d23716f354
This makes it possible for people to drop a default.nix into folders along the way that add additional things into the attribute set at that level. These default.nix files are imported and merged with the rest of the traversal from that point on. In theory nothing stops a user from putting a derivation into one of them, but the effects of merging that derivation's underlying attribute set with random other things from the traversal are undefined. This feature is being introduced for a slight revamp of the thirdParty layout.
79 lines
2 KiB
Nix
79 lines
2 KiB
Nix
initPath: { pkgs, ... } @ args:
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let
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inherit (builtins)
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attrNames
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filter
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head
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isString
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length
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listToAttrs
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map
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match
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readDir
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split
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tail
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toPath
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toString;
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attrsToList = attrs: map (name: {
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inherit name;
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value = attrs."${name}";
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}) (attrNames attrs);
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isFile = s: s == "regular";
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isDir = s: s == "directory";
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joinPath = p: f: toPath ((toString p) + "/" + f);
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isNixFile = file:
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let res = match "(.*)\.nix" file;
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in if res == null then null else head res;
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filterNixFiles = dir:
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let files = filter (e: isFile e.value && e.name != "default.nix") dir;
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nixFiles = map (f: {
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# Name and value are intentionally flipped to get the
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# correct attribute set structure back out
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name = isNixFile f.name;
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value = f.name; # i.e. the path
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}) files;
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in filter (f: isString f.name) nixFiles;
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# Some packages require that their position in the tree is passed in
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# as an argument. To do this the root directory (i.e. $PWD during
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# imports) is chopped off the front of the path components in
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# imports.
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pathParts = p: tail (filter isString (split "/" (toString p)));
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initLen = length (pathParts ./.);
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drop = n: l:
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if n == 0
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then l
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else if l == []
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then []
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else drop (n - 1) (tail l);
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argsWithPath = args: parts: args // {
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locatedAt = drop initLen parts;
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};
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traverse = path: dir:
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let nixFiles = filterNixFiles dir;
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imported = map (f: {
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inherit (f) name;
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value = import (joinPath path f.value) args;
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}) nixFiles;
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dirs = map (d: {
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inherit (d) name;
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value = readTree (joinPath path d.name);
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}) (filter (e: isDir e.value) dir);
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in listToAttrs (imported ++ dirs);
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importOr = path: dir: f:
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let contents = f path (attrsToList dir);
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in if dir ? "default.nix"
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then import path (argsWithPath args (pathParts path)) // contents
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else contents;
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readTree = path: importOr path (readDir path) traverse;
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in readTree initPath
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