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lib.fileset.unions: init

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This commit is contained in:
Silvan Mosberger 2023-09-13 23:29:57 +02:00
parent d866a0bda1
commit bd52895222
1 changed files with 65 additions and 0 deletions
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65
lib/fileset/default.nix
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@ -9,11 +9,16 @@ let
;
inherit (builtins)
isList
isPath
pathExists
typeOf
;
inherit (lib.lists)
imap0
;
inherit (lib.path)
hasPrefix
splitRoot
@ -135,6 +140,8 @@ The only way to change which files get added to the store is by changing the `fi
/*
The file set containing all files that are in either of two given file sets.
This is the same as [`unions`](#function-library-lib.fileset.unions),
but takes just two file sets instead of a list.
See also [Union (set theory)](https://en.wikipedia.org/wiki/Union_(set_theory)).
The given file sets are evaluated as lazily as possible,
@ -175,4 +182,62 @@ The only way to change which files get added to the store is by changing the `fi
in
_unionMany filesets;
/*
The file set containing all files that are in any of the given file sets.
This is the same as [`union`](#function-library-lib.fileset.unions),
but takes a list of file sets instead of just two.
See also [Union (set theory)](https://en.wikipedia.org/wiki/Union_(set_theory)).
The given file sets are evaluated as lazily as possible,
with earlier elements being evaluated first if needed.
Type:
unions :: [ FileSet ] -> FileSet
Example:
# Create a file set containing selected files
unions [
# Include the single file `Makefile` in the current directory
# This errors if the file doesn't exist
./Makefile
# Recursively include all files in the `src/code` directory
# If this directory is empty this has no effect
./src/code
# Include the files `run.sh` and `unit.c` from the `tests` directory
./tests/run.sh
./tests/unit.c
# Include the `LICENSE` file from the parent directory
../LICENSE
]
*/
unions =
# A list of file sets.
# Must contain at least 1 element.
# The elements can also be paths,
# which get [implicitly coerced to file sets](#sec-fileset-path-coercion).
filesets:
let
# We cannot rename matched attribute arguments, so let's work around it with an extra `let in` statement
maybeFilesets = filesets;
in
let
# Annotate the elements with context, used by _coerceMany for better errors
annotated = imap0 (i: el: {
context = "element ${toString i} of the argument";
value = el;
}) maybeFilesets;
filesets = _coerceMany "lib.fileset.unions" annotated;
in
if ! isList maybeFilesets then
throw "lib.fileset.unions: Expected argument to be a list, but got a ${typeOf maybeFilesets}."
else if maybeFilesets == [ ] then
# TODO: This could be supported, but requires an extra internal representation for the empty file set
throw "lib.fileset.unions: Expected argument to be a list with at least one element, but it contains no elements."
else
_unionMany filesets;
}