chapters/09.markdown @ 063fab1bea84

More Mappings
=============

I know we've talked a lot about mappings so far, but we're going to practice
them again now.  Mappings are one of the easiest and fastest ways to make your
Vim editing more productive so it's good to focus on them quite a bit.

One concept that has showed up in several examples but that we haven't
explicitly talked about is mapping a sequence of multiple keys.

Run the following command:

    :::vim
    :nnoremap jk dd

Now make sure you're in normal mode and press `j` followed quickly by `k`.  Vim
will delete the current line.

Now try pressing only `j` and waiting for a bit.  If you don't press `k` quickly
after the `j`, Vim decides that you don't want to activate the mapping and
instead runs the normal `j` functionality (moving down a line).

This mapping will make it painful to move around, so let's remove it.  Run the
following command:

    :::vim
    :nunmap jk

Now typing `jk` in normal mode will move down and then up a line as usual.

A More Complicated Mapping
--------------------------

You've seen a bunch of simple mappings so far, so it's time to look at something
with a bit more meat to it.  Run the following command:

    :::vim
    :nnoremap <leader>" viw<esc>a"<esc>hbi"<esc>lel

Now *that's* an interesting mapping!  First, go ahead and try it out.  Enter
normal mode, put your cursor over a word in your text and type `<leader>"`.  Vim
will surround the word in double quotes!

How does this work?  Let's split it apart into pieces and think of what each one
does:

    :::text
    viw<esc>a"<esc>hbi"<esc>lel

* `viw`: visually select the current word
* `<esc>`: exit visual mode, which leaves the cursor on the last character of
  the word
* `a`: enter insert mode *after* the current character
* `"`: insert a `"` into the text, because we're in insert mode
* `<esc>`: return to normal mode
* `h`: move left one character
* `b`: move back to the beginning of the word
* `i`: enter insert mode *before* the current character
* `"`: insert a `"` into the text again
* `<esc>`: return to normal mode
* `l`: move right, which puts our cursor on the first character of the word
* `e`: move to the end of the word
* `l`: move right, which puts our cursor over the ending quote

Remember: because we used `nnoremap` instead of `nmap` it doesn't matter if
you've mapped any of the keys in this sequence to something else.  Vim will use
the default functionality for all of them.

Hopefully you can see how much potential Vim's mappings have, as well as how
unreadable they can become.

Exercises
---------

Create a mapping similar to the one we just looked at, but for single quotes
instead of double quotes.

Try using `vnoremap` to add a mapping that will wrap whatever text you have
*visually selected* in quotes.  You'll probably need the `` `< `` and `` `> ``
commands for this, so read up on them with `` :help `< ``.

Map `H` in normal mode to go to the beginning of the current line.  Since `h`
moves left you can think of `H` as a "stronger" `h`.

Map `L` in normal mode to go to the end of the current line. Since `l`
moves right you can think of `L` as a "stronger" `l`.

Find out what commands you just overwrote by reading `:help H` and `:help L`.
Decide whether you care about them.

Add all of these mappings to your `~/.vimrc` file, making sure to use your "edit
my `~/.vimrc`" and "source my `~/.vimrc`" mappings to do so.