1*rileft.txt* For Vim version 8.2. Last change: 2021 Jun 13 2 3 4 VIM REFERENCE MANUAL by Avner Lottem 5 updated by Nadim Shaikli 6 7 8Right to Left display mode for Vim *rileft* 9 10 11These functions were originally created by Avner Lottem: 12 E-mail: [email protected] 13 Phone: +972-4-8307322 14 15 *E26* 16{only available when compiled with the |+rightleft| feature} 17 18 19Introduction 20------------ 21Some languages such as Arabic, Farsi, Hebrew (among others) require the 22ability to display their text from right-to-left. Files in those languages 23are stored conventionally and the right-to-left requirement is only a 24function of the display engine (per the Unicode specification). In 25right-to-left oriented files the characters appear on the screen from 26right to left. 27 28Bidirectionality (or bidi for short) is what Unicode offers as a full 29solution to these languages. Bidi offers the user the ability to view 30both right-to-left as well as left-to-right text properly at the same time 31within the same window. Vim currently, due to simplicity, does not offer 32bidi and is merely opting to present a functional means to display/enter/use 33right-to-left languages. An older hybrid solution in which direction is 34encoded for every character (or group of characters) are not supported either 35as this kind of support is out of the scope of a simple addition to an 36existing editor (and it's not sanctioned by Unicode either). 37 38 39Highlights 40---------- 41o Editing left-to-right files as in the original Vim, no change. 42 43o Viewing and editing files in right-to-left windows. File orientation 44 is per window, so it is possible to view the same file in right-to-left 45 and left-to-right modes, simultaneously. (Useful for editing mixed files 46 in which both right-to-left and left-to-right text exist). 47 48o Compatibility to the original Vim. Almost all features work in 49 right-to-left mode (see Bugs below). 50 51o Backing from reverse insert mode to the correct place in the file 52 (if possible). 53 54o No special terminal with right-to-left capabilities is required. The 55 right-to-left changes are completely hardware independent. 56 57o Many languages use and require right-to-left support. These languages 58 can quite easily be supported given the inclusion of their required 59 keyboard mappings and some possible minor code change. Some of the 60 current supported languages include - |arabic.txt|, |farsi.txt| and 61 |hebrew.txt|. 62 63 64Of Interest... 65-------------- 66 67o Invocations 68 ----------- 69 + 'rightleft' ('rl') sets window orientation to right-to-left. 70 + 'delcombine' ('deco'), boolean, if editing UTF-8 encoded languages, 71 allows one to remove a composing character which gets superimposed 72 on those that preceded them (some languages require this). 73 + 'rightleftcmd' ('rlc') sets the command-line within certain modes 74 (such as search) to be utilized in right-to-left orientation as well. 75 76o Typing backwards *ins-reverse* 77 ---------------- 78 In lieu of using the full-fledged 'rightleft' option, one can opt for 79 reverse insertion. When the 'revins' (reverse insert) option is set, 80 inserting happens backwards. This can be used to type right-to-left 81 text. When inserting characters the cursor is not moved and the text 82 moves rightwards. A <BS> deletes the character under the cursor. 83 CTRL-W and CTRL-U also work in the opposite direction. <BS>, CTRL-W 84 and CTRL-U do not stop at the start of insert or end of line, no matter 85 how the 'backspace' option is set. 86 87 There is no reverse replace mode (yet). 88 89 If the 'showmode' option is set, "-- REVERSE INSERT --" will be shown 90 in the status line when reverse Insert mode is active. 91 92o Pasting when in a rightleft window 93 ---------------------------------- 94 When cutting text with the mouse and pasting it in a rightleft window 95 the text will be reversed, because the characters come from the cut buffer 96 from the left to the right, while inserted in the file from the right to 97 the left. In order to avoid it, toggle 'revins' before pasting. 98 99 100Bugs 101---- 102o Does not handle CTRL-A and CTRL-X commands (add and subtract) correctly 103 when in rightleft window. 104 105o Does not support reverse insert and rightleft modes on the command-line. 106 However, functionality of the editor is not reduced, because it is 107 possible to enter mappings, abbreviations and searches typed from the 108 left to the right on the command-line. 109 110o Somewhat slower in right-to-left mode, because right-to-left motion is 111 emulated inside Vim, not by the controlling terminal. 112 113o When the Athena GUI is used, the bottom scrollbar works in the wrong 114 direction. This is difficult to fix. 115 116o When both 'rightleft' and 'revins' are on: 'textwidth' does not work. 117 Lines do not wrap at all; you just get a single, long line. 118 119o There is no full bidirectionality (bidi) support. 120 121 122 vim:tw=78:ts=8:noet:ft=help:norl: 123