Unicode

Functions for Unicode strings.

List of functions

Unicode::IsUtf(String) -> Bool

Checks whether a string is a valid utf-8 sequence. For example, the string "\xF0" isn't a valid utf-8 sequence, while the string "\xF0\x9F\x90\xB1" correctly describes a utf-8 cat emoji.
Unicode::GetLength(Utf8{Flags:AutoMap}) -> Uint64

Returns the utf-8 string's length in characters (unicode code points). Surrogate pairs are counted as one character.
```
SELECT Unicode::GetLength("жніўня"); -- 6
```
Unicode::Find(string:Utf8{Flags:AutoMap}, subString:Utf8, [pos:Uint64?]) -> Uint64?
Unicode::RFind(string:Utf8{Flags:AutoMap}, subString:Utf8, [pos:Uint64?]) -> Uint64?

Searches for the first (or the last in the case of RFind) substring occurrence in the string starting from the pos position. Returns the first character position from the found string. Null is returned in case of failure.
```
SELECT Unicode::Find("aaa", "bb"); -- Null
```
Unicode::Substring(string:Utf8{Flags:AutoMap}, from:Uint64?, len:Uint64?) -> Utf8

Returns a substring from the string, starting from the from character, with length equaling len characters. If the len argument is omitted, the substring is taken to the end of the source string. If from is greater than the source string length, an empty "" string is returned.
```
SELECT Unicode::Substring("0123456789abcdefghij", 10); -- "abcdefghij"
```
Unicode::Normalize... functions reduce the transmitted utf-8 string to a normal form:
- Unicode::Normalize(Utf8{Flags:AutoMap}) -> Utf8 -- NFC
- Unicode::NormalizeNFD(Utf8{Flags:AutoMap}) -> Utf8
- Unicode::NormalizeNFC(Utf8{Flags:AutoMap}) -> Utf8
- Unicode::NormalizeNFKD(Utf8{Flags:AutoMap}) -> Utf8
- Unicode::NormalizeNFKC(Utf8{Flags:AutoMap}) -> Utf8
Unicode::Translit(string:Utf8{Flags:AutoMap}, [lang:String?]) -> Utf8

Transliterates with Latin letters the words from the passed string, consisting entirely of characters of the alphabet of the language passed by the second argument. If no language is specified, the words are transliterated from Russian. Available languages: "kaz", "rus", "tur", and "ukr".
```
SELECT Unicode::Translit("Тот уголок земли, где я провел"); -- "Tot ugolok zemli, gde ya provel"
```
Unicode::LevensteinDistance(stringA:Utf8{Flags:AutoMap}, stringB:Utf8{Flags:AutoMap}) -> Uint64

Calculates the Levenshtein distance for the passed strings.
Unicode::Fold(Utf8{Flags:AutoMap}, [ Language:String?, DoLowerCase:Bool?, DoRenyxa:Bool?, DoSimpleCyr:Bool?, FillOffset:Bool? ]) -> Utf8

Performs case folding for the transmitted string.
Parameters:
- Language is set according to the same rules as in Unicode::Translit().
- DoLowerCase converts a string to lowercase letters, true by default.
- DoRenyxa converts diacritical characters to similar Latin characters, true by default.
- DoSimpleCyr converts diacritical Cyrillic characters to similar Latin characters, true by default.
- FillOffset parameter is not used.
```
SELECT Unicode::Fold("Kongreßstraße",  false AS DoSimpleCyr, false AS DoRenyxa); -- "kongressstrasse"
SELECT Unicode::Fold("ҫурт"); -- "сурт"
SELECT Unicode::Fold("Eylül", "Turkish" AS Language); -- "eylul"
```
Unicode::ReplaceAll(input:Utf8{Flags:AutoMap}, find:Utf8, replacement:Utf8) -> Utf8
Unicode::ReplaceFirst(input:Utf8{Flags:AutoMap}, find:Utf8, replacement:Utf8) -> Utf8
Unicode::ReplaceLast(input:Utf8{Flags:AutoMap}, find:Utf8, replacement:Utf8) -> Utf8

Replaces all/first/last occurrence(s) of the find string in input through replacement.
Unicode::RemoveAll(input:Utf8{Flags:AutoMap}, symbols:Utf8) -> Utf8
Unicode::RemoveFirst(input:Utf8{Flags:AutoMap}, symbols:Utf8) -> Utf8
Unicode::RemoveLast(input:Utf8{Flags:AutoMap}, symbols:Utf8) -> Utf8

Removes all/first/last occurrence(s) of characters defined in a symbols set from input. The second argument is interpreted as an unordered set of characters to be deleted.
```
SELECT Unicode::ReplaceLast("absence", "enc", ""); -- "abse"
SELECT Unicode::RemoveAll("abandon", "an"); -- "bdo"
```
Unicode::ToCodePointList(Utf8{Flags:AutoMap}) -> List<Uint32>

Splits the string into a unicode sequence of codepoints.

Unicode::FromCodePointList(List<Uint32>{Flags:AutoMap}) -> Utf8

Forms a unicode string from codepoints.

SELECT Unicode::ToCodePointList("Щавель"); -- [1065, 1072, 1074, 1077, 1083, 1100]
SELECT Unicode::FromCodePointList(AsList(99,111,100,101,32,112,111,105,110,116,115,32,99,111,110,118,101,114,116,101,114)); -- "code points converter"

Unicode::Reverse(Utf8{Flags:AutoMap}) -> Utf8

Reverses the string.
Unicode::ToLower(Utf8{Flags:AutoMap}) -> Utf8
Unicode::ToUpper(Utf8{Flags:AutoMap}) -> Utf8
Unicode::ToTitle(Utf8{Flags:AutoMap}) -> Utf8

Changes the character case in the string to upper, lower, or title case.
Unicode::SplitToList( string:Utf8?, separator:Utf8, [ DelimeterString:Bool?, SkipEmpty:Bool?, Limit:Uint64? ]) -> List<Utf8>

Splits the string into substrings with a separator.
string — Source string.
separator — Separator.
Parameters:
- DelimeterString:Bool? — treating a separator as a string (true by default) or a set of characters "any of" (false).
- SkipEmpty:Bool? — whether to skip empty strings in the result, false by default.
- Limit:Uint64? — limits the number of fetched components (unlimited by default); if the limit is exceeded, the raw suffix of the source string is returned in the last item.

Unicode::JoinFromList(List<Utf8>{Flags:AutoMap}, separator:Utf8) -> Utf8

Concatenates a list of strings into a single string using a separator.

SELECT Unicode::SplitToList("One, two, three, four, five", ", ", 2 AS Limit); -- ["One", "two", "three, four, five"]
SELECT Unicode::JoinFromList(["One", "two", "three", "four", "five"], ";"); -- "One;two;three;four;five"

Unicode::ToUint64(string:Utf8{Flags:AutoMap}, [prefix:Uint16?]) -> Uint64

Converts from the string into a number. The second optional argument sets the numeral system. By default, 0 (automatic detection by prefix).

Supported prefixes: 0x(0X) (base-16), 0 (base-8). Default system: base-10.
The - sign before a number is interpreted as in the C's unsigned arithmetic. For example, -0x1 -> UI64_MAX.
If a string contains invalid characters, or a number is beyond ui64, the function finishes with an error.

Unicode::TryToUint64(string:Utf8{Flags:AutoMap}, [prefix:Uint16?]) -> Uint64?

Similar to the Unicode::ToUint64() function, but returns NULL instead of an error.

SELECT Unicode::ToUint64("77741"); -- 77741
SELECT Unicode::ToUint64("-77741"); -- 18446744073709473875
SELECT Unicode::TryToUint64("asdh831"); -- Null

Unicode::Strip(string:Utf8{Flags:AutoMap}) -> Utf8

Cuts off the string's outermost characters of Space Unicode category.
```
SELECT Unicode::Strip("\u2002ыкль\u2002"u); -- "ыкль"
```
Unicode::IsAscii(string:Utf8{Flags:AutoMap}) -> Bool

Checks whether the utf-8 string consists exclusively of ASCII characters.
Unicode::IsSpace(string:Utf8{Flags:AutoMap}) -> Bool
Unicode::IsUpper(string:Utf8{Flags:AutoMap}) -> Bool
Unicode::IsLower(string:Utf8{Flags:AutoMap}) -> Bool
Unicode::IsAlpha(string:Utf8{Flags:AutoMap}) -> Bool
Unicode::IsAlnum(string:Utf8{Flags:AutoMap}) -> Bool
Unicode::IsHex(string:Utf8{Flags:AutoMap}) -> Bool

Checks whether the utf-8 string satisfies the specified condition.
Unicode::IsUnicodeSet(string:Utf8{Flags:AutoMap}, unicode_set:Utf8) -> Bool

Checks whether the utf-8 string consists exclusively of characters indicated in unicode_set. Characters in unicode_set must be indicated in square brackets.
```
SELECT Unicode::IsUnicodeSet("ваоао"u, "[вао]"u); -- true
SELECT Unicode::IsUnicodeSet("ваоао"u, "[ваб]"u); -- false
```

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