diff options
| -rw-r--r-- | nix/readTree/README.md | 13 | ||||
| -rw-r--r-- | nix/readTree/default.nix | 68 | ||||
| -rw-r--r-- | nix/readTree/tests/default.nix | 10 | ||||
| -rw-r--r-- | nix/readTree/tests/test-tree-traversal/skip-tree/a/default.nix | 1 | ||||
| -rw-r--r-- | nix/readTree/tests/test-tree-traversal/skip-tree/b/.skip-tree | 1 | ||||
| -rw-r--r-- | nix/readTree/tests/test-tree-traversal/skip-tree/b/default.nix | 1 |
6 files changed, 76 insertions, 18 deletions
diff --git a/nix/readTree/README.md b/nix/readTree/README.md index f8bbe2255e..5d430d1cfc 100644 --- a/nix/readTree/README.md +++ b/nix/readTree/README.md @@ -52,14 +52,17 @@ true;` attribute merged into it. `readTree` will follow any subdirectories of a tree and import all Nix files, with some exceptions: +* If a folder contains a `default.nix` file, no *sibling* Nix files will be + imported - however children are traversed as normal. +* If a folder contains a `default.nix` it is loaded and, if it + evaluates to a set, *merged* with the children. If it evaluates to + anything other than a set, else the children are *not traversed*. +* A folder can opt out from readTree completely by containing a + `.skip-tree` file. The content of the file is not read. These + folders will be missing completely from the readTree structure. * A folder can declare that its children are off-limit by containing a `.skip-subtree` file. Since the content of the file is not checked, it can be useful to leave a note for a human in the file. -* If a folder contains a `default.nix` file, no *sibling* Nix files will be - imported - however children are traversed as normal. -* If a folder contains a `default.nix` it is loaded and, if it evaluates to a - set, *merged* with the children. If it evaluates to anything else the children - are *not traversed*. * The `default.nix` of the top-level folder on which readTree is called is **not** read to avoid infinite recursion (as, presumably, this file is where readTree itself is called). diff --git a/nix/readTree/default.nix b/nix/readTree/default.nix index e243e85517..15680082cd 100644 --- a/nix/readTree/default.nix +++ b/nix/readTree/default.nix @@ -41,7 +41,8 @@ let readDirVisible = path: let children = readDir path; - isVisible = f: f == ".skip-subtree" || (substring 0 1 f) != "."; + # skip hidden files, except for those that contain special instructions to readTree + isVisible = f: f == ".skip-subtree" || f == ".skip-tree" || (substring 0 1 f) != "."; names = filter isVisible (attrNames children); in listToAttrs (map @@ -86,16 +87,39 @@ let pathType = builtins.typeOf importedFile; in if pathType != "lambda" - then builtins.throw "readTree: trying to import ${toString path}, but it’s a ${pathType}, you need to make it a function like { depot, pkgs, ... }" + then throw "readTree: trying to import ${toString path}, but it’s a ${pathType}, you need to make it a function like { depot, pkgs, ... }" else importedFile (filter parts (argsWithPath args parts)); nixFileName = file: let res = match "(.*)\\.nix" file; in if res == null then null else head res; - readTree = { args, initPath, rootDir, parts, argsFilter, scopedArgs }: + # Internal implementation of readTree, which handles things like the + # skipping of trees and subtrees. + # + # This method returns an attribute sets with either of two shapes: + # + # { ok = ...; } # a tree was read successfully + # { skip = true; } # a tree was skipped + # + # The higher-level `readTree` method assembles the final attribute + # set out of these results at the top-level, and the internal + # `children` implementation unwraps and processes nested trees. + readTreeImpl = { args, initPath, rootDir, parts, argsFilter, scopedArgs }: let dir = readDirVisible initPath; + + # Determine whether any part of this tree should be skipped. + # + # Adding a `.skip-subtree` file will still allow the import of + # the current node's "default.nix" file, but stop recursion + # there. + # + # Adding a `.skip-tree` file will completely ignore the folder + # in which this file is located. + skipTree = hasAttr ".skip-tree" dir; + skipSubtree = skipTree || hasAttr ".skip-subtree" dir; + joinChild = c: initPath + ("/" + c); self = @@ -103,19 +127,17 @@ let then { __readTree = [ ]; } else importFile args scopedArgs initPath parts argsFilter; - # Import subdirectories of the current one, unless the special - # `.skip-subtree` file exists which makes readTree ignore the - # children. + # Import subdirectories of the current one, unless any skip + # instructions exist. # # This file can optionally contain information on why the tree # should be ignored, but its content is not inspected by # readTree filterDir = f: dir."${f}" == "directory"; - children = if hasAttr ".skip-subtree" dir then [ ] else - map + filteredChildren = map (c: { name = c; - value = readTree { + value = readTreeImpl { inherit argsFilter scopedArgs; args = args; initPath = (joinChild c); @@ -125,9 +147,15 @@ let }) (filter filterDir (attrNames dir)); + # Remove skipped children from the final set, and unwrap the + # result set. + children = + if skipSubtree then [ ] + else map ({ name, value }: { inherit name; value = value.ok; }) (filter (child: child.value ? ok) filteredChildren); + # Import Nix files nixFiles = - if hasAttr ".skip-subtree" dir then [ ] + if skipSubtree then [ ] else filter (f: f != null) (map nixFileName (attrNames dir)); nixChildren = map (c: @@ -154,9 +182,23 @@ let ); in - if isAttrs nodeValue - then merge nodeValue (allChildren // (marker parts allChildren)) - else nodeValue; + if skipTree + then { skip = true; } + else { + ok = + if isAttrs nodeValue + then merge nodeValue (allChildren // (marker parts allChildren)) + else nodeValue; + }; + + # Top-level implementation of readTree itself. + readTree = args: + let + tree = readTreeImpl args; + in + if tree ? skip + then throw "Top-level folder has a .skip-tree marker and could not be read by readTree!" + else tree.ok; # Helper function to fetch subtargets from a target. This is a # temporary helper to warn on the use of the `meta.targets` diff --git a/nix/readTree/tests/default.nix b/nix/readTree/tests/default.nix index fcca141714..6f9eb02eff 100644 --- a/nix/readTree/tests/default.nix +++ b/nix/readTree/tests/default.nix @@ -41,6 +41,16 @@ let }; traversal-logic = it "corresponds to the traversal logic in the README" [ + (assertEq "skip-tree/a is read" + tree-tl.skip-tree.a + "a is read normally") + (assertEq "skip-tree does not contain b" + (builtins.attrNames tree-tl.skip-tree) + [ "__readTree" "__readTreeChildren" "a" ]) + (assertEq "skip-tree children list does not contain b" + tree-tl.skip-tree.__readTreeChildren + [ "a" ]) + (assertEq "skip subtree default.nix is read" tree-tl.skip-subtree.but "the default.nix is still read") diff --git a/nix/readTree/tests/test-tree-traversal/skip-tree/a/default.nix b/nix/readTree/tests/test-tree-traversal/skip-tree/a/default.nix new file mode 100644 index 0000000000..186488be3c --- /dev/null +++ b/nix/readTree/tests/test-tree-traversal/skip-tree/a/default.nix @@ -0,0 +1 @@ +_: "a is read normally" diff --git a/nix/readTree/tests/test-tree-traversal/skip-tree/b/.skip-tree b/nix/readTree/tests/test-tree-traversal/skip-tree/b/.skip-tree new file mode 100644 index 0000000000..34936b45d1 --- /dev/null +++ b/nix/readTree/tests/test-tree-traversal/skip-tree/b/.skip-tree @@ -0,0 +1 @@ +b subfolder should be skipped completely diff --git a/nix/readTree/tests/test-tree-traversal/skip-tree/b/default.nix b/nix/readTree/tests/test-tree-traversal/skip-tree/b/default.nix new file mode 100644 index 0000000000..7903f8e95a --- /dev/null +++ b/nix/readTree/tests/test-tree-traversal/skip-tree/b/default.nix @@ -0,0 +1 @@ +throw "b is skipped completely" |