kakoune/contrib/TRAMPOLINE

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                  Mawww's experiment for a better code editor
+=----------------------------------------------------------------------------=+

This walk-through is an introduction to Kakoune's basic editing capabilities
to help new users transition over easily from another editor, or simply
learn how to write and edit documents with style.

During the learning period, it is useful to activate an automatically displayed
contextual help for commands in normal mode: `:set -add global autoinfo normal`

In the first section, you will learn about the primitives of the editing
language to be able to get to a level of knowledge of the editor that
guarantees that you can work with it efficiently.

In the second section, for users who've gone through the basics and want to
move on to more advanced functionalities, we explain other primitives whose
role has a less dominant place in an everyday editing session, but still
prove themselves powerful when used on the right occasion.

Finally, as this document is in no way an exhaustive list of features, don't
hesitate to check out the official documentation to complement your tool-set,
ask questions to more seasoned users on IRC, and check the documentation
using the built-in `:doc` command.

+=--------------------------------=+ BASICS +=--------------------------------=+

                    =[ MODES

                    Kakoune uses a paradigm called "modal editing" to allow
       .---,        users to either have every single key they type inserted
       | i |        into the file being edited (called "insert mode"),
       `---'        or execute commands that are triggered by the keys hit
                    (the "normal mode").  Aside from arrow keys, most keys
       .---,        described in this document are "editing primitives" that
       |esc|        have to be hit in normal mode, which is the default mode
       `---'        when you start the editor. To enter insert mode, hit the
                    `i` key, and to leave it and return to normal mode, hit the 
                    escape key.


                    =[ MOVEMENT
       .---,
       | ↑ |        Movement in a buffer (the representation of the contents
   .---'---'---,    of a file opened by Kakoune) can be achieved using the arrow
   | ← | ↓ | → |    keys, which will move the cursor up one column/row into
   `---'---'---`    a given direction.

                    However, furthering the tradition of mode-based editors,
 .---,---,---,---,  the `h`, `j`, `k` and `l` keys can be used for the same
 | h | j | k | l |  purpose, and will respectively move the cursor to the
 `---'---'---'---`  left, down, up, right by one, when hit. Using those keys
   |   |   |   |    is the recommended way of moving around in a buffer.
 .---,---,---,---,  If you're not familiar with this concept, the proximity
 | ← | ↓ | ↑ | → |  of those four keys with the rest of the lettered keys
 `---'---'---'---`  on a `qwerty` layout allows faster interaction with the
                    primitives than if the user had to move their hand to
   .---,            reach the arrow keys.
   | g |_.
   `---' |`.---,    Another way of moving the cursor is the "goto" utility,
         | | g |    invoked by hitting the `g` key. A menu will pop up with a
         | `---'    summary of all the possible keys that can be hit, along with
          `.---,    the location where they will move the cursor to, but the
           | e |    most used ones that we are interested in, for now, are `g`
           `---'    and `e`. The first one will jump to the beginning of the
                    buffer, and the second one to its end.


                    =[ VIEW

   .---,            Displacing the cursor can sometimes move the view into an
   | v |_.          inconvenient configuration, leaving some necessary context
   `---' |`.---,    off-screen, or simply feel uncomfortable to type into.
         | | t |    Kakoune provides a menu (similar to the `goto` menu
         | `---'    mentioned in the previous section) that allows users to
         |`.---,    move the current view in relation to the position of the
         | | b |    cursor. Upon hitting the `v` key, a short menu appears
         | `---'    which allows us to hit a second key according to how the
          `.---,    view should be centered vertically: to leave the cursor
           | v |    respectively on top, at the bottom or in the middle of the
           `---'    current view, hit the `t`, `b` or `v` keys.


                    =[ SEARCH

                    In order to move the cursor to a specific word, the search
                    command is the way to go. This functionality allows
        .---,       the user to jump to the next occurrence of a piece of text.
        | / |       Upon hitting the `/` key, a prompt reading "search"
        `---'       will pop up in the status bar in which you can type
                    your text and validate using the `<ret>` (return) key.
     .---, .---,    You'll notice that as you type, the cursor changes location
     |alt|+| / |    to automatically give you a preview of where the cursor
     `---' `---'    would be displaced to if you validated the search. However,
                    this behavior is only a preview, exiting prompt mode with
                    the `<esc>` (escape) key will leave the current position
        .---,       of the cursor unchanged. Note that you can also use a
        | n |       regular expression as input.  By default the search
        `---'       function will look for results forward, starting from
                    the current location of the cursor, but you can search
     .---, .---,    backwards using `<a-/>` (alt + `/`).
     |alt|+| n |
     `---' `---'    Jumping from one match to the other forward can be achieved
                    using the `n` key, and backwards using the `<a-n>` (alt +
                    `n`) key combination.


                    =[ SELECTIONS

                    You have certainly noticed that when searching for
        .---,       text, the cursor extends to highlight the entire match.
        | ; |       In fact, what we know in other editors as a "cursor" is
        `---'       actually a single character wide selection in Kakoune,
                    and can be expanded using primitives. When "expanded",
     .---, .---,    the selection is an area whose beginning is the "anchor"
     |alt|+| ; |    and the end the "secondary cursor". To switch anchor and
     `---' `---'    cursor, use `<a-;>`, and to collapse the selection onto
                    its anchor, use `;`.

                    Moreover, not only Kakoune expands the principle of
                    "cursor" by introducing selections, but it also allows
        .---,       multiple selections within the same buffer. This makes
        | % |       it very convenient to modify text in multiple locations
        `---'       at once, as editing primitives apply to all the currently
                    selected text.
        .---,
        | s |       Example: to remove all occurrences of the word "foo", one
        `---'       would select the entire buffer (`%`), select occurrences of
                    the word (`s`, "\bfoo\b", `<ret>`), then remove it (`d`).

                    ==[ SELECTING OBJECTS

                    In addition to allowing text selection using regular
     .---, .---,    expressions, certain objects are defined by default to
     |alt|+| i |    allow easy selection of text. Objects are bits of text
     `---' `---'    in the buffer that are identified according to their
                    structure, rather than their contents, e.g., a paragraph,
     .---, .---,    a sentence, or a word. When the cursor is located within
     |alt|+| a |    the boundaries of an object you want to interact with,
     `---' `---'    several options are available: selecting the contents of an
                    object without its boundaries (`<a-i>`), a part of it (from
        .---,       the anchor to its end or its beginning, respectively `]`
        | ] |       and `[`), or the entire object (`<a-a>`). Those "selection
        `---'       ranges" are the first part of a two stages shortcut,
                    as once you've used the key that dictates what part of
        .---,       the object is to be selected, a menu with a description
        | [ |       of all the object types select-able will be displayed,
        `---'       giving a summary of all the keys you can hit to complete
                    the selection procedure.

                    Example: to select the paragraph in which the anchor lies,
                    invoke the "inner object selection" shortcut (`<a-i>`),
                    locate "paragraph" in the information box that pops up and
    .---,           hit the according key (`p`). The entire two steps sequence
    | [ |_.         is thus: `<a-i> p`.
    `---' |`.---,
          | | ( |   Example: to select everything between the anchor and the
          | `---'   beginning of the current parenthesis pair, use the selection
           `.---,   sequence: `[ (`. Note that common objects that use
            | r |   pairs of opening/closing punctuation signs (brackets,
            `---'   braces, quotes etc) have an alternative second key that
                    is displayed in the information menu that you can use to
                    minimize finger gymnastics. The previous shortcut could
                    thus also be written: `[ b`.

                    ==[ MOVEMENT SELECTIONS

                    If objects are an easy way to select content-agnostic
    .---,           data in a buffer, they can also be seen as a way to move
    | [ |_.         about the buffer. As selecting objects will displace the
    `---'  `.---,   anchor into a given direction, you can wrap or move around
            | p |   particular chunks of text without using the conventional
            `---'   means (e.g., arrow keys or jumps), turning them partially
                    into movement primitives.
    .---,
    | ] |_.         Example: one of the most used object selection combination
    `---'  `.---,   is the "object end/begin paragraph" one: using `[` or
            | p |   `]` will displace the anchor into a given direction, and
            `---'   applying that to the paragraph object allows "jumping"
                    from one newline separated block of text to another.
                    The resulting shortcut is thus: `] p` to move forward, or
                    `[ p` to move backward.


                    =[ FILTERING A SELECTION

                    Selecting an entire buffer (`%`) or parts of it (`s`) is a
                    natural and basic operation in a typical editing session,
     .---, .---,    however, there are some cases where we need to be able to
     |alt|+| k |    drop some selections arbitrarily, as opposed to trying
     `---' `---'    to select the ones we need directly. This concept becomes
                    very useful when coming up with a regular expression for
     .---, .---,    the basic selection primitive (`s`) is too tedious (if
     |alt|+| K |    even possible), that's why the editor provides us with a
     `---' `---'    "keep matching" and a "keep not matching" operations,
                    in order to respectively keep exclusively the selections
                    who match or do not match a given regular expression.

                    Example: when parsing a log file whose lines follow the
                    usual log pattern (e.g. "[1484383442] ERROR: some data"),
                    we want to be able to select all the lines individually
     .---, .---,    (`%`, `<a-s>` to split all the lines), keep those that
     |alt|+| s |    start with a bracketed time-stamp (`<a-k>^\[`), but
     `---' `---'    exclude the debug messages (`<a-K>DEBUG`). Of course,
                    it's possible to come up with a regular expression to
                    match those simple requirements, but it would take more
                    work to write it than to organically apply filters on a
                    general selection, individually.


                    =[ SELECTION DUPLICATION

        .---,       Duplicating content can be achieved using a widely
        | y |       implemented concept: yanking and pasting. Yanking the
        `---'       current selection (`y`) into the copy register allows the
        .---,       user to subsequently insert the copied text in the buffer
        | p |       (`p`).
        `---'
        .---,       Note that the default "paste" primitive will insert the
        | P |       contents of the copy register after the current selection,
        `---'       if you want copied text to be inserted before the current
                    selection then you can use the `P` key.


                    =[ DELETING / REPLACING SELECTIONS

                    Text replacement is a two-step process in Kakoune, which
        .---,       involves selecting text to be replaced, and then erasing it
        | d |       to insert the replacement text. After selections have been
        `---'       made, you can simply hit the deletion primitive (`d`), then
        .---,       either enter insert mode to write down the replacement text
        | c |       (`i`), or stay in command mode to paste the replacement
        `---'       text stored in the copy register. As deleting and entering
        .---,       insert mode can be redundant, a primitive that implements
        | R |       deletion followed by insert mode entrance was implemented:
        `---'       `c`. You can also directly replace the current selection
                    with the content of the copy register using a primitive
                    also implemented for that purpose: `R`.


                    =[ UNDO / REDO

                    Mistakes or wrong decisions can happen while editing.
        .---,       To go back to earlier states of the buffer, you can press
        | u |       the `u` key several times. On the contrary, pressing `U`
        `---'       allows traveling forward in the history tree.


+=-------------------------------=+ ADVANCED +=-------------------------------=+

                    =[ SPLITTING

                    The selection primitive (`s`) is a powerful tool to select
                    chunks of data, but sometimes the format of said data isn't
        .---,       uniform enough to allow creating clear cut selections. In
        | S |       order to avoid having to write overly complicated regular
        `---'       expressions that select precisely the wanted text, the
                    splitting primitive (`S`) allows applying a delimiter to
                    the current selection, splitting it into separate chunks.

                    Example: selecting the items in a CSV-style list (e.g.,
                    "1,2,3,4") is as simple as selecting the line, then
                    splitting it using the comma separator (`S,`). Note that
                    more advanced splitting is possible, since the delimiter
                    passed to this primitive is a regular expression.


                    =[ ROTATING

                    Often used in conjunction with the splitting primitive
                    (`S`), the rotation primitive (`<a-)>`) shifts all the
                    selections clock-wise. Note that a count (described after)
                    allows the rotation to take place in sub-groups whose size
     .---, .---,    is given by the count parameter.
     |alt|+| ) |
     `---' `---'    Example: in a numbered list where all the numbers are
                    selected (e.g., `1 2 3 4 5 6 7 8 9 0`), a rotation using
                    this primitive will shift all the numbers by one selection
                    forward, while leaving the original multiple selections
                    untouched (e.g., `0 1 2 3 4 5 6 7 8 9`).


                    =[ COUNTS

   .---,            In order to pass a count to a primitive, simply type the
   |0-9|_.          number out before hitting the primitive key/combination.
   `---' |`.---,    Counts allow primitives to specialize or extend their
         | | g |    original functionality by using it as a parameter,
         | `---'    acting on their side effect.
         |`.---,
         | | G |    Example: in order to respectively jump or select up to a
         | `---'    particular line, pass the line number to the `g` or `G`
         |`.---,    primitives (e.g., `42g` or `7G`).
         | | o |
         | `---'    Example: creating an arbitrary amount of new lines
          `.---,    above or below the current line and spawning a new selection
           | O |    for each of them is achieved by passing the number of lines
           `---'    as a count respectively to the `o` and `O` primitives.


                    =[ REGISTERS

                    Similarly to counts, registers influence the behavior of
   .---,            certain primitives. They are storage structures identified
   | " |_.          by a single character, and are populated by primitives as a
   `---'  `.---,    result of a side effect. Although primitives populate a
           |a-z|    specific register by default, it's possible to modify which
           `---'    is going to be populated upon execution using the double
                    quote (`"`) primitive, and subsequently hitting a key that
        .---,       will serve as an identifier.
        | * |
        `---'       Example: the smart search primitive (`*`) uses the current
                    selection as a search pattern, which will be saved to the
   .---,            `/` register. In order to use this primitive to execute a
   | " |_. .---,    temporary search, one could make this primitive save the
   `---'  `| _ |    pattern to a different register, to preserve the default one,
           `---'    e.g., `"m*` to save the pattern to the `m` register, or even
                    `"_*` to save the pattern to a "null" register, which does 
                    not store anything written to it.

                    ==[ CAPTURE GROUPS

                    Although registers can pass as mere buffer metadata,
     .---, .---,    they are an integral part of an editing session. The
     |ctl|+| r |    `<c-r>` key combination allows to insert into the buffer
     `---' `---'    the value of a register, whose identifier is typed right
                    after the combination.

.---, .---,         Example: inserting the name of the current buffer in insert
|ctl|+| r |_.       mode can be achieved using the `%` register, which holds
`---' `---'  `.---, this information: `<c-r>%`.
              | % |
              `---' Other registers that are set automatically are
                    the numbered registers, which hold the values of the groups
                    matched in the last search or select operation (`/` and
.---, .---,         `s` primitives).
|ctl|+| r |_.
`---' `---'  `.---, Example: when using the search primitive (`/`) with a
              |0-9| regular expression containing groups to match a list of
              `---' first and last names (e.g., `(\w+) (\w+)` on `John Doe`),
                    issuing `<c-r>1` would insert the first name (`John`),
                    and `<c-r>2` the last name (`Doe`).


                    =[ CUSTOM SELECTIONS

                    Despite the ability to select bits of data using regular
                    expressions, there are times when using them isn't enough,
                    and additional manual editing of the selections is
        .---,       needed. In order to loop through all the selections and
        | ) |       remove the current one, two primitives are available:
        `---'       respectively the parenthesis (`)`), and the alt/comma
                    key combination (`<a-,>`).
     .---, .---,
     |alt|+| , |    Example: given a list of three numbers all selected
     `---' `---'    individually, (e.g., `1 2 3`), deselecting the second
                    selection would be done by hitting the parenthesis primitive
                    (`)`) until the according selection is the current one,
                    then hitting `<a-,>` to end up with only the first
                    and third number selected.

                    However, being able to trim out some selections out
        .---,       of a bigger set isn't always convenient, as it doesn't
        | ^ |       allow more advanced constructs such as combining sets of
        `---'       multiple-selections that result from different regular
        .---,       expressions. To allow that, the save mark (`Z`) and append
        | Z |       mark (`<a-z>`) come in handy, as they respectively save
        `---'       the current selection to the mark register (`^`), and
                    show a menu that allows appending the current selection
.---, .---,         to the mark register upon hitting the `a` key. That way,
|alt|+| z |_.       it becomes possible to chain and save (append) several
`---' `---'  `.---, selections made using completely different methods
              | a | (select, split etc) without being forced to preserve
              `---' them at all times.
        .---,
        | z |       Restoring a mark saved to the mark register using those
        `---'       primitives can be achieved by using the restore mark
                    primitive (`z`).


                    =[ LEVERAGING SHELL COMMANDS

                    UNIX systems provide with some tools whose purpose is
                    to interact with raw data, and being a UNIX compliant
        .---,       aspiring tool itself, Kakoune allows leveraging those
        | | |       tools to modify a buffer's contents. Upon invoking the pipe
        `---'       primitive (`|`), an input field pops up which prompts for
                    a shell command, to which the selections will individually
                    be sent through the command's standard input.

                    Example: wrapping a selection can be achieved by invoking
                    the `fold` utility, e.g., `|fold -w80`. You could also want
                    to see a patch of all the modifications made to the buffer
                    since it was last saved: `%|diff -u <c-r>% -`. Note that
                    the `<c-r>%` has to be typed interactively, as it will
                    insert the name of the buffer into the command.

                    Another equally useful primitive that doesn't depend on
        .---,       the contents of the current selections is the exclamation
        | ! |       mark primitive (`!`), which simply insert the output of
        `---'       the given shell command before each selection.

                    Example: in order to insert the date of the day at the
                    beginning of the current buffer, one could use `gg`
                    followed with `!date`.

                    But not all shell-related primitives insert data into
                    the current buffer, the `$` key is in fact a way to
        .---,       apply a predicate to all selections, in order to filter
        | $ |       them out. The command passed to this primitive will be
        `---'       executed in a new shell using each individual selection for
                    context, which will either be kept if the command returned
                    a successful exit code (zero) or dropped otherwise (any
                    non-zero value).

                    Example: after selecting all the lines in a buffer and
                    splitting them individually (`%`, `<a-s>`), keeping every
                    odd-numbered line can be achieved with the following
                    sequence: `$` `[ $((kak_reg_hash)) -ne 0 ]`.


                    =[ REPEATING ACTIONS

                    ==[ PUNCTUAL INTERACTIONS

                    In order to modify text efficiently or insert redundant
                    bits of data, two primitives are available. The dot `.`
        .---,       primitive repeats the last change that was made in insert
        | . |       mode (e.g., writing down text after hitting the insert
        `---'       primitive `i`). Similarly, repeating the last selection
                    (e.g., make with the find primitive `f`) can be achieved
                    using the `<a-.>` primitive.

                    Example: to select a paragraph to append a newline
     .---, .---,    character to it and cycle through the following paragraphs
     |alt|+| . |    to repeat the same insertion an arbitrary amount of times,
     `---' `---'    one would first select the paragraph with `]p`, append a
                    newline to it `a<ret><esc>`, then repeat both operations
                    as needed with `<a-.>` and `.` respectively.

                    ==[ COMPLEX CHANGES

                    Transforming successive chunks of formatted data can
        .---,       be cumbersome when done manually, and lack hindsight
        | q |       when writing a script for that particular purpose
        `---'       non-interactively. The middle ground between the two
        .---,       solutions is to record the modifications made to one
        | Q |       chunk interactively, and replay the sequence of keys
        `---'       at will. The sequence in question is a macro: the `Q`
                    primitive will create a new one (i.e., record all the keys
.---, .---,         hit henceforth until the escape key `<esc>` is hit), and
|ctl|+| r |_.       the `q` primitive will replay the keys saved in the macro.
`---' `---'  `.---,
              | @ | Notes: macros can easily be translated into a proper
              `---' script, as they are saved in the `@` register, which you
                    can insert into a buffer using `<c-r>@`.