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# Definitions related to run-time type checking. Used in particular
# to type-check NixOS configurations.
{ lib }:
with lib.lists;
with lib.attrsets;
with lib.options;
with lib.trivial;
with lib.strings;
let
inherit (lib.modules) mergeDefinitions;
outer_types =
rec {
isType = type: x: (x._type or "") == type;
setType = typeName: value: value // {
_type = typeName;
};
# Default type merging function
# takes two type functors and return the merged type
defaultTypeMerge = f: f':
let wrapped = f.wrapped.typeMerge f'.wrapped.functor;
payload = f.binOp f.payload f'.payload;
in
# cannot merge different types
if f.name != f'.name
then null
# simple types
else if (f.wrapped == null && f'.wrapped == null)
&& (f.payload == null && f'.payload == null)
then f.type
# composed types
else if (f.wrapped != null && f'.wrapped != null) && (wrapped != null)
then f.type wrapped
# value types
else if (f.payload != null && f'.payload != null) && (payload != null)
then f.type payload
else null;
# Default type functor
defaultFunctor = name: {
inherit name;
type = types.${name} or null;
wrapped = null;
payload = null;
binOp = a: b: null;
};
isOptionType = isType "option-type";
mkOptionType =
{ # Human-readable representation of the type, should be equivalent to
# the type function name.
name
, # Description of the type, defined recursively by embedding the wrapped type if any.
description ? null
, # 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
, # Whether this type has a value representing nothingness. If it does,
# this should be a value of the form { value = <the nothing value>; }
# If it doesn't, this should be {}
# This may be used when a value is required for `mkIf false`. This allows the extra laziness in e.g. `lazyAttrsOf`.
emptyValue ? {}
, # Return a flat list of sub-options. Used to generate
# documentation.
getSubOptions ? prefix: {}
, # List of modules if any, or null if none.
getSubModules ? null
, # Function for building the same option type with a different list of
# modules.
substSubModules ? m: null
, # Function that merge type declarations.
# internal, takes a functor as argument and returns the merged type.
# returning null means the type is not mergeable
typeMerge ? defaultTypeMerge functor
, # The type functor.
# internal, representation of the type as an attribute set.
# name: name of the type
# type: type function.
# wrapped: the type wrapped in case of compound types.
# payload: values of the type, two payloads of the same type must be
# combinable with the binOp binary operation.
# binOp: binary operation that merge two payloads of the same type.
functor ? defaultFunctor name
, # The deprecation message to display when this type is used by an option
# If null, the type isn't deprecated
deprecationMessage ? null
}:
{ _type = "option-type";
inherit name check merge emptyValue getSubOptions getSubModules substSubModules typeMerge functor deprecationMessage;
description = if description == null then name else description;
};
# When adding new types don't forget to document them in
# nixos/doc/manual/development/option-types.xml!
types = rec {
anything = mkOptionType {
name = "anything";
description = "anything";
check = value: true;
merge = loc: defs:
let
getType = value:
if isAttrs value && isCoercibleToString value
then "stringCoercibleSet"
else builtins.typeOf value;
# Returns the common type of all definitions, throws an error if they
# don't have the same type
commonType = foldl' (type: def:
if getType def.value == type
then type
else throw "The option `${showOption loc}' has conflicting option types in ${showFiles (getFiles defs)}"
) (getType (head defs).value) defs;
mergeFunction = {
# Recursively merge attribute sets
set = (attrsOf anything).merge;
# Safe and deterministic behavior for lists is to only accept one definition
# listOf only used to apply mkIf and co.
list =
if length defs > 1
then throw "The option `${showOption loc}' has conflicting definitions, in ${showFiles (getFiles defs)}."
else (listOf anything).merge;
# This is the type of packages, only accept a single definition
stringCoercibleSet = mergeOneOption;
# Otherwise fall back to only allowing all equal definitions
}.${commonType} or mergeEqualOption;
in mergeFunction loc defs;
};
unspecified = mkOptionType {
name = "unspecified";
};
bool = mkOptionType {
name = "bool";
description = "boolean";
check = isBool;
merge = mergeEqualOption;
};
int = mkOptionType {
name = "int";
description = "signed integer";
check = isInt;
merge = mergeEqualOption;
};
# Specialized subdomains of int
ints =
let
betweenDesc = lowest: highest:
"${toString lowest} and ${toString highest} (both inclusive)";
between = lowest: highest:
assert lib.assertMsg (lowest <= highest)
"ints.between: lowest must be smaller than highest";
addCheck int (x: x >= lowest && x <= highest) // {
name = "intBetween";
description = "integer between ${betweenDesc lowest highest}";
};
ign = lowest: highest: name: docStart:
between lowest highest // {
inherit name;
description = docStart + "; between ${betweenDesc lowest highest}";
};
unsign = bit: range: ign 0 (range - 1)
"unsignedInt${toString bit}" "${toString bit} bit unsigned integer";
sign = bit: range: ign (0 - (range / 2)) (range / 2 - 1)
"signedInt${toString bit}" "${toString bit} bit signed integer";
in {
/* An int with a fixed range.
*
* Example:
* (ints.between 0 100).check (-1)
* => false
* (ints.between 0 100).check (101)
* => false
* (ints.between 0 0).check 0
* => true
*/
inherit between;
unsigned = addCheck types.int (x: x >= 0) // {
name = "unsignedInt";
description = "unsigned integer, meaning >=0";
};
positive = addCheck types.int (x: x > 0) // {
name = "positiveInt";
description = "positive integer, meaning >0";
};
u8 = unsign 8 256;
u16 = unsign 16 65536;
# the biggest int a 64-bit Nix accepts is 2^63 - 1 (9223372036854775808), for a 32-bit Nix it is 2^31 - 1 (2147483647)
# the smallest int a 64-bit Nix accepts is -2^63 (-9223372036854775807), for a 32-bit Nix it is -2^31 (-2147483648)
# u32 = unsign 32 4294967296;
# u64 = unsign 64 18446744073709551616;
s8 = sign 8 256;
s16 = sign 16 65536;
# s32 = sign 32 4294967296;
};
# Alias of u16 for a port number
port = ints.u16;
float = mkOptionType {
name = "float";
description = "floating point number";
check = isFloat;
merge = mergeEqualOption;
};
str = mkOptionType {
name = "str";
description = "string";
check = isString;
merge = mergeEqualOption;
};
strMatching = pattern: mkOptionType {
name = "strMatching ${escapeNixString pattern}";
description = "string matching the pattern ${pattern}";
check = x: str.check x && builtins.match pattern x != null;
inherit (str) merge;
};
# Merge multiple definitions by concatenating them (with the given
# separator between the values).
separatedString = sep: mkOptionType rec {
name = "separatedString";
description = if sep == ""
then "Concatenated string" # for types.string.
else "strings concatenated with ${builtins.toJSON sep}"
;
check = isString;
merge = loc: defs: concatStringsSep sep (getValues defs);
functor = (defaultFunctor name) // {
payload = sep;
binOp = sepLhs: sepRhs:
if sepLhs == sepRhs then sepLhs
else null;
};
};
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 "" // {
name = "string";
deprecationMessage = "See https://github.com/NixOS/nixpkgs/pull/66346 for better alternative types.";
};
attrs = mkOptionType {
name = "attrs";
description = "attribute set";
check = isAttrs;
merge = loc: foldl' (res: def: res // def.value) {};
emptyValue = { value = {}; };
};
# derivation is a reserved keyword.
package = mkOptionType {
name = "package";
check = x: isDerivation x || isStorePath x;
merge = loc: defs:
let res = mergeOneOption loc defs;
in if isDerivation res then res else toDerivation res;
};
shellPackage = package // {
check = x: (package.check x) && (hasAttr "shellPath" x);
};
path = mkOptionType {
name = "path";
check = x: isCoercibleToString x && builtins.substring 0 1 (toString x) == "/";
merge = mergeEqualOption;
};
listOf = elemType: mkOptionType rec {
name = "listOf";
description = "list of ${elemType.description}s";
check = isList;
merge = loc: defs:
map (x: x.value) (filter (x: x ? value) (concatLists (imap1 (n: def:
imap1 (m: def':
(mergeDefinitions
(loc ++ ["[definition ${toString n}-entry ${toString m}]"])
elemType
[{ inherit (def) file; value = def'; }]
).optionalValue
) def.value
) defs)));
emptyValue = { value = {}; };
getSubOptions = prefix: elemType.getSubOptions (prefix ++ ["*"]);
getSubModules = elemType.getSubModules;
substSubModules = m: listOf (elemType.substSubModules m);
functor = (defaultFunctor name) //
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