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nixpkgs/pkgs/lib/default.nix
Michael Raskin c87887ddd0 Oops. A typo fix 
svn path=/nixpkgs/trunk/; revision=13727
2009-01-08 23:04:18 +00:00

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# Utility functions.
let
inherit (builtins)
head tail isList stringLength substring lessThan sub
listToAttrs attrNames hasAttr;
in
rec {
listOfListsToAttrs = ll : builtins.listToAttrs (map (l : { name = (head l); value = (head (tail l)); }) ll);
# Identity function.
id = x: x;
# accumulates / merges all attr sets until null is fed.
# example: sumArgs id { a = 'a'; x = 'x'; } { y = 'y'; x = 'X'; } null
# result : { a = 'a'; x = 'X'; y = 'Y'; }
innerSumArgs = f : x : y : (if y == null then (f x)
else (innerSumArgs f (x // y)));
sumArgs = f : innerSumArgs f {};
# Advanced sumArgs version. Hm, twice as slow, I'm afraid.
# composedArgs id (x:x//{a="b";}) (x:x//{b=x.a + "c";}) null;
# {a="b" ; b="bc";};
innerComposedArgs = f : x : y : (if y==null then (f x)
else (if (builtins.isAttrs y) then
(innerComposedArgs f (x//y))
else (innerComposedArgs f (y x))));
composedArgs = f: innerComposedArgs f {};
defaultMergeArg = x : y: if builtins.isAttrs y then
y
else
(y x);
defaultMerge = x: y: x // (defaultMergeArg x y);
sumTwoArgs = f: x: y:
f (defaultMerge x y);
foldArgs = merger: f: init: x:
let arg=(merger init (defaultMergeArg init x)); in
# now add the function with composed args already applied to the final attrs
setAttrMerge "passthru" {} (f arg) ( x : x // { function = foldArgs merger f arg; } );
# returns f x // { passthru.fun = y : f (merge x y); } while preserving other passthru names.
# example: let ex = applyAndFun (x : removeAttrs x ["fixed"]) (mergeOrApply mergeAttr) {name = 6;};
# usage1 = ex.passthru.fun { name = 7; }; # result: { name = 7;}
# usage2 = ex.passthru.fun (a: a // {name = __add a.name 1; }); # result: { a = 7; }
# fix usage:
# usage3a = ex.passthru.fun (a: a // {name2 = a.fixed.toBePassed; }); # usage3a will fail because toBePassed is not yet given
# usage3b usage3a.passthru.fun { toBePassed = "foo";}; # result { name = 7; name2 = "foo"; toBePassed = "foo"; fixed = <this attrs>; }
applyAndFun = f : merge : x : assert (__isAttrs x || __isFunction x);
let takeFix = if (__isFunction x) then x else (attr: merge attr x); in
setAttrMerge "passthru" {} (fix (fixed : f (takeFix {inherit fixed;})))
( y : y //
{
fun = z : applyAndFun f merge (fixed: merge (takeFix fixed) z);
funMerge = z : applyAndFun f merge (fixed: let e = takeFix fixed; in merge e (merge e z));
} );
mergeOrApply = merge : x : y : if (__isFunction y) then y x else merge x y;
# rec { # an example of how composedArgsAndFun can be used
# a = composedArgsAndFun (x : x) { a = ["2"]; meta = { d = "bar";}; };
# # meta.d will be lost ! It's your task to preserve it (eg using a merge function)
# b = a.passthru.function { a = [ "3" ]; meta = { d2 = "bar2";}; };
# # instead of passing/ overriding values you can use a merge function:
# c = b.passthru.function ( x: { a = x.a ++ ["4"]; }); # consider using (maybeAttr "a" [] x)
# }
# result:
# {
# a = { a = ["2"]; meta = { d = "bar"; }; passthru = { function = .. }; };
# b = { a = ["3"]; meta = { d2 = "bar2"; }; passthru = { function = .. }; };
# c = { a = ["3" "4"]; meta = { d2 = "bar2"; }; passthru = { function = .. }; };
# # c2 is equal to c
# }
composedArgsAndFun = f: foldArgs defaultMerge f {};
# example a = pairMap (x : y : x + y) ["a" "b" "c" "d"];
# result: ["ab" "cd"]
innerPairMap = acc: f: l:
if l == [] then acc else
innerPairMap (acc ++ [(f (head l)(head (tail l)))])
f (tail (tail l));
pairMap = innerPairMap [];
# "Fold" a binary function `op' between successive elements of
# `list' with `nul' as the starting value, i.e., `fold op nul [x_1
# x_2 ... x_n] == op x_1 (op x_2 ... (op x_n nul))'. (This is
# Haskell's foldr).
fold = op: nul: list:
if list == []
then nul
else op (head list) (fold op nul (tail list));
# Haskell's fold
foldl = op: nul: list:
if list == []
then nul
else fold op (op nul (head list)) (tail list);
# Concatenate a list of lists.
concatList = x : y : x ++ y;
concatLists = fold concatList [];
# Concatenate a list of strings.
concatStrings =
fold (x: y: x + y) "";
# Map and concatenate the result.
concatMap = f: list: concatLists (map f list);
concatMapStrings = f: list: concatStrings (map f list);
# Place an element between each element of a list, e.g.,
# `intersperse "," ["a" "b" "c"]' returns ["a" "," "b" "," "c"].
intersperse = separator: list:
if list == [] || tail list == []
then list
else [(head list) separator]
++ (intersperse separator (tail list));
toList = x : if (__isList x) then x else [x];
concatStringsSep = separator: list:
concatStrings (intersperse separator list);
makeLibraryPath = paths: concatStringsSep ":" (map (path: path + "/lib") paths);
# Flatten the argument into a single list; that is, nested lists are
# spliced into the top-level lists. E.g., `flatten [1 [2 [3] 4] 5]
# == [1 2 3 4 5]' and `flatten 1 == [1]'.
flatten = x:
if isList x
then fold (x: y: (flatten x) ++ y) [] x
else [x];
# Return an attribute from nested attribute sets. For instance ["x"
# "y"] applied to some set e returns e.x.y, if it exists. The
# default value is returned otherwise.
# comment: there is also builtins.getAttr ? (is there a better name for this function?)
getAttr = attrPath: default: e:
let attr = head attrPath;
in
if attrPath == [] then e
else if builtins ? hasAttr && builtins.hasAttr attr e
then getAttr (tail attrPath) default (builtins.getAttr attr e)
else default;
# shortcut for getAttr ["name"] default attrs
maybeAttr = name: default: attrs:
if (__hasAttr name attrs) then (__getAttr name attrs) else default;
# Filter a list using a predicate; that is, return a list containing
# every element from `list' for which `pred' returns true.
filter = pred: list:
fold (x: y: if pred x then [x] ++ y else y) [] list;
# Return true if `list' has an element `x':
elem = x: list: fold (a: bs: x == a || bs) false list;
# Find the sole element in the list matching the specified
# predicate, returns `default' if no such element exists, or
# `multiple' if there are multiple matching elements.
findSingle = pred: default: multiple: list:
let found = filter pred list;
in if found == [] then default
else if tail found != [] then multiple
else head found;
# Return true iff function `pred' returns true for at least element
# of `list'.
any = pred: list:
if list == [] then false
else if pred (head list) then true
else any pred (tail list);
# Return true iff function `pred' returns true for all elements of
# `list'.
all = pred: list:
if list == [] then true
else if pred (head list) then all pred (tail list)
else false;
# much shorter implementations using map and fold (are lazy as well)
# which ones are better?
# true if all/ at least one element(s) satisfy f
# all = f : l : fold logicalAND true (map f l);
# any = f : l : fold logicalOR false (map f l);
# Return true if each element of a list is equal, false otherwise.
eqLists = xs: ys:
if xs == [] && ys == [] then true
else if xs == [] || ys == [] then false
else head xs == head ys && eqLists (tail xs) (tail ys);
# Workaround, but works in stable Nix now.
eqStrings = a: b: (a+(substring 0 0 b)) == ((substring 0 0 a)+b);
# Determine whether a filename ends in the given suffix.
hasSuffix = ext: fileName:
let lenFileName = stringLength fileName;
lenExt = stringLength ext;
in !(lessThan lenFileName lenExt) &&
substring (sub lenFileName lenExt) lenFileName fileName == ext;
hasSuffixHack = a: b: hasSuffix (a+(substring 0 0 b)) ((substring 0 0 a)+b);
# Bring in a path as a source, filtering out all Subversion and CVS
# directories, as well as backup files (*~).
cleanSource =
let filter = name: type: let baseName = baseNameOf (toString name); in ! (
# Filter out Subversion and CVS directories.
(type == "directory" && (baseName == ".svn" || baseName == "CVS")) ||
# Filter out backup files.
(hasSuffix "~" baseName)
);
in src: builtins.filterSource filter src;
# Get all files ending with the specified suffices from the given
# directory. E.g. `sourceFilesBySuffices ./dir [".xml" ".c"]'.
sourceFilesBySuffices = path: exts:
let filter = name: type:
let base = baseNameOf (toString name);
in type != "directory" && any (ext: hasSuffix ext base) exts;
in builtins.filterSource filter path;
# Return a singleton list or an empty list, depending on a boolean
# value. Useful when building lists with optional elements
# (e.g. `++ optional (system == "i686-linux") flashplayer').
optional = cond: elem: if cond then [elem] else [];
# Return a list or an empty list, dependening on a boolean value.
optionals = cond: elems: if cond then elems else [];
optionalString = cond: string: if cond then string else "";
# Return the second argument if the first one is true or the empty version
# of the second argument.
ifEnable = cond: val:
if cond then val
else if builtins.isList val then []
else if builtins.isAttrs val then {}
# else if builtins.isString val then ""
else if (val == true || val == false) then false
else null;
# Return a list of integers from `first' up to and including `last'.
range = first: last:
if builtins.lessThan last first
then []
else [first] ++ range (builtins.add first 1) last;
# Return true only if there is an attribute and it is true.
checkFlag = attrSet: name:
if (name == "true") then true else
if (name == "false") then false else
if (isInList (getAttr ["flags"] [] attrSet) name) then true else
getAttr [name] false attrSet ;
logicalOR = x: y: x || y;
logicalAND = x: y: x && y;
# Input : attrSet, [ [name default] ... ], name
# Output : its value or default.
getValue = attrSet: argList: name:
( getAttr [name] (if checkFlag attrSet name then true else
if argList == [] then null else
let x = builtins.head argList; in
if (head x) == name then
(head (tail x))
else (getValue attrSet
(tail argList) name)) attrSet );
# Input : attrSet, [[name default] ...], [ [flagname reqs..] ... ]
# Output : are reqs satisfied? It's asserted.
checkReqs = attrSet : argList : condList :
(
fold logicalAND true
(map (x: let name = (head x) ; in
((checkFlag attrSet name) ->
(fold logicalAND true
(map (y: let val=(getValue attrSet argList y); in
(val!=null) && (val!=false))
(tail x))))) condList)) ;
isInList = list: x:
if (list == []) then false else
if (x == (head list)) then true else
isInList (tail list) x;
uniqList = {inputList, outputList ? []}:
if (inputList == []) then outputList else
let x=head inputList;
newOutputList = outputList ++
(if (isInList outputList x) then [] else [x]);
in uniqList {outputList=newOutputList;
inputList = (tail inputList);};
uniqListExt = {inputList, outputList ? [],
getter ? (x : x), compare ? (x: y: x==y)}:
if (inputList == []) then outputList else
let x=head inputList;
isX = y: (compare (getter y) (getter x));
newOutputList = outputList ++
(if any isX outputList then [] else [x]);
in uniqListExt {outputList=newOutputList;
inputList = (tail inputList);
inherit getter compare;
};
condConcat = name: list: checker:
if list == [] then name else
if checker (head list) then
condConcat
(name + (head (tail list)))
(tail (tail list))
checker
else condConcat
name (tail (tail list)) checker;
# Merge sets of attributes and use the function f to merge
# attributes values.
zip = f: sets:
builtins.listToAttrs (map (name: {
inherit name;
value =
f name
(map (__getAttr name)
(filter (__hasAttr name) sets));
}) (concatMap builtins.attrNames sets));
# divide a list in two depending on the evaluation of a predicate.
partition = pred:
fold (h: t:
if pred h
then { right = [h] ++ t.right; wrong = t.wrong; }
else { right = t.right; wrong = [h] ++ t.wrong; }
) { right = []; wrong = []; };
# Take a function and evaluate it with its own returned value.
fix = f:
(rec { result = f result; }).result;
# flatten a list of elements by following the properties of the elements.
# key : return the key which correspond to the value.
# value : return the value inserted in the returned list.
# next : return the list of following elements.
# keys : lists of keys already seen.
# default: result if 'x' is empty.
# x : list of values that have to be processed.
uniqFlatten = prop@{key, value, next, ...}: keys: default: x:
if x == []
then default
else
let h = head x; t = tail x;
k = key h; v = value h; n = next h;
in
if elem k keys
then uniqFlatten prop keys default t
else uniqFlatten prop (keys ++ [k]) (default ++ [v]) (n ++ t)
;
/* If. ThenElse. Always. */
# create "if" statement that can be dealyed on sets until a "then-else" or
# "always" set is reached. When an always set is reached the condition
# is ignore.
isIf = attrs: (typeOf attrs) == "if";
mkIf = condition: thenelse:
if isIf thenelse then
mkIf (condition && thenelse.condition) thenelse.thenelse
else {
_type = "if";
inherit condition thenelse;
};
isThenElse = attrs: (typeOf attrs) == "then-else";
mkThenElse = attrs:
assert attrs ? thenPart && attrs ? elsePart;
attrs // { _type = "then-else"; };
isAlways = attrs: (typeOf attrs) == "always";
mkAlways = value: { inherit value; _type = "always"; };
pushIf = f: attrs:
if isIf attrs then pushIf f (
let val = attrs.thenelse; in
# evaluate the condition.
if isThenElse val then
if attrs.condition then
val.thenPart
else
val.elsePart
# ignore the condition.
else if isAlways val then
val.value
# otherwise
else
f attrs.condition val)
else
attrs;
# take care otherwise you will have to handle this by hand.
rmIf = pushIf (condition: val: val);
evalIf = pushIf (condition: val:
# guess: empty else part.
ifEnable condition val
);
delayIf = pushIf (condition: val:
# rewrite the condition on sub-attributes.
mapAttrs (name: mkIf condition) val
);
/* Options. */
mkOption = attrs: attrs // {_type = "option";};
typeOf = x: if (__isAttrs x && x ? _type) then x._type else "";
isOption = attrs: (typeOf attrs) == "option";
addDefaultOptionValues = defs: opts: opts //
builtins.listToAttrs (map (defName:
{ name = defName;
value =
let
defValue = builtins.getAttr defName defs;
optValue = builtins.getAttr defName opts;
in
if typeOf defValue == "option"
then
# `defValue' is an option.
if builtins.hasAttr defName opts
then builtins.getAttr defName opts
else defValue.default
else
# `defValue' is an attribute set containing options.
# So recurse.
if builtins.hasAttr defName opts && builtins.isAttrs optValue
then addDefaultOptionValues defValue optValue
else addDefaultOptionValues defValue {};
}
) (builtins.attrNames defs));
mergeDefaultOption = name: list:
if list != [] && tail list == [] then head list
else if all __isFunction list then x: mergeDefaultOption (map (f: f x) list)
else if all __isList list then concatLists list
else if all __isAttrs list then mergeAttrs list
else if all (x: true == x || false == x) list then fold logicalOR false list
else if all (x: x == toString x) list then concatStrings list
else abort "${name}: Cannot merge values.";
mergeTypedOption = typeName: predicate: merge: name: list:
if all predicate list then merge list
else abort "${name}: Expect a ${typeName}.";
mergeEnableOption = mergeTypedOption "boolean"
(x: true == x || false == x) (fold logicalOR false);
mergeListOption = mergeTypedOption "list"
__isList concatLists;
mergeStringOption = mergeTypedOption "string"
(x: if builtins ? isString then builtins.isString x else x + "")
concatStrings;
# Merge sets of options and bindings.
# noOption: function to call if no option is declared.
mergeOptionSets = noOption: path: opts:
if all __isAttrs opts then
zip (attr: opts:
let
name = if path == "" then attr else path + "." + attr;
test = partition isOption opts;
opt = ({ merge = mergeDefaultOption; apply = id; } // head test.right);
in
if test.right == [] then mergeOptionSets noOption name (map delayIf test.wrong)
else if tail test.right != [] then throw "Multiple options for '${name}'."
else if test.wrong == [] then opt.apply opt.default
else opt.apply (opt.merge name (map evalIf test.wrong))
) opts
else noOption path opts;
# Keep all option declarations and add an attribute "name" inside
# each option which contains the path that has to be followed to
# access it.
filterOptionSets = path: opts:
if all __isAttrs opts then
zip (attr: opts:
let
name = if path == "" then attr else path + "." + attr;
test = partition isOption opts;
in
if test.right == [] then filterOptionSets name (map delayIf test.wrong)
else if tail test.right != [] then throw "Multiple options for '${name}'."
else { inherit name; } // (head test.right)
) opts
else {};
# Evaluate a list of option sets that would be merged with the
# function "merge" which expects two arguments. The attribute named
# "require" is used to imports option declarations and bindings.
fixOptionSetsFun = merge: pkgs: opts:
let
# ignore all conditions that are on require attributes.
rmRequireIf = conf:
let conf2 = delayIf conf; in
if conf2 ? require then
conf2 // { require = rmIf conf2.require; }
else
conf2;
# call configuration "files" with one of the existing convention.
optionSet = config: configFun:
if __isFunction configFun then
let result = configFun { inherit pkgs config; }; in
# {pkgs, config, ...}: {..}
if builtins.isAttrs result then result
# pkgs: config: {..}
else configFun pkgs config
# {..}
else configFun;
processConfig = config: configFun:
rmRequireIf (optionSet config configFun);
prop = config: rec {
key = id;
prepare = x: processConfig config x;
value = x: removeAttrs (prepare x) ["require"];
next = x: toList (getAttr ["require"] [] (prepare x));
};
in config:
merge "" (uniqFlatten (prop config) [] [] (toList opts));
fixOptionSets = merge: pkgs: opts:
fix (fixOptionSetsFun merge pkgs opts);
optionAttrSetToDocList = (l: attrs:
(if (getAttr ["_type"] "" attrs) == "option" then
[({
#inherit (attrs) description;
description = if attrs ? description then attrs.description else
throw ("No description ${toString l} : ${whatis attrs}");
}
//(if attrs ? example then {inherit(attrs) example;} else {} )
//(if attrs ? default then {inherit(attrs) default;} else {} )
//{name = l;}
)]
else (concatLists (map (s: (optionAttrSetToDocList
(l + (if l=="" then "" else ".") + s) (builtins.getAttr s attrs)))
(builtins.attrNames attrs)))));
innerModifySumArgs = f: x: a: b: if b == null then (f a b) // x else
innerModifySumArgs f x (a // b);
modifySumArgs = f: x: innerModifySumArgs f x {};
debugVal = if builtins ? trace then x: (builtins.trace x x) else x: x;
debugXMLVal = if builtins ? trace then x: (builtins.trace (builtins.toXML x) x) else x: x;
# this can help debug your code as well - designed to not produce thousands of lines
traceWhatis = x : __trace (whatis x) x;
traceMarked = str: x: __trace (str + (whatis x)) x;
attrNamesToStr = a : concatStringsSep "; " (map (x : "${x}=") (__attrNames a));
whatis = x :
if (__isAttrs x) then
if (x ? outPath) then "x is a derivation, name ${if x ? name then x.name else "<no name>"}, { ${attrNamesToStr x} }"
else "x is attr set { ${attrNamesToStr x} }"
else if (__isFunction x) then "x is a function"
else if (x == []) then "x is an empty list"
else if (__isList x) then "x is a list, first item is : ${whatis (__head x)}"
else if (x == true) then "x is boolean true"
else if (x == false) then "x is boolean false"
else if (x == null) then "x is null"
else "x is probably a string starting, starting characters: ${__substring 0 50 x}..";
# trace the arguments passed to function and its result
traceCall = n : f : a : let t = n2 : x : traceMarked "${n} ${n2}:" x; in t "result" (f (t "arg 1" a));
traceCall2 = n : f : a : b : let t = n2 : x : traceMarked "${n} ${n2}:" x; in t "result" (f (t "arg 1" a) (t "arg 2" b));
traceCall3 = n : f : a : b : c : let t = n2 : x : traceMarked "${n} ${n2}:" x; in t "result" (f (t "arg 1" a) (t "arg 2" b) (t "arg 3" c));
innerClosePropagation = ready: list: if list == [] then ready else
if (head list) ? propagatedBuildInputs then
innerClosePropagation (ready ++ [(head list)])
((head list).propagatedBuildInputs ++ (tail list)) else
innerClosePropagation (ready ++ [(head list)]) (tail list);
closePropagation = list: (uniqList {inputList = (innerClosePropagation [] list);});
stringToCharacters = s : let l = __stringLength s; in
if (__lessThan l 1) then [""] else [(__substring 0 1 s)] ++ stringToCharacters (__substring 1 (__sub l 1) s);
# should this be implemented as primop ? Yes it should..
escapeShellArg = s :
let escapeChar = x : if ( x == "'" ) then "'\"'\"'" else x;
in "'" + concatStrings (map escapeChar (stringToCharacters s) ) +"'";
defineShList = name : list : "\n${name}=(${concatStringsSep " " (map escapeShellArg list)})\n";
# this as well :-) arg: http://foo/bar/bz.ext returns bz.ext
dropPath = s :
if s == "" then "" else
let takeTillSlash = left : c : s :
if left == 0 then s
else if (__substring left 1 s == "/") then
(__substring (__add left 1) (__sub c 1) s)
else takeTillSlash (__sub left 1) (__add c 1) s; in
takeTillSlash (__sub (__stringLength s) 1) 1 s;
# calls a function (f attr value ) for each record item. returns a list
# should be renamed to mapAttrsFlatten
mapRecordFlatten = f : r : map (attr: f attr (builtins.getAttr attr r) ) (attrNames r);
# maps a function on each attr value
# f = attr : value : ..
mapAttrs = f : r : listToAttrs ( mapRecordFlatten (a : v : nv a ( f a v ) ) r);
# to be used with listToAttrs (_a_ttribute _v_alue)
nv = name : value : { inherit name value; };
# attribute set containing one attribute
nvs = name : value : listToAttrs [ (nv name value) ];
# adds / replaces an attribute of an attribute set
setAttr = set : name : v : set // (nvs name v);
# setAttrMerge (similar to mergeAttrsWithFunc but only merges the values of a particular name)
# setAttrMerge "a" [] { a = [2];} (x : x ++ [3]) -> { a = [2 3]; }
# setAttrMerge "a" [] { } (x : x ++ [3]) -> { a = [ 3]; }
setAttrMerge = name : default : attrs : f :
setAttr attrs name (f (maybeAttr name default attrs));
# iterates over a list of attributes collecting the attribute attr if it exists
catAttrs = attr : l : fold ( s : l : if (hasAttr attr s) then [(builtins.getAttr attr s)] ++ l else l) [] l;
mergeAttr = x : y : x // y;
mergeAttrs = fold mergeAttr {};
attrVals = nameList : attrSet :
map (x: builtins.getAttr x attrSet) nameList;
# Using f = a : b = b the result is similar to //
# merge attributes with custom function handling the case that the attribute
# exists in both sets
mergeAttrsWithFunc = f : set1 : set2 :
fold (n: set : if (__hasAttr n set)
then setAttr set n (f (__getAttr n set) (__getAttr n set2))
else set )
set1 (__attrNames set2);
# merging two attribute set concatenating the values of same attribute names
# eg { a = 7; } { a = [ 2 3 ]; } becomes { a = [ 7 2 3 ]; }
mergeAttrsConcatenateValues = mergeAttrsWithFunc ( a : b : (toList a) ++ (toList b) );
# merges attributes using //, if a name exisits in both attributes
# an error will be triggered unless its listed in mergeLists
# so you can mergeAttrsNoOverride { buildInputs = [a]; } { buildInputs = [a]; } {} to get
# { buildInputs = [a b]; }
# merging buildPhase does'nt really make sense. The cases will be rare where appending /prefixing will fit your needs?
# in these cases the first buildPhase will override the second one
# ! depreceated, use mergeAttrByFunc instead
mergeAttrsNoOverride = { mergeLists ? ["buildInputs" "propagatedBuildInputs"],
overrideSnd ? [ "buildPhase" ]
} : attrs1 : attrs2 :
fold (n: set :
setAttr set n ( if (__hasAttr n set)
then # merge
if elem n mergeLists # attribute contains list, merge them by concatenating
then (__getAttr n attrs2) ++ (__getAttr n attrs1)
else if elem n overrideSnd
then __getAttr n attrs1
else throw "error mergeAttrsNoOverride, attribute ${n} given in both attributes - no merge func defined"
else __getAttr n attrs2 # add attribute not existing in attr1
)) attrs1 (__attrNames attrs2);
# example usage:
# mergeAttrByFunc {
# inherit mergeAttrBy; # defined below
# buildInputs = [ a b ];
# } {
# buildInputs = [ c d ];
# };
# will result in
# { mergeAttrsBy = [...]; buildInputs = [ a b c d ]; }
# is used by prepareDerivationArgs and can be used when composing using
# foldArgs, composedArgsAndFun or applyAndFun. Example: composableDerivation in all-packages.nix
mergeAttrByFunc = x : y :
let
mergeAttrBy2 = { mergeAttrBy=mergeAttr; }
// (maybeAttr "mergeAttrBy" {} x)
// (maybeAttr "mergeAttrBy" {} y); in
mergeAttrs [
x y
(mapAttrs ( a : v : # merge special names using given functions
if (__hasAttr a x)
then if (__hasAttr a y)
then v (__getAttr a x) (__getAttr a y) # both have attr, use merge func
else (__getAttr a x) # only x has attr
else (__getAttr a y) # only y has attr)
) (removeAttrs mergeAttrBy2
# don't merge attrs which are neither in x nor y
(filter (a : (! __hasAttr a x) && (! __hasAttr a y) )
(__attrNames mergeAttrBy2))
)
)
];
mergeAttrsByFuncDefaults = foldl mergeAttrByFunc { inherit mergeAttrBy; };
# sane defaults (same name as attr name so that inherit can be used)
mergeAttrBy = # { buildInputs = concatList; [...]; passthru = mergeAttr; [..]; }
listToAttrs (map (n : nv n concatList) [ "buildInputs" "propagatedBuildInputs" "configureFlags" "prePhases" "postAll" ])
// listToAttrs (map (n : nv n mergeAttr) [ "passthru" "meta" "cfg" "flags" ]);
# returns atribute values as a list
flattenAttrs = set : map ( attr : builtins.getAttr attr set) (attrNames set);
mapIf = cond : f : fold ( x : l : if (cond x) then [(f x)] ++ l else l) [];
# pick attrs subset_attr_names and apply f
subsetmap = f : attrs : subset_attr_names :
listToAttrs (fold ( attr : r : if __hasAttr attr attrs
then r ++ [ ( nv attr ( f (__getAttr attr attrs) ) ) ] else r ) []
subset_attr_names );
# prepareDerivationArgs tries to make writing configurable derivations easier
# example:
# prepareDerivationArgs {
# mergeAttrBy = {
# myScript = x : y : x ++ "\n" ++ y;
# };
# cfg = {
# readlineSupport = true;
# };
# flags = {
# readline = {
# set = {
# configureFlags = [ "--with-compiler=${compiler}" ];
# buildInputs = [ compiler ];
# pass = { inherit compiler; READLINE=1; };
# assertion = compiler.dllSupport;
# myScript = "foo";
# };
# unset = { configureFlags = ["--without-compiler"]; };
# };
# };
# src = ...
# buildPhase = '' ... '';
# name = ...
# myScript = "bar";
# };
# if you don't have need for unset you can omit the surrounding set = { .. } attr
# all attrs except flags cfg and mergeAttrBy will be merged with the
# additional data from flags depending on config settings
# It's used in composableDerivation in all-packages.nix. It's also used
# heavily in the new python and libs implementation
#
# should we check for misspelled cfg options?
prepareDerivationArgs = args:
let args2 = { cfg = {}; flags = {}; } // args;
flagName = name : "${name}Support";
cfgWithDefaults = (listToAttrs (map (n : nv (flagName n) false) (attrNames args2.flags)))
// args2.cfg;
opts = flattenAttrs (mapAttrs (a : v :
let v2 = if (v ? set || v ? unset) then v else { set = v; };
n = if (__getAttr (flagName a) cfgWithDefaults) then "set" else "unset";
attr = maybeAttr n {} v2; in
if (maybeAttr "assertion" true attr)
then attr
else throw "assertion of flag ${a} of derivation ${args.name} failed"
) args2.flags );
in removeAttrs
(mergeAttrsByFuncDefaults ([args] ++ opts ++ [{ passthru = cfgWithDefaults; }]))
["flags" "cfg" "mergeAttrBy" "fixed" ]; # fixed may be passed as fix argument or such
}
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