tvl-depot/nix/writeTree/default.nix

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{ depot, lib, pkgs, ... }:
let
inherit (lib) fix pipe mapAttrsToList isAttrs concatLines isString isDerivation isPath;
# TODO(sterni): move to //nix/utils with clearer naming and alternative similar to lib.types.path
isPathLike = value:
isPath value
|| isDerivation value
|| (isString value && builtins.hasContext value);
esc = s: lib.escapeShellArg /* ensure paths import into store */ "${s}";
writeTreeAtPath = path: tree:
''
mkdir -p "$out/"${esc path}
''
+ pipe tree [
(mapAttrsToList (k: v:
if isPathLike v then
"cp -R --reflink=auto ${v} \"$out/\"${esc path}/${esc k}"
else if lib.isAttrs v then
writeTreeAtPath (path + "/" + k) v
else
throw "invalid type (expected path, derivation, string with context, or attrs)"))
concatLines
];
/* Create a directory tree specified by a Nix attribute set structure.
Each value in `tree` should either be a file, a directory, or another tree
attribute set. Those paths will be written to a directory tree
corresponding to the structure of the attribute set.
Type: string -> attrSet -> derivation
*/
writeTree = name: tree:
pkgs.runCommandLocal name { } (writeTreeAtPath "" tree);
in
# __functor trick so readTree can add the tests attribute
{
__functor = _: writeTree;
}