Module String


module String: Extlib.ExtString.String
String operations.
Author(s): Xavier Leroy (base library), Nicolas Cannasse, David Teller, Edgar Friendly

exception Invalid_string
An exception thrown when some operation required a string and received an unacceptable string.
type t = string 
The type of strings.
val length : string -> int
Return the length (number of characters) of the given string.
val is_empty : string -> bool
is_empty s returns true if s is the empty string, false otherwise.

Usually a tad faster than comparing s with "".

val get : string -> int -> char
String.get s n returns character number n in string s. The first character is character number 0. The last character is character number String.length s - 1. You can also write s.[n] instead of String.get s n.

Raise Invalid_argument "index out of bounds" if n is outside the range 0 to (String.length s - 1).

val set : string -> int -> char -> unit
String.set s n c modifies string s in place, replacing the character number n by c. You can also write s.[n] <- c instead of String.set s n c. Raise Invalid_argument "index out of bounds" if n is outside the range 0 to (String.length s - 1).
val create : int -> string
String.create n returns a fresh string of length n. The string initially contains arbitrary characters. Raise Invalid_argument if n < 0 or n > Sys.max_string_length.

Constructors

val make : int -> char -> string
String.make n c returns a fresh string of length n, filled with the character c. Raise Invalid_argument if n < 0 or n > Sys.max_string_length.
val init : int -> (int -> char) -> string
init l f returns the string of length l with the chars f 0 , f 1 , f 2 ... f (l-1).
val enum : string -> char Enum.t
Conversions

Returns an enumeration of the characters of a string.

val of_enum : char Enum.t -> string
Creates a string from a character enumeration.
val backwards : string -> char Enum.t
Returns an enumeration of the characters of a string, from last to first.
val of_backwards : char Enum.t -> string
Build a string from an enumeration, starting with last character, ending with first.
val of_list : char list -> string
Converts a list of characters to a string.
val to_list : string -> char list
Converts a string to the list of its characters.
val of_int : int -> string
Returns the string representation of an int.
val of_float : float -> string
Returns the string representation of an float.
val of_char : char -> string
Returns a string containing one given character.
val to_int : string -> int
Returns the integer represented by the given string or raises Invalid_string if the string does not represent an integer.
val to_float : string -> float
Returns the float represented by the given string or raises Invalid_string if the string does not represent a float.

String traversals

val map : (char -> char) -> string -> string
map f s returns a string where all characters c in s have been replaced by f c. *
val fold_left : ('a -> char -> 'a) -> 'a -> string -> 'a
fold_left f a s is f (... (f (f a s.[0]) s.[1]) ...) s.[n-1]
val fold_right : (char -> 'a -> 'a) -> string -> 'a -> 'a
fold_right f s b is f s.[0] (f s.[1] (... (f s.[n-1] b) ...))
val filter : (char -> bool) -> string -> string
filter f s returns a copy of string s in which only characters c such that f c = true remain.
val filter_map : (char -> char option) -> string -> string
filter_map f s calls (f a0) (f a1).... (f an) where a0..an are the characters of s. It returns the string of characters ci such as f ai = Some ci (when f returns None, the corresponding element of s is discarded).
val iter : (char -> unit) -> string -> unit
String.iter f s applies function f in turn to all the characters of s. It is equivalent to f s.[0]; f s.[1]; ...; f s.[String.length s - 1]; ().
val iteri : (int -> char -> unit) -> string -> unit
String.iteri f s is equivalent to f 0 s.[0]; f 1 s.[1]; ...; f len s.[len] where len is length of string s.

Finding

val index : string -> char -> int
String.index s c returns the position of the leftmost occurrence of character c in string s. Raise Not_found if c does not occur in s.
val rindex : string -> char -> int
String.rindex s c returns the position of the rightmost occurrence of character c in string s. Raise Not_found if c does not occur in s.
val index_from : string -> int -> char -> int
Same as String.index, but start searching at the character position given as second argument. String.index s c is equivalent to String.index_from s 0 c.
val rindex_from : string -> int -> char -> int
Same as String.rindex, but start searching at the character position given as second argument. String.rindex s c is equivalent to String.rindex_from s (String.length s - 1) c.
val contains : string -> char -> bool
String.contains s c tests if character c appears in the string s.
val contains_from : string -> int -> char -> bool
String.contains_from s start c tests if character c appears in the substring of s starting from start to the end of s.
Raises Invalid_argument if start is not a valid index of s.
val rcontains_from : string -> int -> char -> bool
String.rcontains_from s stop c tests if character c appears in the substring of s starting from the beginning of s to index stop.
Raises Invalid_argument if stop is not a valid index of s.
val find : string -> string -> int
find s x returns the starting index of the first occurrence of string x within string s.

Note This implementation is optimized for short strings.
Raises Invalid_string if x is not a substring of s.

val find_from : string -> int -> string -> int
find_from s ofs x behaves as find s x but starts searching at offset ofs. find s x is equivalent to find_from s 0 x.
val rfind : string -> string -> int
rfind s x returns the starting index of the last occurrence of string x within string s.

Note This implementation is optimized for short strings.
Raises Invalid_string if x is not a substring of s.

val rfind_from : string -> int -> string -> int
rfind_from s ofs x behaves as rfind s x but starts searching at offset ofs. rfind s x is equivalent to rfind_from s (String.length s - 1) x.
val ends_with : string -> string -> bool
ends_with s x returns true if the string s is ending with x, false otherwise.
val starts_with : string -> string -> bool
starts_with s x returns true if s is starting with x, false otherwise.
val exists : string -> string -> bool
exists str sub returns true if sub is a substring of str or false otherwise.

Transformations

val lchop : string -> string
Returns the same string but without the first character. does nothing if the string is empty.
val rchop : string -> string
Returns the same string but without the last character. does nothing if the string is empty.
val trim : string -> string
Returns the same string but without the leading and trailing whitespaces.
val quote : string -> string
Add quotes around a string and escape any quote appearing in that string. This function is used typically when you need to generate source code from a string.

quote "foo" returns "\"foo\"" quote "\"foo\"" returns "\\\"foo\\\"" etc.

val left : string -> int -> string
left r len returns the string containing the len first characters of r
val right : string -> int -> string
left r len returns the string containing the len last characters of r
val head : string -> int -> string
as String.left
val tail : string -> int -> string
tail r pos returns the string containing all but the pos first characters of r
val strip : ?chars:string -> string -> string
Returns the string without the chars if they are at the beginning or at the end of the string. By default chars are " \t\r\n".
val uppercase : string -> string
Return a copy of the argument, with all lowercase letters translated to uppercase, including accented letters of the ISO Latin-1 (8859-1) character set.
val lowercase : string -> string
Return a copy of the argument, with all uppercase letters translated to lowercase, including accented letters of the ISO Latin-1 (8859-1) character set.
val capitalize : string -> string
Return a copy of the argument, with the first character set to uppercase.
val uncapitalize : string -> string
Return a copy of the argument, with the first character set to lowercase.
val copy : string -> string
Return a copy of the given string.
val sub : string -> int -> int -> string
String.sub s start len returns a fresh string of length len, containing the characters number start to start + len - 1 of string s.
Raises Invalid_argument if start and len do not designate a valid substring of s; that is, if start < 0, or len < 0, or start + len > String.length s.
val fill : string -> int -> int -> char -> unit
String.fill s start len c modifies string s in place, replacing the characters number start to start + len - 1 by c.
Raises Invalid_argument if start and len do not designate a valid substring of s.
val blit : string -> int -> string -> int -> int -> unit
String.blit src srcoff dst dstoff len copies len characters from string src, starting at character number srcoff, to string dst, starting at character number dstoff. It works correctly even if src and dst are the same string, and the source and destination chunks overlap.
Raises Invalid_argument if srcoff and len do not designate a valid substring of src, or if dstoff and len do not designate a valid substring of dst.
val concat : string -> string list -> string
String.concat sep sl concatenates the list of strings sl, inserting the separator string sep between each.
val escaped : string -> string
Return a copy of the argument, with special characters represented by escape sequences, following the lexical conventions of Objective Caml. If there is no special character in the argument, return the original string itself, not a copy.
val replace_chars : (char -> string) -> string -> string
replace_chars f s returns a string where all chars c of s have been replaced by the string returned by f c.
val replace : str:string -> sub:string -> by:string -> bool * string
replace ~str ~sub ~by returns a tuple constisting of a boolean and a string where the first occurrence of the string sub within str has been replaced by the string by. The boolean is true if a subtitution has taken place.
val repeat : string -> int -> string
repeat s n returns s ^ s ^ ... ^ s

Splitting around

val split : string -> string -> string * string
split s sep splits the string s between the first occurrence of sep.
Raises Invalid_string if the separator is not found.
val rsplit : string -> string -> string * string
rsplit s sep splits the string s between the last occurrence of sep.
Raises Invalid_string if the separator is not found.
val nsplit : string -> string -> string list
nsplit s sep splits the string s into a list of strings which are separated by sep. nsplit "" _ returns the empty list.
val join : string -> string list -> string
Same as String.concat
val slice : ?first:int -> ?last:int -> string -> string
slice ?first ?last s returns a "slice" of the string which corresponds to the characters s.[first], s.[first+1], ..., s[last-1]. Note that the character at index last is not included! If first is omitted it defaults to the start of the string, i.e. index 0, and if last is omitted is defaults to point just past the end of s, i.e. length s. Thus, slice s is equivalent to copy s.

Negative indexes are interpreted as counting from the end of the string. For example, slice ~last:(-2) s will return the string s, but without the last two characters.

This function never raises any exceptions. If the indexes are out of bounds they are automatically clipped.

val splice : string -> int -> int -> string -> string
String.splice s off len rep cuts out the section of s indicated by off and len and replaces it by rep

Negative indexes are interpreted as counting from the end of the string. If off+len is greater than length s, the end of the string is used, regardless of the value of len.

val explode : string -> char list
explode s returns the list of characters in the string s.
val implode : char list -> string
implode cs returns a string resulting from concatenating the characters in the list cs.

Comparisons

val compare : t -> t -> int
The comparison function for strings, with the same specification as Standard.compare. Along with the type t, this function compare allows the module String to be passed as argument to the functors Set.Make and Map.Make.
val icompare : t -> t -> int
Compare two strings, case-insensitive.
module String.IString: Extlib.Interfaces.OrderedType  with type t = t
uses icompare as ordering function
val numeric_compare : t -> t -> int
Compare two strings, sorting "abc32def" before "abc210abc"
module String.NumString: Extlib.Interfaces.OrderedType  with type t = t
uses numeric_compare as its ordering function

Boilerplate code


S-Expressions

val t_of_sexp : Sexplib.Sexp.t -> t
val sexp_of_t : t -> Sexplib.Sexp.t

Printing

val print : 'a Extlib.InnerIO.output -> string -> unit
Print a string.
val println : 'a Extlib.InnerIO.output -> string -> unit
Print a string, end the line.
val print_quoted : 'a Extlib.InnerIO.output -> string -> unit
Print a string, with quotes.

print_quoted stdout "foo" prints "foo" (with the quotes)

print_quoted stdout "\"bar\"" prints "\"bar\"" (with the quotes)

val t_printer : t Value_printer.t
module String.Cap: sig .. end
Capabilities for strings.