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|
{ lib }:
with lib.lists;
with lib.strings;
with lib.trivial;
with lib.attrsets;
with lib.options;
with lib.debug;
with lib.types;
rec {
/* Evaluate a set of modules. The result is a set of two
attributes: ‘options’: the nested set of all option declarations,
and ‘config’: the nested set of all option values.
!!! Please think twice before adding to this argument list! The more
that is specified here instead of in the modules themselves the harder
it is to transparently move a set of modules to be a submodule of another
config (as the proper arguments need to be replicated at each call to
evalModules) and the less declarative the module set is. */
evalModules = { modules
, prefix ? []
, # This should only be used for special arguments that need to be evaluated
# when resolving module structure (like in imports). For everything else,
# there's _module.args. If specialArgs.modulesPath is defined it will be
# used as the base path for disabledModules.
specialArgs ? {}
, # This would be remove in the future, Prefer _module.args option instead.
args ? {}
, # This would be remove in the future, Prefer _module.check option instead.
check ? true
}:
let
# This internal module declare internal options under the `_module'
# attribute. These options are fragile, as they are used by the
# module system to change the interpretation of modules.
internalModule = rec {
_file = ./modules.nix;
key = _file;
options = {
_module.args = mkOption {
type = types.attrsOf types.unspecified;
internal = true;
description = "Arguments passed to each module.";
};
_module.check = mkOption {
type = types.bool;
internal = true;
default = check;
description = "Whether to check whether all option definitions have matching declarations.";
};
};
config = {
_module.args = args;
};
};
closed = closeModules (modules ++ [ internalModule ]) ({ inherit config options lib; } // specialArgs);
options = mergeModules prefix (reverseList (filterModules (specialArgs.modulesPath or "") closed));
# Traverse options and extract the option values into the final
# config set. At the same time, check whether all option
# definitions have matching declarations.
# !!! _module.check's value can't depend on any other config values
# without an infinite recursion. One way around this is to make the
# 'config' passed around to the modules be unconditionally unchecked,
# and only do the check in 'result'.
config = yieldConfig prefix options;
yieldConfig = prefix: set:
let res = removeAttrs (mapAttrs (n: v:
if isOption v then v.value
else yieldConfig (prefix ++ [n]) v) set) ["_definedNames"];
in
if options._module.check.value && set ? _definedNames then
foldl' (res: m:
foldl' (res: name:
if set ? ${name} then res else throw "The option `${showOption (prefix ++ [name])}' defined in `${m.file}' does not exist.")
res m.names)
res set._definedNames
else
res;
result = { inherit options config; };
in result;
# Filter disabled modules. Modules can be disabled allowing
# their implementation to be replaced.
filterModules = modulesPath: modules:
let
moduleKey = m: if isString m then toString modulesPath + "/" + m else toString m;
disabledKeys = map moduleKey (concatMap (m: m.disabledModules) modules);
in
filter (m: !(elem m.key disabledKeys)) modules;
/* Close a set of modules under the ‘imports’ relation. */
closeModules = modules: args:
let
toClosureList = file: parentKey: imap1 (n: x:
if isAttrs x || isFunction x then
let key = "${parentKey}:anon-${toString n}"; in
unifyModuleSyntax file key (unpackSubmodule (applyIfFunction key) x args)
else
let file = toString x; key = toString x; in
unifyModuleSyntax file key (applyIfFunction key (import x) args));
in
builtins.genericClosure {
startSet = toClosureList unknownModule "" modules;
operator = m: toClosureList m.file m.key m.imports;
};
/* Massage a module into canonical form, that is, a set consisting
of ‘options’, ‘config’ and ‘imports’ attributes. */
unifyModuleSyntax = file: key: m:
let metaSet = if m ? meta
then { meta = m.meta; }
else {};
in
if m ? config || m ? options then
let badAttrs = removeAttrs m ["_file" "key" "disabledModules" "imports" "options" "config" "meta"]; in
if badAttrs != {} then
throw "Module `${key}' has an unsupported attribute `${head (attrNames badAttrs)}'. This is caused by assignments to the top-level attributes `config' or `options'."
else
{ file = m._file or file;
key = toString m.key or key;
disabledModules = m.disabledModules or [];
imports = m.imports or [];
options = m.options or {};
config = mkMerge [ (m.config or {}) metaSet ];
}
else
{ file = m._file or file;
key = toString m.key or key;
disabledModules = m.disabledModules or [];
imports = m.require or [] ++ m.imports or [];
options = {};
config = mkMerge [ (removeAttrs m ["_file" "key" "disabledModules" "require" "imports"]) metaSet ];
};
applyIfFunction = key: f: args@{ config, options, lib, ... }: if isFunction f then
let
# Module arguments are resolved in a strict manner when attribute set
# deconstruction is used. As the arguments are now defined with the
# config._module.args option, the strictness used on the attribute
# set argument would cause an infinite loop, if the result of the
# option is given as argument.
#
# To work-around the strictness issue on the deconstruction of the
# attributes set argument, we create a new attribute set which is
# constructed to satisfy the expected set of attributes. Thus calling
# a module will resolve strictly the attributes used as argument but
# not their values. The values are forwarding the result of the
# evaluation of the option.
requiredArgs = builtins.attrNames (lib.functionArgs f);
context = name: ''while evaluating the module argument `${name}' in "${key}":'';
extraArgs = builtins.listToAttrs (map (name: {
inherit name;
value = builtins.addErrorContext (context name)
(args.${name} or config._module.args.${name});
}) requiredArgs);
# Note: we append in the opposite order such that we can add an error
# context on the explicited arguments of "args" too. This update
# operator is used to make the "args@{ ... }: with args.lib;" notation
# works.
in f (args // extraArgs)
else
f;
/* We have to pack and unpack submodules. We cannot wrap the expected
result of the function as we would no longer be able to list the arguments
of the submodule. (see applyIfFunction) */
unpackSubmodule = unpack: m: args:
if isType "submodule" m then
{ _file = m.file; } // (unpack m.submodule args)
else unpack m args;
packSubmodule = file: m:
{ _type = "submodule"; file = file; submodule = m; };
/* Merge a list of modules. This will recurse over the option
declarations in all modules, combining them into a single set.
At the same time, for each option declaration, it will merge the
corresponding option definitions in all machines, returning them
in the ‘value’ attribute of each option. */
mergeModules = prefix: modules:
mergeModules' prefix modules
(concatMap (m: map (config: { inherit (m) file; inherit config; }) (pushDownProperties m.config)) modules);
mergeModules' = prefix: options: configs:
listToAttrs (map (name: {
# We're descending into attribute ‘name’.
inherit name;
value =
let
loc = prefix ++ [name];
# Get all submodules that declare ‘name’.
decls = concatMap (m:
if m.options ? ${name}
then [ { inherit (m) file; options = m.options.${name}; } ]
else []
) options;
# Get all submodules that define ‘name’.
defns = concatMap (m:
if m.config ? ${name}
then map (config: { inherit (m) file; inherit config; })
(pushDownProperties m.config.${name})
else []
) configs;
nrOptions = count (m: isOption m.options) decls;
# Extract the definitions for this loc
defns' = map (m: { inherit (m) file; value = m.config.${name}; })
(filter (m: m.config ? ${name}) configs);
in
if nrOptions == length decls then
let opt = fixupOptionType loc (mergeOptionDecls loc decls);
in evalOptionValue loc opt defns'
else if nrOptions != 0 then
let
firstOption = findFirst (m: isOption m.options) "" decls;
firstNonOption = findFirst (m: !isOption m.options) "" decls;
in
throw "The option `${showOption loc}' in `${firstOption.file}' is a prefix of options in `${firstNonOption.file}'."
else
mergeModules' loc decls defns;
}) (concatMap (m: attrNames m.options) options))
// { _definedNames = map (m: { inherit (m) file; names = attrNames m.config; }) configs; };
/* Merge multiple option declarations into a single declaration. In
general, there should be only one declaration of each option.
The exception is the ‘options’ attribute, which specifies
sub-options. These can be specified multiple times to allow one
module to add sub-options to an option declared somewhere else
(e.g. multiple modules define sub-options for ‘fileSystems’).
'loc' is the list of attribute names where the option is located.
'opts' is a list of modules. Each module has an options attribute which
correspond to the definition of 'loc' in 'opt.file'. */
mergeOptionDecls = loc: opts:
foldl' (res: opt:
let t = res.type;
t' = opt.options.type;
mergedType = t.typeMerge t'.functor;
typesMergeable = mergedType != null;
typeSet = if (bothHave "type") && typesMergeable
then { type = mergedType; }
else {};
bothHave = k: opt.options ? ${k} && res ? ${k
|