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# https://github.com/siers/nix-gitignore/
{ lib, runCommand }:
# An interesting bit from the gitignore(5):
# - A slash followed by two consecutive asterisks then a slash matches
# - zero or more directories. For example, "a/**/b" matches "a/b",
# - "a/x/b", "a/x/y/b" and so on.
with builtins;
let
debug = a: trace a a;
last = l: elemAt l ((length l) - 1);
throwIfOldNix = let required = "2.0"; in
if compareVersions nixVersion required == -1
then throw "nix (v${nixVersion} =< v${required}) is too old for nix-gitignore"
else true;
in rec {
# [["good/relative/source/file" true] ["bad.tmpfile" false]] -> root -> path
filterPattern = patterns: root:
(name: _type:
let
relPath = lib.removePrefix ((toString root) + "/") name;
matches = pair: (match (head pair) relPath) != null;
matched = map (pair: [(matches pair) (last pair)]) patterns;
in
last (last ([[true true]] ++ (filter head matched)))
);
# string -> [[regex bool]]
gitignoreToPatterns = gitignore:
assert throwIfOldNix;
let
# ignore -> bool
isComment = i: (match "^(#.*|$)" i) != null;
# ignore -> [ignore bool]
computeNegation = l:
let split = match "^(!?)(.*)" l;
in [(elemAt split 1) (head split == "!")];
# ignore -> regex
substWildcards =
let
special = "^$.+{}()";
escs = "\\*?";
splitString =
let recurse = str : [(substring 0 1 str)] ++
(if str == "" then [] else (recurse (substring 1 (stringLength(str)) str) ));
in str : recurse str;
chars = s: filter (c: c != "" && !isList c) (splitString s);
escape = s: map (c: "\\" + c) (chars s);
in
replaceStrings
((chars special) ++ (escape escs) ++ ["**/" "**" "*" "?"])
((escape special) ++ (escape escs) ++ ["(.*/)?" ".*" "[^/]*" "[^/]"]);
# (regex -> regex) -> regex -> regex
mapAroundCharclass = f: r: # rl = regex or list
let slightFix = replaceStrings ["\\]"] ["]"];
in
concatStringsSep ""
(map (rl: if isList rl then slightFix (elemAt rl 0) else f rl)
(split "(\\[([^\\\\]|\\\\.)+])" r));
# regex -> regex
handleSlashPrefix = l:
let
split = (match "^(/?)(.*)" l);
findSlash = l: if (match ".+/.+" l) != null then "" else l;
hasSlash = mapAroundCharclass findSlash l != l;
in
(if (elemAt split 0) == "/" || hasSlash
then "^"
else "(^|.*/)"
) + (elemAt split 1);
# regex -> regex
handleSlashSuffix = l:
let split = (match "^(.*)/$" l);
in if split != null then (elemAt split 0) + "($|/.*)" else l;
# (regex -> regex) -> [regex, bool] -> [regex, bool]
mapPat = f: l: [(f (head l)) (last l)];
in
map (l: # `l' for "line"
mapPat (l: handleSlashSuffix (handleSlashPrefix (mapAroundCharclass substWildcards l)))
(computeNegation l))
(filter (l: !isList l && !isComment l)
(split "\n" gitignore));
gitignoreFilter = ign: root: filterPattern (gitignoreToPatterns ign) root;
# string|[string|file] (→ [string|file] → [string]) -> string
gitignoreCompileIgnore = file_str_patterns: root:
let
onPath = f: a: if typeOf a == "path" then f a else a;
str_patterns = map (onPath readFile) (lib.toList file_str_patterns);
in concatStringsSep "\n" str_patterns;
gitignoreFilterPure = filter: patterns: root: name: type:
gitignoreFilter (gitignoreCompileIgnore patterns root) root name type
&& filter name type;
# This is a very hacky way of programming this!
# A better way would be to reuse existing filtering by making multiple gitignore functions per each root.
# Then for each file find the set of roots with gitignores (and functions).
# This would make gitignoreFilterSource very different from gitignoreFilterPure.
# rootPath → gitignoresConcatenated
compileRecursiveGitignore = root:
let
dirOrIgnore = file: type: baseNameOf file == ".gitignore" || type == "directory";
ignores = builtins.filterSource dirOrIgnore root;
in readFile (
runCommand "${baseNameOf root}-recursive-gitignore" {} ''
cd ${ignores}
find -type f -exec sh -c '
rel="$(realpath --relative-to=. "$(dirname "$1")")/"
if [ "$rel" = "./" ]; then rel=""; fi
awk -v prefix="$rel" -v root="$1" -v top="$(test -z "$rel" && echo 1)" "
BEGIN { print \"# \"root }
/^!?[^\\/]+\/?$/ {
match(\$0, /^!?/, negation)
sub(/^!?/, \"\")
if (top) { middle = \"\" } else { middle = \"**/\" }
print negation[0] prefix middle \$0
}
/^!?(\\/|.*\\/.+$)/ {
match(\$0, /^!?/, negation)
sub(/^!?/, \"\")
if (!top) sub(/^\//, \"\")
print negation[0] prefix \$0
}
END { print \"\" }
" "$1"
' sh {} \; > $out
'');
withGitignoreFile = patterns: root:
lib.toList patterns ++ [(root + "/.gitignore")];
withRecursiveGitignoreFile = patterns: root:
lib.toList patterns ++ [(compileRecursiveGitignore root)];
# filterSource derivatives
gitignoreFilterSourcePure = filter: patterns: root:
filterSource (gitignoreFilterPure filter patterns root) root;
gitignoreFilterSource = filter: patterns: root:
gitignoreFilterSourcePure filter (withGitignoreFile patterns root) root;
gitignoreFilterRecursiveSource = filter: patterns: root:
gitignoreFilterSourcePure filter (withRecursiveGitignoreFile patterns root) root;
# "Filter"-less alternatives
gitignoreSourcePure = gitignoreFilterSourcePure (_: _: true);
gitignoreSource = patterns: let type = typeOf patterns; in
if (type == "string" && pathExists patterns) || type == "path"
then throw
"type error in gitignoreSource(patterns -> source -> path), "
"use [] or \"\" if there are no additional patterns"
else gitignoreFilterSource (_: _: true) patterns;
gitignoreRecursiveSource = gitignoreFilterSourcePure (_: _: true);
}
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