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nixpkgs/lib/strings.nix
Robert Hensing d103811173 lib.isStringLike: Remove use of list 
In the current implementation of Nix, this list would be allocated
over and over. Iirc pennae tried to optimize static list allocation,
but gained no significant performance improvement.
2022-12-31 01:33:47 +01:00

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Nix
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/* String manipulation functions. */
{ lib }:
let
inherit (builtins) length;
in
rec {
inherit (builtins)
compareVersions
elem
elemAt
filter
fromJSON
head
isInt
isList
isAttrs
isPath
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 $PATH) containing the
binaries for a set of packages.
Example:
makeBinPath ["/root" "/usr" "/usr/local"]
=> "/root/bin:/usr/bin:/usr/local/bin"
*/
makeBinPath = makeSearchPathOutput "bin" "bin";
/* Normalize path, removing extraneous /s
Type: normalizePath :: string -> string
Example:
normalizePath "/a//b///c/"
=> "/a/b/c/"
*/
normalizePath = s: (builtins.foldl' (x: y: if y == "/" && hasSuffix "/" x then x else x+y) "" (stringToCharacters s));
/* Depending on the boolean `cond', return either the given string
or the empty string. Useful to concatenate against a bigger string.
Type: optionalString :: bool -> string -> string
Example:
optionalString true "some-string"
=> "some-string"
optionalString false "some-string"
=> ""
*/
optionalString =
# Condition
cond:
# String to return if condition is true
string: if cond then string else "";
/* Determine whether a string has given prefix.
Type: hasPrefix :: string -> string -> bool
Example:
hasPrefix "foo" "foobar"
=> true
hasPrefix "foo" "barfoo"
=> false
*/
hasPrefix =
# Prefix to check for
pref:
# Input string
str: substring 0 (stringLength pref) str == pref;
/* Determine whether a string has given suffix.
Type: hasSuffix :: string -> string -> bool
Example:
hasSuffix "foo" "foobar"
=> false
hasSuffix "foo" "barfoo"
=> true
*/
hasSuffix =
# Suffix to check for
suffix:
# Input string
content:
let
lenContent = stringLength content;
lenSuffix = stringLength suffix;
in lenContent >= lenSuffix &&
substring (lenContent - lenSuffix) lenContent content == suffix;
/* Determine whether a string contains the given infix
Type: hasInfix :: string -> string -> bool
Example:
hasInfix "bc" "abcd"
=> true
hasInfix "ab" "abcd"
=> true
hasInfix "cd" "abcd"
=> true
hasInfix "foo" "abcd"
=> false
*/
hasInfix = infix: content:
builtins.match ".*${escapeRegex infix}.*" "${content}" != null;
/* Convert a string to a list of characters (i.e. singleton strings).
This allows you to, e.g., map a function over each character. However,
note that this will likely be horribly inefficient; Nix is not a
general purpose programming language. Complex string manipulations
should, if appropriate, be done in a derivation.
Also note that Nix treats strings as a list of bytes and thus doesn't
handle unicode.
Type: stringToCharacters :: string -> [string]
Example:
stringToCharacters ""
=> [ ]
stringToCharacters "abc"
=> [ "a" "b" "c" ]
stringToCharacters "🦄"
=> [ "<EFBFBD>" "<EFBFBD>" "<EFBFBD>" "<EFBFBD>" ]
*/
stringToCharacters = s:
map (p: substring p 1 s) (lib.range 0 (stringLength s - 1));
/* Manipulate a string character by character and replace them by
strings before concatenating the results.
Type: stringAsChars :: (string -> string) -> string -> string
Example:
stringAsChars (x: if x == "a" then "i" else x) "nax"
=> "nix"
*/
stringAsChars =
# Function to map over each individual character
f:
# Input string
s: concatStrings (
map f (stringToCharacters s)
);
/* Convert char to ascii value, must be in printable range
Type: charToInt :: string -> int
Example:
charToInt "A"
=> 65
charToInt "("
=> 40
*/
charToInt = let
table = import ./ascii-table.nix;
in c: builtins.getAttr c table;
/* Escape occurrence of the elements of `list` in `string` by
prefixing it with a backslash.
Type: escape :: [string] -> string -> string
Example:
escape ["(" ")"] "(foo)"
=> "\\(foo\\)"
*/
escape = list: replaceStrings list (map (c: "\\${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' < & >''
=> "&quot;test&quot; &apos;test&apos; &lt; &amp; &gt;"
*/
escapeXML = builtins.replaceStrings
["\"" "'" "<" ">" "&"]
["&quot;" "&apos;" "&lt;" "&gt;" "&amp;"];
# 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 <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
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<feature>=<value> 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}=${value}";
/* Create a -D<condition>={true,false} string that can be passed to typical
Meson invocations.
Type: mesonBool :: string -> bool -> string
@param condition The condition to be made true or false
@param flag The controlling flag of the condition
Example:
mesonBool "hardened" true
=> "-Dhardened=true"
mesonBool "static" false
=> "-Dstatic=false"
*/
mesonBool = condition: flag:
assert (lib.isString condition);
assert (lib.isBool flag);
mesonOption condition (lib.boolToString flag);
/* Create a -D<feature>={enabled,disabled} string that can be passed to
typical Meson invocations.
Type: mesonEnable :: string -> bool -> string
@param feature The feature to be enabled or disabled
@param flag The controlling flag
Example:
mesonEnable "docs" true
=> "-Ddocs=enabled"
mesonEnable "savage" false
=> "-Dsavage=disabled"
*/
mesonEnable = feature: flag:
assert (lib.isString feature);
assert (lib.isBool flag);
mesonOption feature (if flag then "enabled" else "disabled");
/* Create an --{enable,disable}-<feat> string that can be passed to
standard GNU Autoconf scripts.
Example:
enableFeature true "shared"
=> "--enable-shared"
enableFeature false "shared"
=> "--disable-shared"
*/
enableFeature = enable: feat:
assert isString feat; # e.g. passing openssl instead of "openssl"
"--${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;
/* 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:
isString x ||
isPath 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 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;
}
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