9.nix-gitignore/find-files.nix
2019-11-22 23:19:16 +01:00

294 lines
10 KiB
Nix

{ lib ? import <nixpkgs/lib> }:
let
parse-ini = import ./parse-git-config.nix { inherit lib; };
parse-gitignore = import ./rules.nix { inherit lib; };
in
rec {
inherit (builtins) dirOf baseNameOf abort split hasAttr readFile readDir pathExists;
inherit (lib.lists) filter length head tail concatMap take;
inherit (lib.attrsets) filterAttrs mapAttrs attrNames;
inherit (lib.strings) hasPrefix removePrefix splitString;
inherit (lib) strings flip any;
inherit lib;
inherit parse-ini;
# TODO: 'filesystem.nix'
# - readLines function with CRLF support
# TODO: check assumption that a relative core.excludesFile is relative to HOME
# TODO: write test for trailing slash (matches dir only)
gitignoreFilter = basePath:
let
patternsBelowP = findPatternsTree basePath;
basePathStr = toString basePath;
in
path: type: let
localDirPath = removePrefix basePathStr (toString (dirOf path));
localDirPathElements = splitString "/" localDirPath;
patternResult = parse-gitignore.runFilterPattern (getPatterns patternsBelowP localDirPathElements)."/patterns" path type;
nonempty = any (nodeName: gitignoreFilter (basePath + "/${nodeName}") != false)
(attrNames (readDir path));
in patternResult && (type == "directory" -> nonempty);
getPatterns =
patternTree: pathElems:
if length pathElems == 0
then patternTree
else let hd = head pathElems; in
if hd == "" || hd == "."
then getPatterns patternTree (tail pathElems)
else
if hasAttr hd patternTree
then getPatterns patternTree."${hd}" (tail pathElems)
else
# Files are not in the tree, so we return the
# most patterns we could find here.
patternTree;
#####
# Constructing a tree of patterns per non-ignored subdirectory, recursively
#
/* Given a dir, return a tree of patterns mirroring the directory structure,
where the patterns on the nodes towards the leaves become more specific.
It's a tree where the nodes are attribute sets and the keys are directory basenames.
The patterns are mixed into the attrsets using the special key "/patterns".
Leaves are simply {}
*/
findPatternsTree = dir:
let
listOfStartingPatterns = map ({contextDir, file, ...}:
parse-gitignore.gitignoreFilter (readFile file) contextDir
) (findAncestryGitignores dir);
startingPatterns = builtins.foldl'
parse-gitignore.mergePattern
(defaultPatterns dir) # not the unit of merge but a set of defaults
listOfStartingPatterns;
in
findDescendantPatternsTree startingPatterns dir;
# We do an eager-looking descent ourselves, in order to memoize the patterns.
# In fact it is lazy, so some directories' patterns will not need to be
# evaluated if not requested. This works out nicely when the user adds a
# filter *before* the gitignore filter.
#
# This function assumes that the gitignore files that are specified *in*
# dir, in the *ancestry* of dir or globally are already included in
# currentPatterns.
findDescendantPatternsTree = currentPatterns: dir:
let nodes = readDir dir;
dirs = filterAttrs (name: type:
type == nodeTypes.directory &&
(parse-gitignore.runFilterPattern currentPatterns (dir + "/${name}") type)
) nodes;
in mapAttrs (name: _t:
let subdir = dir + "/${name}";
ignore = subdir + "/.gitignore";
newPatterns = map (file:
parse-gitignore.mergePattern
currentPatterns # Performance: this is where you could potentially filter out patterns irrelevant to subdir
(parse-gitignore.gitignoreFilter (readFile file) subdir)
) (guardFile ignore);
subdirPatterns = headOr currentPatterns newPatterns;
in
findDescendantPatternsTree subdirPatterns subdir
) dirs // { "/patterns" = currentPatterns; };
defaultPatterns = root: parse-gitignore.gitignoreFilter ".git" root; # no trailing slash, because of worktree references
#####
# Finding the gitignore files in the current directory, towards the root and
# in the user config.
#
findAncestryGitignores = path:
let
up = inspectDirAndUp path;
inherit (up) localIgnores gitDir worktreeRoot;
globalIgnores = map (file: { contextDir = worktreeRoot; inherit file; }) maybeGlobalIgnoresFile;
# TODO: can local config override global core.excludesFile?
# localConfigItems = parse-ini.parseIniFile (gitDir + "/config");
in
globalIgnores ++ localIgnores;
#####
# Functions for getting "context" from directory ancestry, repo
#
/* path -> { localIgnores : list {contextDir, file}
, gitDir : path }
Precondition: dir exists and is a directory
*/
inspectDirAndUp = dirPath: let
go = p: acc:
let
parentDir = dirOf p;
dirInfo = inspectDir p;
isHighest = dirInfo.isWorkTreeRoot || p == /. || p == "/";
dirs = [dirInfo] ++ acc;
getIgnores = di: if di.hasGitignore
then [{ contextDir = di.dirPath; file = di.dirPath + "/.gitignore"; }]
else [];
in
if isHighest || isForbiddenDir (toString parentDir)
then
{
localIgnores = concatMap getIgnores dirs;
worktreeRoot = p;
inherit (dirInfo) gitDir;
}
else
go parentDir dirs
;
in go dirPath [];
# isForbiddenDir: string -> bool
#
# Some directories should never be traversed when looking for .git
# - for performance
# - to help lorri and possibly other tools that monitor which paths are read
# during evaluation
isForbiddenDir = p:
p == builtins.storeDir || p == "/";
inspectDir = dirPath:
let
d = readDir dirPath;
dotGitType = d.".git" or null;
isWorkTreeRoot = pathExists (dirPath + "/.git");
gitDir = if dotGitType == nodeTypes.directory then dirPath + "/.git"
else if dotGitType == nodeTypes.regular then readDotGitFile (dirPath + "/.git")
else if dotGitType == nodeTypes.symlink then throw "gitignore.nix: ${toString dirPath}/.git is a symlink. This is not supported (yet?)."
else if dotGitType == null then null
else throw "gitignore.nix: ${toString dirPath}/.git is of unknown node type ${dotGitType}";
# directory should probably be ignored here, but to figure out the node type, we
# currently don't have a builtin to do it directly and readDir is expensive,
# particularly for a tool like lorri.
hasGitignore = pathExists (dirPath + "/.gitignore");
in { inherit isWorkTreeRoot hasGitignore gitDir dirPath; };
/* .git file path -> GIT_DIR
Used for establishing $GIT_DIR when the worktree is an external worktree,
when .git is a file.
*/
readDotGitFile = filepath:
let contents = readFile filepath;
lines = lib.strings.splitString "\n" contents;
gitdirLines = map (strings.removePrefix "gitdir: ") (filter (lib.strings.hasPrefix "gitdir: ") lines);
errNoGitDirLine = abort ("Could not find a gitdir line in " + filepath);
in /. + headOr errNoGitDirLine gitdirLines
;
/* default -> list -> head or default
*/
headOr = default: l:
if length l == 0 then default else head l;
#####
# Finding git config
#
maybeXdgGitConfigFile =
for
(guardNonEmptyString (builtins.getEnv "XDG_CONFIG_HOME"))
(xdgConfigHome:
guardFile (/. + xdgConfigHome + "/git/config")
);
maybeGlobalConfig = take 1 (guardFile ~/.gitconfig
++ maybeXdgGitConfigFile
++ guardFile ~/.config/git/config);
globalConfigItems = for maybeGlobalConfig (globalConfigFile:
parse-ini.parseIniFile globalConfigFile
);
globalConfiguredExcludesFile = take 1 (
for
globalConfigItems
({section, key, value}:
for
(guard (section == "core" && key == "excludesFile"))
(_:
resolveFile (~/.) value
)
)
);
xdgExcludesFile = for
(guardNonEmptyString (builtins.getEnv "XDG_CONFIG_HOME"))
(xdgConfigHome:
guardFile (/. + xdgConfigHome + "/git/ignore")
);
maybeGlobalIgnoresFile = take 1
( globalConfiguredExcludesFile
++ xdgExcludesFile
++ guardFile ~/.config/git/ignore);
/* Given baseDir, which generalizes the idea of working directory,
resolve a file path relative to that directory.
It will return at most 1 path; 0 if no such file could be found.
Absolute paths and home-relative (~) paths ignore the baseDir, unless
the
*/
resolveFile = baseDir: path: take 1
( if hasPrefix "/" path then guardFile (/. + path) else
(if hasPrefix "~" path then guardFile (~/. + removePrefix "~" path) else [])
++ guardFile (baseDir + "/" + path)
)
;
#####
# List as a search and backtracking tool
#
nullableToList = x: if x == null then [] else [x];
for = l: f: concatMap f l;
guard = b: if b then [{}] else [];
guardFile = p: if nodeTypes.isFile (safeGetNodeType p) then [p] else [];
guardNonEmptyString = s: if s == "" then [s] else [];
guardNonNull = a: if a != null then a else [];
#####
# Working with readDir output
#
nodeTypes.directory = "directory";
nodeTypes.regular = "regular";
nodeTypes.symlink = "symlink";
# TODO: Assumes that it's a file when it's a symlink
nodeTypes.isFile = p: p == nodeTypes.regular || p == nodeTypes.symlink;
#####
# Generic file system functions
#
/* path -> nullable nodeType
* Without throwing (unrecoverable) errors
*/
safeGetNodeType = path:
if toString path == "/" then nodeTypes.directory
else if pathExists path
then let parentDir = readDir (dirOf path);
in parentDir."${baseNameOf path}" or null
else null;
}