Gawk extension for vis de/encoding of strings

Encodes non-printable, multibyte chars and a select set of printable chars as \ddd octal numbers I.e. whitespace is encoded as the string \040

The functions available are:

• vis::enc(input:str, chars_to_encode: Optional[str]) -> str
• vis::dec(input:str) -> str

The optional second argument to vis:enc, overrides the default set of printable characters that will be encoded.

The default set is (see also https://man.netbsd.org/vis.3 )

*? [#';"&<>()|]$!^~`\ 

plus \n and \t

Usage in gawk

Gawk loads extension using either:

• -l <path>
• @load <libname> looks for lib in directory specified by envvar AWKLIBPATH can be with or without .so/.dll suffix
• See https://www.gnu.org/software/gawk/manual/html_node/Loading-Shared-Libraries.html Example:

gawk -l bazel-bin/libgawk_vis.so '
BEGIN {
    print vis::enc("hello world")  # hello\040world
    print vis::dec("hello\040world")  # hello world
    print vis::enc("(◕‿◕)")  # \050\342\227\225\342\200\277\342\227\225\051
}' 

Or with bazel run if you don't have a recent version of gawk

 bazel run //:visgawk -- '
BEGIN {
    print vis::enc("hello world")  # hello\040world
    print vis::dec("hello\040world")  # hello world
    print vis::enc("(◕‿◕)")  # \050\342\227\225\342\200\277\342\227\225\051
}'

Using in bazel

The target //:libgawk_vis.so is a fileset with just the extension

Building

If you just want the shared lib, run:

bazel build //:gawk_vis

and the sharedlib is in bazel-bin/libgawk_vis.so