*: add default.nix/readTree
This makes all Nix files addressable from root by file path.
For instance, if a file is located in //foo/bar:baz.nix containing:
{ pkgs, ... }:
pkgs.stdenv.mkDerivation {
pname = "foo";
# ...
}
You can then do:
nix-build -A foo.bar.baz
All nix files loaded this way must be a function taking a 'config'
attrset - see nix/readTree.nix for more information. Currently the
config attrset contains the following fields:
- hscloud: the root of the hscloud repository itself, which allows
for traversal via readTree (eg. hscloud.foo.bar.baz)
- pkgs: nixpkgs
- pkgsSrc: nixpkgs souce/channel, useful to load NixOS modules.
- lib, stdenv: lib and stdenv from pkgs.
Change-Id: Ieaacdcabceec18dd6c670d346928bff08b66cf79
diff --git a/nix/readtree.nix b/nix/readtree.nix
new file mode 100644
index 0000000..066d326
--- /dev/null
+++ b/nix/readtree.nix
@@ -0,0 +1,96 @@
+# The MIT License (MIT)
+#
+# Copyright (c) 2019 Vincent Ambo
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+{ ... }:
+
+args: initPath:
+
+let
+ inherit (builtins)
+ attrNames
+ baseNameOf
+ filter
+ hasAttr
+ head
+ isAttrs
+ length
+ listToAttrs
+ map
+ match
+ readDir
+ substring;
+
+ argsWithPath = parts:
+ let meta.locatedAt = parts;
+ in meta // (if isAttrs args then args else args meta);
+
+ readDirVisible = path:
+ let
+ children = readDir path;
+ isVisible = f: f == ".skip-subtree" || (substring 0 1 f) != ".";
+ names = filter isVisible (attrNames children);
+ in listToAttrs (map (name: {
+ inherit name;
+ value = children.${name};
+ }) names);
+
+ # The marker is added to every set that was imported directly by
+ # readTree.
+ importWithMark = path: parts:
+ let imported = import path (argsWithPath parts);
+ in if (isAttrs imported)
+ then imported // { __readTree = true; }
+ else imported;
+
+ nixFileName = file:
+ let res = match "(.*)\.nix" file;
+ in if res == null then null else head res;
+
+ readTree = path: parts:
+ let
+ dir = readDirVisible path;
+ self = importWithMark path parts;
+ joinChild = c: path + ("/" + c);
+
+ # Import subdirectories of the current one, unless the special
+ # `.skip-subtree` file exists which makes readTree ignore the
+ # children.
+ #
+ # This file can optionally contain information on why the tree
+ # should be ignored, but its content is not inspected by
+ # readTree
+ filterDir = f: dir."${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) ]