mirror of
https://github.com/NixOS/nixpkgs.git
synced 2024-12-05 21:33:07 +00:00
970 lines
28 KiB
Nix
970 lines
28 KiB
Nix
/* String manipulation functions. */
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{ lib }:
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let
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inherit (builtins) length;
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in
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rec {
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inherit (builtins)
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compareVersions
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elem
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elemAt
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filter
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fromJSON
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head
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isInt
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isList
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isAttrs
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isString
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match
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parseDrvName
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readFile
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replaceStrings
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split
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storeDir
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stringLength
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substring
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tail
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toJSON
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typeOf
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unsafeDiscardStringContext
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;
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/* Concatenate a list of strings.
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Type: concatStrings :: [string] -> string
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Example:
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concatStrings ["foo" "bar"]
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=> "foobar"
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*/
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concatStrings = builtins.concatStringsSep "";
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/* Map a function over a list and concatenate the resulting strings.
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Type: concatMapStrings :: (a -> string) -> [a] -> string
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Example:
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concatMapStrings (x: "a" + x) ["foo" "bar"]
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=> "afooabar"
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*/
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concatMapStrings = f: list: concatStrings (map f list);
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/* Like `concatMapStrings` except that the f functions also gets the
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position as a parameter.
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Type: concatImapStrings :: (int -> a -> string) -> [a] -> string
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Example:
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concatImapStrings (pos: x: "${toString pos}-${x}") ["foo" "bar"]
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=> "1-foo2-bar"
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*/
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concatImapStrings = f: list: concatStrings (lib.imap1 f list);
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/* Place an element between each element of a list
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Type: intersperse :: a -> [a] -> [a]
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Example:
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intersperse "/" ["usr" "local" "bin"]
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=> ["usr" "/" "local" "/" "bin"].
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*/
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intersperse =
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# Separator to add between elements
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separator:
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# Input list
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list:
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if list == [] || length list == 1
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then list
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else tail (lib.concatMap (x: [separator x]) list);
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/* Concatenate a list of strings with a separator between each element
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Type: concatStringsSep :: string -> [string] -> string
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Example:
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concatStringsSep "/" ["usr" "local" "bin"]
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=> "usr/local/bin"
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*/
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concatStringsSep = builtins.concatStringsSep or (separator: list:
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lib.foldl' (x: y: x + y) "" (intersperse separator list));
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/* Maps a function over a list of strings and then concatenates the
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result with the specified separator interspersed between
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elements.
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Type: concatMapStringsSep :: string -> (a -> string) -> [a] -> string
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Example:
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concatMapStringsSep "-" (x: toUpper x) ["foo" "bar" "baz"]
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=> "FOO-BAR-BAZ"
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*/
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concatMapStringsSep =
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# Separator to add between elements
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sep:
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# Function to map over the list
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f:
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# List of input strings
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list: concatStringsSep sep (map f list);
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/* Same as `concatMapStringsSep`, but the mapping function
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additionally receives the position of its argument.
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Type: concatIMapStringsSep :: string -> (int -> a -> string) -> [a] -> string
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Example:
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concatImapStringsSep "-" (pos: x: toString (x / pos)) [ 6 6 6 ]
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=> "6-3-2"
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*/
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concatImapStringsSep =
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# Separator to add between elements
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sep:
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# Function that receives elements and their positions
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f:
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# List of input strings
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list: concatStringsSep sep (lib.imap1 f list);
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/* Construct a Unix-style, colon-separated search path consisting of
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the given `subDir` appended to each of the given paths.
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Type: makeSearchPath :: string -> [string] -> string
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Example:
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makeSearchPath "bin" ["/root" "/usr" "/usr/local"]
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=> "/root/bin:/usr/bin:/usr/local/bin"
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makeSearchPath "bin" [""]
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=> "/bin"
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*/
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makeSearchPath =
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# Directory name to append
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subDir:
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# List of base paths
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paths:
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concatStringsSep ":" (map (path: path + "/" + subDir) (filter (x: x != null) paths));
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/* Construct a Unix-style search path by appending the given
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`subDir` to the specified `output` of each of the packages. If no
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output by the given name is found, fallback to `.out` and then to
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the default.
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Type: string -> string -> [package] -> string
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Example:
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makeSearchPathOutput "dev" "bin" [ pkgs.openssl pkgs.zlib ]
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=> "/nix/store/9rz8gxhzf8sw4kf2j2f1grr49w8zx5vj-openssl-1.0.1r-dev/bin:/nix/store/wwh7mhwh269sfjkm6k5665b5kgp7jrk2-zlib-1.2.8/bin"
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*/
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makeSearchPathOutput =
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# Package output to use
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output:
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# Directory name to append
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subDir:
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# List of packages
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pkgs: makeSearchPath subDir (map (lib.getOutput output) pkgs);
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/* Construct a library search path (such as RPATH) containing the
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libraries for a set of packages
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Example:
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makeLibraryPath [ "/usr" "/usr/local" ]
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=> "/usr/lib:/usr/local/lib"
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pkgs = import <nixpkgs> { }
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makeLibraryPath [ pkgs.openssl pkgs.zlib ]
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=> "/nix/store/9rz8gxhzf8sw4kf2j2f1grr49w8zx5vj-openssl-1.0.1r/lib:/nix/store/wwh7mhwh269sfjkm6k5665b5kgp7jrk2-zlib-1.2.8/lib"
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*/
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makeLibraryPath = makeSearchPathOutput "lib" "lib";
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/* Construct a binary search path (such as $PATH) containing the
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binaries for a set of packages.
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Example:
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makeBinPath ["/root" "/usr" "/usr/local"]
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=> "/root/bin:/usr/bin:/usr/local/bin"
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*/
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makeBinPath = makeSearchPathOutput "bin" "bin";
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/* Depending on the boolean `cond', return either the given string
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or the empty string. Useful to concatenate against a bigger string.
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Type: optionalString :: bool -> string -> string
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Example:
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optionalString true "some-string"
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=> "some-string"
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optionalString false "some-string"
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=> ""
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*/
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optionalString =
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# Condition
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cond:
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# String to return if condition is true
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string: if cond then string else "";
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/* Determine whether a string has given prefix.
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Type: hasPrefix :: string -> string -> bool
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Example:
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hasPrefix "foo" "foobar"
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=> true
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hasPrefix "foo" "barfoo"
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=> false
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*/
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hasPrefix =
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# Prefix to check for
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pref:
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# Input string
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str: substring 0 (stringLength pref) str == pref;
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/* Determine whether a string has given suffix.
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Type: hasSuffix :: string -> string -> bool
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Example:
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hasSuffix "foo" "foobar"
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=> false
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hasSuffix "foo" "barfoo"
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=> true
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*/
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hasSuffix =
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# Suffix to check for
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suffix:
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# Input string
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content:
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let
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lenContent = stringLength content;
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lenSuffix = stringLength suffix;
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in lenContent >= lenSuffix &&
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substring (lenContent - lenSuffix) lenContent content == suffix;
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/* Determine whether a string contains the given infix
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Type: hasInfix :: string -> string -> bool
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Example:
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hasInfix "bc" "abcd"
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=> true
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hasInfix "ab" "abcd"
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=> true
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hasInfix "cd" "abcd"
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=> true
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hasInfix "foo" "abcd"
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=> false
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*/
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hasInfix = infix: content:
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builtins.match ".*${escapeRegex infix}.*" "${content}" != null;
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/* Convert a string to a list of characters (i.e. singleton strings).
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This allows you to, e.g., map a function over each character. However,
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note that this will likely be horribly inefficient; Nix is not a
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general purpose programming language. Complex string manipulations
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should, if appropriate, be done in a derivation.
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Also note that Nix treats strings as a list of bytes and thus doesn't
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handle unicode.
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Type: stringToCharacters :: string -> [string]
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Example:
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stringToCharacters ""
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=> [ ]
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stringToCharacters "abc"
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=> [ "a" "b" "c" ]
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stringToCharacters "💩"
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=> [ "<EFBFBD>" "<EFBFBD>" "<EFBFBD>" "<EFBFBD>" ]
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*/
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stringToCharacters = s:
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map (p: substring p 1 s) (lib.range 0 (stringLength s - 1));
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/* Manipulate a string character by character and replace them by
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strings before concatenating the results.
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Type: stringAsChars :: (string -> string) -> string -> string
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Example:
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stringAsChars (x: if x == "a" then "i" else x) "nax"
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=> "nix"
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*/
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stringAsChars =
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# Function to map over each individual character
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f:
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# Input string
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s: concatStrings (
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map f (stringToCharacters s)
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);
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/* Escape occurrence of the elements of `list` in `string` by
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prefixing it with a backslash.
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Type: escape :: [string] -> string -> string
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Example:
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escape ["(" ")"] "(foo)"
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=> "\\(foo\\)"
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*/
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escape = list: replaceChars list (map (c: "\\${c}") list);
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/* Quote string to be used safely within the Bourne shell.
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Type: escapeShellArg :: string -> string
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Example:
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escapeShellArg "esc'ape\nme"
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=> "'esc'\\''ape\nme'"
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*/
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escapeShellArg = arg: "'${replaceStrings ["'"] ["'\\''"] (toString arg)}'";
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/* Quote all arguments to be safely passed to the Bourne shell.
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Type: escapeShellArgs :: [string] -> string
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Example:
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escapeShellArgs ["one" "two three" "four'five"]
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=> "'one' 'two three' 'four'\\''five'"
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*/
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escapeShellArgs = concatMapStringsSep " " escapeShellArg;
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/* Test whether the given name is a valid POSIX shell variable name.
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Type: string -> bool
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Example:
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isValidPosixName "foo_bar000"
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=> true
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isValidPosixName "0-bad.jpg"
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=> false
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*/
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isValidPosixName = name: match "[a-zA-Z_][a-zA-Z0-9_]*" name != null;
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/* Translate a Nix value into a shell variable declaration, with proper escaping.
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The value can be a string (mapped to a regular variable), a list of strings
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(mapped to a Bash-style array) or an attribute set of strings (mapped to a
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Bash-style associative array). Note that "string" includes string-coercible
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values like paths or derivations.
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Strings are translated into POSIX sh-compatible code; lists and attribute sets
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assume a shell that understands Bash syntax (e.g. Bash or ZSH).
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Type: string -> (string | listOf string | attrsOf string) -> string
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Example:
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''
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${toShellVar "foo" "some string"}
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[[ "$foo" == "some string" ]]
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''
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*/
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toShellVar = name: value:
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lib.throwIfNot (isValidPosixName name) "toShellVar: ${name} is not a valid shell variable name" (
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if isAttrs value && ! isCoercibleToString value then
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"declare -A ${name}=(${
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concatStringsSep " " (lib.mapAttrsToList (n: v:
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"[${escapeShellArg n}]=${escapeShellArg v}"
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) value)
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})"
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else if isList value then
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"declare -a ${name}=(${escapeShellArgs value})"
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else
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"${name}=${escapeShellArg value}"
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);
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/* Translate an attribute set into corresponding shell variable declarations
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using `toShellVar`.
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Type: attrsOf (string | listOf string | attrsOf string) -> string
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Example:
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let
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foo = "value";
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bar = foo;
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in ''
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${toShellVars { inherit foo bar; }}
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[[ "$foo" == "$bar" ]]
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''
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*/
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toShellVars = vars: concatStringsSep "\n" (lib.mapAttrsToList toShellVar vars);
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/* Turn a string into a Nix expression representing that string
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Type: string -> string
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Example:
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escapeNixString "hello\${}\n"
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=> "\"hello\\\${}\\n\""
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*/
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escapeNixString = s: escape ["$"] (toJSON s);
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/* Turn a string into an exact regular expression
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Type: string -> string
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Example:
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escapeRegex "[^a-z]*"
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=> "\\[\\^a-z]\\*"
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*/
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escapeRegex = escape (stringToCharacters "\\[{()^$?*+|.");
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/* Quotes a string if it can't be used as an identifier directly.
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Type: string -> string
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Example:
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escapeNixIdentifier "hello"
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=> "hello"
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escapeNixIdentifier "0abc"
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=> "\"0abc\""
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*/
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escapeNixIdentifier = s:
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# Regex from https://github.com/NixOS/nix/blob/d048577909e383439c2549e849c5c2f2016c997e/src/libexpr/lexer.l#L91
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if match "[a-zA-Z_][a-zA-Z0-9_'-]*" s != null
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then s else escapeNixString s;
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/* Escapes a string such that it is safe to include verbatim in an XML
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document.
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Type: string -> string
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Example:
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escapeXML ''"test" 'test' < & >''
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=> ""test" 'test' < & >"
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*/
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escapeXML = builtins.replaceStrings
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["\"" "'" "<" ">" "&"]
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[""" "'" "<" ">" "&"];
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# Obsolete - use replaceStrings instead.
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replaceChars = builtins.replaceStrings or (
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del: new: s:
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let
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substList = lib.zipLists del new;
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subst = c:
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let found = lib.findFirst (sub: sub.fst == c) null substList; in
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if found == null then
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c
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else
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found.snd;
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in
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stringAsChars subst s);
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# Case conversion utilities.
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lowerChars = stringToCharacters "abcdefghijklmnopqrstuvwxyz";
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upperChars = stringToCharacters "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
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/* Converts an ASCII string to lower-case.
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Type: toLower :: string -> string
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Example:
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toLower "HOME"
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=> "home"
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*/
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toLower = replaceChars upperChars lowerChars;
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/* Converts an ASCII string to upper-case.
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Type: toUpper :: string -> string
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Example:
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toUpper "home"
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=> "HOME"
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*/
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toUpper = replaceChars lowerChars upperChars;
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/* Appends string context from another string. This is an implementation
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detail of Nix.
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Strings in Nix carry an invisible `context` which is a list of strings
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representing store paths. If the string is later used in a derivation
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attribute, the derivation will properly populate the inputDrvs and
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inputSrcs.
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Example:
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pkgs = import <nixpkgs> { };
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addContextFrom pkgs.coreutils "bar"
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=> "bar"
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*/
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addContextFrom = a: b: substring 0 0 a + b;
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/* Cut a string with a separator and produces a list of strings which
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were separated by this separator.
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Example:
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splitString "." "foo.bar.baz"
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=> [ "foo" "bar" "baz" ]
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splitString "/" "/usr/local/bin"
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=> [ "" "usr" "local" "bin" ]
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*/
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splitString = _sep: _s:
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let
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sep = builtins.unsafeDiscardStringContext _sep;
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s = builtins.unsafeDiscardStringContext _s;
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splits = builtins.filter builtins.isString (builtins.split (escapeRegex sep) s);
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in
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map (v: addContextFrom _sep (addContextFrom _s v)) splits;
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/* Return a string without the specified prefix, if the prefix matches.
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Type: string -> string -> string
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Example:
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removePrefix "foo." "foo.bar.baz"
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=> "bar.baz"
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removePrefix "xxx" "foo.bar.baz"
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=> "foo.bar.baz"
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*/
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removePrefix =
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# Prefix to remove if it matches
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prefix:
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# Input string
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str:
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let
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preLen = stringLength prefix;
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sLen = stringLength str;
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in
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if hasPrefix prefix str then
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substring preLen (sLen - preLen) str
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else
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str;
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/* Return a string without the specified suffix, if the suffix matches.
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Type: string -> string -> string
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Example:
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removeSuffix "front" "homefront"
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=> "home"
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removeSuffix "xxx" "homefront"
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=> "homefront"
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*/
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removeSuffix =
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# Suffix to remove if it matches
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suffix:
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# Input string
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str:
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let
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sufLen = stringLength suffix;
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sLen = stringLength str;
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in
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if sufLen <= sLen && suffix == substring (sLen - sufLen) sufLen str then
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substring 0 (sLen - sufLen) str
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else
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str;
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/* Return true if string v1 denotes a version older than v2.
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Example:
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versionOlder "1.1" "1.2"
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=> true
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versionOlder "1.1" "1.1"
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=> false
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*/
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versionOlder = v1: v2: compareVersions v2 v1 == 1;
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/* Return true if string v1 denotes a version equal to or newer than v2.
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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: (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: (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 = 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:
|
||
assert isString feat; # e.g. passing openssl instead of "openssl"
|
||
"--${if enable then "enable" else "disable"}-${feat}";
|
||
|
||
/* Create an --{enable-<feat>=<value>,disable-<feat>} string that can be passed to
|
||
standard GNU Autoconf scripts.
|
||
|
||
Example:
|
||
enableFeatureAs true "shared" "foo"
|
||
=> "--enable-shared=foo"
|
||
enableFeatureAs false "shared" (throw "ignored")
|
||
=> "--disable-shared"
|
||
*/
|
||
enableFeatureAs = enable: feat: value: enableFeature enable feat + optionalString enable "=${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:
|
||
assert isString feat; # e.g. passing openssl instead of "openssl"
|
||
"--${if with_ then "with" else "without"}-${feat}";
|
||
|
||
/* Create an --{with-<feat>=<value>,without-<feat>} string that can be passed to
|
||
standard GNU Autoconf scripts.
|
||
|
||
Example:
|
||
withFeatureAs true "shared" "foo"
|
||
=> "--with-shared=foo"
|
||
withFeatureAs false "shared" (throw "ignored")
|
||
=> "--without-shared"
|
||
*/
|
||
withFeatureAs = with_: feat: value: withFeature with_ feat + optionalString with_ "=${value}";
|
||
|
||
/* Create a fixed width string with additional prefix to match
|
||
required width.
|
||
|
||
This function will fail if the input string is longer than the
|
||
requested length.
|
||
|
||
Type: fixedWidthString :: int -> string -> string -> string
|
||
|
||
Example:
|
||
fixedWidthString 5 "0" (toString 15)
|
||
=> "00015"
|
||
*/
|
||
fixedWidthString = width: filler: str:
|
||
let
|
||
strw = lib.stringLength str;
|
||
reqWidth = width - (lib.stringLength filler);
|
||
in
|
||
assert lib.assertMsg (strw <= width)
|
||
"fixedWidthString: requested string length (${
|
||
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);
|
||
|
||
/* Convert a float to a string, but emit a warning when precision is lost
|
||
during the conversion
|
||
|
||
Example:
|
||
floatToString 0.000001
|
||
=> "0.000001"
|
||
floatToString 0.0000001
|
||
=> trace: warning: Imprecise conversion from float to string 0.000000
|
||
"0.000000"
|
||
*/
|
||
floatToString = float: let
|
||
result = toString float;
|
||
precise = float == fromJSON result;
|
||
in lib.warnIf (!precise) "Imprecise conversion from float to string ${result}"
|
||
result;
|
||
|
||
/* Check whether a value can be coerced to a string */
|
||
isCoercibleToString = x:
|
||
elem (typeOf x) [ "path" "string" "null" "int" "float" "bool" ] ||
|
||
(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 !(isList x) && isCoercibleToString x then
|
||
let str = toString x; in
|
||
substring 0 1 str == "/"
|
||
&& dirOf str == storeDir
|
||
else
|
||
false;
|
||
|
||
/* Parse a 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 = fromJSON str; in
|
||
if isInt may_be_int
|
||
then may_be_int
|
||
else throw "Could not convert ${str} to int.";
|
||
|
||
/* Read a list of paths from `file`, relative to the `rootPath`.
|
||
Lines beginning with `#` are treated as comments and ignored.
|
||
Whitespace is significant.
|
||
|
||
NOTE: This function is not performant and should be avoided.
|
||
|
||
Example:
|
||
readPathsFromFile /prefix
|
||
./pkgs/development/libraries/qt-5/5.4/qtbase/series
|
||
=> [ "/prefix/dlopen-resolv.patch" "/prefix/tzdir.patch"
|
||
"/prefix/dlopen-libXcursor.patch" "/prefix/dlopen-openssl.patch"
|
||
"/prefix/dlopen-dbus.patch" "/prefix/xdg-config-dirs.patch"
|
||
"/prefix/nix-profiles-library-paths.patch"
|
||
"/prefix/compose-search-path.patch" ]
|
||
*/
|
||
readPathsFromFile = lib.warn "lib.readPathsFromFile is deprecated, use a list instead"
|
||
(rootPath: file:
|
||
let
|
||
lines = lib.splitString "\n" (readFile file);
|
||
removeComments = lib.filter (line: line != "" && !(lib.hasPrefix "#" line));
|
||
relativePaths = removeComments lines;
|
||
absolutePaths = map (path: rootPath + "/${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" (readFile file);
|
||
|
||
|
||
/* Creates a valid derivation name from a potentially invalid one.
|
||
|
||
Type: sanitizeDerivationName :: String -> String
|
||
|
||
Example:
|
||
sanitizeDerivationName "../hello.bar # foo"
|
||
=> "-hello.bar-foo"
|
||
sanitizeDerivationName ""
|
||
=> "unknown"
|
||
sanitizeDerivationName pkgs.hello
|
||
=> "-nix-store-2g75chlbpxlrqn15zlby2dfh8hr9qwbk-hello-2.10"
|
||
*/
|
||
sanitizeDerivationName =
|
||
let okRegex = match "[[:alnum:]+_?=-][[:alnum:]+._?=-]*";
|
||
in
|
||
string:
|
||
# First detect the common case of already valid strings, to speed those up
|
||
if stringLength string <= 207 && okRegex string != null
|
||
then unsafeDiscardStringContext string
|
||
else lib.pipe string [
|
||
# Get rid of string context. This is safe under the assumption that the
|
||
# resulting string is only used as a derivation name
|
||
unsafeDiscardStringContext
|
||
# Strip all leading "."
|
||
(x: elemAt (match "\\.*(.*)" x) 0)
|
||
# Split out all invalid characters
|
||
# https://github.com/NixOS/nix/blob/2.3.2/src/libstore/store-api.cc#L85-L112
|
||
# https://github.com/NixOS/nix/blob/2242be83c61788b9c0736a92bb0b5c7bbfc40803/nix-rust/src/store/path.rs#L100-L125
|
||
(split "[^[:alnum:]+._?=-]+")
|
||
# Replace invalid character ranges with a "-"
|
||
(concatMapStrings (s: if lib.isList s then "-" else s))
|
||
# Limit to 211 characters (minus 4 chars for ".drv")
|
||
(x: substring (lib.max (stringLength x - 207) 0) (-1) x)
|
||
# If the result is empty, replace it with "unknown"
|
||
(x: if stringLength x == 0 then "unknown" else x)
|
||
];
|
||
|
||
/* Computes the Levenshtein distance between two strings.
|
||
Complexity O(n*m) where n and m are the lengths of the strings.
|
||
Algorithm adjusted from https://stackoverflow.com/a/9750974/6605742
|
||
|
||
Type: levenshtein :: string -> string -> int
|
||
|
||
Example:
|
||
levenshtein "foo" "foo"
|
||
=> 0
|
||
levenshtein "book" "hook"
|
||
=> 1
|
||
levenshtein "hello" "Heyo"
|
||
=> 3
|
||
*/
|
||
levenshtein = a: b: let
|
||
# Two dimensional array with dimensions (stringLength a + 1, stringLength b + 1)
|
||
arr = lib.genList (i:
|
||
lib.genList (j:
|
||
dist i j
|
||
) (stringLength b + 1)
|
||
) (stringLength a + 1);
|
||
d = x: y: lib.elemAt (lib.elemAt arr x) y;
|
||
dist = i: j:
|
||
let c = if substring (i - 1) 1 a == substring (j - 1) 1 b
|
||
then 0 else 1;
|
||
in
|
||
if j == 0 then i
|
||
else if i == 0 then j
|
||
else lib.min
|
||
( lib.min (d (i - 1) j + 1) (d i (j - 1) + 1))
|
||
( d (i - 1) (j - 1) + c );
|
||
in d (stringLength a) (stringLength b);
|
||
|
||
/* Returns the length of the prefix common to both strings.
|
||
*/
|
||
commonPrefixLength = a: b:
|
||
let
|
||
m = lib.min (stringLength a) (stringLength b);
|
||
go = i: if i >= m then m else if substring i 1 a == substring i 1 b then go (i + 1) else i;
|
||
in go 0;
|
||
|
||
/* Returns the length of the suffix common to both strings.
|
||
*/
|
||
commonSuffixLength = a: b:
|
||
let
|
||
m = lib.min (stringLength a) (stringLength b);
|
||
go = i: if i >= m then m else if substring (stringLength a - i - 1) 1 a == substring (stringLength b - i - 1) 1 b then go (i + 1) else i;
|
||
in go 0;
|
||
|
||
/* Returns whether the levenshtein distance between two strings is at most some value
|
||
Complexity is O(min(n,m)) for k <= 2 and O(n*m) otherwise
|
||
|
||
Type: levenshteinAtMost :: int -> string -> string -> bool
|
||
|
||
Example:
|
||
levenshteinAtMost 0 "foo" "foo"
|
||
=> true
|
||
levenshteinAtMost 1 "foo" "boa"
|
||
=> false
|
||
levenshteinAtMost 2 "foo" "boa"
|
||
=> true
|
||
levenshteinAtMost 2 "This is a sentence" "this is a sentense."
|
||
=> false
|
||
levenshteinAtMost 3 "This is a sentence" "this is a sentense."
|
||
=> true
|
||
|
||
*/
|
||
levenshteinAtMost = let
|
||
infixDifferAtMost1 = x: y: stringLength x <= 1 && stringLength y <= 1;
|
||
|
||
# This function takes two strings stripped by their common pre and suffix,
|
||
# and returns whether they differ by at most two by Levenshtein distance.
|
||
# Because of this stripping, if they do indeed differ by at most two edits,
|
||
# we know that those edits were (if at all) done at the start or the end,
|
||
# while the middle has to have stayed the same. This fact is used in the
|
||
# implementation.
|
||
infixDifferAtMost2 = x: y:
|
||
let
|
||
xlen = stringLength x;
|
||
ylen = stringLength y;
|
||
# This function is only called with |x| >= |y| and |x| - |y| <= 2, so
|
||
# diff is one of 0, 1 or 2
|
||
diff = xlen - ylen;
|
||
|
||
# Infix of x and y, stripped by the left and right most character
|
||
xinfix = substring 1 (xlen - 2) x;
|
||
yinfix = substring 1 (ylen - 2) y;
|
||
|
||
# x and y but a character deleted at the left or right
|
||
xdelr = substring 0 (xlen - 1) x;
|
||
xdell = substring 1 (xlen - 1) x;
|
||
ydelr = substring 0 (ylen - 1) y;
|
||
ydell = substring 1 (ylen - 1) y;
|
||
in
|
||
# A length difference of 2 can only be gotten with 2 delete edits,
|
||
# which have to have happened at the start and end of x
|
||
# Example: "abcdef" -> "bcde"
|
||
if diff == 2 then xinfix == y
|
||
# A length difference of 1 can only be gotten with a deletion on the
|
||
# right and a replacement on the left or vice versa.
|
||
# Example: "abcdef" -> "bcdez" or "zbcde"
|
||
else if diff == 1 then xinfix == ydelr || xinfix == ydell
|
||
# No length difference can either happen through replacements on both
|
||
# sides, or a deletion on the left and an insertion on the right or
|
||
# vice versa
|
||
# Example: "abcdef" -> "zbcdez" or "bcdefz" or "zabcde"
|
||
else xinfix == yinfix || xdelr == ydell || xdell == ydelr;
|
||
|
||
in k: if k <= 0 then a: b: a == b else
|
||
let f = a: b:
|
||
let
|
||
alen = stringLength a;
|
||
blen = stringLength b;
|
||
prelen = commonPrefixLength a b;
|
||
suflen = commonSuffixLength a b;
|
||
presuflen = prelen + suflen;
|
||
ainfix = substring prelen (alen - presuflen) a;
|
||
binfix = substring prelen (blen - presuflen) b;
|
||
in
|
||
# Make a be the bigger string
|
||
if alen < blen then f b a
|
||
# If a has over k more characters than b, even with k deletes on a, b can't be reached
|
||
else if alen - blen > k then false
|
||
else if k == 1 then infixDifferAtMost1 ainfix binfix
|
||
else if k == 2 then infixDifferAtMost2 ainfix binfix
|
||
else levenshtein ainfix binfix <= k;
|
||
in f;
|
||
}
|