1085 lines
33 KiB
Nix
1085 lines
33 KiB
Nix
{ lib }:
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# Operations on attribute sets.
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let
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inherit (builtins) head tail length;
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inherit (lib.trivial) id mergeAttrs;
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inherit (lib.strings) concatStringsSep concatMapStringsSep escapeNixIdentifier sanitizeDerivationName;
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inherit (lib.lists) foldr foldl' concatMap concatLists elemAt all partition groupBy take foldl;
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in
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rec {
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inherit (builtins) attrNames listToAttrs hasAttr isAttrs getAttr removeAttrs;
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/* Return an attribute from nested attribute sets.
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Example:
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x = { a = { b = 3; }; }
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# ["a" "b"] is equivalent to x.a.b
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# 6 is a default value to return if the path does not exist in attrset
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attrByPath ["a" "b"] 6 x
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=> 3
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attrByPath ["z" "z"] 6 x
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=> 6
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Type:
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attrByPath :: [String] -> Any -> AttrSet -> Any
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*/
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attrByPath =
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# A list of strings representing the attribute path to return from `set`
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attrPath:
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# Default value if `attrPath` does not resolve to an existing value
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default:
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# The nested attribute set to select values from
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set:
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let attr = head attrPath;
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in
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if attrPath == [] then set
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else if set ? ${attr}
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then attrByPath (tail attrPath) default set.${attr}
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else default;
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/* Return if an attribute from nested attribute set exists.
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Example:
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x = { a = { b = 3; }; }
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hasAttrByPath ["a" "b"] x
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=> true
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hasAttrByPath ["z" "z"] x
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=> false
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Type:
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hasAttrByPath :: [String] -> AttrSet -> Bool
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*/
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hasAttrByPath =
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# A list of strings representing the attribute path to check from `set`
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attrPath:
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# The nested attribute set to check
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e:
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let attr = head attrPath;
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in
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if attrPath == [] then true
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else if e ? ${attr}
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then hasAttrByPath (tail attrPath) e.${attr}
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else false;
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/* Create a new attribute set with `value` set at the nested attribute location specified in `attrPath`.
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Example:
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setAttrByPath ["a" "b"] 3
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=> { a = { b = 3; }; }
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Type:
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setAttrByPath :: [String] -> Any -> AttrSet
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*/
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setAttrByPath =
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# A list of strings representing the attribute path to set
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attrPath:
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# The value to set at the location described by `attrPath`
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value:
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let
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len = length attrPath;
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atDepth = n:
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if n == len
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then value
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else { ${elemAt attrPath n} = atDepth (n + 1); };
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in atDepth 0;
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/* Like `attrByPath`, but without a default value. If it doesn't find the
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path it will throw an error.
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Example:
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x = { a = { b = 3; }; }
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getAttrFromPath ["a" "b"] x
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=> 3
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getAttrFromPath ["z" "z"] x
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=> error: cannot find attribute `z.z'
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Type:
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getAttrFromPath :: [String] -> AttrSet -> Any
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*/
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getAttrFromPath =
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# A list of strings representing the attribute path to get from `set`
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attrPath:
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# The nested attribute set to find the value in.
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set:
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let errorMsg = "cannot find attribute `" + concatStringsSep "." attrPath + "'";
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in attrByPath attrPath (abort errorMsg) set;
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/* Map each attribute in the given set and merge them into a new attribute set.
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Type:
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concatMapAttrs :: (String -> a -> AttrSet) -> AttrSet -> AttrSet
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Example:
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concatMapAttrs
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(name: value: {
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${name} = value;
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${name + value} = value;
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})
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{ x = "a"; y = "b"; }
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=> { x = "a"; xa = "a"; y = "b"; yb = "b"; }
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*/
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concatMapAttrs = f: v:
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foldl' mergeAttrs { }
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(attrValues
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(mapAttrs f v)
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);
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/* Update or set specific paths of an attribute set.
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Takes a list of updates to apply and an attribute set to apply them to,
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and returns the attribute set with the updates applied. Updates are
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represented as `{ path = ...; update = ...; }` values, where `path` is a
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list of strings representing the attribute path that should be updated,
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and `update` is a function that takes the old value at that attribute path
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as an argument and returns the new
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value it should be.
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Properties:
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- Updates to deeper attribute paths are applied before updates to more
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shallow attribute paths
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- Multiple updates to the same attribute path are applied in the order
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they appear in the update list
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- If any but the last `path` element leads into a value that is not an
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attribute set, an error is thrown
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- If there is an update for an attribute path that doesn't exist,
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accessing the argument in the update function causes an error, but
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intermediate attribute sets are implicitly created as needed
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Example:
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updateManyAttrsByPath [
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{
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path = [ "a" "b" ];
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update = old: { d = old.c; };
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}
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{
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path = [ "a" "b" "c" ];
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update = old: old + 1;
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}
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{
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path = [ "x" "y" ];
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update = old: "xy";
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}
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] { a.b.c = 0; }
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=> { a = { b = { d = 1; }; }; x = { y = "xy"; }; }
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Type: updateManyAttrsByPath :: [{ path :: [String]; update :: (Any -> Any); }] -> AttrSet -> AttrSet
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*/
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updateManyAttrsByPath = let
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# When recursing into attributes, instead of updating the `path` of each
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# update using `tail`, which needs to allocate an entirely new list,
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# we just pass a prefix length to use and make sure to only look at the
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# path without the prefix length, so that we can reuse the original list
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# entries.
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go = prefixLength: hasValue: value: updates:
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let
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# Splits updates into ones on this level (split.right)
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# And ones on levels further down (split.wrong)
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split = partition (el: length el.path == prefixLength) updates;
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# Groups updates on further down levels into the attributes they modify
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nested = groupBy (el: elemAt el.path prefixLength) split.wrong;
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# Applies only nested modification to the input value
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withNestedMods =
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# Return the value directly if we don't have any nested modifications
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if split.wrong == [] then
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if hasValue then value
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else
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# Throw an error if there is no value. This `head` call here is
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# safe, but only in this branch since `go` could only be called
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# with `hasValue == false` for nested updates, in which case
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# it's also always called with at least one update
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let updatePath = (head split.right).path; in
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throw
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( "updateManyAttrsByPath: Path '${showAttrPath updatePath}' does "
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+ "not exist in the given value, but the first update to this "
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+ "path tries to access the existing value.")
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else
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# If there are nested modifications, try to apply them to the value
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if ! hasValue then
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# But if we don't have a value, just use an empty attribute set
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# as the value, but simplify the code a bit
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mapAttrs (name: go (prefixLength + 1) false null) nested
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else if isAttrs value then
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# If we do have a value and it's an attribute set, override it
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# with the nested modifications
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value //
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mapAttrs (name: go (prefixLength + 1) (value ? ${name}) value.${name}) nested
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else
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# However if it's not an attribute set, we can't apply the nested
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# modifications, throw an error
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let updatePath = (head split.wrong).path; in
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throw
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( "updateManyAttrsByPath: Path '${showAttrPath updatePath}' needs to "
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+ "be updated, but path '${showAttrPath (take prefixLength updatePath)}' "
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+ "of the given value is not an attribute set, so we can't "
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+ "update an attribute inside of it.");
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# We get the final result by applying all the updates on this level
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# after having applied all the nested updates
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# We use foldl instead of foldl' so that in case of multiple updates,
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# intermediate values aren't evaluated if not needed
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in foldl (acc: el: el.update acc) withNestedMods split.right;
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in updates: value: go 0 true value updates;
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/* Return the specified attributes from a set.
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Example:
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attrVals ["a" "b" "c"] as
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=> [as.a as.b as.c]
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Type:
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attrVals :: [String] -> AttrSet -> [Any]
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*/
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attrVals =
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# The list of attributes to fetch from `set`. Each attribute name must exist on the attrbitue set
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nameList:
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# The set to get attribute values from
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set: map (x: set.${x}) nameList;
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/* Return the values of all attributes in the given set, sorted by
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attribute name.
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Example:
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attrValues {c = 3; a = 1; b = 2;}
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=> [1 2 3]
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Type:
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attrValues :: AttrSet -> [Any]
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*/
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attrValues = builtins.attrValues or (attrs: attrVals (attrNames attrs) attrs);
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/* Given a set of attribute names, return the set of the corresponding
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attributes from the given set.
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Example:
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getAttrs [ "a" "b" ] { a = 1; b = 2; c = 3; }
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=> { a = 1; b = 2; }
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Type:
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getAttrs :: [String] -> AttrSet -> AttrSet
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*/
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getAttrs =
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# A list of attribute names to get out of `set`
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names:
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# The set to get the named attributes from
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attrs: genAttrs names (name: attrs.${name});
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/* Collect each attribute named `attr` from a list of attribute
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sets. Sets that don't contain the named attribute are ignored.
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Example:
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catAttrs "a" [{a = 1;} {b = 0;} {a = 2;}]
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=> [1 2]
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Type:
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catAttrs :: String -> [AttrSet] -> [Any]
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*/
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catAttrs = builtins.catAttrs or
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(attr: l: concatLists (map (s: if s ? ${attr} then [s.${attr}] else []) l));
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/* Filter an attribute set by removing all attributes for which the
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given predicate return false.
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Example:
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filterAttrs (n: v: n == "foo") { foo = 1; bar = 2; }
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=> { foo = 1; }
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Type:
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filterAttrs :: (String -> Any -> Bool) -> AttrSet -> AttrSet
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*/
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filterAttrs =
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# Predicate taking an attribute name and an attribute value, which returns `true` to include the attribute, or `false` to exclude the attribute.
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pred:
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# The attribute set to filter
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set:
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listToAttrs (concatMap (name: let v = set.${name}; in if pred name v then [(nameValuePair name v)] else []) (attrNames set));
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/* Filter an attribute set recursively by removing all attributes for
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which the given predicate return false.
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Example:
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filterAttrsRecursive (n: v: v != null) { foo = { bar = null; }; }
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=> { foo = {}; }
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Type:
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filterAttrsRecursive :: (String -> Any -> Bool) -> AttrSet -> AttrSet
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*/
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filterAttrsRecursive =
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# Predicate taking an attribute name and an attribute value, which returns `true` to include the attribute, or `false` to exclude the attribute.
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pred:
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# The attribute set to filter
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set:
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listToAttrs (
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concatMap (name:
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let v = set.${name}; in
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if pred name v then [
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(nameValuePair name (
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if isAttrs v then filterAttrsRecursive pred v
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else v
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))
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] else []
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) (attrNames set)
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);
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/*
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Like [`lib.lists.foldl'`](#function-library-lib.lists.foldl-prime) but for attribute sets.
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Iterates over every name-value pair in the given attribute set.
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The result of the callback function is often called `acc` for accumulator. It is passed between callbacks from left to right and the final `acc` is the return value of `foldlAttrs`.
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Attention:
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There is a completely different function
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`lib.foldAttrs`
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which has nothing to do with this function, despite the similar name.
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Example:
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foldlAttrs
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(acc: name: value: {
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sum = acc.sum + value;
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names = acc.names ++ [name];
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})
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{ sum = 0; names = []; }
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{
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foo = 1;
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bar = 10;
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}
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->
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{
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sum = 11;
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names = ["bar" "foo"];
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}
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foldlAttrs
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(throw "function not needed")
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123
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{};
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->
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123
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foldlAttrs
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(acc: _: _: acc)
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3
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{ z = throw "value not needed"; a = throw "value not needed"; };
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->
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3
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The accumulator doesn't have to be an attrset.
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It can be as simple as a number or string.
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foldlAttrs
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(acc: _: v: acc * 10 + v)
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1
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{ z = 1; a = 2; };
|
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->
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121
|
||
|
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Type:
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foldlAttrs :: ( a -> String -> b -> a ) -> a -> { ... :: b } -> a
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*/
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foldlAttrs = f: init: set:
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foldl'
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(acc: name: f acc name set.${name})
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init
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(attrNames set);
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|
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/* Apply fold functions to values grouped by key.
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|
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Example:
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foldAttrs (item: acc: [item] ++ acc) [] [{ a = 2; } { a = 3; }]
|
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=> { a = [ 2 3 ]; }
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|
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Type:
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foldAttrs :: (Any -> Any -> Any) -> Any -> [AttrSets] -> Any
|
||
|
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*/
|
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foldAttrs =
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# A function, given a value and a collector combines the two.
|
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op:
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# The starting value.
|
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nul:
|
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# A list of attribute sets to fold together by key.
|
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list_of_attrs:
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foldr (n: a:
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foldr (name: o:
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o // { ${name} = op n.${name} (a.${name} or nul); }
|
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) a (attrNames n)
|
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) {} list_of_attrs;
|
||
|
||
|
||
/* Recursively collect sets that verify a given predicate named `pred`
|
||
from the set `attrs`. The recursion is stopped when the predicate is
|
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verified.
|
||
|
||
Example:
|
||
collect isList { a = { b = ["b"]; }; c = [1]; }
|
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=> [["b"] [1]]
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|
||
collect (x: x ? outPath)
|
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{ a = { outPath = "a/"; }; b = { outPath = "b/"; }; }
|
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=> [{ outPath = "a/"; } { outPath = "b/"; }]
|
||
|
||
Type:
|
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collect :: (AttrSet -> Bool) -> AttrSet -> [x]
|
||
*/
|
||
collect =
|
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# Given an attribute's value, determine if recursion should stop.
|
||
pred:
|
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# The attribute set to recursively collect.
|
||
attrs:
|
||
if pred attrs then
|
||
[ attrs ]
|
||
else if isAttrs attrs then
|
||
concatMap (collect pred) (attrValues attrs)
|
||
else
|
||
[];
|
||
|
||
/* Return the cartesian product of attribute set value combinations.
|
||
|
||
Example:
|
||
cartesianProductOfSets { a = [ 1 2 ]; b = [ 10 20 ]; }
|
||
=> [
|
||
{ a = 1; b = 10; }
|
||
{ a = 1; b = 20; }
|
||
{ a = 2; b = 10; }
|
||
{ a = 2; b = 20; }
|
||
]
|
||
Type:
|
||
cartesianProductOfSets :: AttrSet -> [AttrSet]
|
||
*/
|
||
cartesianProductOfSets =
|
||
# Attribute set with attributes that are lists of values
|
||
attrsOfLists:
|
||
foldl' (listOfAttrs: attrName:
|
||
concatMap (attrs:
|
||
map (listValue: attrs // { ${attrName} = listValue; }) attrsOfLists.${attrName}
|
||
) listOfAttrs
|
||
) [{}] (attrNames attrsOfLists);
|
||
|
||
|
||
/* Utility function that creates a `{name, value}` pair as expected by `builtins.listToAttrs`.
|
||
|
||
Example:
|
||
nameValuePair "some" 6
|
||
=> { name = "some"; value = 6; }
|
||
|
||
Type:
|
||
nameValuePair :: String -> Any -> { name :: String; value :: Any; }
|
||
*/
|
||
nameValuePair =
|
||
# Attribute name
|
||
name:
|
||
# Attribute value
|
||
value:
|
||
{ inherit name value; };
|
||
|
||
|
||
/* Apply a function to each element in an attribute set, creating a new attribute set.
|
||
|
||
Example:
|
||
mapAttrs (name: value: name + "-" + value)
|
||
{ x = "foo"; y = "bar"; }
|
||
=> { x = "x-foo"; y = "y-bar"; }
|
||
|
||
Type:
|
||
mapAttrs :: (String -> Any -> Any) -> AttrSet -> AttrSet
|
||
*/
|
||
mapAttrs = builtins.mapAttrs or
|
||
(f: set:
|
||
listToAttrs (map (attr: { name = attr; value = f attr set.${attr}; }) (attrNames set)));
|
||
|
||
|
||
/* Like `mapAttrs`, but allows the name of each attribute to be
|
||
changed in addition to the value. The applied function should
|
||
return both the new name and value as a `nameValuePair`.
|
||
|
||
Example:
|
||
mapAttrs' (name: value: nameValuePair ("foo_" + name) ("bar-" + value))
|
||
{ x = "a"; y = "b"; }
|
||
=> { foo_x = "bar-a"; foo_y = "bar-b"; }
|
||
|
||
Type:
|
||
mapAttrs' :: (String -> Any -> { name :: String; value :: Any; }) -> AttrSet -> AttrSet
|
||
*/
|
||
mapAttrs' =
|
||
# A function, given an attribute's name and value, returns a new `nameValuePair`.
|
||
f:
|
||
# Attribute set to map over.
|
||
set:
|
||
listToAttrs (map (attr: f attr set.${attr}) (attrNames set));
|
||
|
||
|
||
/* Call a function for each attribute in the given set and return
|
||
the result in a list.
|
||
|
||
Example:
|
||
mapAttrsToList (name: value: name + value)
|
||
{ x = "a"; y = "b"; }
|
||
=> [ "xa" "yb" ]
|
||
|
||
Type:
|
||
mapAttrsToList :: (String -> a -> b) -> AttrSet -> [b]
|
||
|
||
*/
|
||
mapAttrsToList =
|
||
# A function, given an attribute's name and value, returns a new value.
|
||
f:
|
||
# Attribute set to map over.
|
||
attrs:
|
||
map (name: f name attrs.${name}) (attrNames attrs);
|
||
|
||
/*
|
||
Deconstruct an attrset to a list of name-value pairs as expected by [`builtins.listToAttrs`](https://nixos.org/manual/nix/stable/language/builtins.html#builtins-listToAttrs).
|
||
Each element of the resulting list is an attribute set with these attributes:
|
||
- `name` (string): The name of the attribute
|
||
- `value` (any): The value of the attribute
|
||
|
||
The following is always true:
|
||
```nix
|
||
builtins.listToAttrs (attrsToList attrs) == attrs
|
||
```
|
||
|
||
:::{.warning}
|
||
The opposite is not always true. In general expect that
|
||
```nix
|
||
attrsToList (builtins.listToAttrs list) != list
|
||
```
|
||
|
||
This is because the `listToAttrs` removes duplicate names and doesn't preserve the order of the list.
|
||
:::
|
||
|
||
Example:
|
||
attrsToList { foo = 1; bar = "asdf"; }
|
||
=> [ { name = "bar"; value = "asdf"; } { name = "foo"; value = 1; } ]
|
||
|
||
Type:
|
||
attrsToList :: AttrSet -> [ { name :: String; value :: Any; } ]
|
||
|
||
*/
|
||
attrsToList = mapAttrsToList nameValuePair;
|
||
|
||
|
||
/* Like `mapAttrs`, except that it recursively applies itself to
|
||
the *leaf* attributes of a potentially-nested attribute set:
|
||
the second argument of the function will never be an attrset.
|
||
Also, the first argument of the argument function is a *list*
|
||
of the attribute names that form the path to the leaf attribute.
|
||
|
||
For a function that gives you control over what counts as a leaf,
|
||
see `mapAttrsRecursiveCond`.
|
||
|
||
Example:
|
||
mapAttrsRecursive (path: value: concatStringsSep "-" (path ++ [value]))
|
||
{ n = { a = "A"; m = { b = "B"; c = "C"; }; }; d = "D"; }
|
||
=> { n = { a = "n-a-A"; m = { b = "n-m-b-B"; c = "n-m-c-C"; }; }; d = "d-D"; }
|
||
|
||
Type:
|
||
mapAttrsRecursive :: ([String] -> a -> b) -> AttrSet -> AttrSet
|
||
*/
|
||
mapAttrsRecursive =
|
||
# A function, given a list of attribute names and a value, returns a new value.
|
||
f:
|
||
# Set to recursively map over.
|
||
set:
|
||
mapAttrsRecursiveCond (as: true) f set;
|
||
|
||
|
||
/* Like `mapAttrsRecursive`, but it takes an additional predicate
|
||
function that tells it whether to recurse into an attribute
|
||
set. If it returns false, `mapAttrsRecursiveCond` does not
|
||
recurse, but does apply the map function. If it returns true, it
|
||
does recurse, and does not apply the map function.
|
||
|
||
Example:
|
||
# To prevent recursing into derivations (which are attribute
|
||
# sets with the attribute "type" equal to "derivation"):
|
||
mapAttrsRecursiveCond
|
||
(as: !(as ? "type" && as.type == "derivation"))
|
||
(x: ... do something ...)
|
||
attrs
|
||
|
||
Type:
|
||
mapAttrsRecursiveCond :: (AttrSet -> Bool) -> ([String] -> a -> b) -> AttrSet -> AttrSet
|
||
*/
|
||
mapAttrsRecursiveCond =
|
||
# A function, given the attribute set the recursion is currently at, determine if to recurse deeper into that attribute set.
|
||
cond:
|
||
# A function, given a list of attribute names and a value, returns a new value.
|
||
f:
|
||
# Attribute set to recursively map over.
|
||
set:
|
||
let
|
||
recurse = path:
|
||
let
|
||
g =
|
||
name: value:
|
||
if isAttrs value && cond value
|
||
then recurse (path ++ [name]) value
|
||
else f (path ++ [name]) value;
|
||
in mapAttrs g;
|
||
in recurse [] set;
|
||
|
||
|
||
/* Generate an attribute set by mapping a function over a list of
|
||
attribute names.
|
||
|
||
Example:
|
||
genAttrs [ "foo" "bar" ] (name: "x_" + name)
|
||
=> { foo = "x_foo"; bar = "x_bar"; }
|
||
|
||
Type:
|
||
genAttrs :: [ String ] -> (String -> Any) -> AttrSet
|
||
*/
|
||
genAttrs =
|
||
# Names of values in the resulting attribute set.
|
||
names:
|
||
# A function, given the name of the attribute, returns the attribute's value.
|
||
f:
|
||
listToAttrs (map (n: nameValuePair n (f n)) names);
|
||
|
||
|
||
/* Check whether the argument is a derivation. Any set with
|
||
`{ type = "derivation"; }` counts as a derivation.
|
||
|
||
Example:
|
||
nixpkgs = import <nixpkgs> {}
|
||
isDerivation nixpkgs.ruby
|
||
=> true
|
||
isDerivation "foobar"
|
||
=> false
|
||
|
||
Type:
|
||
isDerivation :: Any -> Bool
|
||
*/
|
||
isDerivation =
|
||
# Value to check.
|
||
value: value.type or null == "derivation";
|
||
|
||
/* Converts a store path to a fake derivation.
|
||
|
||
Type:
|
||
toDerivation :: Path -> Derivation
|
||
*/
|
||
toDerivation =
|
||
# A store path to convert to a derivation.
|
||
path:
|
||
let
|
||
path' = builtins.storePath path;
|
||
res =
|
||
{ type = "derivation";
|
||
name = sanitizeDerivationName (builtins.substring 33 (-1) (baseNameOf path'));
|
||
outPath = path';
|
||
outputs = [ "out" ];
|
||
out = res;
|
||
outputName = "out";
|
||
};
|
||
in res;
|
||
|
||
|
||
/* If `cond` is true, return the attribute set `as`,
|
||
otherwise an empty attribute set.
|
||
|
||
Example:
|
||
optionalAttrs (true) { my = "set"; }
|
||
=> { my = "set"; }
|
||
optionalAttrs (false) { my = "set"; }
|
||
=> { }
|
||
|
||
Type:
|
||
optionalAttrs :: Bool -> AttrSet -> AttrSet
|
||
*/
|
||
optionalAttrs =
|
||
# Condition under which the `as` attribute set is returned.
|
||
cond:
|
||
# The attribute set to return if `cond` is `true`.
|
||
as:
|
||
if cond then as else {};
|
||
|
||
|
||
/* Merge sets of attributes and use the function `f` to merge attributes
|
||
values.
|
||
|
||
Example:
|
||
zipAttrsWithNames ["a"] (name: vs: vs) [{a = "x";} {a = "y"; b = "z";}]
|
||
=> { a = ["x" "y"]; }
|
||
|
||
Type:
|
||
zipAttrsWithNames :: [ String ] -> (String -> [ Any ] -> Any) -> [ AttrSet ] -> AttrSet
|
||
*/
|
||
zipAttrsWithNames =
|
||
# List of attribute names to zip.
|
||
names:
|
||
# A function, accepts an attribute name, all the values, and returns a combined value.
|
||
f:
|
||
# List of values from the list of attribute sets.
|
||
sets:
|
||
listToAttrs (map (name: {
|
||
inherit name;
|
||
value = f name (catAttrs name sets);
|
||
}) names);
|
||
|
||
|
||
/* Merge sets of attributes and use the function f to merge attribute values.
|
||
Like `lib.attrsets.zipAttrsWithNames` with all key names are passed for `names`.
|
||
|
||
Implementation note: Common names appear multiple times in the list of
|
||
names, hopefully this does not affect the system because the maximal
|
||
laziness avoid computing twice the same expression and `listToAttrs` does
|
||
not care about duplicated attribute names.
|
||
|
||
Example:
|
||
zipAttrsWith (name: values: values) [{a = "x";} {a = "y"; b = "z";}]
|
||
=> { a = ["x" "y"]; b = ["z"]; }
|
||
|
||
Type:
|
||
zipAttrsWith :: (String -> [ Any ] -> Any) -> [ AttrSet ] -> AttrSet
|
||
*/
|
||
zipAttrsWith =
|
||
builtins.zipAttrsWith or (f: sets: zipAttrsWithNames (concatMap attrNames sets) f sets);
|
||
|
||
|
||
/* Merge sets of attributes and combine each attribute value in to a list.
|
||
|
||
Like `lib.attrsets.zipAttrsWith` with `(name: values: values)` as the function.
|
||
|
||
Example:
|
||
zipAttrs [{a = "x";} {a = "y"; b = "z";}]
|
||
=> { a = ["x" "y"]; b = ["z"]; }
|
||
|
||
Type:
|
||
zipAttrs :: [ AttrSet ] -> AttrSet
|
||
*/
|
||
zipAttrs =
|
||
# List of attribute sets to zip together.
|
||
sets:
|
||
zipAttrsWith (name: values: values) sets;
|
||
|
||
/*
|
||
Merge a list of attribute sets together using the `//` operator.
|
||
In case of duplicate attributes, values from later list elements take precedence over earlier ones.
|
||
The result is the same as `foldl mergeAttrs { }`, but the performance is better for large inputs.
|
||
For n list elements, each with an attribute set containing m unique attributes, the complexity of this operation is O(nm log n).
|
||
|
||
Type:
|
||
mergeAttrsList :: [ Attrs ] -> Attrs
|
||
|
||
Example:
|
||
mergeAttrsList [ { a = 0; b = 1; } { c = 2; d = 3; } ]
|
||
=> { a = 0; b = 1; c = 2; d = 3; }
|
||
mergeAttrsList [ { a = 0; } { a = 1; } ]
|
||
=> { a = 1; }
|
||
*/
|
||
mergeAttrsList = list:
|
||
let
|
||
# `binaryMerge start end` merges the elements at indices `index` of `list` such that `start <= index < end`
|
||
# Type: Int -> Int -> Attrs
|
||
binaryMerge = start: end:
|
||
# assert start < end; # Invariant
|
||
if end - start >= 2 then
|
||
# If there's at least 2 elements, split the range in two, recurse on each part and merge the result
|
||
# The invariant is satisfied because each half will have at least 1 element
|
||
binaryMerge start (start + (end - start) / 2)
|
||
// binaryMerge (start + (end - start) / 2) end
|
||
else
|
||
# Otherwise there will be exactly 1 element due to the invariant, in which case we just return it directly
|
||
elemAt list start;
|
||
in
|
||
if list == [ ] then
|
||
# Calling binaryMerge as below would not satisfy its invariant
|
||
{ }
|
||
else
|
||
binaryMerge 0 (length list);
|
||
|
||
|
||
/* Does the same as the update operator '//' except that attributes are
|
||
merged until the given predicate is verified. The predicate should
|
||
accept 3 arguments which are the path to reach the attribute, a part of
|
||
the first attribute set and a part of the second attribute set. When
|
||
the predicate is satisfied, the value of the first attribute set is
|
||
replaced by the value of the second attribute set.
|
||
|
||
Example:
|
||
recursiveUpdateUntil (path: l: r: path == ["foo"]) {
|
||
# first attribute set
|
||
foo.bar = 1;
|
||
foo.baz = 2;
|
||
bar = 3;
|
||
} {
|
||
#second attribute set
|
||
foo.bar = 1;
|
||
foo.quz = 2;
|
||
baz = 4;
|
||
}
|
||
|
||
=> {
|
||
foo.bar = 1; # 'foo.*' from the second set
|
||
foo.quz = 2; #
|
||
bar = 3; # 'bar' from the first set
|
||
baz = 4; # 'baz' from the second set
|
||
}
|
||
|
||
Type:
|
||
recursiveUpdateUntil :: ( [ String ] -> AttrSet -> AttrSet -> Bool ) -> AttrSet -> AttrSet -> AttrSet
|
||
*/
|
||
recursiveUpdateUntil =
|
||
# Predicate, taking the path to the current attribute as a list of strings for attribute names, and the two values at that path from the original arguments.
|
||
pred:
|
||
# Left attribute set of the merge.
|
||
lhs:
|
||
# Right attribute set of the merge.
|
||
rhs:
|
||
let f = attrPath:
|
||
zipAttrsWith (n: values:
|
||
let here = attrPath ++ [n]; in
|
||
if length values == 1
|
||
|| pred here (elemAt values 1) (head values) then
|
||
head values
|
||
else
|
||
f here values
|
||
);
|
||
in f [] [rhs lhs];
|
||
|
||
|
||
/* A recursive variant of the update operator ‘//’. The recursion
|
||
stops when one of the attribute values is not an attribute set,
|
||
in which case the right hand side value takes precedence over the
|
||
left hand side value.
|
||
|
||
Example:
|
||
recursiveUpdate {
|
||
boot.loader.grub.enable = true;
|
||
boot.loader.grub.device = "/dev/hda";
|
||
} {
|
||
boot.loader.grub.device = "";
|
||
}
|
||
|
||
returns: {
|
||
boot.loader.grub.enable = true;
|
||
boot.loader.grub.device = "";
|
||
}
|
||
|
||
Type:
|
||
recursiveUpdate :: AttrSet -> AttrSet -> AttrSet
|
||
*/
|
||
recursiveUpdate =
|
||
# Left attribute set of the merge.
|
||
lhs:
|
||
# Right attribute set of the merge.
|
||
rhs:
|
||
recursiveUpdateUntil (path: lhs: rhs: !(isAttrs lhs && isAttrs rhs)) lhs rhs;
|
||
|
||
|
||
/* Returns true if the pattern is contained in the set. False otherwise.
|
||
|
||
Example:
|
||
matchAttrs { cpu = {}; } { cpu = { bits = 64; }; }
|
||
=> true
|
||
|
||
Type:
|
||
matchAttrs :: AttrSet -> AttrSet -> Bool
|
||
*/
|
||
matchAttrs =
|
||
# Attribute set structure to match
|
||
pattern:
|
||
# Attribute set to find patterns in
|
||
attrs:
|
||
assert isAttrs pattern;
|
||
all id (attrValues (zipAttrsWithNames (attrNames pattern) (n: values:
|
||
let pat = head values; val = elemAt values 1; in
|
||
if length values == 1 then false
|
||
else if isAttrs pat then isAttrs val && matchAttrs pat val
|
||
else pat == val
|
||
) [pattern attrs]));
|
||
|
||
|
||
/* Override only the attributes that are already present in the old set
|
||
useful for deep-overriding.
|
||
|
||
Example:
|
||
overrideExisting {} { a = 1; }
|
||
=> {}
|
||
overrideExisting { b = 2; } { a = 1; }
|
||
=> { b = 2; }
|
||
overrideExisting { a = 3; b = 2; } { a = 1; }
|
||
=> { a = 1; b = 2; }
|
||
|
||
Type:
|
||
overrideExisting :: AttrSet -> AttrSet -> AttrSet
|
||
*/
|
||
overrideExisting =
|
||
# Original attribute set
|
||
old:
|
||
# Attribute set with attributes to override in `old`.
|
||
new:
|
||
mapAttrs (name: value: new.${name} or value) old;
|
||
|
||
|
||
/* Turns a list of strings into a human-readable description of those
|
||
strings represented as an attribute path. The result of this function is
|
||
not intended to be machine-readable.
|
||
Create a new attribute set with `value` set at the nested attribute location specified in `attrPath`.
|
||
|
||
Example:
|
||
showAttrPath [ "foo" "10" "bar" ]
|
||
=> "foo.\"10\".bar"
|
||
showAttrPath []
|
||
=> "<root attribute path>"
|
||
|
||
Type:
|
||
showAttrPath :: [String] -> String
|
||
*/
|
||
showAttrPath =
|
||
# Attribute path to render to a string
|
||
path:
|
||
if path == [] then "<root attribute path>"
|
||
else concatMapStringsSep "." escapeNixIdentifier path;
|
||
|
||
|
||
/* Get a package output.
|
||
If no output is found, fallback to `.out` and then to the default.
|
||
|
||
Example:
|
||
getOutput "dev" pkgs.openssl
|
||
=> "/nix/store/9rz8gxhzf8sw4kf2j2f1grr49w8zx5vj-openssl-1.0.1r-dev"
|
||
|
||
Type:
|
||
getOutput :: String -> Derivation -> String
|
||
*/
|
||
getOutput = output: pkg:
|
||
if ! pkg ? outputSpecified || ! pkg.outputSpecified
|
||
then pkg.${output} or pkg.out or pkg
|
||
else pkg;
|
||
|
||
/* Get a package's `bin` output.
|
||
If the output does not exist, fallback to `.out` and then to the default.
|
||
|
||
Example:
|
||
getBin pkgs.openssl
|
||
=> "/nix/store/9rz8gxhzf8sw4kf2j2f1grr49w8zx5vj-openssl-1.0.1r"
|
||
|
||
Type:
|
||
getBin :: Derivation -> String
|
||
*/
|
||
getBin = getOutput "bin";
|
||
|
||
|
||
/* Get a package's `lib` output.
|
||
If the output does not exist, fallback to `.out` and then to the default.
|
||
|
||
Example:
|
||
getLib pkgs.openssl
|
||
=> "/nix/store/9rz8gxhzf8sw4kf2j2f1grr49w8zx5vj-openssl-1.0.1r-lib"
|
||
|
||
Type:
|
||
getLib :: Derivation -> String
|
||
*/
|
||
getLib = getOutput "lib";
|
||
|
||
|
||
/* Get a package's `dev` output.
|
||
If the output does not exist, fallback to `.out` and then to the default.
|
||
|
||
Example:
|
||
getDev pkgs.openssl
|
||
=> "/nix/store/9rz8gxhzf8sw4kf2j2f1grr49w8zx5vj-openssl-1.0.1r-dev"
|
||
|
||
Type:
|
||
getDev :: Derivation -> String
|
||
*/
|
||
getDev = getOutput "dev";
|
||
|
||
|
||
/* Get a package's `man` output.
|
||
If the output does not exist, fallback to `.out` and then to the default.
|
||
|
||
Example:
|
||
getMan pkgs.openssl
|
||
=> "/nix/store/9rz8gxhzf8sw4kf2j2f1grr49w8zx5vj-openssl-1.0.1r-man"
|
||
|
||
Type:
|
||
getMan :: Derivation -> String
|
||
*/
|
||
getMan = getOutput "man";
|
||
|
||
/* Pick the outputs of packages to place in `buildInputs`
|
||
|
||
Type: chooseDevOutputs :: [Derivation] -> [String]
|
||
|
||
*/
|
||
chooseDevOutputs =
|
||
# List of packages to pick `dev` outputs from
|
||
drvs:
|
||
builtins.map getDev drvs;
|
||
|
||
/* Make various Nix tools consider the contents of the resulting
|
||
attribute set when looking for what to build, find, etc.
|
||
|
||
This function only affects a single attribute set; it does not
|
||
apply itself recursively for nested attribute sets.
|
||
|
||
Example:
|
||
{ pkgs ? import <nixpkgs> {} }:
|
||
{
|
||
myTools = pkgs.lib.recurseIntoAttrs {
|
||
inherit (pkgs) hello figlet;
|
||
};
|
||
}
|
||
|
||
Type:
|
||
recurseIntoAttrs :: AttrSet -> AttrSet
|
||
|
||
*/
|
||
recurseIntoAttrs =
|
||
# An attribute set to scan for derivations.
|
||
attrs:
|
||
attrs // { recurseForDerivations = true; };
|
||
|
||
/* Undo the effect of recurseIntoAttrs.
|
||
|
||
Type:
|
||
dontRecurseIntoAttrs :: AttrSet -> AttrSet
|
||
*/
|
||
dontRecurseIntoAttrs =
|
||
# An attribute set to not scan for derivations.
|
||
attrs:
|
||
attrs // { recurseForDerivations = false; };
|
||
|
||
/* `unionOfDisjoint x y` is equal to `x // y // z` where the
|
||
attrnames in `z` are the intersection of the attrnames in `x` and
|
||
`y`, and all values `assert` with an error message. This
|
||
operator is commutative, unlike (//).
|
||
|
||
Type: unionOfDisjoint :: AttrSet -> AttrSet -> AttrSet
|
||
*/
|
||
unionOfDisjoint = x: y:
|
||
let
|
||
intersection = builtins.intersectAttrs x y;
|
||
collisions = lib.concatStringsSep " " (builtins.attrNames intersection);
|
||
mask = builtins.mapAttrs (name: value: builtins.throw
|
||
"unionOfDisjoint: collision on ${name}; complete list: ${collisions}")
|
||
intersection;
|
||
in
|
||
(x // y) // mask;
|
||
|
||
# DEPRECATED
|
||
zipWithNames = zipAttrsWithNames;
|
||
|
||
# DEPRECATED
|
||
zip = builtins.trace
|
||
"lib.zip is deprecated, use lib.zipAttrsWith instead" zipAttrsWith;
|
||
}
|