String (b0.B0_std.String)

include module type of Stdlib.String

type t = string

val make : int -> char -> string

val init : int -> (int -> char) -> string

val length : string -> int

val get : string -> int -> char

val of_bytes : bytes -> string

val to_bytes : string -> bytes

val blit : string -> int -> bytes -> int -> int -> unit

val concat : string -> string list -> string

val cat : string -> string -> string

val equal : t -> t -> bool

val compare : t -> t -> int

val starts_with : prefix:string -> string -> bool

val ends_with : suffix:string -> string -> bool

val contains_from : string -> int -> char -> bool

val rcontains_from : string -> int -> char -> bool

val contains : string -> char -> bool

val sub : string -> int -> int -> string

val split_on_char : char -> string -> string list

val map : (char -> char) -> string -> string

val mapi : (int -> char -> char) -> string -> string

val fold_left : ('acc -> char -> 'acc) -> 'acc -> string -> 'acc

val fold_right : (char -> 'acc -> 'acc) -> string -> 'acc -> 'acc

val for_all : (char -> bool) -> string -> bool

val exists : (char -> bool) -> string -> bool

val trim : string -> string

val escaped : string -> string

val uppercase_ascii : string -> string

val lowercase_ascii : string -> string

val capitalize_ascii : string -> string

val uncapitalize_ascii : string -> string

val iter : (char -> unit) -> string -> unit

val iteri : (int -> char -> unit) -> string -> unit

val index_from : string -> int -> char -> int

val index_from_opt : string -> int -> char -> int option

val rindex_from : string -> int -> char -> int

val rindex_from_opt : string -> int -> char -> int option

val index : string -> char -> int

val index_opt : string -> char -> int option

val rindex : string -> char -> int

val rindex_opt : string -> char -> int option

val to_seq : t -> char Stdlib.Seq.t

val to_seqi : t -> (int * char) Stdlib.Seq.t

val of_seq : char Stdlib.Seq.t -> t

val get_utf_8_uchar : t -> int -> Stdlib.Uchar.utf_decode

val is_valid_utf_8 : t -> bool

val get_utf_16be_uchar : t -> int -> Stdlib.Uchar.utf_decode

val is_valid_utf_16be : t -> bool

val get_utf_16le_uchar : t -> int -> Stdlib.Uchar.utf_decode

val is_valid_utf_16le : t -> bool

val get_uint8 : string -> int -> int

val get_int8 : string -> int -> int

val get_uint16_ne : string -> int -> int

val get_uint16_be : string -> int -> int

val get_uint16_le : string -> int -> int

val get_int16_ne : string -> int -> int

val get_int16_be : string -> int -> int

val get_int16_le : string -> int -> int

val get_int32_ne : string -> int -> int32

val hash : t -> int

val seeded_hash : int -> t -> int

val get_int32_be : string -> int -> int32

val get_int32_le : string -> int -> int32

val get_int64_ne : string -> int -> int64

val get_int64_be : string -> int -> int64

val get_int64_le : string -> int -> int64

val unsafe_get : string -> int -> char

val unsafe_blit : string -> int -> bytes -> int -> int -> unit

Strings

val empty : string

empty is "".

val head : string -> char option

head s if Some s.[0] if s <> "" and None otherwise.

val of_char : char -> string

of_char c is c as a string.

Predicates

val is_empty : string -> bool

is_empty s is equal empty s.

val includes : affix:string -> string -> bool

includes ~affix s is true iff there exists an index j such that for all indices i of affix, sub.[i] = s.[j+ 1].

Finding indices

TODO. Harmonize indexing errors with find_first. This never raises.

val find_first_index : ?start:int -> (char -> bool) -> string -> int option

find_first_index ~start sat is the index of the first character of s that satisfies sat after or at start (defaults to 0).

val find_last_index : ?start:int -> (char -> bool) -> string -> int option

find_last_index ~start sat is the index of the last character of s that satisfies sat before or at start (defaults to String.length s - 1).

Finding substrings

val find_first : ?start:int -> sub:string -> string -> int option

find_first ~start ~sub s is the start position (if any) of the first occurence of sub in s after or at position start (which includes index start if it exists, defaults to 0). Note if you need to search for sub multiple times in s use find_sub_all it is more efficient.

raises Invalid_argument
if start is not a valid position of s.

val find_last : ?start:int -> sub:string -> string -> int option

find_last ~start ~sub s is the start position (if any) of the last occurences of sub in s before or at position start (which includes index start if it exists, defaults to String.length s).

Note if you need to search for sub multiple times in s use rfind_sub_all it is more efficient.

raises Invalid_argument
if start is not a valid position of s.

val find_all : 
  ?start:int ->
  (int -> 'acc -> 'acc) ->
  sub:string ->
  string ->
  'acc ->
  'acc

find_all ~start f ~sub s acc, starting with acc, folds f over all non-overlapping starting positions of sub in s after or at position start (which includes index start if it exists, defaults to 0). This is acc if sub could not be found in s.

raises Invalid_argument
if start is not a valid position of s.

val rfind_all : 
  ?start:int ->
  (int -> 'acc -> 'acc) ->
  sub:string ->
  string ->
  'acc ->
  'acc

rfind_all ~start f ~sub s acc, starting with acc, folds f over all non-overlapping starting positions of sub in s before or at position start (which includes index start if it exists, defaults to String.length s). This is acc if sub could not be found in s.

raises Invalid_argument
if start is not a valid position of s.

Replacing substrings

val replace_first : ?start:int -> sub:string -> by:string -> string -> string

replace_first ~start ~sub ~by s replaces by by in s the first occurence of sub at or after position start (which includes index start if it exists, defaults to 0) by by.

raises Invalid_argument
if start is not a valid position of s.

val replace_last : ?start:int -> sub:string -> by:string -> string -> string

replace_last ~start ~sub ~by s replaces by by in s the last occurence of sub at or before position start (which includes index start if it exists, defaults to String.length s).

raises Invalid_argument
if start is not a valid position of s.

val replace_all : ?start:int -> sub:string -> by:string -> string -> string

replace_all ~start ~sub ~by replaces in s all non-overlapping occurences of sub at or after position start (default to 0) by by.

raises Invalid_argument
if start is not a valid position of s.

Extracting substrings

val subrange : ?first:int -> ?last:int -> string -> string

subrange ~first ~last s are the consecutive bytes of s whose indices exist in the range [first;last].

first defaults to 0 and last to String.length s - 1.

Note that both first and last can be any integer. If first > last the interval is empty and the empty string is returned.

Breaking

Breaking with magnitudes

val take_first : int -> string -> string

take_first n s are the first n bytes of s. This is s if n >= length s and "" if n <= 0.

val take_last : int -> string -> string

take_last n s are the last n bytes of s. This is s if n >= length s and "" if n <= 0.

val drop_first : int -> string -> string

drop_first n s is s without the first n bytes of s. This is "" if n >= length s and s if n <= 0.

val drop_last : int -> string -> string

drop_last n s is s without the last n bytes of s. This is "" if n >= length s and s if n <= 0.

val cut_first : int -> string -> string * string

cut_first n v is (take_first n v, drop_first n v).

val cut_last : int -> string -> string * string

cut_last n v is (drop_last n v, take_last n v).

Breaking with predicates

val take_first_while : (char -> bool) -> string -> string

take_first_while sat s are the first consecutive sat statisfying bytes of s.

val take_last_while : (char -> bool) -> string -> string

take_last_while sat s are the last consecutive sat satisfying bytes of s.

val drop_first_while : (char -> bool) -> string -> string

drop_first_while sat s is s without the first consecutive sat satisfying bytes of s.

val drop_last_while : (char -> bool) -> string -> string

drop_last_while sat s is s without the last consecutive sat satisfying bytes of s.

val cut_first_while : (char -> bool) -> string -> string * string

cut_first_while sat s is (take_first_while sat s, drop_first_while sat s).

val cut_last_while : (char -> bool) -> string -> string * string

cut_last_while sat s is (drop_last_while sat s, take_last_while sat s).

Breaking with separators

val split_first : sep:string -> string -> (string * string) option

split_first ~sep s is the pair Some (left, right) made of the two (possibly empty) substrings of s that are delimited by the first match of the separator sep or None if sep can't be matched in s. Matching starts at position 0 using find_first.

The invariant concat sep [left; right] = s holds.

val split_last : sep:string -> string -> (string * string) option

split_last ~sep s is like split_first but matching starts at position length s using find_last.

val split_all : ?drop:(string -> bool) -> sep:string -> string -> string list

split_all ~sep s is the list of all substrings of s that are delimited by non-overlapping matches of the separator sep. If sep can't be matched in s, the list [s] is returned. Matches starts at position 0 and are determined using find_all.

Substrings sub for which drop sub is true are not included in the result. drop default to Fun.const false.

The invariant concat sep (split_all ~sep s) = s holds.

val rsplit_all : ?drop:(string -> bool) -> sep:string -> string -> string list

rsplit_all ~sep s is like split_all but matching starts at position length s using rfind_all.

Breaking lines

val fold_ascii_lines : 
  strip_newlines:bool ->
  (int -> 'a -> string -> 'a) ->
  'a ->
  string ->
  'a

fold_ascii_lines ~strip_newlines f acc s folds over the lines of s by calling f linenum acc' line with linenum the one-based line number count, acc' the result of accumulating acc with f so far and line the data of the line (without the newline found in the data if strip_newlines is true).

Lines are delimited by newline sequences which are either one of "\n", "\r\n" or "\r". More precisely the function determines lines and line data as follows:

If s = "", the function considers there are no lines in s and acc is returned without f being called.
If s <> "", s is repeteadly split on the first newline sequences "\n", "\r\n" or "\r" into (left, newline, right), left (or left ^ newline when strip_newlines = false) is given to f and the process is repeated with right until a split can no longer be found. At that point this final string is given to f and the process stops.

val detach_ascii_newline : string -> string * string

detach_ascii_newline s is (data, endline) with:

endline either the suffix "\n", "\r\n" or "\r" of s or "" if s has no such suffix.
data the bytes before endline such that data ^ newline = s

Tokenize

val next_token : 
  ?is_sep:(char -> bool) ->
  ?is_token:(char -> bool) ->
  string ->
  string * string

next_token ~is_sep ~is_token s skips characters satisfying is_sep from s, then gather zero or more consecutive characters satisfying is_token into a string which is returned along the remaining characters after that. is_sep defaults to Char.Ascii.is_white and is_token is Char.Ascii.is_graphic.

val tokens : ?is_sep:(char -> bool) -> string -> string list

tokens s are the strings separated by sequences of is_sep characters (default to Char.Ascii.is_white). The empty list is returned if s is empty or made only of separators.

Uniqueness

val distinct : string list -> string list

distinct ss is ss without duplicates, the list order is preserved.

val unique : ?limit:int -> exists:(string -> bool) -> string -> string

unique ~limit ~exist n is n if exists n is false or r = strf "%s~%d" n d with d the smallest integer such that exists r if false. If no d in [1;limit] satisfies the condition Invalid_argument is raised, limit defaults to 1e6.

Spellchecking

All additions available in OCaml 5.4

val edit_distance : ?limit:int -> t -> t -> int

edit_distance s0 s1 is the number of single character edits (understood as insertion, deletion, substitution, transposition) that are needed to change s0 into s1.

If limit is provided the function returns with limit as soon as it was determined that s0 and s1 have distance of at least limit. This is faster if you have a fixed limit, for example for spellchecking.

The function assumes the strings are UTF-8 encoded and uses Uchar.t for the notion of character. Decoding errors are replaced by Uchar.rep. Normalizing the strings to NFC gives better results.

Note. This implements the simpler Optimal String Alignement (OSA) distance, not the Damerau-Levenshtein distance. With this function "ca" and "abc" have a distance of 3 not 2.

val spellcheck : 
  ?max_dist:(string -> int) ->
  ((string -> unit) -> unit) ->
  string ->
  string list

spellcheck iter_dict s are the strings enumerated by the iterator iter_dict whose edit distance to s is the smallest and at most max_dist s. If multiple corrections are returned their order is as found in iter_dict. The default max_dist s is:

0 if s has 0 to 2 Unicode characters.
1 if s has 3 to 4 Unicode characters.
2 otherwise.

If your dictionary is a list l, a suitable iter_dict is given by (fun yield -> List.iter yield l).

All strings are assumed to be UTF-8 encoded, decoding errors are replaced by Uchar.rep characters.

(Un)escaping bytes

The following functions can only (un)escape a single byte. See also these functions to convert a string to printable ASCII characters.

val byte_escaper : 
  (char -> int) ->
  (bytes -> int -> char -> int) ->
  string ->
  string

byte_escaper char_len set_char is a byte escaper such that:

char_len c is the length of the unescaped byte c in the escaped form. If 1 is returned then c is assumed to be unchanged use byte_replacer if that does not hold
set_char b i c sets an unescaped byte c to its escaped form at index i in b and returns the next writable index. set_char is called regardless if c needs to be escaped or not in the latter case you must write c (use byte_replacer if that is not the case). No bounds check need to be performed on i or the returned value.

For any b, c and i the invariant i + char_len c = set_char b i c must hold.

Here's a small example that escapes '"' by prefixing them by backslashes. double quotes from strings:

let escape_dquotes s =
  let char_len = function '"' -> 2 | _ -> 1 in
  let set_char b i = function
  | '"' -> Bytes.set b i '\\'; Bytes.set b (i+1) '"'; i + 2
  | c -> Bytes.set b i c; i + 1
  in
  String.byte_escaper char_len set_char s

val byte_replacer : 
  (char -> int) ->
  (bytes -> int -> char -> int) ->
  string ->
  string

byte_replacer char_len set_char is like byte_escaper but a byte can be substituted by another one by set_char.

exception Illegal_escape of int

See byte_unescaper.

val byte_unescaper : 
  (string -> int -> int) ->
  (bytes -> int -> string -> int -> int) ->
  string ->
  (string, int) Stdlib.result

byte_unescaper char_len_at set_char is a byte unescaper such that:

char_len_at s i is the length of an escaped byte at index i of s. If 1 is returned then the byte is assumed to be unchanged by the unescape, use byte_unreplacer if that does not hold.
set_char b k s i sets at index k in b the unescaped byte read at index i in s and returns the next readable index in s. set_char is called regardless of wheter the byte at i must be unescaped or not in the latter case you must write s.i only (use byte_unreplacer if that is not the case). No bounds check need to be performed on k, i or the returned value.

For any b, s, k and i the invariant i + char_len_at s i = set_char b k s i must hold.

Both char_len_at and set_char may raise Illegal_escape i if the given index i has an illegal or truncated escape. The unescaper turns this exception into Error i if that happens.

val byte_unreplacer : 
  (string -> int -> int) ->
  (bytes -> int -> string -> int -> int) ->
  string ->
  (string, int) Stdlib.result

byte_unreplacer char_len_at set_char is like byte_unescaper except set_char can set a different byte whenever char_len_at returns 1.

ASCII strings

module Ascii : sig ... end

ASCII string support.

Variable substitution

val subst_pct_vars : 
  ?buf:Stdlib.Buffer.t ->
  (string -> string option) ->
  string ->
  string

subst_pct_vars ~buf vars s substitutes in s sub-strings of the form %%VAR%% by the value of vars "VAR" (if any).

ANSI stripping

val strip_ansi_escapes : string -> string

strip_ansi_escapes s removes ANSI escapes from s.

Formatting

val pp : string Fmt.t

pp ppf s prints s's bytes on ppf.

Sets and maps

module Set : sig ... end

String sets.

module Map : sig ... end

String maps.