uuseg 15.0.0 · OCaml Package

Unicode text segmentation on UTF-X OCaml strings.

Uuseg helper functions acting directly on UTF-X encoded OCaml strings.

Warning. All these functions silently replace malformed encoded Unicode data by a Stdlib.Uchar.rep character.

Unicode version 15.0.0

Segment

type 'a folder = 'a -> string -> 'a

The type for segment folders. The function takes an accumulator and a segment. Segments are the UTF-X encoded characters delimited by two `Boundary occurences. If the segmenter has no initial or final `Boundary, the folding function inserts an implicit one. Empty segments – which by definition do not happen with the default segmenters – are not reported.

val fold_utf_8 : [< Uuseg.boundary ] -> 'a folder -> 'a -> string -> 'a

fold_utf_8 b f acc s folds over the b UTF-8 encoded segments of the UTF-8 encoded string s using f and acc.

val fold_utf_16be : [< Uuseg.boundary ] -> 'a folder -> 'a -> string -> 'a

fold_utf16be is like fold_utf_8 but on UTF-16BE encoded strings.

val fold_utf_16le : [< Uuseg.boundary ] -> 'a folder -> 'a -> string -> 'a

fold_utf16le is like fold_utf_8 but on UTF-16BE encoded strings.

Pretty-printers

Using OCaml's Format.pp_print_string with Unicode encoded strings will most of the time derail the pretty-printing process for two reasons. First the Unicode encoding of a character may span more than one byte and pp_print_string considers one character to be one byte. Second there may be a discrepancy between the sequence of user-perceived characters (grapheme clusters e.g. é) and the actual sequences of Unicode characters in the data (e.g. é represented by the decomposition e + ´, <U+0065,U+0301>).

The following formatters fix these problems for many (but not all) scripts.

val pp_utf_8 : Format.formatter -> string -> unit

pp_utf8 ppf s prints the UTF-8 encoded string s. Each grapheme cluster is considered as taking a length of 1.

val pp_utf_8_text : Format.formatter -> string -> unit

pp_utf_8_text ppf s prints the UTF-8 encoded string s. Each grapheme cluster is considered as taking a length of 1. Each line break opportunity is hinted with Format.pp_print_break and mandatory line breaks issue a Format.pp_force_newline call.

Take into account the following points:

Any white space Unicode character occuring before a break opportunity will be translated to a space (U+0020) in output if no break occurs.
The sequence CR LF (U+000D, U+000A) and all kind of mandatory line breaks are translated to whathever line separator is output by Format.pp_force_newline. See pp_utf_8_lines for the list of characters treated as mandatory line breaks.
Soft hyphens are handled but due to limitations in Format are not replaced by hard ones on breaks.

val pp_utf_8_lines : Format.formatter -> string -> unit

pp_utf_8_lines ppf s prints the UTF-8 encoded string s. Each grapheme cluster is considered as taking a length of 1. Each mandatory line break (including the sequence CR LF (U+000D, U+000A)) issues a Format.pp_force_newline and is translated to whathever line separator this function outputs.

This function correctly handles all kinds of line ends present Unicode, as of 7.0.0 this is FORM FEED (U+000C), LINE TABULATION (U+000B), LINE SEPARATOR (U+2028), PARAGRAPH SEPARATOR (U+2020), NEXT LINE (U+085), LINE FEED (U+000A), CARRIAGE RETURN (U+000D), and the sequence CR LF (U+000D, U+000A).

package uuseg

Segment

Pretty-printers