119 lines
4.7 KiB
Nix
119 lines
4.7 KiB
Nix
# Nixpkgs/NixOS option handling.
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let lib = import ./default.nix; in
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with import ./trivial.nix;
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with import ./lists.nix;
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with import ./misc.nix;
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with import ./attrsets.nix;
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with import ./strings.nix;
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rec {
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isOption = lib.isType "option";
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mkOption =
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{ default ? null # Default value used when no definition is given in the configuration.
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, defaultText ? null # Textual representation of the default, for in the manual.
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, example ? null # Example value used in the manual.
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, description ? null # String describing the option.
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, type ? null # Option type, providing type-checking and value merging.
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, apply ? null # Function that converts the option value to something else.
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, internal ? null # Whether the option is for NixOS developers only.
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, visible ? null # Whether the option shows up in the manual.
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, options ? null # Obsolete, used by types.optionSet.
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} @ attrs:
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attrs // { _type = "option"; };
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mkEnableOption = name: mkOption {
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default = false;
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example = true;
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description = "Whether to enable ${name}.";
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type = lib.types.bool;
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};
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mergeDefaultOption = loc: defs:
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let list = getValues defs; in
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if length list == 1 then head list
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else if all builtins.isFunction list then x: mergeDefaultOption loc (map (f: f x) list)
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else if all isList list then concatLists list
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else if all isAttrs list then fold lib.mergeAttrs {} list
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else if all builtins.isBool list then fold lib.or false list
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else if all builtins.isString list then lib.concatStrings list
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else if all builtins.isInt list && all (x: x == head list) list then head list
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else throw "Cannot merge definitions of `${showOption loc}' given in ${showFiles (getFiles defs)}.";
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/* Obsolete, will remove soon. Specify an option type or apply
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function instead. */
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mergeTypedOption = typeName: predicate: merge: loc: list:
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let list' = map (x: x.value) list; in
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if all predicate list then merge list'
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else throw "Expected a ${typeName}.";
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mergeEnableOption = mergeTypedOption "boolean"
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(x: true == x || false == x) (fold lib.or false);
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mergeListOption = mergeTypedOption "list" isList concatLists;
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mergeStringOption = mergeTypedOption "string" builtins.isString lib.concatStrings;
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mergeOneOption = loc: defs:
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if defs == [] then abort "This case should never happen."
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else if length defs != 1 then
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throw "The unique option `${showOption loc}' is defined multiple times, in ${showFiles (getFiles defs)}."
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else (head defs).value;
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getValues = map (x: x.value);
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getFiles = map (x: x.file);
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# Generate documentation template from the list of option declaration like
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# the set generated with filterOptionSets.
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optionAttrSetToDocList = optionAttrSetToDocList' [];
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optionAttrSetToDocList' = prefix: options:
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fold (opt: rest:
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let
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docOption = rec {
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name = showOption opt.loc;
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description = opt.description or (throw "Option `${name}' has no description.");
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declarations = filter (x: x != unknownModule) opt.declarations;
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internal = opt.internal or false;
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visible = opt.visible or true;
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}
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// optionalAttrs (opt ? example) { example = scrubOptionValue opt.example; }
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// optionalAttrs (opt ? default) { default = scrubOptionValue opt.default; }
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// optionalAttrs (opt ? defaultText) { default = opt.defaultText; };
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subOptions =
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let ss = opt.type.getSubOptions opt.loc;
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in if ss != {} then optionAttrSetToDocList' opt.loc ss else [];
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in
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# FIXME: expensive, O(n^2)
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[ docOption ] ++ subOptions ++ rest) [] (collect isOption options);
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/* This function recursively removes all derivation attributes from
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`x' except for the `name' attribute. This is to make the
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generation of `options.xml' much more efficient: the XML
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representation of derivations is very large (on the order of
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megabytes) and is not actually used by the manual generator. */
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scrubOptionValue = x:
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if isDerivation x then { type = "derivation"; drvPath = x.name; outPath = x.name; name = x.name; }
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else if isList x then map scrubOptionValue x
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else if isAttrs x then mapAttrs (n: v: scrubOptionValue v) (removeAttrs x ["_args"])
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else x;
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/* For use in the ‘example’ option attribute. It causes the given
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text to be included verbatim in documentation. This is necessary
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for example values that are not simple values, e.g.,
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functions. */
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literalExample = text: { _type = "literalExample"; inherit text; };
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/* Helper functions. */
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showOption = concatStringsSep ".";
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showFiles = files: concatStringsSep " and " (map (f: "`${f}'") files);
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unknownModule = "<unknown-file>";
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}
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