sh/src/sh_path.erl

-module(sh_path).
-export([escape/1, unescape/1]).

escape(Path) -> R = reserved(), lists:append([char_encode(Char, R) || Char <- Path]).
unescape(Str) -> decode(Str).
reserved() -> sets:from_list([$/, $\\, $:, $%]).
char_encode(Char, Reserved) ->
    case sets:is_element(Char, Reserved) of
        true -> [$% | http_util:integer_to_hexlist(Char)];
        false -> [Char] end.


%% from http_uri:decode/1
decode(String) ->
    do_decode(String).

do_decode([$%,Hex1,Hex2|Rest]) ->
    [hex2dec(Hex1)*16+hex2dec(Hex2)|do_decode(Rest)];
do_decode([First|Rest]) ->
    [First|do_decode(Rest)];
do_decode([]) ->
    [].

hex2dec(X) when (X>=$0) andalso (X=<$9) -> X-$0;
hex2dec(X) when (X>=$A) andalso (X=<$F) -> X-$A+10;
hex2dec(X) when (X>=$a) andalso (X=<$f) -> X-$a+10.