nixpkgs/lib/cli.nix
Profpatsch 582354d3b6 lib/cli: encodeGNUCommandLine -> toGNUCommandLineShell
The semantic difference between `encode` and `to` is not apparent.
Users are likely to confuse both functions (which leads to unexpected
error messages about the wrong types). Like in `generators.nix`, all
functions should be prefixed by `to`.

Furthermore, converting to a string depends on the target context. In
this case, it’s a POSIX shell, so we should name it that (compare
`escapeShellArg` in `strings.nix`).

We can later add versions that escape for embedding in e.g. python
scripts or similar.
2020-01-23 14:47:38 +01:00

78 lines
2.1 KiB
Nix

{ lib }:
rec {
/* Automatically convert an attribute set to command-line options.
This helps protect against malformed command lines and also to reduce
boilerplate related to command-line construction for simple use cases.
`toGNUCommandLine` returns a list of nix strings.
`toGNUCommandLineShell` returns an escaped shell string.
Example:
toGNUCommandLine
{ }
{ data = builtins.toJSON { id = 0; };
X = "PUT";
retry = 3;
retry-delay = null;
url = [ "https://example.com/foo" "https://example.com/bar" ];
silent = false;
verbose = true;
};
=> [ "-X" "PUT" "--data" "{\"id\":0}" "--retry" "3" "--url" "https://example.com/foo" "--url" "https://example.com/bar" "--verbose" ]
toGNUCommandLineShell
{ }
{ data = builtins.toJSON { id = 0; };
X = "PUT";
retry = 3;
retry-delay = null;
url = [ "https://example.com/foo" "https://example.com/bar" ];
silent = false;
verbose = true;
};
=> "'-X' 'PUT' '--data' '{\"id\":0}' '--retry' '3' '--url' 'https://example.com/foo' '--url' 'https://example.com/bar' '--verbose'"
*/
toGNUCommandLineShell =
options: attrs: lib.escapeShellArgs (toGNUCommandLine options attrs);
toGNUCommandLine =
{ renderKey ?
key: if builtins.stringLength key == 1 then "-${key}" else "--${key}"
, renderOption ?
key: value:
if value == null
then []
else [ (renderKey key) (builtins.toString value) ]
, renderBool ? key: value: lib.optional value (renderKey key)
, renderList ? key: value: lib.concatMap (renderOption key) value
}:
options:
let
render = key: value:
if builtins.isBool value
then renderBool key value
else if builtins.isList value
then renderList key value
else renderOption key value;
in
builtins.concatLists (lib.mapAttrsToList render options);
}