/* 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.nix * Documentation in the manual, #sec-generators */ { lib }: with (lib).trivial; let libStr = lib.strings; libAttr = lib.attrsets; inherit (lib) isFunction; in rec { ## -- 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: with builtins; let err = t: v: abort ("generators.mkValueStringDefault: " + "${t} not supported: ${toPretty {} v}"); in if isInt v then toString v # we default to not quoting strings else if isString v then v # isString returns "1", which is not a good default else if true == v then "true" # here it returns to "", which is even less of a good default else if false == v then "false" else if null == v then "null" # if you have lists you probably want to replace this else if isList v then err "lists" v # same as for lists, might want to replace else if isAttrs v then err "attrsets" v # functions can’t be printed of course else if isFunction v then err "functions" v # Floats currently can't be converted to precise strings, # condition warning on nix version once this isn't a problem anymore # See https://github.com/NixOS/nix/pull/3480 else if isFloat v then libStr.floatToString v else err "this value is" (toString v); /* Generate a line of key k and value v, separated by * character sep. If sep appears in k, it is escaped. * Helper for synaxes with different separators. * * mkValueString specifies how values should be formatted. * * mkKeyValueDefault {} ":" "f:oo" "bar" * > "f\:oo:bar" */ mkKeyValueDefault = { mkValueString ? mkValueStringDefault {} }: sep: k: v: "${libStr.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 }: let mkLine = k: v: mkKeyValue k v + "\n"; mkLines = if listsAsDuplicateKeys then k: v: map (mkLine k) (if lib.isList v then v else [v]) else k: v: [ (mkLine k v) ]; in attrs: libStr.concatStrings (lib.concatLists (libAttr.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 = "${pkgs.hello}"; ciao = "bar"; }; * baz = { "also, integers" = 42; }; * } * *> [baz] *> also, integers=42 *> *> [foo] *> ciao=bar *> hi=/nix/store/y93qql1p5ggfnaqjjqhxcw0vqw95rlz0-hello-2.10 * * The mk* configuration attributes can generically change * the way sections and key-value strings are generated. * * For more examples see the test cases in ./tests.nix. */ toINI = { # apply transformations (e.g. escapes) to section names mkSectionName ? (name: libStr.escape [ "[" "]" ] name), # format a setting line from key and value mkKeyValue ? mkKeyValueDefault {} "=", # allow lists as values for duplicate keys listsAsDuplicateKeys ? false }: attrsOfAttrs: let # map function to string for each key val mapAttrsToStringsSep = sep: mapFn: attrs: libStr.concatStringsSep sep (libAttr.mapAttrsToList mapFn attrs); mkSection = sectName: sectValues: '' [${mkSectionName sectName}] '' + toKeyValue { inherit mkKeyValue listsAsDuplicateKeys; } sectValues; in # map input to ini sections mapAttrsToStringsSep "\n" mkSection attrsOfAttrs; /* 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: with builtins; let mkSectionName = name: let containsQuote = libStr.hasInfix ''"'' name; sections = libStr.splitString "." name; section = head sections; subsections = tail sections; subsection = concatStringsSep "." subsections; in if containsQuote || subsections == [ ] then name else ''${section} "${subsection}"''; # generation for multiple ini values mkKeyValue = k: v: let mkKeyValue = mkKeyValueDefault { } " = " k; in concatStringsSep "\n" (map (kv: "\t" + mkKeyValue kv) (lib.toList v)); # converts { a.b.c = 5; } to { "a.b".c = 5; } for toINI gitFlattenAttrs = let recurse = path: value: if isAttrs value then lib.mapAttrsToList (name: value: recurse ([ name ] ++ path) value) value else if length path > 1 then { ${concatStringsSep "." (lib.reverseList (tail path))}.${head path} = value; } else { ${head path} = value; }; in attrs: lib.foldl lib.recursiveUpdate { } (lib.flatten (recurse [ ] attrs)); toINI_ = toINI { inherit mkKeyValue mkSectionName; }; in toINI_ (gitFlattenAttrs attrs); /* Generates JSON from an arbitrary (non-function) value. * For more information see the documentation of the builtin. */ toJSON = {}: builtins.toJSON; /* YAML has been a strict superset of JSON since 1.2, so we * use toJSON. Before it only had a few differences referring * to implicit typing rules, so it should work with older * parsers as well. */ toYAML = {}@args: toJSON args; /* Pretty print a value, akin to `builtins.trace`. * Should probably be a builtin as well. */ toPretty = { /* If this option is true, attrsets like { __pretty = fn; val = …; } will use fn to convert val to a pretty printed representation. (This means fn is type Val -> String.) */ allowPrettyValues ? false, /* If this option is true, the output is indented with newlines for attribute sets and lists */ multiline ? true }@args: let go = indent: v: with builtins; let isPath = v: typeOf v == "path"; introSpace = if multiline then "\n${indent} " else " "; outroSpace = if multiline then "\n${indent}" else " "; in if isInt v then toString v else if isFloat v then "~${toString v}" else if isString v then let # Separate a string into its lines newlineSplits = filter (v: ! isList v) (builtins.split "\n" v); # For a '' string terminated by a \n, which happens when the closing '' is on a new line multilineResult = "''" + introSpace + concatStringsSep introSpace (lib.init newlineSplits) + outroSpace + "''"; # For a '' string not terminated by a \n, which happens when the closing '' is not on a new line multilineResult' = "''" + introSpace + concatStringsSep introSpace newlineSplits + "''"; # For single lines, replace all newlines with their escaped representation singlelineResult = "\"" + libStr.escape [ "\"" ] (concatStringsSep "\\n" newlineSplits) + "\""; in if multiline && length newlineSplits > 1 then if lib.last newlineSplits == "" then multilineResult else 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 + libStr.concatMapStringsSep introSpace (go (indent + " ")) v + outroSpace + "]" else if isFunction v then let fna = lib.functionArgs v; showFnas = concatStringsSep ", " (libAttr.mapAttrsToList (name: hasDefVal: if hasDefVal then name + "?" else name) fna); in if fna == {} then "" else "" else if isAttrs v then # apply pretty values if allowed if attrNames v == [ "__pretty" "val" ] && allowPrettyValues then v.__pretty v.val else if v == {} then "{ }" else if v ? type && v.type == "derivation" then "" else "{" + introSpace + libStr.concatStringsSep introSpace (libAttr.mapAttrsToList (name: value: "${libStr.escapeNixIdentifier name} = ${go (indent + " ") value};") v) + outroSpace + "}" else abort "generators.toPretty: should never happen (v = ${v})"; in go ""; # PLIST handling toPlist = {}: v: let isFloat = builtins.isFloat or (x: false); expr = ind: x: with builtins; if x == null then "" else if isBool x then bool ind x else if isInt x then int ind x else if isString x then str ind x else if isList x then list ind x else if isAttrs x then attrs ind x else if isFloat x then float ind x else abort "generators.toPlist: should never happen (v = ${v})"; literal = ind: x: ind + x; bool = ind: x: literal ind (if x then "" else ""); int = ind: x: literal ind "${toString x}"; str = ind: x: literal ind "${x}"; key = ind: x: literal ind "${x}"; float = ind: x: literal ind "${toString x}"; indent = ind: expr "\t${ind}"; item = ind: libStr.concatMapStringsSep "\n" (indent ind); list = ind: x: libStr.concatStringsSep "\n" [ (literal ind "") (item ind x) (literal ind "") ]; attrs = ind: x: libStr.concatStringsSep "\n" [ (literal ind "") (attr ind x) (literal ind "") ]; attr = let attrFilter = name: value: name != "_module" && value != null; in ind: x: libStr.concatStringsSep "\n" (lib.flatten (lib.mapAttrsToList (name: value: lib.optional (attrFilter name value) [ (key "\t${ind}" name) (expr "\t${ind}" value) ]) x)); in '' ${expr "" v} ''; /* Translate a simple Nix expression to Dhall notation. * Note that integers are translated to Integer and never * the Natural type. */ toDhall = { }@args: v: with builtins; let concatItems = lib.strings.concatStringsSep ", "; in if isAttrs v then "{ ${ concatItems (lib.attrsets.mapAttrsToList (key: value: "${key} = ${toDhall args value}") v) } }" else if isList v then "[ ${concatItems (map (toDhall args) v)} ]" else if isInt v then "${if v < 0 then "" else "+"}${toString v}" else if isBool v then (if v then "True" else "False") else if isFunction v then abort "generators.toDhall: cannot convert a function to Dhall" else if isNull v then abort "generators.toDhall: cannot convert a null to Dhall" else builtins.toJSON v; }