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lib: add functions to create DAGs from lists
This commit is contained in:
Robert Helgesson
parent
79e03fbe24
commit
28614ed7a1
4 changed files with 149 additions and 7 deletions
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@ -11,12 +11,13 @@ The module system in Home Manager is based entirely on the NixOS module system s
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Overall the basic option types are the same in Home Manager as NixOS. A few Home Manager options, however, make use of custom types that are worth describing in more detail. These are the option types `dagOf` and `gvariant` that are used, for example, by <<opt-programs.ssh.matchBlocks>> and <<opt-dconf.settings>>.
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`hm.types.dagOf`::
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[[sec-option-types-dag]]`hm.types.dagOf`::
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Options of this type have attribute sets as values where each member is a node in a {wikipedia-dag}[directed acyclic graph] (DAG). This allows the attribute set entries to express dependency relations among themselves. This can, for example, be used to control the order of match blocks in a OpenSSH client configuration or the order of activation script blocks in <<opt-home.activation>>.
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A number of functions are provided to create DAG nodes. The functions are shown below with examples using an option `foo.bar` of type `hm.types.dagOf types.int`.
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`hm.dag.entryAnywhere (value: T)`:::
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--
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[[sec-option-types-dag-entryAnywhere]]`hm.dag.entryAnywhere (value: T) : DagEntry<T>`:::
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Indicates that `value` can be placed anywhere within the DAG. This is also the default for plain attribute set entries, that is
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[source,nix]
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@ -37,7 +38,7 @@ foo.bar = {
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are equivalent.
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`hm.dag.entryAfter (afters: list string) (value: T)`:::
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[[sec-option-types-dag-entryAfter]]`hm.dag.entryAfter (afters: list string) (value: T) : DagEntry<T>` :::
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Indicates that `value` must be placed _after_ each of the attribute names in the given list. For example
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[source,nix]
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@ -50,7 +51,7 @@ foo.bar = {
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would place `b` after `a` in the graph.
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`hm.dag.entryBefore (befores: list string) (value: T)`:::
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[[sec-option-types-dag-entryBefore]]`hm.dag.entryBefore (befores: list string) (value: T) : DagEntry<T>` :::
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Indicates that `value` must be placed _before_ each of the attribute names in the given list. For example
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[source,nix]
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@ -63,7 +64,7 @@ foo.bar = {
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would place `b` before `a` in the graph.
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`hm.dag.entryBetween (befores: list string) (afters: list string) (value: T)`:::
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[[sec-option-types-dag-entryBetween]]`hm.dag.entryBetween (befores: list string) (afters: list string) (value: T) : DagEntry<T>` :::
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Indicates that `value` must be placed _before_ the attribute names in the first list and _after_ the attribute names in the second list. For example
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[source,nix]
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@ -76,6 +77,93 @@ foo.bar = {
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----
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would place `c` before `b` and after `a` in the graph.
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--
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There are also a set of functions that generate a DAG from a list.
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These are convenient when you just want to have a linear list of DAG entries,
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without having to manually enter the relationship between each entry.
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Each of these functions take a `tag` as argument and the DAG entries will be named `${tag}-${index}`.
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[[sec-option-types-dag-entriesAnywhere]]`hm.dag.entriesAnywhere (tag: string) (values: [T]) : Dag<T>`:::
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Creates a DAG with the given values with each entry labeled using the given tag. For example
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[source,nix]
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foo.bar = hm.dag.entriesAnywhere "a" [ 0 1 ];
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is equivalent to
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[source,nix]
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----
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foo.bar = {
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a-0 = 0;
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a-1 = hm.dag.entryAfter [ "a-0" ] 1;
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}
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----
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+
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[[sec-option-types-dag-entriesAfter]]`hm.dag.entriesAfter (tag: string) (afters: list string) (values: [T]) : Dag<T>`:::
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Creates a DAG with the given values with each entry labeled using the given tag.
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The list of values are placed are placed _after_ each of the attribute names in `afters`.
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For example
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[source,nix]
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foo.bar =
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{ b = 0; }
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// hm.dag.entriesAfter "a" [ "b" ] [ 1 2 ];
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is equivalent to
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[source,nix]
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----
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foo.bar = {
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b = 0;
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a-0 = hm.dag.entryAfter [ "b" ] 1;
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a-1 = hm.dag.entryAfter [ "a-0" ] 2;
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}
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----
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+
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[[sec-option-types-dag-entriesBefore]]`hm.dag.entriesBefore (tag: string) (befores: list string) (values: [T]) : Dag<T>`:::
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Creates a DAG with the given values with each entry labeled using the given tag.
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The list of values are placed _before_ each of the attribute names in `befores`.
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For example
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[source,nix]
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foo.bar =
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{ b = 0; }
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// hm.dag.entriesBefore "a" [ "b" ] [ 1 2 ];
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is equivalent to
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[source,nix]
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----
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foo.bar = {
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b = 0;
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a-0 = 1;
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a-1 = hm.dag.entryBetween [ "b" ] [ "a-0" ] 2;
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}
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----
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[[sec-option-types-dag-entriesBetween]]`hm.dag.entriesBetween (tag: string) (befores: list string) (afters: list string) (values: [T]) : Dag<T>`:::
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Creates a DAG with the given values with each entry labeled using the given tag.
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The list of values are placed _before_ each of the attribute names in `befores`
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and _after_ each of the attribute names in `afters`.
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For example
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[source,nix]
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foo.bar =
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{ b = 0; c = 3; }
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// hm.dag.entriesBetween "a" [ "b" ] [ "c" ] [ 1 2 ];
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is equivalent to
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[source,nix]
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----
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foo.bar = {
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b = 0;
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c = 3;
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a-0 = hm.dag.entryAfter [ "c" ] 1;
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a-1 = hm.dag.entryBetween [ "b" ] [ "a-0" ] 2;
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}
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----
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[[sec-option-types-gvariant]]`hm.types.gvariant`::
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This type is useful for options representing {gvariant-description}[GVariant] values. The type accepts all primitive GVariant types as well as arrays, tuples, ``maybe'' types, and dictionaries.
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@ -9,7 +9,7 @@
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{ lib }:
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let inherit (lib) all filterAttrs hm mapAttrs toposort;
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let inherit (lib) all filterAttrs head hm mapAttrs length tail toposort;
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in {
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empty = { };
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@ -100,4 +100,30 @@ in {
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entryAfter = hm.dag.entryBetween [ ];
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entryBefore = before: hm.dag.entryBetween before [ ];
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# Given a list of entries, this function places them in order within the DAG.
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# Each entry is labeled "${tag}-${entry index}" and other DAG entries can be
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# added with 'before' or 'after' referring these indexed entries.
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#
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# The entries as a whole can be given a relation to other DAG nodes. All
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# generated nodes are then placed before or after those dependencies.
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entriesBetween = tag:
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let
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go = i: before: after: entries:
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let
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name = "${tag}-${toString i}";
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i' = i + 1;
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in if entries == [ ] then
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hm.dag.empty
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else if length entries == 1 then {
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"${name}" = hm.dag.entryBetween before after (head entries);
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} else
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{
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"${name}" = hm.dag.entryAfter after (head entries);
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} // go (i + 1) before [ name ] (tail entries);
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in go 0;
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entriesAnywhere = tag: hm.dag.entriesBetween tag [ ] [ ];
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entriesAfter = tag: hm.dag.entriesBetween tag [ ];
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entriesBefore = tag: before: hm.dag.entriesBetween tag before [ ];
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}
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@ -2,3 +2,11 @@ before:before
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merged:left,middle,middle,right
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between:between
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after:after
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list-anywhere-0:list-anywhere-0
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list-before-0:list-before-0,sneaky-merge
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list-before-1:list-before-1
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list-anywhere-1:list-anywhere-1
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inside-list:inside-list
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list-after-0:list-after-0
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list-after-1:list-after-1
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list-anywhere-2:list-anywhere-2
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@ -27,7 +27,27 @@ in {
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{ merged = dag.entryBefore [ "between" ] "middle"; }
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{ merged = mkBefore "left"; }
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{ merged = dag.entryBetween [ "after" ] [ "before" ] (mkAfter "right"); }
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{ merged = dag.entryBefore [ "between" ] "middle"; }
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{
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merged = dag.entryBefore [ "between" ] "middle";
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}
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# Some tests of list entries.
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(dag.entriesAnywhere "list-anywhere" [
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"list-anywhere-0"
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"list-anywhere-1"
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"list-anywhere-2"
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])
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{ inside-list = dag.entryAfter [ "list-anywhere-1" ] "inside-list"; }
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(dag.entriesBefore "list-before" [ "list-anywhere-1" ] [
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"list-before-0"
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"list-before-1"
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])
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(dag.entriesAfter "list-after" [ "list-before-0" ] [
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"list-after-0"
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"list-after-1"
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])
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(dag.entriesAnywhere "list-empty" [ ])
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{ "list-before-0" = mkAfter "sneaky-merge"; }
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];
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home.file."result.txt".text = result;
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