nixpkgs/pkgs/lib/options.nix
Nicolas Pierron c6267a8c9d Add declarations and definitions to options. This allow you to retrieve
the location of the definition with the defined value.

Filter the source location for the documentation.

svn path=/nixpkgs/trunk/; revision=17253
2009-09-18 15:10:11 +00:00

261 lines
8.1 KiB
Nix

# Nixpkgs/NixOS option handling.
let lib = import ./default.nix; in
with { inherit (builtins) head tail; };
with import ./trivial.nix;
with import ./lists.nix;
with import ./misc.nix;
with import ./attrsets.nix;
with import ./properties.nix;
rec {
inherit (lib) typeOf;
isOption = attrs: (typeOf attrs) == "option";
mkOption = attrs: attrs // {
_type = "option";
# name (this is the name of the attributem it is automatically generated by the traversal)
# default (value used when no definition exists)
# example (documentation)
# description (documentation)
# type (option type, provide a default merge function and ensure type correctness)
# merge (function used to merge definitions into one definition: [ /type/ ] -> /type/)
# apply (convert the option value to ease the manipulation of the option result)
# options (set of sub-options declarations & definitions)
};
mapSubOptions = f: opt:
if opt ? options then
opt // {
options = map f (toList opt.options);
}
else
opt;
# Make the option declaration more user-friendly by adding default
# settings and some verifications based on the declaration content (like
# type correctness).
addOptionMakeUp = {name, recurseInto}: decl:
let
init = {
inherit name;
merge = mergeDefaultOption;
apply = lib.id;
};
mergeFromType = opt:
if decl ? type && decl.type ? merge then
opt // { merge = decl.type.merge; }
else
opt;
addDeclaration = opt: opt // decl;
ensureMergeInputType = opt:
if decl ? type then
opt // {
merge = list:
if all decl.type.check list then
opt.merge list
else
throw "One of the definitions has a bad type.";
}
else opt;
ensureDefaultType = opt:
if decl ? type && decl ? default then
opt // {
default =
if decl.type.check decl.default then
decl.default
else
throw "The default value has a bad type.";
}
else opt;
handleOptionSets = opt:
if decl ? type && decl.type.hasOptions then
let
optionConfig = opts: config:
map (f: lib.applyIfFunction f config)
(opt.options ++ toList opts);
in
opt // {
merge = list:
decl.type.iter
(path: opts:
(lib.fix
(fixableMergeFun (recurseInto path) (optionConfig opts))
).config
)
opt.name
(opt.merge list);
options =
let path = decl.type.docPath opt.name; in
(lib.fix
(fixableMergeFun (recurseInto path) (optionConfig []))
).options;
}
else
opt;
in
foldl (opt: f: f opt) init [
# default settings
mergeFromType
# user settings
addDeclaration
# override settings
ensureMergeInputType
ensureDefaultType
handleOptionSets
];
# Merge a list of options containning different field. This is useful to
# separate the merge & apply fields from the interface.
mergeOptionDecls = opts:
if opts == [] then {}
else if tail opts == [] then
let opt = head opts; in
if opt ? options then
opt // { options = toList opt.options; }
else
opt
else
fold (opt1: opt2:
lib.addErrorContext "opt1 = ${lib.showVal opt1}\nopt2 = ${lib.showVal opt2}" (
# You cannot merge if two options have the same field.
assert opt1 ? default -> ! opt2 ? default;
assert opt1 ? example -> ! opt2 ? example;
assert opt1 ? description -> ! opt2 ? description;
assert opt1 ? merge -> ! opt2 ? merge;
assert opt1 ? apply -> ! opt2 ? apply;
assert opt1 ? type -> ! opt2 ? type;
if opt1 ? options || opt2 ? options then
opt1 // opt2 // {
options =
(toList (attrByPath ["options"] [] opt1))
++ (toList (attrByPath ["options"] [] opt2));
}
else
opt1 // opt2
)) {} opts;
# !!! This function will be removed because this can be done with the
# multiple option declarations.
addDefaultOptionValues = defs: opts: opts //
builtins.listToAttrs (map (defName:
{ name = defName;
value =
let
defValue = builtins.getAttr defName defs;
optValue = builtins.getAttr defName opts;
in
if typeOf defValue == "option"
then
# `defValue' is an option.
if hasAttr defName opts
then builtins.getAttr defName opts
else defValue.default
else
# `defValue' is an attribute set containing options.
# So recurse.
if hasAttr defName opts && isAttrs optValue
then addDefaultOptionValues defValue optValue
else addDefaultOptionValues defValue {};
}
) (attrNames defs));
mergeDefaultOption = list:
if list != [] && tail list == [] then head list
else if all builtins.isFunction list then x: mergeDefaultOption (map (f: f x) list)
else if all isList list then concatLists list
else if all isAttrs list then fold lib.mergeAttrs {} list
else if all (x: true == x || false == x) list then fold lib.or false list
else if all (x: x == toString x) list then lib.concatStrings list
else throw "Cannot merge values.";
mergeTypedOption = typeName: predicate: merge: list:
if all predicate list then merge list
else throw "Expect a ${typeName}.";
mergeEnableOption = mergeTypedOption "boolean"
(x: true == x || false == x) (fold lib.or false);
mergeListOption = mergeTypedOption "list" isList concatLists;
mergeStringOption = mergeTypedOption "string"
(x: if builtins ? isString then builtins.isString x else x + "")
lib.concatStrings;
mergeOneOption = list:
if list == [] then abort "This case should never happen."
else if tail list != [] then throw "Multiple definitions. Only one is allowed for this option."
else head list;
fixableMergeFun = merge: f: config:
merge (
# generate the list of option sets.
f config
);
fixableMergeModules = merge: initModules: {...}@args: config:
fixableMergeFun merge (config:
lib.moduleClosure initModules (args // { inherit config; })
) config;
fixableDefinitionsOf = initModules: {...}@args:
fixableMergeModules (modules: (lib.moduleMerge "" modules).config) initModules args;
fixableDeclarationsOf = initModules: {...}@args:
fixableMergeModules (modules: (lib.moduleMerge "" modules).options) initModules args;
definitionsOf = initModules: {...}@args:
(lib.fix (module:
fixableMergeModules (lib.moduleMerge "") initModules args module.config
)).config;
declarationsOf = initModules: {...}@args:
(lib.fix (module:
fixableMergeModules (lib.moduleMerge "") initModules args module.config
)).options;
# Generate documentation template from the list of option declaration like
# the set generated with filterOptionSets.
optionAttrSetToDocList = ignore: newOptionAttrSetToDocList;
newOptionAttrSetToDocList = attrs:
let options = collect isOption attrs; in
fold (opt: rest:
let
docOption = {
inherit (opt) name;
description = if opt ? description then opt.description else
throw "Option ${opt.name}: No description.";
declarations = map (x: toString x.source) opt.declarations;
definitions = map (x: toString x.source) opt.definitions;
}
// (if opt ? example then {inherit(opt) example;} else {})
// (if opt ? default then {inherit(opt) default;} else {});
subOptions =
if opt ? options then
newOptionAttrSetToDocList opt.options
else
[];
in
[ docOption ] ++ subOptions ++ rest
) [] options;
}