns1 | comment ) . (lns1 | comment | empty2 )* )?
test lns get "foo=0" = ?
test lns get "foo=0\n" = ?
test lns get "foo=0bar=9" = ?
test lns get "foo=0bar=9\n" = ?
test lns put "\n\n#baz\nfoo=0\n" after set "/foo2" "8" = ?
test lns get "foo=0\n#hello\nbar=9" = ?
test lns get "foo=0\n#hello\nbar=9\n" = ?
test lns get "foo=0\n\n\n\nbar=9" = ?
test lns get "foo=0\n\n\nbar=9\n" = ?
This works OK -- it matches comments and it matches directives smushed on the
same line (valid lvm.conf syntax) and handles optional trailing newlines
without a problem. I've also half way got it handling empty lines, however as
the last 2 tests demonstrate it only handles empty lines in groups of 2. In the
empty2 lens I was attempting to match any \n followed by another \n the idea
being that this would catch a newline that appears after a configuration line
since it's newline is optional. If I remove the optional newline match from the
lns1 lens then the put methods don't generate output that contains a newline
for new trees.
Any help here would be greatly appreciated!
Thanks,
Aaron
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