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nixpkgs/pkgs/lib/misc.nix
Marc Weber e0fab80c27 experimental/multiple-versions-in-one-file 
This patch introduces mergeAttrsByVersion to lib.

In some cases it does make sense to keep "experimental" and "older" versions of
the same package in one file because it follows the "do it once only" principle.
Very often many versions share their build instructions - so even though I
understand Eelcos opinion that different versions should be put into their own
.nix files - its my feeling telling me that this is fastest for most cases.

I agree with Eelco that if tweaks for individual versions become too much they
should be split into individual files.

See comments above mergeAttrsByVersion learn about its usage.

Signed-off-by: Marc Weber <marco-oweber@gmx.de>
2013-05-08 15:43:07 +03:00

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let lib = import ./default.nix;
inherit (builtins) isFunction hasAttr getAttr head tail isList isAttrs isInt attrNames;
in
with import ./lists.nix;
with import ./attrsets.nix;
with import ./strings.nix;
rec {
# returns default if env var is not set
maybeEnv = name: default:
let value = builtins.getEnv name; in
if value == "" then default else value;
defaultMergeArg = x : y: if builtins.isAttrs y then
y
else
(y x);
defaultMerge = x: y: x // (defaultMergeArg x y);
foldArgs = merger: f: init: x:
let arg=(merger init (defaultMergeArg init x));
# now add the function with composed args already applied to the final attrs
base = (setAttrMerge "passthru" {} (f arg)
( z : z // rec {
function = foldArgs merger f arg;
args = (lib.attrByPath ["passthru" "args"] {} z) // x;
} ));
withStdOverrides = base // {
override = base.passthru.function;
deepOverride = a : (base.passthru.function ((lib.mapAttrs (lib.deepOverrider a) base.passthru.args) // a));
} ;
in
withStdOverrides;
# predecessors: proposed replacement for applyAndFun (which has a bug cause it merges twice)
# the naming "overridableDelayableArgs" tries to express that you can
# - override attr values which have been supplied earlier
# - use attr values before they have been supplied by accessing the fix point
# name "fixed"
# f: the (delayed overridden) arguments are applied to this
#
# initial: initial attrs arguments and settings. see defaultOverridableDelayableArgs
#
# returns: f applied to the arguments // special attributes attrs
# a) merge: merge applied args with new args. Wether an argument is overridden depends on the merge settings
# b) replace: this let's you replace and remove names no matter which merge function has been set
#
# examples: see test cases "res" below;
overridableDelayableArgs =
f : # the function applied to the arguments
initial : # you pass attrs, the functions below are passing a function taking the fix argument
let
takeFixed = if isFunction initial then initial else (fixed : initial); # transform initial to an expression always taking the fixed argument
tidy = args :
let # apply all functions given in "applyPreTidy" in sequence
applyPreTidyFun = fold ( n : a : x : n ( a x ) ) lib.id (maybeAttr "applyPreTidy" [] args);
in removeAttrs (applyPreTidyFun args) ( ["applyPreTidy"] ++ (maybeAttr "removeAttrs" [] args) ); # tidy up args before applying them
fun = n : x :
let newArgs = fixed :
let args = takeFixed fixed;
mergeFun = getAttr n args;
in if isAttrs x then (mergeFun args x)
else assert isFunction x;
mergeFun args (x ( args // { inherit fixed; }));
in overridableDelayableArgs f newArgs;
in
(f (tidy (lib.fix takeFixed))) // {
merge = fun "mergeFun";
replace = fun "keepFun";
};
defaultOverridableDelayableArgs = f :
let defaults = {
mergeFun = mergeAttrByFunc; # default merge function. merge strategie (concatenate lists, strings) is given by mergeAttrBy
keepFun = a : b : { inherit (a) removeAttrs mergeFun keepFun mergeAttrBy; } // b; # even when using replace preserve these values
applyPreTidy = []; # list of functions applied to args before args are tidied up (usage case : prepareDerivationArgs)
mergeAttrBy = mergeAttrBy // {
applyPreTidy = a : b : a ++ b;
removeAttrs = a : b: a ++ b;
};
removeAttrs = ["mergeFun" "keepFun" "mergeAttrBy" "removeAttrs" "fixed" ]; # before applying the arguments to the function make sure these names are gone
};
in (overridableDelayableArgs f defaults).merge;
# 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 {};
# shortcut for attrByPath ["name"] default attrs
maybeAttrNullable = name: default: attrs:
if attrs == null then default else
if __hasAttr name attrs then (__getAttr name attrs) else default;
# shortcut for attrByPath ["name"] default attrs
maybeAttr = name: default: attrs:
if __hasAttr name attrs then (__getAttr name attrs) else default;
# 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 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 (elem name (attrByPath ["flags"] [] attrSet)) then true else
attrByPath [name] false attrSet ;
# Input : attrSet, [ [name default] ... ], name
# Output : its value or default.
getValue = attrSet: argList: name:
( attrByPath [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 lib.and true
(map (x: let name = (head x) ; in
((checkFlag attrSet name) ->
(fold lib.and true
(map (y: let val=(getValue attrSet argList y); in
(val!=null) && (val!=false))
(tail x))))) condList)) ;
# This function has O(n^2) performance.
uniqList = {inputList, acc ? []} :
let go = xs : acc :
if xs == []
then []
else let x = head xs;
y = if elem x acc then [] else [x];
in y ++ go (tail xs) (y ++ acc);
in go inputList acc;
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;
lazyGenericClosure = {startSet, operator}:
let
work = list: doneKeys: result:
if list == [] then
result
else
let x = head list; key = x.key; in
if elem key doneKeys then
work (tail list) doneKeys result
else
work (tail list ++ operator x) ([key] ++ doneKeys) ([x] ++ result);
in
work startSet [] [];
genericClosure =
if builtins ? genericClosure then builtins.genericClosure
else lazyGenericClosure;
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 {};
innerClosePropagation = acc : xs :
if xs == []
then acc
else let y = head xs;
ys = tail xs;
in if ! isAttrs y
then innerClosePropagation acc ys
else let acc' = [y] ++ acc;
in innerClosePropagation
acc'
(uniqList { inputList = (maybeAttrNullable "propagatedBuildInputs" [] y)
++ (maybeAttrNullable "propagatedNativeBuildInputs" [] y)
++ ys;
acc = acc';
}
);
closePropagation = list: (uniqList {inputList = (innerClosePropagation [] list);});
# calls a function (f attr value ) for each record item. returns a list
mapAttrsFlatten = f : r : map (attr: f attr (builtins.getAttr attr r) ) (attrNames r);
# attribute set containing one attribute
nvs = name : value : listToAttrs [ (nameValuePair 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));
# 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 )
(set2 // 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
# ! deprecated, 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, defaultOverridableDelayableArgs and can be used when composing using
# foldArgs, composedArgsAndFun or applyAndFun. Example: composableDerivation in all-packages.nix
mergeAttrByFunc = x : y :
let
mergeAttrBy2 = { mergeAttrBy=lib.mergeAttrs; }
// (maybeAttr "mergeAttrBy" {} x)
// (maybeAttr "mergeAttrBy" {} y); in
fold lib.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; };
mergeAttrsByFuncDefaultsClean = list: removeAttrs (mergeAttrsByFuncDefaults list) ["mergeAttrBy"];
# merge attrs based on version key into mkDerivation args, see mergeAttrBy to learn about smart merge defaults
#
# This function is best explained by an example:
#
# {version ? "2.0"} :
#
# mkDerivation (mergeAttrsByVersion "package-name" version
# { # version specific settings
# "git" = { src = ..; preConfigre = "autogen.sh"; buildInputs = [automake autoconf libtool]; };
# "2.0" = { src = ..; };
# }
# { // shared settings
# buildInputs = [ common build inputs ];
# meta = { .. }
# }
# )
#
# Please note that e.g. Eelco Dolstra usually prefers having one file for
# each version. On the other hand there are valuable additional design goals
# - readability
# - do it once only
# - try to avoid duplication
#
# Marc Weber and Michael Raskin sometimes prefer keeping older
# versions around for testing and regression tests - as long as its cheap to
# do so.
#
# Very often it just happens that the "shared" code is the bigger part.
# Then using this function might be appropriate.
#
# Be aware that its easy to cause recompilations in all versions when using this function
mergeAttrsByVersion = name: version: attrsByVersion: base:
mergeAttrsByFuncDefaultsClean [ { name = "${name}-${version}"; } base (maybeAttr version (throw "bad version ${version} for ${name}") attrsByVersion)];
# sane defaults (same name as attr name so that inherit can be used)
mergeAttrBy = # { buildInputs = concatList; [...]; passthru = mergeAttr; [..]; }
listToAttrs (map (n : nameValuePair n lib.concat)
[ "nativeBuildInputs" "buildInputs" "propagatedBuildInputs" "configureFlags" "prePhases" "postAll" "patches" ])
// listToAttrs (map (n : nameValuePair n lib.mergeAttrs) [ "passthru" "meta" "cfg" "flags" ])
// listToAttrs (map (n : nameValuePair n (a: b: "${a}\n${b}") ) [ "preConfigure" "postInstall" ])
;
# prepareDerivationArgs tries to make writing configurable derivations easier
# example:
# prepareDerivationArgs {
# mergeAttrBy = {
# myScript = x : y : x ++ "\n" ++ y;
# };
# cfg = {
# readlineSupport = true;
# };
# flags = {
# readline = {
# set = {
# configureFlags = [ "--with-compiler=${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?
# TODO use args.mergeFun here as well?
prepareDerivationArgs = args:
let args2 = { cfg = {}; flags = {}; } // args;
flagName = name : "${name}Support";
cfgWithDefaults = (listToAttrs (map (n : nameValuePair (flagName n) false) (attrNames args2.flags)))
// args2.cfg;
opts = attrValues (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" ];
nixType = x:
if isAttrs x then
if x ? outPath then "derivation"
else "aattrs"
else if isFunction x then "function"
else if isList x then "list"
else if x == true then "bool"
else if x == false then "bool"
else if x == null then "null"
else if isInt x then "int"
else "string";
}
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