nixpkgs/lib/types.nix

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# Definitions related to run-time type checking. Used in particular
# to type-check NixOS configurations.
with import ./lists.nix;
with import ./attrsets.nix;
with import ./options.nix;
with import ./trivial.nix;
with import ./strings.nix;
rec {
isType = type: x: (x._type or "") == type;
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typeOf = x: x._type or "";
setType = typeName: value: value // {
_type = typeName;
};
isOptionType = isType "option-type";
mkOptionType =
{ # Human-readable representation of the type.
name
, # Function applied to each definition that should return true if
# its type-correct, false otherwise.
check ? (x: true)
, # Merge a list of definitions together into a single value.
# This function is called with two arguments: the location of
# the option in the configuration as a list of strings
# (e.g. ["boot" "loader "grub" "enable"]), and a list of
# definition values and locations (e.g. [ { file = "/foo.nix";
# value = 1; } { file = "/bar.nix"; value = 2 } ]).
merge ? mergeDefaultOption
, # Return a flat list of sub-options. Used to generate
# documentation.
getSubOptions ? prefix: {}
}:
{ _type = "option-type";
inherit name check merge getSubOptions;
};
types = rec {
unspecified = mkOptionType {
name = "unspecified";
};
bool = mkOptionType {
name = "boolean";
check = builtins.isBool;
merge = loc: fold (x: y: x.value || y) false;
};
int = mkOptionType {
name = "integer";
check = builtins.isInt;
merge = mergeOneOption;
};
str = mkOptionType {
name = "string";
check = builtins.isString;
merge = mergeOneOption;
};
# Merge multiple definitions by concatenating them (with the given
# separator between the values).
separatedString = sep: mkOptionType {
name = "string";
check = builtins.isString;
merge = loc: defs: concatStringsSep sep (getValues defs);
};
lines = separatedString "\n";
commas = separatedString ",";
envVar = separatedString ":";
# Deprecated; should not be used because it quietly concatenates
# strings, which is usually not what you want.
string = separatedString "";
attrs = mkOptionType {
name = "attribute set";
check = isAttrs;
merge = loc: fold (def: mergeAttrs def.value) {};
};
# derivation is a reserved keyword.
package = mkOptionType {
name = "derivation";
check = isDerivation;
merge = mergeOneOption;
};
path = mkOptionType {
name = "path";
# Hacky: there is no isPath primop.
check = x: builtins.unsafeDiscardStringContext (builtins.substring 0 1 (toString x)) == "/";
merge = mergeOneOption;
};
# drop this in the future:
list = builtins.trace "`types.list' is deprecated; use `types.listOf' instead" types.listOf;
listOf = elemType: mkOptionType {
name = "list of ${elemType.name}s";
check = value: isList value && all elemType.check value;
merge = loc: defs:
concatLists (imap (n: def: imap (m: def':
elemType.merge (loc ++ ["[${toString n}-${toString m}]"])
[{ inherit (def) file; value = def'; }]) def.value) defs);
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getSubOptions = prefix: elemType.getSubOptions (prefix ++ ["*"]);
};
attrsOf = elemType: mkOptionType {
name = "attribute set of ${elemType.name}s";
check = x: isAttrs x && all elemType.check (attrValues x);
merge = loc: defs:
zipAttrsWith (name: elemType.merge (loc ++ [name]))
# Push down position info.
(map (def: listToAttrs (mapAttrsToList (n: def':
{ name = n; value = { inherit (def) file; value = def'; }; }) def.value)) defs);
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getSubOptions = prefix: elemType.getSubOptions (prefix ++ ["<name>"]);
};
# List or attribute set of ...
loaOf = elemType:
let
convertIfList = defIdx: def:
if isList def.value then
{ inherit (def) file;
value = listToAttrs (
imap (elemIdx: elem:
{ name = "unnamed-${toString defIdx}.${toString elemIdx}";
value = elem;
}) def.value);
}
else
def;
listOnly = listOf elemType;
attrOnly = attrsOf elemType;
in mkOptionType {
name = "list or attribute set of ${elemType.name}s";
check = x:
if isList x then listOnly.check x
else if isAttrs x then attrOnly.check x
else false;
merge = loc: defs: attrOnly.merge loc (imap convertIfList defs);
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getSubOptions = prefix: elemType.getSubOptions (prefix ++ ["<name?>"]);
};
uniq = elemType: mkOptionType {
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inherit (elemType) name check;
merge = mergeOneOption;
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getSubOptions = elemType.getSubOptions;
};
nullOr = elemType: mkOptionType {
name = "null or ${elemType.name}";
check = x: builtins.isNull x || elemType.check x;
merge = loc: defs:
let nrNulls = count (def: isNull def.value) defs; in
if nrNulls == length defs then null
else if nrNulls != 0 then
throw "The option `${showOption loc}' is defined both null and not null, in ${showFiles (getFiles defs)}."
else elemType.merge loc defs;
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getSubOptions = elemType.getSubOptions;
};
functionTo = elemType: mkOptionType {
name = "function that evaluates to a(n) ${elemType.name}";
check = builtins.isFunction;
merge = loc: defs:
fnArgs: elemType.merge loc (map (fn: { inherit (fn) file; value = fn.value fnArgs; }) defs);
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getSubOptions = elemType.getSubOptions;
};
submodule = opts:
let
opts' = toList opts;
inherit (import ./modules.nix) evalModules;
in
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mkOptionType rec {
name = "submodule";
check = x: isAttrs x || builtins.isFunction x;
merge = loc: defs:
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let
coerce = def: if builtins.isFunction def then def else { config = def; };
modules = opts' ++ map (def: { _file = def.file; imports = [(coerce def.value)]; }) defs;
in (evalModules { inherit modules; args.name = last loc; prefix = loc; }).config;
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getSubOptions = prefix: (evalModules
{ modules = opts'; inherit prefix;
# FIXME: hack to get shit to evaluate.
args = { name = ""; }; }).options;
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};
# Obsolete alternative to configOf. It takes its option
# declarations from the options attribute of containing option
# declaration.
optionSet = mkOptionType {
name = /* builtins.trace "types.optionSet is deprecated; use types.submodule instead" */ "option set";
};
# Augment the given type with an additional type check function.
addCheck = elemType: check: elemType // { check = x: elemType.check x && check x; };
};
}