#+TITLE: Evil-snipe layer

#+TAGS: layer|vim

[[file:img/Cat_With_Rifle.jpg]]

* Table of Contents                     :TOC_5_gh:noexport:
- [[#description][Description]]
  - [[#features][Features:]]
- [[#install][Install]]
  - [[#layer][Layer]]
  - [[#improved-f-and-t-search-behavior][Improved f and t search behavior]]
  - [[#two-character-search-with-s][Two-character search with s]]
  - [[#more-scopes][More scopes]]
  - [[#symbol-groups][Symbol groups]]
- [[#key-bindings][Key bindings]]

* Description
This layer adds various replacements for vim's default search functions.

** Features:
- Alternative implementation of vim's default search operations.
- Replacement of evil-surround with a two-character search.
- Support for alternative scopes for default search operations.
- Support for alternative motions based on configurable regexps.

* Install
** Layer
To use this configuration layer, add it to your =~/.spacemacs=. You will need to
add =evil-snipe= to the existing =dotspacemacs-configuration-layers= list in this
file.

** Improved f and t search behavior
With evil-snipe you can define your own search scope for ~f~ and ~t~ searches
which means that you won't have to jump to the correct line before searching
with ~f~ / ~t~ / ~F~ / ~T~. And after you have found a match, you can just press
~f~ or ~t~ again afterwards to continue the search. No need to use ~;~ / ~​,​~.

This alternate behavior is disabled by default, to enable it set the
layer variable =evil-snipe-enable-alternate-f-and-t-behaviors= to =t=:

#+BEGIN_SRC emacs-lisp
  (setq-default dotspacemacs-configuration-layers
    '((evil-snipe :variables evil-snipe-enable-alternate-f-and-t-behaviors t)))
#+END_SRC

** Two-character search with s
With the ~s~/~S~ keys you can do a simple search like ~f~/~t~, but instead of
searching for one character, you search for two. This makes the search a lot
more precise than regular ~f~/~t~ searches. While you can search forward or
backwards in the buffer with ~/~ and ~?~, ~s~ / ~S~ are much easier to reach,
don't require you to press enter and they are precise enough for many common
purposes.

** More scopes
Evil-snipe also adds several scope options for searches (set =evil-snipe-scope=
and =evil-snipe-repeat-scope= to one of these, the default value is =buffer=):

| Value         | Description                                                              |
|---------------+--------------------------------------------------------------------------|
| buffer        | search in the rest of the buffer after the cursor (=vim-sneak= behavior) |
| line          | search in the current line after the cursor (=vim-seek= behavior)        |
| visible       | search in the rest of the visible buffer only                            |
| whole-line    | same as =line=, but highlight matches on either side of cursor           |
| whole-buffer  | same as =buffer=, but highlight *all* matches in buffer                  |
| whole-visible | same as =visible=, but highlight *all* visible matches in buffer         |

If you do not want to replace the regular ~f~ / ~F~ / ~t~ / ~T~ behavior, just
remove this line from =evil-snipe/packages.el=:
=(evil-snipe-replace-evil)=

** Symbol groups
With symbol groups you can let a character stand for a regex, for example a
group of characters. By adding a pair of =(CHAR REGEX)= to the list
=evil-snipe-aliases= you can search for a regex very simply:
- Here we set the ~[~ character to mean =all characters [({= *in all modes* so a
  search with ~sa[~ would find ~a[~, ~a{~ or ~a(~.

  #+BEGIN_SRC emacs-lisp
    ;; Alias [ and ] to all types of brackets
    (push '(?\[ "[[{(]") evil-snipe-aliases)
    (push '(?\] "[]})]") evil-snipe-aliases)
  #+END_SRC

- Here we set the char ~:~ to mean "a regex matching python function
  definitions" (but only in python-mode), so by searching with ~f:fff~ you can
  quickly cycle through all function definitions in a buffer!

  #+BEGIN_SRC emacs-lisp
    ;; For python style functions
    (add-hook 'python-mode-hook
              (lambda ()
                (make-variable-buffer-local 'evil-snipe-aliases)
                (push '(?: "def .+:") evil-snipe-aliases)))
  #+END_SRC

* Key bindings

| Key binding | Description                                                                             |
|-------------+-----------------------------------------------------------------------------------------|
| ~f~         | search forward for the next entered character and set the cursor to it's position       |
| ~F~         | search backward for the next entered character and set the cursor to it's position      |
| ~t~         | search forward for the next entered character and set the cursor before it's position   |
| ~T~         | search backward for the next entered character and set the cursor before it's position  |
| ~s~         | search forward for the next entered two characters and set the cursor to it's position  |
| ~S~         | search backward for the next entered two characters and set the cursor to it's position |