nixpkgs/pkgs/lib/options.nix
Eelco Dolstra 599015e8b0 * Split lib/default.nix into several files, as it had become a big
mess.  Also cleaned up some functions:

  - foldl appeared broken (it recursively called fold).
  - Renamed logicalAND/logicalOR to and/or.
  - Removed listOfListsToAttrs, eqStrings: obsolete.
  - Removed isInList, which does the same thing as elem.
  - stringToCharacters: don't return a "" at the end of the list.
  - Renamed concatList to concat, as concatList (singular) is a
    misnomer: it takes two lists.  Likewise, renamed mergeAttr to
    mergeAttrs.

  misc.nix still contains a lot of stuff that should be refactored and
  moved to other files.

svn path=/nixpkgs/trunk/; revision=14013
2009-02-09 16:51:03 +00:00

267 lines
8.7 KiB
Nix

# Nixpkgs/NixOS option handling.
let lib = import ./default.nix; in
with { inherit (builtins) head tail; };
with import ./lists.nix;
with import ./attrsets.nix;
rec {
mkOption = attrs: attrs // {_type = "option";};
typeOf = x: if (__isAttrs x && x ? _type) then x._type else "";
isOption = attrs: (typeOf attrs) == "option";
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 builtins.hasAttr defName opts
then builtins.getAttr defName opts
else defValue.default
else
# `defValue' is an attribute set containing options.
# So recurse.
if builtins.hasAttr defName opts && builtins.isAttrs optValue
then addDefaultOptionValues defValue optValue
else addDefaultOptionValues defValue {};
}
) (builtins.attrNames defs));
mergeDefaultOption = list:
if list != [] && tail list == [] then head list
else if all __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 happens."
else if tail list != [] then throw "Multiple definitions. Only one is allowed for this option."
else head list;
# Handle the traversal of option sets. All sets inside 'opts' are zipped
# and options declaration and definition are separated. If no option are
# declared at a specific depth, then the function recurse into the values.
# Other cases are handled by the optionHandler which contains two
# functions that are used to defined your goal.
# - export is a function which takes two arguments which are the option
# and the list of values.
# - notHandle is a function which takes the list of values are not handle
# by this function.
handleOptionSets = optionHandler@{export, notHandle, ...}: path: opts:
if all __isAttrs opts then
lib.zip (attr: opts:
let
# Compute the path to reach the attribute.
name = if path == "" then attr else path + "." + attr;
# Divide the definitions of the attribute "attr" between
# declaration (isOption) and definitions (!isOption).
test = partition isOption opts;
decls = test.right; defs = test.wrong;
# Return the option declaration and add missing default
# attributes.
opt = {
inherit name;
merge = mergeDefaultOption;
apply = lib.id;
} // (head decls);
# Return the list of option sets.
optAttrs = map delayIf defs;
# return the list of option values.
# Remove undefined values that are coming from evalIf.
optValues = filter (x: !isNotdef x) (map evalIf defs);
in
if decls == [] then handleOptionSets optionHandler name optAttrs
else lib.addErrorContext "while evaluating the option ${name}:" (
if tail decls != [] then throw "Multiple options."
else export opt optValues
)
) opts
else lib.addErrorContext "while evaluating ${path}:" (notHandle opts);
# Merge option sets and produce a set of values which is the merging of
# all options declare and defined. If no values are defined for an
# option, then the default value is used otherwise it use the merge
# function of each option to get the result.
mergeOptionSets = noOption: newMergeOptionSets; # ignore argument
newMergeOptionSets =
handleOptionSets {
export = opt: values:
opt.apply (
if values == [] then
if opt ? default then opt.default
else throw "Not defined."
else opt.merge values
);
notHandle = opts: throw "Used without option declaration.";
};
# Keep all option declarations.
filterOptionSets =
handleOptionSets {
export = opt: values: opt;
notHandle = opts: {};
};
# Evaluate a list of option sets that would be merged with the
# function "merge" which expects two arguments. The attribute named
# "require" is used to imports option declarations and bindings.
#
# * cfg[0-9]: configuration
# * cfgSet[0-9]: configuration set
#
# merge: the function used to merge options sets.
# pkgs: is the set of packages available. (nixpkgs)
# opts: list of option sets or option set functions.
# config: result of this evaluation.
fixOptionSetsFun = merge: pkgs: opts: config:
let
# remove possible mkIf to access the require attribute.
noImportConditions = cfgSet0:
let cfgSet1 = delayIf cfgSet0; in
if cfgSet1 ? require then
cfgSet1 // { require = rmIf cfgSet1.require; }
else
cfgSet1;
# call configuration "files" with one of the existing convention.
argumentHandler = cfg:
let
# {..}
cfg0 = cfg;
# {pkgs, config, ...}: {..}
cfg1 = cfg { inherit pkgs config merge; };
# pkgs: config: {..}
cfg2 = cfg {} {};
in
if __isFunction cfg0 then
if builtins.isAttrs cfg1 then cfg1
else builtins.trace "Use '{pkgs, config, ...}:'." cfg2
else cfg0;
preprocess = cfg0:
let cfg1 = argumentHandler cfg0;
cfg2 = noImportConditions cfg1;
in cfg2;
getRequire = x: toList (getAttr ["require"] [] (preprocess x));
rmRequire = x: removeAttrs (preprocess x) ["require"];
in
merge "" (
map rmRequire (
lib.uniqFlatten getRequire [] [] (toList opts)
)
);
fixOptionSets = merge: pkgs: opts:
lib.fix (fixOptionSetsFun merge pkgs opts);
optionAttrSetToDocList = l: attrs:
if (getAttr ["_type"] "" attrs) == "option" then
[({
#inherit (attrs) description;
description = if attrs ? description then attrs.description else
throw ("No description ${toString l} : ${lib.whatis attrs}");
}
// (if attrs ? example then {inherit(attrs) example;} else {} )
// (if attrs ? default then {inherit(attrs) default;} else {} )
// {name = l;}
)]
else (concatLists (map (s: (optionAttrSetToDocList
(l + (if l=="" then "" else ".") + s) (builtins.getAttr s attrs)))
(builtins.attrNames attrs)));
/* If. ThenElse. Always. */
# !!! cleanup needed
# create "if" statement that can be dealyed on sets until a "then-else" or
# "always" set is reached. When an always set is reached the condition
# is ignore.
isIf = attrs: (typeOf attrs) == "if";
mkIf = condition: thenelse:
if isIf thenelse then
mkIf (condition && thenelse.condition) thenelse.thenelse
else {
_type = "if";
inherit condition thenelse;
};
isNotdef = attrs: (typeOf attrs) == "notdef";
mkNotdef = {_type = "notdef";};
isThenElse = attrs: (typeOf attrs) == "then-else";
mkThenElse = attrs:
assert attrs ? thenPart && attrs ? elsePart;
attrs // { _type = "then-else"; };
isAlways = attrs: (typeOf attrs) == "always";
mkAlways = value: { inherit value; _type = "always"; };
pushIf = f: attrs:
if isIf attrs then pushIf f (
let val = attrs.thenelse; in
# evaluate the condition.
if isThenElse val then
if attrs.condition then
val.thenPart
else
val.elsePart
# ignore the condition.
else if isAlways val then
val.value
# otherwise
else
f attrs.condition val)
else
attrs;
# take care otherwise you will have to handle this by hand.
rmIf = pushIf (condition: val: val);
evalIf = pushIf (condition: val:
if condition then val else mkNotdef
);
delayIf = pushIf (condition: val:
# rewrite the condition on sub-attributes.
lib.mapAttrs (name: mkIf condition) val
);
}