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|
/* Functions that generate widespread file
* formats from nix data structures.
*
* They all follow a similar interface:
* generator { config-attrs } data
*
* `config-attrs` are “holes” in the generators
* with sensible default implementations that
* can be overwritten. The default implementations
* are mostly generators themselves, called with
* their respective default values; they can be reused.
*
* Tests can be found in ./tests/misc.nix
* Documentation in the manual, #sec-generators
*/
{ lib }:
let
inherit (lib)
addErrorContext
assertMsg
attrNames
concatLists
concatMapStringsSep
concatStrings
concatStringsSep
const
elem
escape
filter
flatten
foldl
functionArgs # Note: not the builtin; considers `__functor` in attrsets.
gvariant
hasInfix
head
id
init
isAttrs
isBool
isDerivation
isFloat
isFunction # Note: not the builtin; considers `__functor` in attrsets.
isInt
isList
isPath
isString
last
length
mapAttrs
mapAttrsToList
optionals
recursiveUpdate
replaceStrings
reverseList
splitString
tail
toList
;
inherit (lib.strings)
escapeNixIdentifier
floatToString
match
split
toJSON
typeOf
;
## -- HELPER FUNCTIONS & DEFAULTS --
/* Convert a value to a sensible default string representation.
* The builtin `toString` function has some strange defaults,
* suitable for bash scripts but not much else.
*/
mkValueStringDefault = {}: v:
let err = t: v: abort
("generators.mkValueStringDefault: " +
"${t} not supported: ${toPretty {} v}");
in if isInt v then toString v
# convert derivations to store paths
else if isDerivation v then toString v
# we default to not quoting strings
else if isString v then v
# isString returns "1", which is not a good default
else if true == v then "true"
# here it returns to "", which is even less of a good default
else if false == v then "false"
else if null == v then "null"
# if you have lists you probably want to replace this
else if isList v then err "lists" v
# same as for lists, might want to replace
else if isAttrs v then err "attrsets" v
# functions can’t be printed of course
else if isFunction v then err "functions" v
# Floats currently can't be converted to precise strings,
# condition warning on nix version once this isn't a problem anymore
# See https://github.com/NixOS/nix/pull/3480
else if isFloat v then floatToString v
else err "this value is" (toString v);
/* Generate a line of key k and value v, separated by
* character sep. If sep appears in k, it is escaped.
* Helper for synaxes with different separators.
*
* mkValueString specifies how values should be formatted.
*
* mkKeyValueDefault {} ":" "f:oo" "bar"
* > "f\:oo:bar"
*/
mkKeyValueDefault = {
mkValueString ? mkValueStringDefault {}
}: sep: k: v:
"${escape [sep] k}${sep}${mkValueString v}";
## -- FILE FORMAT GENERATORS --
/* Generate a key-value-style config file from an attrset.
*
* mkKeyValue is the same as in toINI.
*/
toKeyValue = {
mkKeyValue ? mkKeyValueDefault {} "=",
listsAsDuplicateKeys ? false,
indent ? ""
}:
let mkLine = k: v: indent + mkKeyValue k v + "\n";
mkLines = if listsAsDuplicateKeys
then k: v: map (mkLine k) (if isList v then v else [v])
else k: v: [ (mkLine k v) ];
in attrs: concatStrings (concatLists (mapAttrsToList mkLines attrs));
/* Generate an INI-style config file from an
* attrset of sections to an attrset of key-value pairs.
*
* generators.toINI {} {
* foo = { hi = "${pkgs.hello}"; ciao = "bar"; };
* baz = { "also, integers" = 42; };
* }
*
*> [baz]
*> also, integers=42
*>
*> [foo]
*> ciao=bar
*> hi=/nix/store/y93qql1p5ggfnaqjjqhxcw0vqw95rlz0-hello-2.10
*
* The mk* configuration attributes can generically change
* the way sections and key-value strings are generated.
*
* For more examples see the test cases in ./tests/misc.nix.
*/
toINI = {
# apply transformations (e.g. escapes) to section names
mkSectionName ? (name: escape [ "[" "]" ] name),
# format a setting line from key and value
mkKeyValue ? mkKeyValueDefault {} "=",
# allow lists as values for duplicate keys
listsAsDuplicateKeys ? false
}: attrsOfAttrs:
let
# map function to string for each key val
mapAttrsToStringsSep = sep: mapFn: attrs:
concatStringsSep sep
(mapAttrsToList mapFn attrs);
mkSection = sectName: sectValues: ''
[${mkSectionName sectName}]
'' + toKeyValue { inherit mkKeyValue listsAsDuplicateKeys; } sectValues;
in
# map input to ini sections
mapAttrsToStringsSep "\n" mkSection attrsOfAttrs;
/* Generate an INI-style config file from an attrset
* specifying the global section (no header), and an
* attrset of sections to an attrset of key-value pairs.
*
* generators.toINIWithGlobalSection {} {
* globalSection = {
* someGlobalKey = "hi";
* };
* sections = {
* foo = { hi = "${pkgs.hello}"; ciao = "bar"; };
* baz = { "also, integers" = 42; };
* }
*
*> someGlobalKey=hi
*>
*> [baz]
*> also, integers=42
*>
*> [foo]
*> ciao=bar
*> hi=/nix/store/y93qql1p5ggfnaqjjqhxcw0vqw95rlz0-hello-2.10
*
* The mk* configuration attributes can generically change
* the way sections and key-value strings are generated.
*
* For more examples see the test cases in ./tests/misc.nix.
*
* If you don’t need a global section, you can also use
* `generators.toINI` directly, which only takes
* the part in `sections`.
*/
toINIWithGlobalSection = {
# apply transformations (e.g. escapes) to section names
mkSectionName ? (name: escape [ "[" "]" ] name),
# format a setting line from key and value
mkKeyValue ? mkKeyValueDefault {} "=",
# allow lists as values for duplicate keys
listsAsDuplicateKeys ? false
}: { globalSection, sections ? {} }:
( if globalSection == {}
then ""
else (toKeyValue { inherit mkKeyValue listsAsDuplicateKeys; } globalSection)
+ "\n")
+ (toINI { inherit mkSectionName mkKeyValue listsAsDuplicateKeys; } sections);
/* Generate a git-config file from an attrset.
*
* It has two major differences from the regular INI format:
*
* 1. values are indented with tabs
* 2. sections can have sub-sections
*
* generators.toGitINI {
* url."ssh://git@github.com/".insteadOf = "https://github.com";
* user.name = "edolstra";
* }
*
*> [url "ssh://git@github.com/"]
*> insteadOf = "https://github.com"
*>
*> [user]
*> name = "edolstra"
*/
toGitINI = attrs:
let
mkSectionName = name:
let
containsQuote = hasInfix ''"'' name;
sections = splitString "." name;
section = head sections;
subsections = tail sections;
subsection = concatStringsSep "." subsections;
in if containsQuote || subsections == [ ] then
name
else
''${section} "${subsection}"'';
mkValueString = v:
let
escapedV = ''
"${
replaceStrings [ "\n" " " ''"'' "\\" ] [ "\\n" "\\t" ''\"'' "\\\\" ] v
}"'';
in mkValueStringDefault { } (if isString v then escapedV else v);
# generation for multiple ini values
mkKeyValue = k: v:
let mkKeyValue = mkKeyValueDefault { inherit mkValueString; } " = " k;
in concatStringsSep "\n" (map (kv: "\t" + mkKeyValue kv) (toList v));
# converts { a.b.c = 5; } to { "a.b".c = 5; } for toINI
gitFlattenAttrs = let
recurse = path: value:
if isAttrs value && !isDerivation value then
mapAttrsToList (name: value: recurse ([ name ] ++ path) value) value
else if length path > 1 then {
${concatStringsSep "." (reverseList (tail path))}.${head path} = value;
} else {
${head path} = value;
};
in attrs: foldl recursiveUpdate { } (flatten (recurse [ ] attrs));
toINI_ = toINI { inherit mkKeyValue mkSectionName; };
in
toINI_ (gitFlattenAttrs attrs);
# mkKeyValueDefault wrapper that handles dconf INI quirks.
# The main differences of the format is that it requires strings to be quoted.
mkDconfKeyValue = mkKeyValueDefault { mkValueString = v: toString (gvariant.mkValue v); } "=";
# Generates INI in dconf keyfile style. See https://help.gnome.org/admin/system-admin-guide/stable/dconf-keyfiles.html.en
# for details.
toDconfINI = toINI { mkKeyValue = mkDconfKeyValue; };
withRecursion =
{
/* If this option is not null, the given value will stop evaluating at a certain depth */
depthLimit
/* If this option is true, an error will be thrown, if a certain given depth is exceeded */
, throwOnDepthLimit ? true
}:
assert isInt depthLimit;
let
specialAttrs = [
"__functor"
"__functionArgs"
"__toString"
"__pretty"
];
stepIntoAttr = evalNext: name:
if elem name specialAttrs
then id
else evalNext;
transform = depth:
if depthLimit != null && depth > depthLimit then
if throwOnDepthLimit
then throw "Exceeded maximum eval-depth limit of ${toString depthLimit} while trying to evaluate with `generators.withRecursion'!"
else const "<unevaluated>"
else id;
mapAny = depth: v:
let
evalNext = x: mapAny (depth + 1) (transform (depth + 1) x);
in
if isAttrs v then mapAttrs (stepIntoAttr evalNext) v
else if isList v then map evalNext v
else transform (depth + 1) v;
in
mapAny 0;
/* Pretty print a value, akin to `builtins.trace`.
* Should probably be a builtin as well.
* The pretty-printed string should be suitable for rendering default values
* in the NixOS manual. In particular, it should be as close to a valid Nix expression
* as possible.
*/
toPretty = {
/* If this option is true, attrsets like { __pretty = fn; val = …; }
will use fn to convert val to a pretty printed representation.
(This means fn is type Val -> String.) */
allowPrettyValues ? false,
/* If this option is true, the output is indented with newlines for attribute sets and lists */
multiline ? true,
/* Initial indentation level */
indent ? ""
}:
let
go = indent: v:
let introSpace = if multiline then "\n${indent} " else " ";
outroSpace = if multiline then "\n${indent}" else " ";
in if isInt v then toString v
# toString loses precision on floats, so we use toJSON instead. This isn't perfect
# as the resulting string may not parse back as a float (e.g. 42, 1e-06), but for
# pretty-printing purposes this is acceptable.
else if isFloat v then builtins.toJSON v
else if isString v then
let
lines = filter (v: ! isList v) (split "\n" v);
escapeSingleline = escape [ "\\" "\"" "\${" ];
escapeMultiline = replaceStrings [ "\${" "''" ] [ "''\${" "'''" ];
singlelineResult = "\"" + concatStringsSep "\\n" (map escapeSingleline lines) + "\"";
multilineResult = let
escapedLines = map escapeMultiline lines;
# The last line gets a special treatment: if it's empty, '' is on its own line at the "outer"
# indentation level. Otherwise, '' is appended to the last line.
lastLine = last escapedLines;
in "''" + introSpace + concatStringsSep introSpace (init escapedLines)
+ (if lastLine == "" then outroSpace else introSpace + lastLine) + "''";
in
if multiline && length lines > 1 then multilineResult else singlelineResult
else if true == v then "true"
else if false == v then "false"
else if null == v then "null"
else if isPath v then toString v
else if isList v then
if v == [] then "[ ]"
else "[" + introSpace
+ concatMapStringsSep introSpace (go (indent + " ")) v
+ outroSpace + "]"
else if isFunction v
|