diff options
Diffstat (limited to 'lib/strings.nix')
| -rw-r--r-- | lib/strings.nix | 777 |
1 files changed, 777 insertions, 0 deletions
diff --git a/lib/strings.nix b/lib/strings.nix new file mode 100644 index 00000000000..b2fd495e4c8 --- /dev/null +++ b/lib/strings.nix @@ -0,0 +1,777 @@ +/* String manipulation functions. */ +{ lib }: +let + +inherit (builtins) length; + +in + +rec { + + inherit (builtins) + compareVersions + elem + elemAt + filter + fromJSON + head + isInt + isList + 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 <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: "'${replaceStrings ["'"] ["'\\''"] (toString arg)}'"; + + /* Quote all arguments to be safely passed to the Bourne shell. + + Type: escapeShellArgs :: [string] -> string + + Example: + escapeShellArgs ["one" "two three" "four'five"] + => "'one' 'two three' 'four'\\''five'" + */ + escapeShellArgs = concatMapStringsSep " " escapeShellArg; + + /* Turn a string into a Nix expression representing that string + + Type: string -> string + + Example: + escapeNixString "hello\${}\n" + => "\"hello\\\${}\\n\"" + */ + escapeNixString = s: escape ["$"] (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 + ["\"" "'" "<" ">" "&"] + [""" "'" "<" ">" "&"]; + + # 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. + + Example: + splitString "." "foo.bar.baz" + => [ "foo" "bar" "baz" ] + splitString "/" "/usr/local/bin" + => [ "" "usr" "local" "bin" ] + */ + splitString = _sep: _s: + let + sep = builtins.unsafeDiscardStringContext _sep; + s = builtins.unsafeDiscardStringContext _s; + splits = builtins.filter builtins.isString (builtins.split (escapeRegex sep) s); + in + map (v: addContextFrom _sep (addContextFrom _s v)) 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 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 = string: 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) + ]; + +} |