/* String manipulation functions. */ { lib }: let inherit (builtins) length; in rec { inherit (builtins) compareVersions elem elemAt filter fromJSON head isInt isList isAttrs isString match parseDrvName readFile replaceStrings split storeDir stringLength substring tail toJSON typeOf unsafeDiscardStringContext ; /* 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: lib.foldl' (x: y: x + y) "" (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 -> (a -> string) -> [a] -> 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 -> a -> string) -> [a] -> 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) (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 { } 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 $PATH) containing the binaries for a set of packages. Example: makeBinPath ["/root" "/usr" "/usr/local"] => "/root/bin:/usr/bin:/usr/local/bin" */ makeBinPath = makeSearchPathOutput "bin" "bin"; /* Normalize path, removing extraneous /s Type: normalizePath :: string -> string Example: normalizePath "/a//b///c/" => "/a/b/c/" */ normalizePath = s: (builtins.foldl' (x: y: if y == "/" && hasSuffix "/" x then x else x+y) "" (stringToCharacters s)); /* Depending on the boolean `cond', return either the given string or the empty string. Useful to concatenate against a bigger string. Type: optionalString :: bool -> string -> string Example: optionalString true "some-string" => "some-string" optionalString false "some-string" => "" */ optionalString = # Condition cond: # String to return if condition is true string: if cond then string else ""; /* Determine whether a string has given prefix. Type: hasPrefix :: string -> string -> bool Example: hasPrefix "foo" "foobar" => true hasPrefix "foo" "barfoo" => false */ hasPrefix = # Prefix to check for pref: # Input string str: substring 0 (stringLength pref) str == pref; /* Determine whether a string has given suffix. Type: hasSuffix :: string -> string -> bool Example: hasSuffix "foo" "foobar" => false hasSuffix "foo" "barfoo" => true */ hasSuffix = # Suffix to check for suffix: # Input string content: let lenContent = stringLength content; lenSuffix = stringLength suffix; in lenContent >= lenSuffix && substring (lenContent - lenSuffix) lenContent content == suffix; /* Determine whether a string contains the given infix Type: hasInfix :: string -> string -> bool Example: hasInfix "bc" "abcd" => true hasInfix "ab" "abcd" => true hasInfix "cd" "abcd" => true hasInfix "foo" "abcd" => false */ hasInfix = infix: content: builtins.match ".*${escapeRegex infix}.*" "${content}" != null; /* Convert a string to a list of characters (i.e. singleton strings). This allows you to, e.g., map a function over each character. However, note that this will likely be horribly inefficient; Nix is not a general purpose programming language. Complex string manipulations should, if appropriate, be done in a derivation. Also note that Nix treats strings as a list of bytes and thus doesn't handle unicode. Type: stringToCharacters :: string -> [string] Example: stringToCharacters "" => [ ] stringToCharacters "abc" => [ "a" "b" "c" ] stringToCharacters "🦄" => [ "�" "�" "�" "�" ] */ stringToCharacters = s: map (p: substring p 1 s) (lib.range 0 (stringLength s - 1)); /* Manipulate a string character by character and replace them by strings before concatenating the results. Type: stringAsChars :: (string -> string) -> string -> string Example: stringAsChars (x: if x == "a" then "i" else x) "nax" => "nix" */ stringAsChars = # Function to map over each individual character f: # Input string s: concatStrings ( map f (stringToCharacters s) ); /* Convert char to ascii value, must be in printable range Type: charToInt :: string -> int Example: charToInt "A" => 65 charToInt "(" => 40 */ charToInt = let table = import ./ascii-table.nix; in c: builtins.getAttr c table; /* Escape occurrence of the elements of `list` in `string` by prefixing it with a backslash. Type: escape :: [string] -> string -> string Example: escape ["(" ")"] "(foo)" => "\\(foo\\)" */ escape = list: replaceStrings list (map (c: "\\${c}") list); /* Escape occurrence of the element of `list` in `string` by converting to its ASCII value and prefixing it with \\x. Only works for printable ascii characters. Type: escapeC = [string] -> string -> string Example: escapeC [" "] "foo bar" => "foo\\x20bar" */ escapeC = list: replaceStrings list (map (c: "\\x${ toLower (lib.toHexString (charToInt c))}") list); /* Quote string to be used safely within the Bourne shell. Type: escapeShellArg :: string -> string Example: escapeShellArg "esc'ape\nme" => "'esc'\\''ape\nme'" */ escapeShellArg = arg: "'${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; /* Test whether the given name is a valid POSIX shell variable name. Type: string -> bool Example: isValidPosixName "foo_bar000" => true isValidPosixName "0-bad.jpg" => false */ isValidPosixName = name: match "[a-zA-Z_][a-zA-Z0-9_]*" name != null; /* Translate a Nix value into a shell variable declaration, with proper escaping. The value can be a string (mapped to a regular variable), a list of strings (mapped to a Bash-style array) or an attribute set of strings (mapped to a Bash-style associative array). Note that "string" includes string-coercible values like paths or derivations. Strings are translated into POSIX sh-compatible code; lists and attribute sets assume a shell that understands Bash syntax (e.g. Bash or ZSH). Type: string -> (string | listOf string | attrsOf string) -> string Example: '' ${toShellVar "foo" "some string"} [[ "$foo" == "some string" ]] '' */ toShellVar = name: value: lib.throwIfNot (isValidPosixName name) "toShellVar: ${name} is not a valid shell variable name" ( if isAttrs value && ! isStringLike value then "declare -A ${name}=(${ concatStringsSep " " (lib.mapAttrsToList (n: v: "[${escapeShellArg n}]=${escapeShellArg v}" ) value) })" else if isList value then "declare -a ${name}=(${escapeShellArgs value})" else "${name}=${escapeShellArg value}" ); /* Translate an attribute set into corresponding shell variable declarations using `toShellVar`. Type: attrsOf (string | listOf string | attrsOf string) -> string Example: let foo = "value"; bar = foo; in '' ${toShellVars { inherit foo bar; }} [[ "$foo" == "$bar" ]] '' */ toShellVars = vars: concatStringsSep "\n" (lib.mapAttrsToList toShellVar vars); /* Turn a string into a Nix expression representing that string Type: string -> string Example: escapeNixString "hello\${}\n" => "\"hello\\\${}\\n\"" */ escapeNixString = s: escape ["$"] (toJSON s); /* Turn a string into an exact regular expression Type: string -> string Example: escapeRegex "[^a-z]*" => "\\[\\^a-z]\\*" */ escapeRegex = escape (stringToCharacters "\\[{()^$?*+|."); /* Quotes a string if it can't be used as an identifier directly. Type: string -> string Example: escapeNixIdentifier "hello" => "hello" escapeNixIdentifier "0abc" => "\"0abc\"" */ escapeNixIdentifier = s: # Regex from https://github.com/NixOS/nix/blob/d048577909e383439c2549e849c5c2f2016c997e/src/libexpr/lexer.l#L91 if match "[a-zA-Z_][a-zA-Z0-9_'-]*" s != null then s else escapeNixString s; /* Escapes a string such that it is safe to include verbatim in an XML document. Type: string -> string Example: escapeXML ''"test" 'test' < & >'' => ""test" 'test' < & >" */ escapeXML = builtins.replaceStrings ["\"" "'" "<" ">" "&"] [""" "'" "<" ">" "&"]; # warning added 12-12-2022 replaceChars = lib.warn "replaceChars is a deprecated alias of replaceStrings, replace usages of it with replaceStrings." builtins.replaceStrings; # 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 = replaceStrings upperChars lowerChars; /* Converts an ASCII string to upper-case. Type: toUpper :: string -> string Example: toUpper "home" => "HOME" */ toUpper = replaceStrings lowerChars upperChars; /* Appends string context from another string. This is an implementation detail of Nix and should be used carefully. 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 { }; 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. Example: splitString "." "foo.bar.baz" => [ "foo" "bar" "baz" ] splitString "/" "/usr/local/bin" => [ "" "usr" "local" "bin" ] */ splitString = sep: s: let splits = builtins.filter builtins.isString (builtins.split (escapeRegex (toString sep)) (toString s)); in map (addContextFrom s) splits; /* 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: 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: (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 a -D= string that can be passed to typical Meson invocations. Type: mesonOption :: string -> string -> string @param feature The feature to be set @param value The desired value Example: mesonOption "engine" "opengl" => "-Dengine=opengl" */ mesonOption = feature: value: assert (lib.isString feature); assert (lib.isString value); "-D${feature}=${value}"; /* Create a -D={true,false} string that can be passed to typical Meson invocations. Type: mesonBool :: string -> bool -> string @param condition The condition to be made true or false @param flag The controlling flag of the condition Example: mesonBool "hardened" true => "-Dhardened=true" mesonBool "static" false => "-Dstatic=false" */ mesonBool = condition: flag: assert (lib.isString condition); assert (lib.isBool flag); mesonOption condition (lib.boolToString flag); /* Create a -D={enabled,disabled} string that can be passed to typical Meson invocations. Type: mesonEnable :: string -> bool -> string @param feature The feature to be enabled or disabled @param flag The controlling flag Example: mesonEnable "docs" true => "-Ddocs=enabled" mesonEnable "savage" false => "-Dsavage=disabled" */ mesonEnable = feature: flag: assert (lib.isString feature); assert (lib.isBool flag); mesonOption feature (if flag then "enabled" else "disabled"); /* Create an --{enable,disable}- string that can be passed to standard GNU Autoconf scripts. Example: enableFeature true "shared" => "--enable-shared" enableFeature false "shared" => "--disable-shared" */ enableFeature = enable: feat: assert isString feat; # e.g. passing openssl instead of "openssl" "--${if enable then "enable" else "disable"}-${feat}"; /* Create an --{enable-=,disable-} string that can be passed to standard GNU Autoconf scripts. Example: enableFeatureAs true "shared" "foo" => "--enable-shared=foo" enableFeatureAs false "shared" (throw "ignored") => "--disable-shared" */ enableFeatureAs = enable: feat: value: enableFeature enable feat + optionalString enable "=${value}"; /* Create an --{with,without}- 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-=,without-} 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; /* Soft-deprecated function. While the original implementation is available as isConvertibleWithToString, consider using isStringLike instead, if suitable. */ isCoercibleToString = lib.warnIf (lib.isInOldestRelease 2305) "lib.strings.isCoercibleToString is deprecated in favor of either isStringLike or isConvertibleWithToString. Only use the latter if it needs to return true for null, numbers, booleans and list of similarly coercibles." isConvertibleWithToString; /* Check whether a list or other value can be passed to toString. Many types of value are coercible to string this way, including int, float, null, bool, list of similarly coercible values. */ isConvertibleWithToString = x: isStringLike x || elem (typeOf x) [ "null" "int" "float" "bool" ] || (isList x && lib.all isConvertibleWithToString x); /* Check whether a value can be coerced to a string. The value must be a string, path, or attribute set. String-like values can be used without explicit conversion in string interpolations and in most functions that expect a string. */ isStringLike = x: elem (typeOf x) [ "path" "string" ] || 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 isStringLike x then let str = toString x; in substring 0 1 str == "/" && dirOf str == storeDir else false; /* Parse a string as an int. Does not support parsing of integers with preceding zero due to ambiguity between zero-padded and octal numbers. See toIntBase10. Type: string -> int Example: toInt "1337" => 1337 toInt "-4" => -4 toInt " 123 " => 123 toInt "00024" => error: Ambiguity in interpretation of 00024 between octal and zero padded integer. toInt "3.14" => error: floating point JSON numbers are not supported */ toInt = str: let # RegEx: Match any leading whitespace, possibly a '-', one or more digits, # and finally match any trailing whitespace. strippedInput = match "[[:space:]]*(-?[[:digit:]]+)[[:space:]]*" str; # RegEx: Match a leading '0' then one or more digits. isLeadingZero = match "0[[:digit:]]+" (head strippedInput) == []; # Attempt to parse input parsedInput = fromJSON (head strippedInput); generalError = "toInt: Could not convert ${escapeNixString str} to int."; octalAmbigError = "toInt: Ambiguity in interpretation of ${escapeNixString str}" + " between octal and zero padded integer."; in # Error on presence of non digit characters. if strippedInput == null then throw generalError # Error on presence of leading zero/octal ambiguity. else if isLeadingZero then throw octalAmbigError # Error if parse function fails. else if !isInt parsedInput then throw generalError # Return result. else parsedInput; /* Parse a string as a base 10 int. This supports parsing of zero-padded integers. Type: string -> int Example: toIntBase10 "1337" => 1337 toIntBase10 "-4" => -4 toIntBase10 " 123 " => 123 toIntBase10 "00024" => 24 toIntBase10 "3.14" => error: floating point JSON numbers are not supported */ toIntBase10 = str: let # RegEx: Match any leading whitespace, then match any zero padding, # capture possibly a '-' followed by one or more digits, # and finally match any trailing whitespace. strippedInput = match "[[:space:]]*0*(-?[[:digit:]]+)[[:space:]]*" str; # RegEx: Match at least one '0'. isZero = match "0+" (head strippedInput) == []; # Attempt to parse input parsedInput = fromJSON (head strippedInput); generalError = "toIntBase10: Could not convert ${escapeNixString str} to int."; in # Error on presence of non digit characters. if strippedInput == null then throw generalError # In the special case zero-padded zero (00000), return early. else if isZero then 0 # Error if parse function fails. else if !isInt parsedInput then throw generalError # Return result. else parsedInput; /* Read a list of paths from `file`, relative to the `rootPath`. Lines beginning with `#` are treated as comments and ignored. Whitespace is significant. NOTE: This function is not performant and should be avoided. Example: readPathsFromFile /prefix ./pkgs/development/libraries/qt-5/5.4/qtbase/series => [ "/prefix/dlopen-resolv.patch" "/prefix/tzdir.patch" "/prefix/dlopen-libXcursor.patch" "/prefix/dlopen-openssl.patch" "/prefix/dlopen-dbus.patch" "/prefix/xdg-config-dirs.patch" "/prefix/nix-profiles-library-paths.patch" "/prefix/compose-search-path.patch" ] */ readPathsFromFile = lib.warn "lib.readPathsFromFile is deprecated, use a list instead" (rootPath: file: let lines = lib.splitString "\n" (readFile file); removeComments = lib.filter (line: line != "" && !(lib.hasPrefix "#" line)); relativePaths = removeComments lines; absolutePaths = map (path: rootPath + "/${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; }