/* String manipulation functions. */ { lib }: let inherit (builtins) length; in rec { inherit (builtins) stringLength substring head tail isString replaceStrings; /* Concatenate a list of strings. Type: concatStrings :: [string] -> string Example: concatStrings ["foo" "bar"] => "foobar" */ concatStrings = builtins.concatStringsSep ""; /* Map a function over a list and concatenate the resulting strings. Type: concatMapStrings :: (a -> string) -> [a] -> string Example: concatMapStrings (x: "a" + x) ["foo" "bar"] => "afooabar" */ concatMapStrings = f: list: concatStrings (map f list); /* Like `concatMapStrings` except that the f functions also gets the position as a parameter. Type: concatImapStrings :: (int -> a -> string) -> [a] -> string Example: concatImapStrings (pos: x: "${toString pos}-${x}") ["foo" "bar"] => "1-foo2-bar" */ concatImapStrings = f: list: concatStrings (lib.imap1 f list); /* Place an element between each element of a list Type: intersperse :: a -> [a] -> [a] Example: intersperse "/" ["usr" "local" "bin"] => ["usr" "/" "local" "/" "bin"]. */ intersperse = # Separator to add between elements separator: # Input list list: if list == [] || length list == 1 then list else tail (lib.concatMap (x: [separator x]) list); /* Concatenate a list of strings with a separator between each element Type: concatStringsSep :: string -> [string] -> string Example: concatStringsSep "/" ["usr" "local" "bin"] => "usr/local/bin" */ concatStringsSep = builtins.concatStringsSep or (separator: list: concatStrings (intersperse separator list)); /* Maps a function over a list of strings and then concatenates the result with the specified separator interspersed between elements. Type: concatMapStringsSep :: string -> (string -> string) -> [string] -> string Example: concatMapStringsSep "-" (x: toUpper x) ["foo" "bar" "baz"] => "FOO-BAR-BAZ" */ concatMapStringsSep = # Separator to add between elements sep: # Function to map over the list f: # List of input strings list: concatStringsSep sep (map f list); /* Same as `concatMapStringsSep`, but the mapping function additionally receives the position of its argument. Type: concatIMapStringsSep :: string -> (int -> string -> string) -> [string] -> string Example: concatImapStringsSep "-" (pos: x: toString (x / pos)) [ 6 6 6 ] => "6-3-2" */ concatImapStringsSep = # Separator to add between elements sep: # Function that receives elements and their positions f: # List of input strings list: concatStringsSep sep (lib.imap1 f list); /* Construct a Unix-style, colon-separated search path consisting of the given `subDir` appended to each of the given paths. Type: makeSearchPath :: string -> [string] -> string Example: makeSearchPath "bin" ["/root" "/usr" "/usr/local"] => "/root/bin:/usr/bin:/usr/local/bin" makeSearchPath "bin" [""] => "/bin" */ makeSearchPath = # Directory name to append subDir: # List of base paths paths: concatStringsSep ":" (map (path: path + "/" + subDir) (builtins.filter (x: x != null) paths)); /* Construct a Unix-style search path by appending the given `subDir` to the specified `output` of each of the packages. If no output by the given name is found, fallback to `.out` and then to the default. Type: string -> string -> [package] -> string Example: makeSearchPathOutput "dev" "bin" [ pkgs.openssl pkgs.zlib ] => "/nix/store/9rz8gxhzf8sw4kf2j2f1grr49w8zx5vj-openssl-1.0.1r-dev/bin:/nix/store/wwh7mhwh269sfjkm6k5665b5kgp7jrk2-zlib-1.2.8/bin" */ makeSearchPathOutput = # Package output to use output: # Directory name to append subDir: # List of packages pkgs: makeSearchPath subDir (map (lib.getOutput output) pkgs); /* Construct a library search path (such as RPATH) containing the libraries for a set of packages Example: makeLibraryPath [ "/usr" "/usr/local" ] => "/usr/lib:/usr/local/lib" pkgs = import <nixpkgs> { } makeLibraryPath [ pkgs.openssl pkgs.zlib ] => "/nix/store/9rz8gxhzf8sw4kf2j2f1grr49w8zx5vj-openssl-1.0.1r/lib:/nix/store/wwh7mhwh269sfjkm6k5665b5kgp7jrk2-zlib-1.2.8/lib" */ makeLibraryPath = makeSearchPathOutput "lib" "lib"; /* Construct a binary search path (such as $PATH) containing the binaries for a set of packages. Example: makeBinPath ["/root" "/usr" "/usr/local"] => "/root/bin:/usr/bin:/usr/local/bin" */ makeBinPath = makeSearchPathOutput "bin" "bin"; /* Depending on the boolean `cond', return either the given string or the empty string. Useful to concatenate against a bigger string. Type: optionalString :: bool -> string -> string Example: optionalString true "some-string" => "some-string" optionalString false "some-string" => "" */ optionalString = # Condition cond: # String to return if condition is true string: if cond then string else ""; /* Determine whether a string has given prefix. Type: hasPrefix :: string -> string -> bool Example: hasPrefix "foo" "foobar" => true hasPrefix "foo" "barfoo" => false */ hasPrefix = # Prefix to check for pref: # Input string str: substring 0 (stringLength pref) str == pref; /* Determine whether a string has given suffix. Type: hasSuffix :: string -> string -> bool Example: hasSuffix "foo" "foobar" => false hasSuffix "foo" "barfoo" => true */ hasSuffix = # Suffix to check for suffix: # Input string content: let lenContent = stringLength content; lenSuffix = stringLength suffix; in lenContent >= lenSuffix && substring (lenContent - lenSuffix) lenContent content == suffix; /* Determine whether a string contains the given infix Type: hasInfix :: string -> string -> bool Example: hasInfix "bc" "abcd" => true hasInfix "ab" "abcd" => true hasInfix "cd" "abcd" => true hasInfix "foo" "abcd" => false */ hasInfix = infix: content: let drop = x: substring 1 (stringLength x) x; in hasPrefix infix content || content != "" && hasInfix infix (drop content); /* Convert a string to a list of characters (i.e. singleton strings). This allows you to, e.g., map a function over each character. However, note that this will likely be horribly inefficient; Nix is not a general purpose programming language. Complex string manipulations should, if appropriate, be done in a derivation. Also note that Nix treats strings as a list of bytes and thus doesn't handle unicode. Type: stringtoCharacters :: string -> [string] Example: stringToCharacters "" => [ ] stringToCharacters "abc" => [ "a" "b" "c" ] stringToCharacters "💩" => [ "�" "�" "�" "�" ] */ stringToCharacters = s: map (p: substring p 1 s) (lib.range 0 (stringLength s - 1)); /* Manipulate a string character by character and replace them by strings before concatenating the results. Type: stringAsChars :: (string -> string) -> string -> string Example: stringAsChars (x: if x == "a" then "i" else x) "nax" => "nix" */ stringAsChars = # Function to map over each individual character f: # Input string s: concatStrings ( map f (stringToCharacters s) ); /* Escape occurrence of the elements of `list` in `string` by prefixing it with a backslash. Type: escape :: [string] -> string -> string Example: escape ["(" ")"] "(foo)" => "\\(foo\\)" */ escape = list: replaceChars list (map (c: "\\${c}") list); /* Quote string to be used safely within the Bourne shell. Type: escapeShellArg :: string -> string Example: escapeShellArg "esc'ape\nme" => "'esc'\\''ape\nme'" */ escapeShellArg = arg: "'${replaceStrings ["'"] ["'\\''"] (toString arg)}'"; /* Quote all arguments to be safely passed to the Bourne shell. Type: escapeShellArgs :: [string] -> string Example: escapeShellArgs ["one" "two three" "four'five"] => "'one' 'two three' 'four'\\''five'" */ escapeShellArgs = concatMapStringsSep " " escapeShellArg; /* Turn a string into a Nix expression representing that string Type: string -> string Example: escapeNixString "hello\${}\n" => "\"hello\\\${}\\n\"" */ escapeNixString = s: escape ["$"] (builtins.toJSON s); # Obsolete - use replaceStrings instead. replaceChars = builtins.replaceStrings or ( del: new: s: let substList = lib.zipLists del new; subst = c: let found = lib.findFirst (sub: sub.fst == c) null substList; in if found == null then c else found.snd; in stringAsChars subst s); # Case conversion utilities. lowerChars = stringToCharacters "abcdefghijklmnopqrstuvwxyz"; upperChars = stringToCharacters "ABCDEFGHIJKLMNOPQRSTUVWXYZ"; /* Converts an ASCII string to lower-case. Type: toLower :: string -> string Example: toLower "HOME" => "home" */ toLower = replaceChars upperChars lowerChars; /* Converts an ASCII string to upper-case. Type: toUpper :: string -> string Example: toUpper "home" => "HOME" */ toUpper = replaceChars lowerChars upperChars; /* Appends string context from another string. This is an implementation detail of Nix. Strings in Nix carry an invisible `context` which is a list of strings representing store paths. If the string is later used in a derivation attribute, the derivation will properly populate the inputDrvs and inputSrcs. Example: pkgs = import <nixpkgs> { }; addContextFrom pkgs.coreutils "bar" => "bar" */ addContextFrom = a: b: substring 0 0 a + b; /* Cut a string with a separator and produces a list of strings which were separated by this separator. NOTE: this function is not performant and should never be used. Example: splitString "." "foo.bar.baz" => [ "foo" "bar" "baz" ] splitString "/" "/usr/local/bin" => [ "" "usr" "local" "bin" ] */ splitString = _sep: _s: let sep = addContextFrom _s _sep; s = addContextFrom _sep _s; sepLen = stringLength sep; sLen = stringLength s; lastSearch = sLen - sepLen; startWithSep = startAt: substring startAt sepLen s == sep; recurse = index: startAt: let cutUntil = i: [(substring startAt (i - startAt) s)]; in if index <= lastSearch then if startWithSep index then let restartAt = index + sepLen; in cutUntil index ++ recurse restartAt restartAt else recurse (index + 1) startAt else cutUntil sLen; in recurse 0 0; /* Return a string without the specified prefix, if the prefix matches. Type: string -> string -> string Example: removePrefix "foo." "foo.bar.baz" => "bar.baz" removePrefix "xxx" "foo.bar.baz" => "foo.bar.baz" */ removePrefix = # Prefix to remove if it matches prefix: # Input string str: let preLen = stringLength prefix; sLen = stringLength str; in if hasPrefix prefix str then substring preLen (sLen - preLen) str else str; /* Return a string without the specified suffix, if the suffix matches. Type: string -> string -> string Example: removeSuffix "front" "homefront" => "home" removeSuffix "xxx" "homefront" => "homefront" */ removeSuffix = # Suffix to remove if it matches suffix: # Input string str: let sufLen = stringLength suffix; sLen = stringLength str; in if sufLen <= sLen && suffix == substring (sLen - sufLen) sufLen str then substring 0 (sLen - sufLen) str else str; /* Return true if string v1 denotes a version older than v2. Example: versionOlder "1.1" "1.2" => true versionOlder "1.1" "1.1" => false */ versionOlder = v1: v2: builtins.compareVersions v2 v1 == 1; /* Return true if string v1 denotes a version equal to or newer than v2. Example: versionAtLeast "1.1" "1.0" => true versionAtLeast "1.1" "1.1" => true versionAtLeast "1.1" "1.2" => false */ versionAtLeast = v1: v2: !versionOlder v1 v2; /* This function takes an argument that's either a derivation or a derivation's "name" attribute and extracts the name part from that argument. Example: getName "youtube-dl-2016.01.01" => "youtube-dl" getName pkgs.youtube-dl => "youtube-dl" */ getName = x: let parse = drv: (builtins.parseDrvName drv).name; in if isString x then parse x else x.pname or (parse x.name); /* This function takes an argument that's either a derivation or a derivation's "name" attribute and extracts the version part from that argument. Example: getVersion "youtube-dl-2016.01.01" => "2016.01.01" getVersion pkgs.youtube-dl => "2016.01.01" */ getVersion = x: let parse = drv: (builtins.parseDrvName drv).version; in if isString x then parse x else x.version or (parse x.name); /* Extract name with version from URL. Ask for separator which is supposed to start extension. Example: nameFromURL "https://nixos.org/releases/nix/nix-1.7/nix-1.7-x86_64-linux.tar.bz2" "-" => "nix" nameFromURL "https://nixos.org/releases/nix/nix-1.7/nix-1.7-x86_64-linux.tar.bz2" "_" => "nix-1.7-x86" */ nameFromURL = url: sep: let components = splitString "/" url; filename = lib.last components; name = builtins.head (splitString sep filename); in assert name != filename; name; /* Create an --{enable,disable}-<feat> string that can be passed to standard GNU Autoconf scripts. Example: enableFeature true "shared" => "--enable-shared" enableFeature false "shared" => "--disable-shared" */ enableFeature = enable: feat: "--${if enable then "enable" else "disable"}-${feat}"; /* Create an --{enable-<feat>=<value>,disable-<feat>} string that can be passed to standard GNU Autoconf scripts. Example: enableFeature true "shared" "foo" => "--enable-shared=foo" enableFeature false "shared" (throw "ignored") => "--disable-shared" */ enableFeatureAs = enable: feat: value: enableFeature enable feat + optionalString enable "=${value}"; /* Create an --{with,without}-<feat> string that can be passed to standard GNU Autoconf scripts. Example: withFeature true "shared" => "--with-shared" withFeature false "shared" => "--without-shared" */ withFeature = with_: feat: "--${if with_ then "with" else "without"}-${feat}"; /* Create an --{with-<feat>=<value>,without-<feat>} string that can be passed to standard GNU Autoconf scripts. Example: with_Feature true "shared" "foo" => "--with-shared=foo" with_Feature false "shared" (throw "ignored") => "--without-shared" */ withFeatureAs = with_: feat: value: withFeature with_ feat + optionalString with_ "=${value}"; /* Create a fixed width string with additional prefix to match required width. This function will fail if the input string is longer than the requested length. Type: fixedWidthString :: int -> string -> string Example: fixedWidthString 5 "0" (toString 15) => "00015" */ fixedWidthString = width: filler: str: let strw = lib.stringLength str; reqWidth = width - (lib.stringLength filler); in assert lib.assertMsg (strw <= width) "fixedWidthString: requested string length (${ toString width}) must not be shorter than actual length (${ toString strw})"; if strw == width then str else filler + fixedWidthString reqWidth filler str; /* Format a number adding leading zeroes up to fixed width. Example: fixedWidthNumber 5 15 => "00015" */ fixedWidthNumber = width: n: fixedWidthString width "0" (toString n); /* Check whether a value can be coerced to a string */ isCoercibleToString = x: builtins.elem (builtins.typeOf x) [ "path" "string" "null" "int" "float" "bool" ] || (builtins.isList x && lib.all isCoercibleToString x) || x ? outPath || x ? __toString; /* Check whether a value is a store path. Example: isStorePath "/nix/store/d945ibfx9x185xf04b890y4f9g3cbb63-python-2.7.11/bin/python" => false isStorePath "/nix/store/d945ibfx9x185xf04b890y4f9g3cbb63-python-2.7.11/" => true isStorePath pkgs.python => true isStorePath [] || isStorePath 42 || isStorePath {} || … => false */ isStorePath = x: if isCoercibleToString x then let str = toString x; in builtins.substring 0 1 str == "/" && dirOf str == builtins.storeDir else false; /* Parse a string string as an int. Type: string -> int Example: toInt "1337" => 1337 toInt "-4" => -4 toInt "3.14" => error: floating point JSON numbers are not supported */ # Obviously, it is a bit hacky to use fromJSON this way. toInt = str: let may_be_int = builtins.fromJSON str; in if builtins.isInt may_be_int then may_be_int else throw "Could not convert ${str} to int."; /* Read a list of paths from `file`, relative to the `rootPath`. Lines beginning with `#` are treated as comments and ignored. Whitespace is significant. NOTE: This function is not performant and should be avoided. Example: readPathsFromFile /prefix ./pkgs/development/libraries/qt-5/5.4/qtbase/series => [ "/prefix/dlopen-resolv.patch" "/prefix/tzdir.patch" "/prefix/dlopen-libXcursor.patch" "/prefix/dlopen-openssl.patch" "/prefix/dlopen-dbus.patch" "/prefix/xdg-config-dirs.patch" "/prefix/nix-profiles-library-paths.patch" "/prefix/compose-search-path.patch" ] */ readPathsFromFile = rootPath: file: let lines = lib.splitString "\n" (builtins.readFile file); removeComments = lib.filter (line: line != "" && !(lib.hasPrefix "#" line)); relativePaths = removeComments lines; absolutePaths = builtins.map (path: rootPath + "/${path}") relativePaths; in absolutePaths; /* Read the contents of a file removing the trailing \n Type: fileContents :: path -> string Example: $ echo "1.0" > ./version fileContents ./version => "1.0" */ fileContents = file: removeSuffix "\n" (builtins.readFile file); }