516 lines
15 KiB
Nix
516 lines
15 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) stringLength substring head tail isString replaceStrings;
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/* Concatenate a list of strings.
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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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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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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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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 = separator: 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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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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concatStrings (intersperse separator list));
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/* First maps over the list and then concatenates it.
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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 = sep: f: list: concatStringsSep sep (map f list);
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/* First imaps over the list and then concatenates it.
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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 = sep: f: list: concatStringsSep sep (lib.imap1 f list);
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/* Construct a Unix-style search path consisting of each `subDir"
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directory of the given list of packages.
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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 = subDir: packages:
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concatStringsSep ":" (map (path: path + "/" + subDir) packages);
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/* Construct a Unix-style search path, using given package output.
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If no output is found, fallback to `.out` and then to the default.
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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 = output: subDir: 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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/* Construct a perl search path (such as $PERL5LIB)
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FIXME(zimbatm): this should be moved in perl-specific code
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Example:
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pkgs = import <nixpkgs> { }
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makePerlPath [ pkgs.perlPackages.NetSMTP ]
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=> "/nix/store/n0m1fk9c960d8wlrs62sncnadygqqc6y-perl-Net-SMTP-1.25/lib/perl5/site_perl"
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*/
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makePerlPath = makeSearchPathOutput "lib" "lib/perl5/site_perl";
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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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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 = cond: string: if cond then string else "";
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/* Determine whether a string has given prefix.
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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 = pref: str:
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substring 0 (stringLength pref) str == pref;
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/* Determine whether a string has given suffix.
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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 = suffix: 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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/* 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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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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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 = f: s:
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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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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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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: "'${replaceStrings ["'"] ["'\\''"] (toString arg)}'";
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/* Quote all arguments to be safely passed to the Bourne shell.
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Example:
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escapeShellArgs ["one" "two three" "four'five"]
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=> "'one' 'two three' 'four'\\''five'"
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*/
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escapeShellArgs = concatMapStringsSep " " escapeShellArg;
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/* Turn a string into a Nix expression representing that string
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Example:
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escapeNixString "hello\${}\n"
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=> "\"hello\\\${}\\n\""
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*/
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escapeNixString = s: escape ["$"] (builtins.toJSON s);
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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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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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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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NOTE: this function is not performant and should never be used.
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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 = addContextFrom _s _sep;
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s = addContextFrom _sep _s;
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sepLen = stringLength sep;
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sLen = stringLength s;
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lastSearch = sLen - sepLen;
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startWithSep = startAt:
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substring startAt sepLen s == sep;
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recurse = index: startAt:
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let cutUntil = i: [(substring startAt (i - startAt) s)]; in
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if index <= lastSearch then
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if startWithSep index then
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let restartAt = index + sepLen; in
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cutUntil index ++ recurse restartAt restartAt
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else
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recurse (index + 1) startAt
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else
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cutUntil sLen;
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in
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recurse 0 0;
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/* Return the suffix of the second argument if the first argument matches
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its prefix.
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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 = pre: s:
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let
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preLen = stringLength pre;
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sLen = stringLength s;
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in
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if hasPrefix pre s then
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substring preLen (sLen - preLen) s
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else
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s;
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/* Return the prefix of the second argument if the first argument matches
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its suffix.
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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 = suf: s:
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let
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sufLen = stringLength suf;
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sLen = stringLength s;
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in
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if sufLen <= sLen && suf == substring (sLen - sufLen) sufLen s then
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substring 0 (sLen - sufLen) s
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else
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s;
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/* Return true iff 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: builtins.compareVersions v2 v1 == 1;
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/* Return true iff string v1 denotes a version equal to or newer than v2.
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Example:
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versionAtLeast "1.1" "1.0"
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=> true
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versionAtLeast "1.1" "1.1"
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=> true
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versionAtLeast "1.1" "1.2"
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=> false
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*/
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versionAtLeast = v1: v2: !versionOlder v1 v2;
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/* This function takes an argument that's either a derivation or a
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derivation's "name" attribute and extracts the version part from that
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argument.
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Example:
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getVersion "youtube-dl-2016.01.01"
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=> "2016.01.01"
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getVersion pkgs.youtube-dl
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=> "2016.01.01"
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*/
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getVersion = x:
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let
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parse = drv: (builtins.parseDrvName drv).version;
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in if isString x
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then parse x
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else x.version or (parse x.name);
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/* Extract name with version from URL. Ask for separator which is
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supposed to start extension.
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Example:
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nameFromURL "https://nixos.org/releases/nix/nix-1.7/nix-1.7-x86_64-linux.tar.bz2" "-"
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=> "nix"
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nameFromURL "https://nixos.org/releases/nix/nix-1.7/nix-1.7-x86_64-linux.tar.bz2" "_"
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=> "nix-1.7-x86"
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*/
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nameFromURL = url: sep:
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let
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components = splitString "/" url;
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filename = lib.last components;
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name = builtins.head (splitString sep filename);
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in assert name != filename; name;
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/* Create an --{enable,disable}-<feat> string that can be passed to
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standard GNU Autoconf scripts.
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Example:
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enableFeature true "shared"
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=> "--enable-shared"
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enableFeature false "shared"
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=> "--disable-shared"
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*/
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enableFeature = enable: feat: "--${if enable then "enable" else "disable"}-${feat}";
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/* Create a fixed width string with additional prefix to match
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required width.
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Example:
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fixedWidthString 5 "0" (toString 15)
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=> "00015"
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*/
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fixedWidthString = width: filler: str:
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let
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strw = lib.stringLength str;
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reqWidth = width - (lib.stringLength filler);
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in
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assert strw <= width;
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if strw == width then str else filler + fixedWidthString reqWidth filler str;
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/* Format a number adding leading zeroes up to fixed width.
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Example:
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fixedWidthNumber 5 15
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=> "00015"
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*/
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fixedWidthNumber = width: n: fixedWidthString width "0" (toString n);
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/* Check whether a value can be coerced to a string */
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isCoercibleToString = x:
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builtins.elem (builtins.typeOf x) [ "path" "string" "null" "int" "float" "bool" ] ||
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(builtins.isList x && lib.all isCoercibleToString x) ||
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x ? outPath ||
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x ? __toString;
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/* Check whether a value is a store path.
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Example:
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isStorePath "/nix/store/d945ibfx9x185xf04b890y4f9g3cbb63-python-2.7.11/bin/python"
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=> false
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isStorePath "/nix/store/d945ibfx9x185xf04b890y4f9g3cbb63-python-2.7.11/"
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=> true
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isStorePath pkgs.python
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=> true
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isStorePath [] || isStorePath 42 || isStorePath {} || …
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=> false
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*/
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isStorePath = x:
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isCoercibleToString x
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&& builtins.substring 0 1 (toString x) == "/"
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&& dirOf (builtins.toPath x) == builtins.storeDir;
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/* Convert string to int
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Obviously, it is a bit hacky to use fromJSON that way.
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Example:
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toInt "1337"
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=> 1337
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toInt "-4"
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=> -4
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toInt "3.14"
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=> error: floating point JSON numbers are not supported
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*/
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toInt = str:
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let may_be_int = builtins.fromJSON str; in
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if builtins.isInt may_be_int
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then may_be_int
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else throw "Could not convert ${str} to int.";
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/* Read a list of paths from `file', relative to the `rootPath'. Lines
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beginning with `#' are treated as comments and ignored. Whitespace
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is significant.
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NOTE: this function is not performant and should be avoided
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Example:
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readPathsFromFile /prefix
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./pkgs/development/libraries/qt-5/5.4/qtbase/series
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=> [ "/prefix/dlopen-resolv.patch" "/prefix/tzdir.patch"
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"/prefix/dlopen-libXcursor.patch" "/prefix/dlopen-openssl.patch"
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"/prefix/dlopen-dbus.patch" "/prefix/xdg-config-dirs.patch"
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"/prefix/nix-profiles-library-paths.patch"
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"/prefix/compose-search-path.patch" ]
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*/
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readPathsFromFile = rootPath: file:
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let
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root = toString rootPath;
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lines = lib.splitString "\n" (builtins.readFile file);
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removeComments = lib.filter (line: line != "" && !(lib.hasPrefix "#" line));
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relativePaths = removeComments lines;
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absolutePaths = builtins.map (path: builtins.toPath (root + "/" + path)) relativePaths;
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in
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absolutePaths;
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/* Read the contents of a file removing the trailing \n
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Example:
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$ echo "1.0" > ./version
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fileContents ./version
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=> "1.0"
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*/
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fileContents = file: removeSuffix "\n" (builtins.readFile file);
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}
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