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nixpkgs/lib/filesystem.nix
2017-05-01 10:49:59 -04:00

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Nix

{ # haskellPathsInDir : Path -> Map String Path
# A map of all haskell packages defined in the given path,
# identified by having a cabal file with the same name as the
# directory itself.
haskellPathsInDir = root:
let # Files in the root
root-files = builtins.attrNames (builtins.readDir root);
# Files with their full paths
root-files-with-paths =
map (file:
{ name = file; value = root + "/${file}"; }
) root-files;
# Subdirectories of the root with a cabal file.
cabal-subdirs =
builtins.filter ({ name, value }:
builtins.pathExists (value + "/${name}.cabal")
) root-files-with-paths;
in builtins.listToAttrs cabal-subdirs;
# locateDominatingFile : RegExp
# -> Path
# -> Nullable { path : Path;
# matches : [ MatchResults ];
# }
# Find the first directory containing a file matching 'pattern'
# upward from a given 'file'.
# Returns 'null' if no directories contain a file matching 'pattern'.
locateDominatingFile = pattern: file:
let go = path:
let files = builtins.attrNames (builtins.readDir path);
matches = builtins.filter (match: match != null)
(map (builtins.match pattern) files);
in
if builtins.length matches != 0
then { inherit path matches; }
else if path == /.
then null
else go (dirOf path);
parent = dirOf file;
isDir =
let base = baseNameOf file;
type = (builtins.readDir parent).${base} or null;
in file == /. || type == "directory";
in go (if isDir then file else parent);
}