diff options
Diffstat (limited to 'lib/fileset/internal.nix')
| -rw-r--r-- | lib/fileset/internal.nix | 581 |
1 files changed, 525 insertions, 56 deletions
diff --git a/lib/fileset/internal.nix b/lib/fileset/internal.nix index 2c329edb390..0769e654c8f 100644 --- a/lib/fileset/internal.nix +++ b/lib/fileset/internal.nix @@ -7,14 +7,15 @@ let isString pathExists readDir - typeOf split + trace + typeOf ; inherit (lib.attrsets) + attrNames attrValues mapAttrs - setAttrByPath zipAttrsWith ; @@ -25,9 +26,9 @@ let inherit (lib.lists) all commonPrefix - drop elemAt filter + findFirst findFirstIndex foldl' head @@ -64,7 +65,7 @@ rec { # - Increment this version # - Add an additional migration function below # - Update the description of the internal representation in ./README.md - _currentVersion = 2; + _currentVersion = 3; # Migrations between versions. The 0th element converts from v0 to v1, and so on migrations = [ @@ -89,8 +90,38 @@ rec { _internalVersion = 2; } ) + + # Convert v2 into v3: filesetTree's now have a representation for an empty file set without a base path + ( + filesetV2: + filesetV2 // { + # All v1 file sets are not the new empty file set + _internalIsEmptyWithoutBase = false; + _internalVersion = 3; + } + ) ]; + _noEvalMessage = '' + lib.fileset: Directly evaluating a file set is not supported. + To turn it into a usable source, use `lib.fileset.toSource`. + To pretty-print the contents, use `lib.fileset.trace` or `lib.fileset.traceVal`.''; + + # The empty file set without a base path + _emptyWithoutBase = { + _type = "fileset"; + + _internalVersion = _currentVersion; + + # The one and only! + _internalIsEmptyWithoutBase = true; + + # Due to alphabetical ordering, this is evaluated last, + # which makes the nix repl output nicer than if it would be ordered first. + # It also allows evaluating it strictly up to this error, which could be useful + _noEval = throw _noEvalMessage; + }; + # Create a fileset, see ./README.md#fileset # Type: path -> filesetTree -> fileset _create = base: tree: @@ -103,14 +134,17 @@ rec { _type = "fileset"; _internalVersion = _currentVersion; + + _internalIsEmptyWithoutBase = false; _internalBase = base; _internalBaseRoot = parts.root; _internalBaseComponents = components parts.subpath; _internalTree = tree; - # Double __ to make it be evaluated and ordered first - __noEval = throw '' - lib.fileset: Directly evaluating a file set is not supported. Use `lib.fileset.toSource` to turn it into a usable source instead.''; + # Due to alphabetical ordering, this is evaluated last, + # which makes the nix repl output nicer than if it would be ordered first. + # It also allows evaluating it strictly up to this error, which could be useful + _noEval = throw _noEvalMessage; }; # Coerce a value to a fileset, erroring when the value cannot be coerced. @@ -133,16 +167,21 @@ rec { else value else if ! isPath value then - if isStringLike value then + if value ? _isLibCleanSourceWith then + throw '' + ${context} is a `lib.sources`-based value, but it should be a file set or a path instead. + To convert a `lib.sources`-based value to a file set you can use `lib.fileset.fromSource`. + Note that this only works for sources created from paths.'' + else if isStringLike value then throw '' - ${context} ("${toString value}") is a string-like value, but it should be a path instead. + ${context} ("${toString value}") is a string-like value, but it should be a file set or a path instead. Paths represented as strings are not supported by `lib.fileset`, use `lib.sources` or derivations instead.'' else throw '' - ${context} is of type ${typeOf value}, but it should be a path instead.'' + ${context} is of type ${typeOf value}, but it should be a file set or a path instead.'' else if ! pathExists value then throw '' - ${context} (${toString value}) does not exist.'' + ${context} (${toString value}) is a path that does not exist.'' else _singleton value; @@ -155,19 +194,25 @@ rec { _coerce "${functionContext}: ${context}" value ) list; - firstBaseRoot = (head filesets)._internalBaseRoot; + # Find the first value with a base, there may be none! + firstWithBase = findFirst (fileset: ! fileset._internalIsEmptyWithoutBase) null filesets; + # This value is only accessed if first != null + firstBaseRoot = firstWithBase._internalBaseRoot; # Finds the first element with a filesystem root different than the first element, if any differentIndex = findFirstIndex (fileset: - firstBaseRoot != fileset._internalBaseRoot + # The empty value without a base doesn't have a base path + ! fileset._internalIsEmptyWithoutBase + && firstBaseRoot != fileset._internalBaseRoot ) null filesets; in - if differentIndex != null then + # Only evaluates `differentIndex` if there are any elements with a base + if firstWithBase != null && differentIndex != null then throw '' ${functionContext}: Filesystem roots are not the same: - ${(head list).context}: root "${toString firstBaseRoot}" - ${(elemAt list differentIndex).context}: root "${toString (elemAt filesets differentIndex)._internalBaseRoot}" - Different roots are not supported.'' + ${(head list).context}: Filesystem root is "${toString firstBaseRoot}" + ${(elemAt list differentIndex).context}: Filesystem root is "${toString (elemAt filesets differentIndex)._internalBaseRoot}" + Different filesystem roots are not supported.'' else filesets; @@ -203,22 +248,22 @@ rec { // value; /* - Simplify a filesetTree recursively: - - Replace all directories that have no files with `null` + A normalisation of a filesetTree suitable filtering with `builtins.path`: + - Replace all directories that have no files with `null`. This removes directories that would be empty - - Replace all directories with all files with `"directory"` + - Replace all directories with all files with `"directory"`. This speeds up the source filter function Note that this function is strict, it evaluates the entire tree Type: Path -> filesetTree -> filesetTree */ - _simplifyTree = path: tree: + _normaliseTreeFilter = path: tree: if tree == "directory" || isAttrs tree then let entries = _directoryEntries path tree; - simpleSubtrees = mapAttrs (name: _simplifyTree (path + "/${name}")) entries; - subtreeValues = attrValues simpleSubtrees; + normalisedSubtrees = mapAttrs (name: _normaliseTreeFilter (path + "/${name}")) entries; + subtreeValues = attrValues normalisedSubtrees; in # This triggers either when all files in a directory are filtered out # Or when the directory doesn't contain any files at all @@ -228,10 +273,112 @@ rec { else if all isString subtreeValues then "directory" else - simpleSubtrees + normalisedSubtrees + else + tree; + + /* + A minimal normalisation of a filesetTree, intended for pretty-printing: + - If all children of a path are recursively included or empty directories, the path itself is also recursively included + - If all children of a path are fully excluded or empty directories, the path itself is an empty directory + - Other empty directories are represented with the special "emptyDir" string + While these could be replaced with `null`, that would take another mapAttrs + + Note that this function is partially lazy. + + Type: Path -> filesetTree -> filesetTree (with "emptyDir"'s) + */ + _normaliseTreeMinimal = path: tree: + if tree == "directory" || isAttrs tree then + let + entries = _directoryEntries path tree; + normalisedSubtrees = mapAttrs (name: _normaliseTreeMinimal (path + "/${name}")) entries; + subtreeValues = attrValues normalisedSubtrees; + in + # If there are no entries, or all entries are empty directories, return "emptyDir". + # After this branch we know that there's at least one file + if all (value: value == "emptyDir") subtreeValues then + "emptyDir" + + # If all subtrees are fully included or empty directories + # (both of which are coincidentally represented as strings), return "directory". + # This takes advantage of the fact that empty directories can be represented as included directories. + # Note that the tree == "directory" check allows avoiding recursion + else if tree == "directory" || all (value: isString value) subtreeValues then + "directory" + + # If all subtrees are fully excluded or empty directories, return null. + # This takes advantage of the fact that empty directories can be represented as excluded directories + else if all (value: isNull value || value == "emptyDir") subtreeValues then + null + + # Mix of included and excluded entries + else + normalisedSubtrees else tree; + # Trace a filesetTree in a pretty way when the resulting value is evaluated. + # This can handle both normal filesetTree's, and ones returned from _normaliseTreeMinimal + # Type: Path -> filesetTree (with "emptyDir"'s) -> Null + _printMinimalTree = base: tree: + let + treeSuffix = tree: + if isAttrs tree then + "" + else if tree == "directory" then + " (all files in directory)" + else + # This does "leak" the file type strings of the internal representation, + # but this is the main reason these file type strings even are in the representation! + # TODO: Consider removing that information from the internal representation for performance. + # The file types can still be printed by querying them only during tracing + " (${tree})"; + + # Only for attribute set trees + traceTreeAttrs = prevLine: indent: tree: + foldl' (prevLine: name: + let + subtree = tree.${name}; + + # Evaluating this prints the line for this subtree + thisLine = + trace "${indent}- ${name}${treeSuffix subtree}" prevLine; + in + if subtree == null || subtree == "emptyDir" then + # Don't print anything at all if this subtree is empty + prevLine + else if isAttrs subtree then + # A directory with explicit entries + # Do print this node, but also recurse + traceTreeAttrs thisLine "${indent} " subtree + else + # Either a file, or a recursively included directory + # Do print this node but no further recursion needed + thisLine + ) prevLine (attrNames tree); + + # Evaluating this will print the first line + firstLine = + if tree == null || tree == "emptyDir" then + trace "(empty)" null + else + trace "${toString base}${treeSuffix tree}" null; + in + if isAttrs tree then + traceTreeAttrs firstLine "" tree + else + firstLine; + + # Pretty-print a file set in a pretty way when the resulting value is evaluated + # Type: fileset -> Null + _printFileset = fileset: + if fileset._internalIsEmptyWithoutBase then + trace "(empty)" null + else + _printMinimalTree fileset._internalBase + (_normaliseTreeMinimal fileset._internalBase fileset._internalTree); + # Turn a fileset into a source filter function suitable for `builtins.path` # Only directories recursively containing at least one files are recursed into # Type: Path -> fileset -> (String -> String -> Bool) @@ -239,7 +386,7 @@ rec { let # Simplify the tree, necessary to make sure all empty directories are null # which has the effect that they aren't included in the result - tree = _simplifyTree fileset._internalBase fileset._internalTree; + tree = _normaliseTreeFilter fileset._internalBase fileset._internalTree; # The base path as a string with a single trailing slash baseString = @@ -279,7 +426,7 @@ rec { # Filter suited when there's some files # This can't be used for when there's no files, because the base directory is always included nonEmpty = - path: _: + path: type: let # Add a slash to the path string, turning "/foo" to "/foo/", # making sure to not have any false prefix matches below. @@ -288,40 +435,147 @@ rec { # meaning this function can never receive "/" as an argument pathSlash = path + "/"; in - # Same as `hasPrefix pathSlash baseString`, but more efficient. - # With base /foo/bar we need to include /foo: - # hasPrefix "/foo/" "/foo/bar/" - if substring 0 (stringLength pathSlash) baseString == pathSlash then - true - # Same as `! hasPrefix baseString pathSlash`, but more efficient. - # With base /foo/bar we need to exclude /baz - # ! hasPrefix "/baz/" "/foo/bar/" - else if substring 0 baseLength pathSlash != baseString then - false - else - # Same as `removePrefix baseString path`, but more efficient. - # From the above code we know that hasPrefix baseString pathSlash holds, so this is safe. - # We don't use pathSlash here because we only needed the trailing slash for the prefix matching. - # With base /foo and path /foo/bar/baz this gives - # inTree (split "/" (removePrefix "/foo/" "/foo/bar/baz")) - # == inTree (split "/" "bar/baz") - # == inTree [ "bar" "baz" ] - inTree (split "/" (substring baseLength (-1) path)); + ( + # Same as `hasPrefix pathSlash baseString`, but more efficient. + # With base /foo/bar we need to include /foo: + # hasPrefix "/foo/" "/foo/bar/" + if substring 0 (stringLength pathSlash) baseString == pathSlash then + true + # Same as `! hasPrefix baseString pathSlash`, but more efficient. + # With base /foo/bar we need to exclude /baz + # ! hasPrefix "/baz/" "/foo/bar/" + else if substring 0 baseLength pathSlash != baseString then + false + else + # Same as `removePrefix baseString path`, but more efficient. + # From the above code we know that hasPrefix baseString pathSlash holds, so this is safe. + # We don't use pathSlash here because we only needed the trailing slash for the prefix matching. + # With base /foo and path /foo/bar/baz this gives + # inTree (split "/" (removePrefix "/foo/" "/foo/bar/baz")) + # == inTree (split "/" "bar/baz") + # == inTree [ "bar" "baz" ] + inTree (split "/" (substring baseLength (-1) path)) + ) + # This is a way have an additional check in case the above is true without any significant performance cost + && ( + # This relies on the fact that Nix only distinguishes path types "directory", "regular", "symlink" and "unknown", + # so everything except "unknown" is allowed, seems reasonable to rely on that + type != "unknown" + || throw '' + lib.fileset.toSource: `fileset` contains a file that cannot be added to the store: ${path} + This file is neither a regular file nor a symlink, the only file types supported by the Nix store. + Therefore the file set cannot be added to the Nix store as is. Make sure to not include that file to avoid this error.'' + ); in # Special case because the code below assumes that the _internalBase is always included in the result # which shouldn't be done when we have no files at all in the base # This also forces the tree before returning the filter, leads to earlier error messages - if tree == null then + if fileset._internalIsEmptyWithoutBase || tree == null then empty else nonEmpty; + # Turn a builtins.filterSource-based source filter on a root path into a file set + # containing only files included by the filter. + # The filter is lazily called as necessary to determine whether paths are included + # Type: Path -> (String -> String -> Bool) -> fileset + _fromSourceFilter = root: sourceFilter: + let + # During the recursion we need to track both: + # - The path value such that we can safely call `readDir` on it + # - The path string value such that we can correctly call the `filter` with it + # + # While we could just recurse with the path value, + # this would then require converting it to a path string for every path, + # which is a fairly expensive operation + + # Create a file set from a directory entry + fromDirEntry = path: pathString: type: + # The filter needs to run on the path as a string + if ! sourceFilter pathString type then + null + else if type == "directory" then + fromDir path pathString + else + type; + + # Create a file set from a directory + fromDir = path: pathString: + mapAttrs + # This looks a bit funny, but we need both the path-based and the path string-based values + (name: fromDirEntry (path + "/${name}") (pathString + "/${name}")) + # We need to readDir on the path value, because reading on a path string + # would be unspecified if there are multiple filesystem roots + (readDir path); + + rootPathType = pathType root; + + # We need to convert the path to a string to imitate what builtins.path calls the filter function with. + # We don't want to rely on `toString` for this though because it's not very well defined, see ../path/README.md + # So instead we use `lib.path.splitRoot` to safely deconstruct the path into its filesystem root and subpath + # We don't need the filesystem root though, builtins.path doesn't expose that in any way to the filter. + # So we only need the components, which we then turn into a string as one would expect. + rootString = "/" + concatStringsSep "/" (components (splitRoot root).subpath); + in + if rootPathType == "directory" then + # We imitate builtins.path not calling the filter on the root path + _create root (fromDir root rootString) + else + # Direct files are always included by builtins.path without calling the filter + # But we need to lift up the base path to its parent to satisfy the base path invariant + _create (dirOf root) + { + ${baseNameOf root} = rootPathType; + }; + + # Transforms the filesetTree of a file set to a shorter base path, e.g. + # _shortenTreeBase [ "foo" ] (_create /foo/bar null) + # => { bar = null; } + _shortenTreeBase = targetBaseComponents: fileset: + let + recurse = index: + # If we haven't reached the required depth yet + if index < length fileset._internalBaseComponents then + # Create an attribute set and recurse as the value, this can be lazily evaluated this way + { ${elemAt fileset._internalBaseComponents index} = recurse (index + 1); } + else + # Otherwise we reached the appropriate depth, here's the original tree + fileset._internalTree; + in + recurse (length targetBaseComponents); + + # Transforms the filesetTree of a file set to a longer base path, e.g. + # _lengthenTreeBase [ "foo" "bar" ] (_create /foo { bar.baz = "regular"; }) + # => { baz = "regular"; } + _lengthenTreeBase = targetBaseComponents: fileset: + let + recurse = index: tree: + # If the filesetTree is an attribute set and we haven't reached the required depth yet + if isAttrs tree && index < length targetBaseComponents then + # Recurse with the tree under the right component (which might not exist) + recurse (index + 1) (tree.${elemAt targetBaseComponents index} or null) + else + # For all values here we can just return the tree itself: + # tree == null -> the result is also null, everything is excluded + # tree == "directory" -> the result is also "directory", + # because the base path is always a directory and everything is included + # isAttrs tree -> the result is `tree` + # because we don't need to recurse any more since `index == length longestBaseComponents` + tree; + in + recurse (length fileset._internalBaseComponents) fileset._internalTree; + # Computes the union of a list of filesets. # The filesets must already be coerced and validated to be in the same filesystem root # Type: [ Fileset ] -> Fileset _unionMany = filesets: let - first = head filesets; + # All filesets that have a base, aka not the ones that are the empty value without a base + filesetsWithBase = filter (fileset: ! fileset._internalIsEmptyWithoutBase) filesets; + + # The first fileset that has a base. + # This value is only accessed if there are at all. + firstWithBase = head filesetsWithBase; # To be able to union filesetTree's together, they need to have the same base path. # Base paths can be unioned by taking their common prefix, @@ -332,14 +586,14 @@ rec { # so this cannot cause a stack overflow due to a build-up of unevaluated thunks. commonBaseComponents = foldl' (components: el: commonPrefix components el._internalBaseComponents) - first._internalBaseComponents + firstWithBase._internalBaseComponents # We could also not do the `tail` here to avoid a list allocation, # but then we'd have to pay for a potentially expensive # but unnecessary `commonPrefix` call - (tail filesets); + (tail filesetsWithBase); # The common base path assembled from a filesystem root and the common components - commonBase = append first._internalBaseRoot (join commonBaseComponents); + commonBase = append firstWithBase._internalBaseRoot (join commonBaseComponents); # A list of filesetTree's that all have the same base path # This is achieved by nesting the trees into the components they have over the common base path @@ -347,18 +601,18 @@ rec { # So the tree under `/foo/bar` gets nested under `{ bar = ...; ... }`, # while the tree under `/foo/baz` gets nested under `{ baz = ...; ... }` # Therefore allowing combined operations over them. - trees = map (fileset: - setAttrByPath - (drop (length commonBaseComponents) fileset._internalBaseComponents) - fileset._internalTree - ) filesets; + trees = map (_shortenTreeBase commonBaseComponents) filesetsWithBase; # Folds all trees together into a single one using _unionTree # We do not use a fold here because it would cause a thunk build-up # which could cause a stack overflow for a large number of trees resultTree = _unionTrees trees; in - _create commonBase resultTree; + # If there's no values with a base, we have no files + if filesetsWithBase == [ ] then + _emptyWithoutBase + else + _create commonBase resultTree; # The union of multiple filesetTree's with the same base path. # Later elements are only evaluated if necessary. @@ -379,4 +633,219 @@ rec { # The non-null elements have to be attribute sets representing partial trees # We need to recurse into those zipAttrsWith (name: _unionTrees) withoutNull; + + # Computes the intersection of a list of filesets. + # The filesets must already be coerced and validated to be in the same filesystem root + # Type: Fileset -> Fileset -> Fileset + _intersection = fileset1: fileset2: + let + # The common base components prefix, e.g. + # (/foo/bar, /foo/bar/baz) -> /foo/bar + # (/foo/bar, /foo/baz) -> /foo + commonBaseComponentsLength = + # TODO: Have a `lib.lists.commonPrefixLength` function such that we don't need the list allocation from commonPrefix here + length ( + commonPrefix + fileset1._internalBaseComponents + fileset2._internalBaseComponents + ); + + # To be able to intersect filesetTree's together, they need to have the same base path. + # Base paths can be intersected by taking the longest one (if any) + + # The fileset with the longest base, if any, e.g. + # (/foo/bar, /foo/bar/baz) -> /foo/bar/baz + # (/foo/bar, /foo/baz) -> null + longestBaseFileset = + if commonBaseComponentsLength == length fileset1._internalBaseComponents then + # The common prefix is the same as the first path, so the second path is equal or longer + fileset2 + else if commonBaseComponentsLength == length fileset2._internalBaseComponents then + # The common prefix is the same as the second path, so the first path is longer + fileset1 + else + # The common prefix is neither the first nor the second path + # This means there's no overlap between the two sets + null; + + # Whether the result should be the empty value without a base + resultIsEmptyWithoutBase = + # If either fileset is the empty fileset without a base, the intersection is too + fileset1._internalIsEmptyWithoutBase + || fileset2._internalIsEmptyWithoutBase + # If there is no overlap between the base paths + || longestBaseFileset == null; + + # Lengthen each fileset's tree to the longest base prefix + tree1 = _lengthenTreeBase longestBaseFileset._internalBaseComponents fileset1; + tree2 = _lengthenTreeBase longestBaseFileset._internalBaseComponents fileset2; + + # With two filesetTree's with the same base, we can compute their intersection + resultTree = _intersectTree tree1 tree2; + in + if resultIsEmptyWithoutBase then + _emptyWithoutBase + else + _create longestBaseFileset._internalBase resultTree; + + # The intersection of two filesetTree's with the same base path + # The second element is only evaluated as much as necessary. + # Type: filesetTree -> filesetTree -> filesetTree + _intersectTree = lhs: rhs: + if isAttrs lhs && isAttrs rhs then + # Both sides are attribute sets, we can recurse for the attributes existing on both sides + mapAttrs + (name: _intersectTree lhs.${name}) + (builtins.intersectAttrs lhs rhs) + else if lhs == null || isString rhs then + # If the lhs is null, the result should also be null + # And if the rhs is the identity element + # (a string, aka it includes everything), then it's also the lhs + lhs + else + # In all other cases it's the rhs + rhs; + + # Compute the set difference between two file sets. + # The filesets must already be coerced and validated to be in the same filesystem root. + # Type: Fileset -> Fileset -> Fileset + _difference = positive: negative: + let + # The common base components prefix, e.g. + # (/foo/bar, /foo/bar/baz) -> /foo/bar + # (/foo/bar, /foo/baz) -> /foo + commonBaseComponentsLength = + # TODO: Have a `lib.lists.commonPrefixLength` function such that we don't need the list allocation from commonPrefix here + length ( + commonPrefix + positive._internalBaseComponents + negative._internalBaseComponents + ); + + # We need filesetTree's with the same base to be able to compute the difference between them + # This here is the filesetTree from the negative file set, but for a base path that matches the positive file set. + # Examples: + # For `difference /foo /foo/bar`, `negativeTreeWithPositiveBase = { bar = "directory"; }` + # because under the base path of `/foo`, only `bar` from the negative file set is included + # For `difference /foo/bar /foo`, `negativeTreeWithPositiveBase = "directory"` + # because under the base path of `/foo/bar`, everything from the negative file set is included + # For `difference /foo /bar`, `negativeTreeWithPositiveBase = null` + # because under the base path of `/foo`, nothing from the negative file set is included + negativeTreeWithPositiveBase = + if commonBaseComponentsLength == length positive._internalBaseComponents then + # The common prefix is the same as the positive base path, so the second path is equal or longer. + # We need to _shorten_ the negative filesetTree to the same base path as the positive one + # E.g. for `difference /foo /foo/bar` the common prefix is /foo, equal to the positive file set's base + # So we need to shorten the base of the tree for the negative argument from /foo/bar to just /foo + _shortenTreeBase positive._internalBaseComponents negative + else if commonBaseComponentsLength == length negative._internalBaseComponents then + # The common prefix is the same as the negative base path, so the first path is longer. + # We need to lengthen the negative filesetTree to the same base path as the positive one. + # E.g. for `difference /foo/bar /foo` the common prefix is /foo, equal to the negative file set's base + # So we need to lengthen the base of the tree for the negative argument from /foo to /foo/bar + _lengthenTreeBase positive._internalBaseComponents negative + else + # The common prefix is neither the first nor the second path. + # This means there's no overlap between the two file sets, + # and nothing from the negative argument should get removed from the positive one + # E.g for `difference /foo /bar`, we remove nothing to get the same as `/foo` + null; + + resultingTree = + _differenceTree + positive._internalBase + positive._internalTree + negativeTreeWithPositiveBase; + in + # If the first file set is empty, we can never have any files in the result + if positive._internalIsEmptyWithoutBase then + _emptyWithoutBase + # If the second file set is empty, nothing gets removed, so the result is just the first file set + else if negative._internalIsEmptyWithoutBase then + positive + else + # We use the positive file set base for the result, + # because only files from the positive side may be included, + # which is what base path is for + _create positive._internalBase resultingTree; + + # Computes the set difference of two filesetTree's + # Type: Path -> filesetTree -> filesetTree + _differenceTree = path: lhs: rhs: + # If the lhs doesn't have any files, or the right hand side includes all files + if lhs == null || isString rhs then + # The result will always be empty + null + # If the right hand side has no files + else if rhs == null then + # The result is always the left hand side, because nothing gets removed + lhs + else + # Otherwise we always have two attribute sets to recurse into + mapAttrs (name: lhsValue: + _differenceTree (path + "/${name}") lhsValue (rhs.${name} or null) + ) (_directoryEntries path lhs); + + # Filters all files in a path based on a predicate + # Type: ({ name, type, ... } -> Bool) -> Path -> FileSet + _fileFilter = predicate: root: + let + # Check the predicate for a single file + # Type: String -> String -> filesetTree + fromFile = name: type: + if + predicate { + inherit name type; + # To ensure forwards compatibility with more arguments being added in the future, + # adding an attribute which can't be deconstructed :) + "lib.fileset.fileFilter: The predicate function passed as the first argument must be able to handle extra attributes for future compatibility. If you're using `{ name, file }:`, use `{ name, file, ... }:` instead." = null; + } + then + type + else + null; + + # Check the predicate for all files in a directory + # Type: Path -> filesetTree + fromDir = path: + mapAttrs (name: type: + if type == "directory" then + fromDir (path + "/${name}") + else + fromFile name type + ) (readDir path); + + rootType = pathType root; + in + if rootType == "directory" then + _create root (fromDir root) + else + # Single files are turned into a directory containing that file or nothing. + _create (dirOf root) { + ${baseNameOf root} = + fromFile (baseNameOf root) rootType; + }; + + # Support for `builtins.fetchGit` with `submodules = true` was introduced in 2.4 + # https://github.com/NixOS/nix/commit/55cefd41d63368d4286568e2956afd535cb44018 + _fetchGitSubmodulesMinver = "2.4"; + + # Mirrors the contents of a Nix store path relative to a local path as a file set. + # Some notes: + # - The store path is read at evaluation time. + # - The store path must not include files that don't exist in the respective local path. + # + # Type: Path -> String -> FileSet + _mirrorStorePath = localPath: storePath: + let + recurse = focusedStorePath: + mapAttrs (name: type: + if type == "directory" then + recurse (focusedStorePath + "/${name}") + else + type + ) (builtins.readDir focusedStorePath); + in + _create localPath + (recurse storePath); } |