tvl-depot/read-tree.nix
Vincent Ambo 01bad09eed refactor: Introduce new layout with nixpkgs in third_party
This is not the final layout yet, but makes it so that my top-level
attribute set is no longer overlaid into nixpkgs itself.

This is useful for other people who are importing my monorepo.
2019-12-09 02:40:48 +00:00

81 lines
2.2 KiB
Nix

# TODO(tazjin): if there's a default.nix, keep traversing but don't import .nix files?
# TODO(tazjin): avoid {} by only calling functions *after* checking what they are
args: initPath:
let
inherit (builtins)
attrNames
filter
head
isString
length
listToAttrs
map
match
readDir
split
tail
toString;
attrsToList = attrs: map (name: {
inherit name;
value = attrs."${name}";
}) (attrNames attrs);
isFile = s: s == "regular";
isDir = s: s == "directory";
joinPath = p: f: p + ("/" + f);
isNixFile = file:
let res = match "(.*)\.nix" file;
in if res == null then null else head res;
filterNixFiles = dir:
let files = filter (e: isFile e.value && e.name != "default.nix") dir;
nixFiles = map (f: {
# Name and value are intentionally flipped to get the
# correct attribute set structure back out
name = isNixFile f.name;
value = f.name; # i.e. the path
}) files;
in filter (f: isString f.name) nixFiles;
# Some packages require that their position in the tree is passed in
# as an argument. To do this the root directory (i.e. $PWD during
# imports) is chopped off the front of the path components in
# imports.
pathParts = p: tail (filter isString (split "/" (toString p)));
initLen = length (pathParts ./.);
drop = n: l:
if n == 0
then l
else if l == []
then []
else drop (n - 1) (tail l);
argsWithPath = args: parts: args // {
locatedAt = drop initLen parts;
};
traverse = path: dir:
let nixFiles = filterNixFiles dir;
imported = map (f: {
inherit (f) name;
value = import (joinPath path f.value) args;
}) nixFiles;
dirs = map (d: {
inherit (d) name;
value = readTree (joinPath path d.name);
}) (filter (e: isDir e.value) dir);
in listToAttrs (imported ++ dirs);
importOr = path: dir: f:
let contents = f path (attrsToList dir);
in if dir ? "default.nix"
then import path (argsWithPath args (pathParts path)) // contents
else contents;
readTree = path: importOr path (readDir path) traverse;
in readTree initPath