package charInfo_width

CharInfo_width

Determine column width of a character.

Description

CharInfo_width.width c returns the column width of c where c is of type Camomile.UChar.t and the value returned is of type int.

This module is implemented purely in OCaml and the width function follows the prototype of POSIX's wcwidth. i.e. If c is a printable character, the value is at least 0. If c is null character (L'\0'), the value is 0. Otherwise, -1 is returned. The width_exn function, when encounter an unprintable character, it raises Failure "unprintable character" instead of returning -1.

By default, the width and width_exn function is compatible with ncursesw, ncursesw based CLIs, terminals. The way they consider the width of a character is the same.

An optional parameter, cfg, can extend extra width info. The current width info table of ncursesw, xterm, xterm-compatible terminal is inadequate and limited, so is the default cfg of this module. When implement raw mode command-line interface, e.g. readline, a text editor, better extend extra width info by cfg. An on going sample repository of width table is here: charInfo_width_extra

This module also provides a function, CharInfo_width.width_utext to calculate the width of a unicode string. The returned value is either Ok width or Error pos-of-unprintable-character.