nixpkgs/lib/options.nix
Jan Tojnar c652b64a26
lib/options: Relax showOption quoting
124cccbe3b
broke the build of NixOS manual.

It does not make sense to be as strict as with attributes since we
are not limited by the CLI's inability to handle numbers.
Placeholders should not be quoted either as they are not part of Nix
syntax but a meta-level construct.
2020-04-14 04:49:17 +02:00

214 lines
7.7 KiB
Nix

# Nixpkgs/NixOS option handling.
{ lib }:
with lib.trivial;
with lib.lists;
with lib.attrsets;
with lib.strings;
rec {
/* Returns true when the given argument is an option
Type: isOption :: a -> bool
Example:
isOption 1 // => false
isOption (mkOption {}) // => true
*/
isOption = lib.isType "option";
/* Creates an Option attribute set. mkOption accepts an attribute set with the following keys:
All keys default to `null` when not given.
Example:
mkOption { } // => { _type = "option"; }
mkOption { defaultText = "foo"; } // => { _type = "option"; defaultText = "foo"; }
*/
mkOption =
{
# Default value used when no definition is given in the configuration.
default ? null,
# Textual representation of the default, for the manual.
defaultText ? null,
# Example value used in the manual.
example ? null,
# String describing the option.
description ? null,
# Related packages used in the manual (see `genRelatedPackages` in ../nixos/lib/make-options-doc/default.nix).
relatedPackages ? null,
# Option type, providing type-checking and value merging.
type ? null,
# Function that converts the option value to something else.
apply ? null,
# Whether the option is for NixOS developers only.
internal ? null,
# Whether the option shows up in the manual.
visible ? null,
# Whether the option can be set only once
readOnly ? null,
# Deprecated, used by types.optionSet.
options ? null
} @ attrs:
attrs // { _type = "option"; };
/* Creates an Option attribute set for a boolean value option i.e an
option to be toggled on or off:
Example:
mkEnableOption "foo"
=> { _type = "option"; default = false; description = "Whether to enable foo."; example = true; type = { ... }; }
*/
mkEnableOption =
# Name for the created option
name: mkOption {
default = false;
example = true;
description = "Whether to enable ${name}.";
type = lib.types.bool;
};
/* This option accepts anything, but it does not produce any result.
This is useful for sharing a module across different module sets
without having to implement similar features as long as the
values of the options are not accessed. */
mkSinkUndeclaredOptions = attrs: mkOption ({
internal = true;
visible = false;
default = false;
description = "Sink for option definitions.";
type = mkOptionType {
name = "sink";
check = x: true;
merge = loc: defs: false;
};
apply = x: throw "Option value is not readable because the option is not declared.";
} // attrs);
mergeDefaultOption = loc: defs:
let list = getValues defs; in
if length list == 1 then head list
else if all isFunction list then x: mergeDefaultOption loc (map (f: f x) list)
else if all isList list then concatLists list
else if all isAttrs list then foldl' lib.mergeAttrs {} list
else if all isBool list then foldl' lib.or false list
else if all isString list then lib.concatStrings list
else if all isInt list && all (x: x == head list) list then head list
else throw "Cannot merge definitions of `${showOption loc}' given in ${showFiles (getFiles defs)}.";
mergeOneOption = loc: defs:
if defs == [] then abort "This case should never happen."
else if length defs != 1 then
throw "The unique option `${showOption loc}' is defined multiple times, in:\n - ${concatStringsSep "\n - " (getFiles defs)}."
else (head defs).value;
/* "Merge" option definitions by checking that they all have the same value. */
mergeEqualOption = loc: defs:
if defs == [] then abort "This case should never happen."
else foldl' (val: def:
if def.value != val then
throw "The option `${showOption loc}' has conflicting definitions, in ${showFiles (getFiles defs)}."
else
val) (head defs).value defs;
/* Extracts values of all "value" keys of the given list.
Type: getValues :: [ { value :: a } ] -> [a]
Example:
getValues [ { value = 1; } { value = 2; } ] // => [ 1 2 ]
getValues [ ] // => [ ]
*/
getValues = map (x: x.value);
/* Extracts values of all "file" keys of the given list
Type: getFiles :: [ { file :: a } ] -> [a]
Example:
getFiles [ { file = "file1"; } { file = "file2"; } ] // => [ "file1" "file2" ]
getFiles [ ] // => [ ]
*/
getFiles = map (x: x.file);
# Generate documentation template from the list of option declaration like
# the set generated with filterOptionSets.
optionAttrSetToDocList = optionAttrSetToDocList' [];
optionAttrSetToDocList' = prefix: options:
concatMap (opt:
let
docOption = rec {
loc = opt.loc;
name = showOption opt.loc;
description = opt.description or (lib.warn "Option `${name}' has no description." "This option has no description.");
declarations = filter (x: x != unknownModule) opt.declarations;
internal = opt.internal or false;
visible = opt.visible or true;
readOnly = opt.readOnly or false;
type = opt.type.description or null;
}
// optionalAttrs (opt ? example) { example = scrubOptionValue opt.example; }
// optionalAttrs (opt ? default) { default = scrubOptionValue opt.default; }
// optionalAttrs (opt ? defaultText) { default = opt.defaultText; }
// optionalAttrs (opt ? relatedPackages && opt.relatedPackages != null) { inherit (opt) relatedPackages; };
subOptions =
let ss = opt.type.getSubOptions opt.loc;
in if ss != {} then optionAttrSetToDocList' opt.loc ss else [];
in
[ docOption ] ++ optionals docOption.visible subOptions) (collect isOption options);
/* This function recursively removes all derivation attributes from
`x` except for the `name` attribute.
This is to make the generation of `options.xml` much more
efficient: the XML representation of derivations is very large
(on the order of megabytes) and is not actually used by the
manual generator.
*/
scrubOptionValue = x:
if isDerivation x then
{ type = "derivation"; drvPath = x.name; outPath = x.name; name = x.name; }
else if isList x then map scrubOptionValue x
else if isAttrs x then mapAttrs (n: v: scrubOptionValue v) (removeAttrs x ["_args"])
else x;
/* For use in the `example` option attribute. It causes the given
text to be included verbatim in documentation. This is necessary
for example values that are not simple values, e.g., functions.
*/
literalExample = text: { _type = "literalExample"; inherit text; };
# Helper functions.
/* Convert an option, described as a list of the option parts in to a
safe, human readable version.
Example:
(showOption ["foo" "bar" "baz"]) == "foo.bar.baz"
(showOption ["foo" "bar.baz" "tux"]) == "foo.\"bar.baz\".tux"
Placeholders will not be quoted as they are not actual values:
(showOption ["foo" "*" "bar"]) == "foo.*.bar"
(showOption ["foo" "<name>" "bar"]) == "foo.<name>.bar"
Unlike attributes, options can also start with numbers:
(showOption ["windowManager" "2bwm" "enable"]) == "windowManager.2bwm.enable"
*/
showOption = parts:
let
escapeOptionPart = part:
if part == "*" || builtins.match "<.+>" part != null || builtins.match "[a-zA-Z0-9_][a-zA-Z0-9_'-]+" part != null
then part
else escapeNixIdentifier part;
in concatMapStringsSep "." escapeOptionPart parts;
showFiles = files: concatStringsSep " and " (map (f: "`${f}'") files);
unknownModule = "<unknown-file>";
}