nixpkgs/pkgs/lib/modules.nix

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# NixOS module 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 {
# Unfortunately this can also be a string.
isPath = x: !(
builtins.isFunction x
|| builtins.isAttrs x
|| builtins.isInt x
|| builtins.isBool x
|| builtins.isList x
);
importIfPath = path:
if isPath path then
import path
else
path;
applyIfFunction = f: arg:
if builtins.isFunction f then
f arg
else
f;
# Convert module to a set which has imports / options and config
# attributes.
unifyModuleSyntax = m:
let
getImports = m:
if m ? config || m ? options then
attrByPath ["imports"] [] m
else
toList (rmProperties (attrByPath ["require"] [] (delayProperties m)));
getImportedPaths = m: filter isPath (getImports m);
getImportedSets = m: filter (x: !isPath x) (getImports m);
getConfig = m:
removeAttrs (delayProperties m) ["require"];
in
if m ? config || m ? options then
m
else
{
imports = getImportedPaths m;
config = getConfig m;
} // (
if getImportedSets m != [] then
assert tail (getImportedSets m) == [];
{ options = head (getImportedSets m); }
else
{}
);
moduleClosure = initModules: args:
let
moduleImport = m: lib.addErrorContext "Import module ${m}." (
(unifyModuleSyntax (applyIfFunction (import m) args)) // {
# used by generic closure to avoid duplicated imports.
key = m;
paths = [ m ];
}
);
getImports = m: attrByPath ["imports"] [] m;
in
lazyGenericClosure {
startSet = map moduleImport initModules;
operator = m: map moduleImport (getImports m);
};
selectDeclsAndDefs = modules:
lib.concatMap (m:
if m ? config || m ? options then
[ (attrByPath ["options"] {} m) ]
++ [ (attrByPath ["config"] {} m) ]
else
[ m ]
) modules;
}