core/lib/cli.nix

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Nix
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2024-05-01 22:14:04 +00:00
{ 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.
# Inputs
`options`
: 1\. Function argument
`attrs`
: 2\. Function argument
# Examples
:::{.example}
## `lib.cli.toGNUCommandLineShell` usage example
```nix
cli.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"
]
cli.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 = {
# how to string-format the option name;
# by default one character is a short option (`-`),
# more than one characters a long option (`--`).
mkOptionName ?
k: if builtins.stringLength k == 1
then "-${k}"
else "--${k}",
# how to format a boolean value to a command list;
# by default its a flag option
# (only the option name if true, left out completely if false).
mkBool ? k: v: lib.optional v (mkOptionName k),
# how to format a list value to a command list;
# by default the option name is repeated for each value
# and `mkOption` is applied to the values themselves.
mkList ? k: v: lib.concatMap (mkOption k) v,
# how to format any remaining value to a command list;
# on the toplevel, booleans and lists are handled by `mkBool` and `mkList`,
# though they can still appear as values of a list.
# By default, everything is printed verbatim and complex types
# are forbidden (lists, attrsets, functions). `null` values are omitted.
mkOption ?
k: v: if v == null
then []
else [ (mkOptionName k) (lib.generators.mkValueStringDefault {} v) ]
}:
options:
let
render = k: v:
if builtins.isBool v then mkBool k v
else if builtins.isList v then mkList k v
else mkOption k v;
in
builtins.concatLists (lib.mapAttrsToList render options);
}