Insert Mode: CTRL-G U Examples, Function Calls, Text Wrapping with 'textwidth' and 'wrapmargin'

also expands abbreviations before this. An example for using CTRL-G U: > inoremap <Left> <C-G>U<Left> inoremap <Right> <C-G>U<Right> inoremap <expr> <Home> col('.') == match(getline('.'), '\S') + 1 ? \ repeat('<C-G>U<Left>', col('.') - 1) : \ (col('.') < match(getline('.'), '\S') ? \ repeat('<C-G>U<Right>', match(getline('.'), '\S') + 0) : \ repeat('<C-G>U<Left>', col('.') - 1 - match(getline('.'), '\S'))) inoremap <expr> <End> repeat('<C-G>U<Right>', col('$') - col('.')) inoremap ( ()<C-G>U<Left> This makes it possible to use the cursor keys in Insert mode, without starting a new undo block and therefore using |.| (redo) will work as expected. Also entering a text like (with the "(" mapping from above): Lorem ipsum (dolor will be repeatable by using |.| to the expected Lorem ipsum (dolor) Using CTRL-O splits undo: the text typed before and after it is undone separately. If you want to avoid this (e.g., in a mapping) you might be able to use CTRL-R = |i_CTRL-R|. E.g., to call a function: > :imap <F2> <C-R>=MyFunc()<CR> When the 'whichwrap' option is set appropriately, the <Left> and <Right> keys on the first/last character in the line make the cursor wrap to the previous/next line. The CTRL-G j and CTRL-G k commands can be used to insert text in front of a column. Example: > int i; int j; Position the cursor on the first "int", type "istatic <C-G>j ". The result is: > static int i; int j; When inserting the same text in front of the column in every line, use the Visual blockwise command "I" |v_b_I|. ============================================================================== 3. 'textwidth' and 'wrapmargin' options *ins-textwidth* The 'textwidth' option can be used to automatically break a line before it gets too long. Set the 'textwidth' option to the desired maximum line length. If you then type more characters (not spaces or tabs), the last word will be put on a new line (unless it is the only word on the line). If you set 'textwidth' to 0, this feature is disabled. The 'wrapmargin' option does almost the same. The difference is that 'textwidth' has a fixed width while 'wrapmargin' depends on the width of the screen. When using 'wrapmargin' this is equal to using 'textwidth' with a value equal to (columns - 'wrapmargin'), where columns is the width of the screen. When 'textwidth' and 'wrapmargin' are both set, 'textwidth' is used. If you don't really want to break the line, but view the line wrapped at a convenient place, see the 'linebreak' option. The line is only broken automatically when using Insert mode, or when appending to a line. When in replace mode and the line length is not changed, the line will not be broken. Long lines are broken if you enter a non-white character after the margin. The situations where a line will be broken can be restricted by adding characters to the 'formatoptions' option: "l" Only break a line if it was not longer than 'textwidth' when the insert started. "v" Only break at a white character that has been entered during the current insert command. This is mostly Vi-compatible. "lv" Only break if the line was not longer than 'textwidth' when the insert started and only at a white character that has been entered during the current insert command. Only differs from "l" when entering non-white characters while crossing the 'textwidth' boundary. Normally an internal function will be used to decide where to break the line. If you want to do it in a different way set the 'formatexpr' option to an expression that will take care of the line break. If you want to format a block of text, you can use the "gq" operator. Type "gq" and a movement command to move the cursor to the end of the block. In many cases, the command "gq}" will do what you want (format until the end of paragraph). Alternatively, you can use "gqap", which will format the whole paragraph, no matter where the cursor currently

This section provides further examples of using CTRL-G U to control undo behavior in insert mode, particularly with cursor keys and parenthesis insertion. It also demonstrates how to call functions from insert mode using CTRL-R. The section then transitions to discuss the 'textwidth' and 'wrapmargin' options, which automatically break lines in insert mode to maintain a desired line length. It explains how these options work, their differences, and how the 'formatoptions' option can be used to control when lines are broken. Finally, it mentions the 'gq' operator for formatting blocks of text.