tvl-depot/nix/readTree/default.nix

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Nix
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{ ... }:
args: initPath:
let
inherit (builtins)
attrNames
baseNameOf
filter
hasAttr
head
length
listToAttrs
map
match
isAttrs
readDir;
argsWithPath = parts: args // {
locatedAt = parts;
};
# The marker is added to every set that was imported directly by
# readTree.
importWithMark = path: parts:
let imported = import path (argsWithPath parts);
in if (isAttrs imported)
then imported // { __readTree = true; }
else imported;
nixFileName = file:
let res = match "(.*)\.nix" file;
in if res == null then null else head res;
readTree = path: parts:
let
dir = readDir path;
self = importWithMark path parts;
joinChild = c: path + ("/" + c);
# Import subdirectories of the current one, unless the special
# `.skip-subtree` file exists which makes readTree ignore the
# children.
#
# This file can optionally contain information on why the tree
# should be ignored, but its content is not inspected by
# readTree
filterDir = f: dir."${f}" == "directory";
children = if hasAttr ".skip-subtree" dir then [] else map (c: {
name = c;
value = readTree (joinChild c) (parts ++ [ c ]);
}) (filter filterDir (attrNames dir));
# Import Nix files
nixFiles = filter (f: f != null) (map nixFileName (attrNames dir));
nixChildren = map (c: let p = joinChild (c + ".nix"); in {
name = c;
value = importWithMark p (parts ++ [ c ]);
}) nixFiles;
in if dir ? "default.nix"
then (if isAttrs self then self // (listToAttrs children) else self)
else listToAttrs (nixChildren ++ children);
in readTree initPath [ (baseNameOf initPath) ]