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author | Alyssa Ross <hi@alyssa.is> | 2019-01-07 02:18:36 +0000 |
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committer | Alyssa Ross <hi@alyssa.is> | 2019-01-07 02:18:47 +0000 |
commit | 36f56d99fa0a0765c9f1de4a5f17a9b05830c3f2 (patch) | |
tree | b3faaf573407b32aa645237a4d16b82778a39a92 /nixpkgs/lib/options.nix | |
parent | 4e31070265257dc67d120c27e0f75c2344fdfa9a (diff) | |
parent | abf060725d7614bd3b9f96764262dfbc2f9c2199 (diff) | |
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Add 'nixpkgs/' from commit 'abf060725d7614bd3b9f96764262dfbc2f9c2199'
git-subtree-dir: nixpkgs git-subtree-mainline: 4e31070265257dc67d120c27e0f75c2344fdfa9a git-subtree-split: abf060725d7614bd3b9f96764262dfbc2f9c2199
Diffstat (limited to 'nixpkgs/lib/options.nix')
-rw-r--r-- | nixpkgs/lib/options.nix | 207 |
1 files changed, 207 insertions, 0 deletions
diff --git a/nixpkgs/lib/options.nix b/nixpkgs/lib/options.nix new file mode 100644 index 000000000000..791930eafbd0 --- /dev/null +++ b/nixpkgs/lib/options.nix @@ -0,0 +1,207 @@ +# 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/doc/manual/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, + # Obsolete, 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 ${showFiles (getFiles defs)}." + else (head defs).value; + + /* "Merge" option definitions by checking that they all have the same value. */ + mergeEqualOption = loc: defs: + if defs == [] then abort "This case should never happen." + else foldl' (val: def: + if def.value != val then + throw "The option `${showOption loc}' has conflicting definitions, in ${showFiles (getFiles defs)}." + else + val) (head defs).value defs; + + /* Extracts values of all "value" keys of the given list. + + Type: getValues :: [ { value :: a } ] -> [a] + + Example: + getValues [ { value = 1; } { value = 2; } ] // => [ 1 2 ] + getValues [ ] // => [ ] + */ + getValues = map (x: x.value); + + /* Extracts values of all "file" keys of the given list + + Type: getFiles :: [ { file :: a } ] -> [a] + + Example: + getFiles [ { file = "file1"; } { file = "file2"; } ] // => [ "file1" "file2" ] + getFiles [ ] // => [ ] + */ + getFiles = map (x: x.file); + + # Generate documentation template from the list of option declaration like + # the set generated with filterOptionSets. + optionAttrSetToDocList = optionAttrSetToDocList' []; + + optionAttrSetToDocList' = prefix: options: + concatMap (opt: + let + docOption = rec { + loc = opt.loc; + name = showOption opt.loc; + description = opt.description or (throw "Option `${name}' 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 ] ++ 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" + */ + showOption = parts: let + escapeOptionPart = part: + let + escaped = lib.strings.escapeNixString part; + in if escaped == "\"${part}\"" + then part + else escaped; + in (concatStringsSep ".") (map escapeOptionPart parts); + showFiles = files: concatStringsSep " and " (map (f: "`${f}'") files); + unknownModule = "<unknown-file>"; + +} |