From f4e0043049523dba68eba917edd2f7e322ab0c2e Mon Sep 17 00:00:00 2001 From: Silvan Mosberger Date: Tue, 10 Oct 2023 19:10:02 +0200 Subject: [PATCH] lib.fileset.fileFilter: init --- lib/fileset/default.nix | 51 ++++++++++++++++++++++++++++++ lib/fileset/internal.nix | 26 ++++++++++++++++ lib/fileset/tests.sh | 67 ++++++++++++++++++++++++++++++++++++++++ 3 files changed, 144 insertions(+) diff --git a/lib/fileset/default.nix b/lib/fileset/default.nix index 7bd701670386..0342be3e0371 100644 --- a/lib/fileset/default.nix +++ b/lib/fileset/default.nix @@ -6,6 +6,7 @@ let _coerceMany _toSourceFilter _unionMany + _fileFilter _printFileset _intersection ; @@ -41,6 +42,7 @@ let ; inherit (lib.trivial) + isFunction pipe ; @@ -278,6 +280,55 @@ If a directory does not recursively contain any file, it is omitted from the sto _unionMany ]; + /* + Filter a file set to only contain files matching some predicate. + + Type: + fileFilter :: + ({ + name :: String, + type :: String, + ... + } -> Bool) + -> FileSet + -> FileSet + + Example: + # Include all regular `default.nix` files in the current directory + fileFilter (file: file.name == "default.nix") ./. + + # Include all non-Nix files from the current directory + fileFilter (file: ! hasSuffix ".nix" file.name) ./. + + # Include all files that start with a "." in the current directory + fileFilter (file: hasPrefix "." file.name) ./. + + # Include all regular files (not symlinks or others) in the current directory + fileFilter (file: file.type == "regular") + */ + fileFilter = + /* + The predicate function to call on all files contained in given file set. + A file is included in the resulting file set if this function returns true for it. + + This function is called with an attribute set containing these attributes: + + - `name` (String): The name of the file + + - `type` (String, one of `"regular"`, `"symlink"` or `"unknown"`): The type of the file. + This matches result of calling [`builtins.readFileType`](https://nixos.org/manual/nix/stable/language/builtins.html#builtins-readFileType) on the file's path. + + Other attributes may be added in the future. + */ + predicate: + # The file set to filter based on the predicate function + fileset: + if ! isFunction predicate then + throw "lib.fileset.fileFilter: Expected the first argument to be a function, but it's a ${typeOf predicate} instead." + else + _fileFilter predicate + (_coerce "lib.fileset.fileFilter: second argument" fileset); + /* The file set containing all files that are in both of two given file sets. See also [Intersection (set theory)](https://en.wikipedia.org/wiki/Intersection_(set_theory)). diff --git a/lib/fileset/internal.nix b/lib/fileset/internal.nix index 9892172955c3..2d52a8cb410b 100644 --- a/lib/fileset/internal.nix +++ b/lib/fileset/internal.nix @@ -638,4 +638,30 @@ rec { else # In all other cases it's the rhs rhs; + + _fileFilter = predicate: fileset: + let + recurse = path: tree: + mapAttrs (name: subtree: + if isAttrs subtree || subtree == "directory" then + recurse (path + "/${name}") subtree + else if + predicate { + inherit name; + type = subtree; + # To ensure forwards compatibility with more arguments being added in the future, + # adding an attribute which can't be deconstructed :) + "lib.fileset.fileFilter: The predicate function passed as the first argument must be able to handle extra attributes for future compatibility. If you're using `{ name, file }:`, use `{ name, file, ... }:` instead." = null; + } + then + subtree + else + null + ) (_directoryEntries path tree); + in + if fileset._internalIsEmptyWithoutBase then + _emptyWithoutBase + else + _create fileset._internalBase + (recurse fileset._internalBase fileset._internalTree); } diff --git a/lib/fileset/tests.sh b/lib/fileset/tests.sh index 529f23ae8871..d8d8dd413189 100755 --- a/lib/fileset/tests.sh +++ b/lib/fileset/tests.sh @@ -678,6 +678,73 @@ tree=( checkFileset 'intersection (unions [ ./a/b ./c/d ./c/e ]) (unions [ ./a ./c/d/f ./c/e ])' +## File filter + +# The predicate is not called when there's no files +tree=() +checkFileset 'fileFilter (file: abort "this is not needed") ./.' +checkFileset 'fileFilter (file: abort "this is not needed") _emptyWithoutBase' + +# The predicate must be able to handle extra attributes +touch a +expectFailure 'toSource { root = ./.; fileset = fileFilter ({ name, type }: true) ./.; }' 'called with unexpected argument '\''"lib.fileset.fileFilter: The predicate function passed as the first argument must be able to handle extra attributes for future compatibility. If you'\''re using `\{ name, file \}:`, use `\{ name, file, ... \}:` instead."'\' +rm -rf -- * + +# .name is the name, and it works correctly, even recursively +tree=( + [a]=1 + [b]=0 + [c/a]=1 + [c/b]=0 + [d/c/a]=1 + [d/c/b]=0 +) +checkFileset 'fileFilter (file: file.name == "a") ./.' +tree=( + [a]=0 + [b]=1 + [c/a]=0 + [c/b]=1 + [d/c/a]=0 + [d/c/b]=1 +) +checkFileset 'fileFilter (file: file.name != "a") ./.' + +# `.type` is the file type +mkdir d +touch d/a +ln -s d/b d/b +mkfifo d/c +expectEqual \ + 'toSource { root = ./.; fileset = fileFilter (file: file.type == "regular") ./.; }' \ + 'toSource { root = ./.; fileset = ./d/a; }' +expectEqual \ + 'toSource { root = ./.; fileset = fileFilter (file: file.type == "symlink") ./.; }' \ + 'toSource { root = ./.; fileset = ./d/b; }' +expectEqual \ + 'toSource { root = ./.; fileset = fileFilter (file: file.type == "unknown") ./.; }' \ + 'toSource { root = ./.; fileset = ./d/c; }' +expectEqual \ + 'toSource { root = ./.; fileset = fileFilter (file: file.type != "regular") ./.; }' \ + 'toSource { root = ./.; fileset = union ./d/b ./d/c; }' +expectEqual \ + 'toSource { root = ./.; fileset = fileFilter (file: file.type != "symlink") ./.; }' \ + 'toSource { root = ./.; fileset = union ./d/a ./d/c; }' +expectEqual \ + 'toSource { root = ./.; fileset = fileFilter (file: file.type != "unknown") ./.; }' \ + 'toSource { root = ./.; fileset = union ./d/a ./d/b; }' +rm -rf -- * + +# It's lazy +tree=( + [b]=1 + [c/a]=1 +) +# Note that union evaluates the first argument first if necessary, that's why we can use ./c/a here +checkFileset 'union ./c/a (fileFilter (file: assert file.name != "a"; true) ./.)' +# but here we need to use ./c +checkFileset 'union (fileFilter (file: assert file.name != "a"; true) ./.) ./c' + ## Tracing # The second trace argument is returned