137 lines
5 KiB
Nix
137 lines
5 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 = attrs: attrs // {
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_type = "option";
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# name (this is the name of the attributem it is automatically generated by the traversal)
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# default (value used when no definition exists)
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# example (documentation)
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# description (documentation)
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# type (option type, provide a default merge function and ensure type correctness)
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# merge (function used to merge definitions into one definition: [ /type/ ] -> /type/)
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# apply (convert the option value to ease the manipulation of the option result)
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# options (set of sub-options declarations & definitions)
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};
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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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# !!! This function will be removed because this can be done with the
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# multiple option declarations.
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addDefaultOptionValues = defs: opts: opts //
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builtins.listToAttrs (map (defName:
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{ name = defName;
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value =
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let
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defValue = builtins.getAttr defName defs;
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optValue = builtins.getAttr defName opts;
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in
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if isOption defValue
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then
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# `defValue' is an option.
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if hasAttr defName opts
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then builtins.getAttr defName opts
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else defValue.default
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else
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# `defValue' is an attribute set containing options.
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# So recurse.
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if hasAttr defName opts && isAttrs optValue
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then addDefaultOptionValues defValue optValue
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else addDefaultOptionValues defValue {};
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}
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) (attrNames defs));
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mergeDefaultOption = list:
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if length list == 1 then head list
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else if all builtins.isFunction list then x: mergeDefaultOption (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
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then head list
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else throw "Cannot merge values.";
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mergeTypedOption = typeName: predicate: merge: list:
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if all predicate list then merge list
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else throw "Expect a ${typeName}.";
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mergeEnableOption = mergeTypedOption "boolean"
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(x: true == x || false == x) (fold lib.or false);
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mergeListOption = mergeTypedOption "list" isList concatLists;
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mergeStringOption = mergeTypedOption "string"
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(x: if builtins ? isString then builtins.isString x else x + "")
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lib.concatStrings;
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mergeOneOption = list:
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if list == [] then abort "This case should never happen."
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else if length list != 1 then throw "Multiple definitions. Only one is allowed for this option."
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else head list;
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# Generate documentation template from the list of option declaration like
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# the set generated with filterOptionSets.
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optionAttrSetToDocList = optionAttrSetToDocList' [];
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optionAttrSetToDocList' = prefix: options:
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fold (opt: rest:
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let
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docOption = rec {
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name = showOption opt.loc;
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description = opt.description or (throw "Option `${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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unknownModule = "<unknown-file>";
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}
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