`module Rope: ``Extlib.Rope`

Heavyweight strings ("ropes")
This module implements ropes as described in Boehm, H., Atkinson, R., and Plass, M. 1995. Ropes: an alternative to strings. Softw. Pract. Exper. 25, 12 (Dec. 1995), 1315-1330.

Ropes are an alternative to strings which support efficient operations:

- determining the length of a rope in constant time
- appending or prepending a small rope to an arbitrarily large one in amortized constant time
- concat, substring, insert, remove operations in amortized logarithmic time
- access to and modification of ropes in logarithmic time

Functional nature and persistence

All operations are non-destructive: the original rope is never modified. When a
new rope is returned as the result of an operation, it will share as much data
as possible with its "parent". For instance, if a rope of length `n`

undergoes
`m`

operations (assume `n >> m`

) like set, append or prepend, the modified
rope will only require `O(m)`

space in addition to that taken by the
original one.

However, Rope is an amortized data structure, and its use in a persistent setting
can easily degrade its amortized time bounds. It is thus mainly intended to be used
ephemerally. In some cases, it is possible to use Rope persistently with the same
amortized bounds by explicitly rebalancing ropes to be reused using `balance`

.
Special care must be taken to avoid calling `balance`

too frequently; in the limit,
calling `balance`

after each modification would defeat the purpose of amortization.

Limitations

The length of ropes is limited to approximately 700 Mb on 32-bit
architectures, 220 Gb on 64 bit architectures.

**Author(s):** Mauricio Fernandez

`type `

t

The type of the ropes.

`exception Out_of_bounds`

Raised when an operation violates the bounds of the rope.

`exception Invalid_rope`

An exception thrown when some operation required a rope
and received an unacceptable rope.

`val max_length : ``int`

Maximum length of the rope (number of UTF-8 characters).

`val empty : ``t`

The empty rope.

`val of_latin1 : ``string -> t`

Constructs a unicode rope from a latin-1 string.

`val of_string : ``string -> t`

`of_string s`

returns a rope corresponding to the UTF-8 encoded string `s`

.`val to_string : ``t -> string`

`to_string t`

returns a UTF-8 encoded string representing `t`

`val of_ustring : ``UTF8.t -> t`

`of_string s`

returns a rope corresponding to the string `s`

.
Operates in `O(n)`

time.`val to_ustring : ``t -> UTF8.t`

`to_ustring r`

returns the string corresponding to the rope `r`

.`val of_uchar : ``UChar.t -> t`

`of_uchar c`

returns a rope containing exactly character `c`

.`val of_char : ``char -> t`

`of_char c`

returns a rope containing exactly Latin-1 character `c`

.`val make : ``int -> UChar.t -> t`

`make i c`

returns a rope of length `i`

consisting of `c`

chars;
it is similar to String.make`val lowercase : ``t -> t`

`lowercase s`

returns a lowercase copy of rope `s`

.
Note that, for some languages, the number of characters in
`lowercase s`

is not the same as the number of characters in
`s`

.

`val uppercase : ``t -> t`

`uppercase s`

returns a uppercase copy of rope `s`

.
Note that, for some languages, the number of characters in
`uppercase s`

is not the same as the number of characters in
`s`

.

`val capitalize : ``t -> t`

Return a copy of the argument, with the first character set to uppercase.

`val uncapitalize : ``t -> t`

Return a copy of the argument, with the first character set to lowercase.

`val join : ``t -> t list -> t`

Same as

`Rope.concat`

`val explode : ``t -> UChar.t list`

`explode s`

returns the list of characters in the rope `s`

.`val implode : ``UChar.t list -> t`

`implode cs`

returns a rope resulting from concatenating
the characters in the list `cs`

.`val is_empty : ``t -> bool`

Returns whether the rope is empty or not.

`val length : ``t -> int`

Returns the length of the rope (

`O(1)`

).
This is number of UTF-8 characters.`val height : ``t -> int`

Returns the height (depth) of the rope.

`val balance : ``t -> t`

`balance r`

returns a balanced copy of the `r`

rope. Note that ropes are
automatically rebalanced when their height exceeds a given threshold, but
`balance`

allows to invoke that operation explicity.`val append : ``t -> t -> t`

`append r u`

concatenates the `r`

and `u`

ropes. In general, it operates
in `O(log(min n1 n2))`

amortized time.
Small ropes are treated specially and can be appended/prepended in
amortized `O(1)`

time.`val (^^^) : ``t -> t -> t`

As

`Rope.append`

`val append_char : ``UChar.t -> t -> t`

`append_char c r`

returns a new rope with the `c`

character at the end
in amortized `O(1)`

time.`val prepend_char : ``UChar.t -> t -> t`

`prepend_char c r`

returns a new rope with the `c`

character at the
beginning in amortized `O(1)`

time.`val get : ``t -> int -> UChar.t`

`get r n`

returns the (n+1)th character from the rope `r`

; i.e.
`get r 0`

returns the first character.
Operates in worst-case `O(log size)`

time.
Raises Out_of_bounds if a character out of bounds is requested.`val set : ``t -> int -> UChar.t -> t`

`set r n c`

returns a copy of rope `r`

where the (n+1)th character
has been set to `c`

. See also `Rope.get`

.
Operates in worst-case `O(log size)`

time.`val sub : ``t -> int -> int -> t`

`sub r m n`

returns a sub-rope of `r`

containing all characters
whose indexes range from `m`

to `m + n - 1`

(included).
Raises Out_of_bounds in the same cases as sub.
Operates in worst-case `O(log size)`

time.`val insert : ``int -> t -> t -> t`

`insert n r u`

returns a copy of the `u`

rope where `r`

has been
inserted between the characters with index `n`

and `n + 1`

in the
original rope. The length of the new rope is
`length u + length r`

.
Operates in amortized `O(log(size r) + log(size u))`

time.`val remove : ``int -> int -> t -> t`

`remove m n r`

returns the rope resulting from deleting the
characters with indexes ranging from `m`

to `m + n - 1`

(included)
from the original rope `r`

. The length of the new rope is
`length r - n`

.
Operates in amortized `O(log(size r))`

time.`val concat : ``t -> t list -> t`

`concat sep sl`

concatenates the list of ropes `sl`

,
inserting the separator rope `sep`

between each.`val iter : ``(UChar.t -> unit) -> t -> unit`

`iter f r`

applies `f`

to all the characters in the `r`

rope,
in order.`val iteri : ``?base:int ->`

(int -> UChar.t -> unit) -> t -> unit

Operates like

`iter`

, but also passes the index of the character
to the given function.`val range_iter : ``(UChar.t -> unit) -> int -> int -> t -> unit`

`rangeiter f m n r`

applies `f`

to all the characters whose
indices `k`

satisfy `m`

<= `k`

< `m + n`

.
It is thus equivalent to `iter f (sub m n r)`

, but does not
create an intermediary rope. `rangeiter`

operates in worst-case
`O(n + log m)`

time, which improves on the `O(n log m)`

bound
from an explicit loop using `get`

.
Raises Out_of_bounds in the same cases as `sub`

.`val range_iteri : ``(int -> UChar.t -> unit) ->`

?base:int -> int -> int -> t -> unit

As

`range_iter`

, but passes base + index of the character in the
subrope defined by next to arguments.`val bulk_iter : ``(UTF8.t -> unit) -> t -> unit`

as iter but over larger chunks of data

`val bulk_iteri : ``?base:int -> (int -> UTF8.t -> unit) -> t -> unit`

as iteri but over larger chunks of data.

`val fold : ``('a -> UChar.t -> 'a) -> 'a -> t -> 'a`

`Rope.fold f a r`

computes ` f (... (f (f a r0) r1)...) rN-1 `

where `rn = Rope.get n r `

and `N = length r`

.`val bulk_fold : ``('a -> UTF8.t -> 'a) -> 'a -> t -> 'a`

As

`Rope.fold`

but over larger chunks of data.`val enum : ``t -> UChar.t Enum.t`

Returns an enumeration of the characters of a rope.

`val bulk_enum : ``t -> UTF8.t Enum.t`

Returns an enumeration of the UTF-8 encoded strings of a rope.
Provided for convenience and speed.

`val of_enum : ``UChar.t Enum.t -> t`

Creates a rope from a character enumeration.

`val of_bulk_enum : ``UTF8.t Enum.t -> t`

Creates a rope from an enumeration of UTF-8 encoded strings.

Provided for convenience and speed.

`val backwards : ``t -> UChar.t Enum.t`

Returns an enumeration of the characters of a rope, from last to first.

`val of_backwards : ``UChar.t Enum.t -> t`

Build a rope from an enumeration, starting with last character, ending with first.

`val init : ``int -> (int -> UChar.t) -> t`

`init l f`

returns the rope of length `l`

with the chars f 0 , f
1 , f 2 ... f (l-1).`val of_int : ``int -> t`

Returns the rope representation of an int.

`val of_float : ``float -> t`

Returns the rope representation of a float.

`val to_int : ``t -> int`

Returns the integer represented by the given rope or
raises

`Invalid_rope`

if the rope does not represent an integer.`val to_float : ``t -> float`

Returns the float represented by the given rope or
raises Invalid_rope if the rope does not represent a float.

`val bulk_map : ``(UTF8.t -> UTF8.t) ->`

t -> t

`map f s`

returns a rope where all ropes `c`

in `s`

have been
replaced by `f c`

. *`val map : ``(UChar.t -> UChar.t) ->`

t -> t

`map f s`

returns a rope where all characters `c`

in `s`

have been
replaced by `f c`

. *`val bulk_filter_map : ``(UTF8.t -> UTF8.t option) ->`

t -> t

`bulk_filter_map f l`

calls `(f a0) (f a1).... (f an)`

where `a0..an`

are
the UTF-encoded strings of `l`

. It returns the list of elements `bi`

such as
`f ai = Some bi`

(when `f`

returns `None`

, the corresponding element of
`l`

is discarded).`val filter_map : ``(UChar.t -> UChar.t option) ->`

t -> t

`filter_map f l`

calls `(f a0) (f a1).... (f an)`

where `a0..an`

are
the characters of `l`

. It returns the list of elements `bi`

such as
`f ai = Some bi`

(when `f`

returns `None`

, the corresponding element of
`l`

is discarded).`val filter : ``(UChar.t -> bool) -> t -> t`

`filter f s`

returns a copy of rope `s`

in which only
characters `c`

such that `f c = true`

remain.`val index : ``t -> UChar.t -> int`

`Rope.index s c`

returns the position of the leftmost
occurrence of character `c`

in rope `s`

.
Raise `Not_found`

if `c`

does not occur in `s`

.`val index_from : ``t -> int -> UChar.t -> int`

Same as

`Rope.index`

, but start searching at the character
position given as second argument. `Rope.index s c`

is
equivalent to `Rope.index_from s 0 c`

.`val rindex : ``t -> UChar.t -> int`

`Rope.rindex s c`

returns the position of the rightmost
occurrence of character `c`

in rope `s`

.
Raise `Not_found`

if `c`

does not occur in `s`

.`val rindex_from : ``t -> int -> UChar.t -> int`

Same as

`Rope.rindex`

, but start
searching at the character position given as second argument.
`rindex s c`

is equivalent to
`rindex_from s (length s - 1) c`

.`val contains : ``t -> UChar.t -> bool`

`contains s c`

tests if character `c`

appears in the rope `s`

.`val contains_from : ``t -> int -> UChar.t -> bool`

`contains_from s start c`

tests if character `c`

appears in
the subrope of `s`

starting from `start`

to the end of `s`

.`Invalid_argument`

if `start`

is not a valid index of `s`

.`val rcontains_from : ``t -> int -> UChar.t -> bool`

`rcontains_from s stop c`

tests if character `c`

appears in the subrope of `s`

starting from the beginning
of `s`

to index `stop`

.`Invalid_argument`

if `stop`

is not a valid index of `s`

.`val find : ``t -> t -> int`

`find s x`

returns the starting index of the first occurrence of
rope `x`

within rope `s`

.
**Note** This implementation is optimized for short ropes.

**Raises** `Invalid_rope`

if `x`

is not a subrope of `s`

.

`val find_from : ``t -> int -> t -> 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 : ``t -> t -> int`

`rfind s x`

returns the starting index of the last occurrence
of rope `x`

within rope `s`

.
**Note** This implementation is optimized for short ropes.

**Raises** `Invalid_rope`

if `x`

is not a subrope of `s`

.

`val rfind_from : ``t -> int -> t -> 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 (length s - 1) x`

.`val starts_with : ``t -> t -> bool`

`starts_with s x`

returns `true`

if `s`

is starting with `x`

, `false`

otherwise.`val ends_with : ``t -> t -> bool`

`ends_with s x`

returns `true`

if the rope `s`

is ending with `x`

, `false`

otherwise.`val exists : ``t -> t -> bool`

`exists str sub`

returns true if `sub`

is a subrope of `str`

or
false otherwise.`val trim : ``t -> t`

`val left : ``t -> int -> t`

`left r len`

returns the rope containing the `len`

first characters of `r`

`val right : ``t -> int -> t`

`left r len`

returns the rope containing the `len`

last characters of `r`

`val head : ``t -> int -> t`

as

`Rope.left`

`val tail : ``t -> int -> t`

`tail r pos`

returns the rope containing all but the `pos`

first characters of `r`

`val strip : ``?chars:UChar.t list -> t -> t`

Returns the rope without the chars if they are at the beginning or
at the end of the rope. By default chars are " \t\r\n".

`val lchop : ``t -> t`

Returns the same rope but without the first character.
does nothing if the rope is empty.

`val rchop : ``t -> t`

Returns the same rope but without the last character.
does nothing if the rope is empty.

`val slice : ``?first:int -> ?last:int -> t -> t`

`slice ?first ?last s`

returns a "slice" of the rope
which corresponds to the characters `s.[first]`

,
`s.[first+1]`

, ..., `s[last-1]`

. Note that the character at
index `last`

is `first`

is omitted it
defaults to the start of the rope, 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 rope. For example, `slice ~last:-2 s`

will return the
rope `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 : ``t -> int -> int -> t -> t`

`splice s off len rep`

returns the rope in which the section of `s`

indicated by `off`

and `len`

has been cut and replaced by `rep`

.
Negative indices are interpreted as counting from the end of the string.

`val fill : ``t -> int -> int -> UChar.t -> t`

`fill s start len c`

returns the rope in which
characters number `start`

to `start + len - 1`

of `s`

has
been replaced by `c`

.`Invalid_argument`

if `start`

and `len`

do not
designate a valid subrope of `s`

.`val blit : ``t -> int -> t -> int -> int -> t`

`blit src srcoff dst dstoff len`

returns a copy
of `dst`

in which `len`

characters have been copied
from rope `src`

, starting at character number `srcoff`

, to
rope `dst`

, starting at character number `dstoff`

. It works
correctly even if `src`

and `dst`

are the same rope,
and the source and destination chunks overlap.`Invalid_argument`

if `srcoff`

and `len`

do not
designate a valid subrope of `src`

, or if `dstoff`

and `len`

do not designate a valid subrope of `dst`

.`val concat : ``t -> t list -> t`

`concat sep sl`

concatenates the list of ropes `sl`

,
inserting the separator rope `sep`

between each.`val escaped : ``t -> t`

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 rope itself,
not a copy.

`val replace_chars : ``(UChar.t -> UTF8.t) ->`

t -> t

`replace_chars f s`

returns a rope where all chars `c`

of `s`

have been
replaced by the rope returned by `f c`

.`val replace : ``str:t ->`

sub:t -> by:t -> bool * t

`replace ~str ~sub ~by`

returns a tuple constisting of a boolean
and a rope where the first occurrence of the rope `sub`

within `str`

has been replaced by the rope `by`

. The boolean
is `true`

if a substitution has taken place, `false`

otherwise.`val split : ``t -> t -> t * t`

`split s sep`

splits the rope `s`

between the first
occurrence of `sep`

.`Invalid_rope`

if the separator is not found.`val rsplit : ``t -> t -> t * t`

`rsplit s sep`

splits the rope `s`

between the last
occurrence of `sep`

.`Invalid_rope`

if the separator is not found.`val nsplit : ``t -> t -> t list`

`nsplit s sep`

splits the rope `s`

into a list of ropes
which are separated by `sep`

.
`nsplit "" _`

returns the empty list.`val compare : ``t -> t -> int`

The comparison function for ropes, with the same specification as

`Standard.compare`

. Along with the type `t`

, this function `compare`

allows the module `Rope`

to be passed as argument to the functors
`Set.Make`

and `Map.Make`

.`val icompare : ``t -> t -> int`

Compare two ropes, case-insensitive.

module Rope.IRope:`Extlib.Interfaces.OrderedType`

`with type t = t`

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 -> t -> unit`

`val t_printer : ``t Value_printer.t`