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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.
let
inherit (builtins) filterSource;
inherit (lib)
concatStringsSep
elemAt
filter
head
isList
length
optionals
optionalString
pathExists
readFile
removePrefix
replaceStrings
stringLength
sub
substring
toList
trace
;
inherit (lib.strings) match split typeOf;
debug = a: trace a a;
last = l: elemAt l ((length l) - 1);
in
rec {
# [["good/relative/source/file" true] ["bad.tmpfile" false]] -> root -> path
filterPattern =
patterns: root:
(
name: _type:
let
relPath = 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:
let
# ignore -> bool
isComment = i: (match "^(#.*|$)" i) != null;
# ignore -> [ignore bool]
computeNegation =
l:
let
split = match "^(!?)(.*)" l;
in
[
(elemAt split 1)
(head split == "!")
];
# regex -> regex
handleHashesBangs = replaceStrings [ "\\#" "\\!" ] [ "#" "!" ];
# ignore -> regex
substWildcards =
let
special = "^$.+{}()";
escs = "\\*?";
splitString =
let
recurse =
str:
[ (substring 0 1 str) ] ++ (optionals (str != "") (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: optionalString ((match ".+/.+" l) == null) 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 (handleHashesBangs (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) (toList file_str_patterns);
in
concatStringsSep "\n" str_patterns;
gitignoreFilterPure =
predicate: patterns: root: name: type:
gitignoreFilter (gitignoreCompileIgnore patterns root) root name type && predicate 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: toList patterns ++ [ ".git" ] ++ [ (root + "/.gitignore") ];
withRecursiveGitignoreFile =
patterns: root: toList patterns ++ [ ".git" ] ++ [ (compileRecursiveGitignore root) ];
# filterSource derivatives
gitignoreFilterSourcePure =
predicate: patterns: root:
filterSource (gitignoreFilterPure predicate patterns root) root;
gitignoreFilterSource =
predicate: patterns: root:
gitignoreFilterSourcePure predicate (withGitignoreFile patterns root) root;
gitignoreFilterRecursiveSource =
predicate: patterns: root:
gitignoreFilterSourcePure predicate (withRecursiveGitignoreFile patterns root) root;
# "Predicate"-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 = gitignoreFilterRecursiveSource (_: _: true);
}
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