navi/docs/cheatsheet_syntax.md
2020-08-29 18:58:55 -03:00

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Cheatsheet syntax
-----------------
* [Syntax overview](#syntax-overview)
* [Folder structure](#folder-structure)
* [Variables](#variables)
* [Advanced variable options](#advanced-variable-options)
* [Variable dependency](#variable-dependency)
* [Multiline snippets](#multiline-snippets)
* [Variable as multiple arguments](#variable-as-multiple-arguments)
### Syntax overview
Cheatsheets are described in `.cheat` files that look like this:
```sh
% git, code
# Change branch
git checkout <branch>
$ branch: git branch | awk '{print $NF}'
```
Lines starting with:
- `%`: determine the start of a new cheatsheet and should contain tags
- `#`: should be descriptions of commands
- `;`: are ignored. You can use them for metacomments
- `$`: should contain commands that generate a list of possible values for a given argument [:information_source:](#variables)
- `@`: should contain tags whose associated cheatsheet you want to base on [:information_source:](#extending-cheatsheets)
All the other non-empty lines are considered as executable commands.
### Folder structure
It's irrelevant how many files are used to store cheatsheets. They can be all in a single file if you wish, as long as you split them accordingly with lines starting with `%`.
### Variables
The interface prompts for variable names inside brackets (eg `<branch>`).
Variable names should only include alphanumeric characters and `_`.
If there's a corresponding line starting with `$` for a variable, suggestions will be displayed. Otherwise, the user will be able to type any value for it.
If you hit `<tab>` the query typed will be prefered. If you hit `<enter>` the selection will be prefered.
### Advanced variable options
For lines starting with `$` you can use `---` to customize the behavior of `fzf` or how the value is going to be used:
```sh
# This will pick the 3rd column and use the first line as header
docker rmi <image_id>
# Even though "false/true" is displayed, this will print "0/1"
echo <mapped>
$ image_id: docker images --- --column 3 --header-lines 1 --delimiter '\s\s+'
$ mapped: echo 'false true' | tr ' ' '\n' --- --map "[[ $0 == t* ]] && echo 1 || echo 0"
```
The supported parameters are:
- `--prevent-extra` *(experimental)*: limits the user to select one of the suggestions;
- `--column <number>`: extracts a single column from the selected result;
- `--map <bash_code>` *(experimental)*: applies a map function to the selected variable value;
In addition, it's possible to forward the following parameters to `fzf`:
- `--multi`;
- `--header-lines <number>`;
- `--delimiter <regex>`;
- `--query <text>`;
- `--filter <text>`;
- `--header <text>`;
- `--preview <bash_code>`;
- `--preview-window <text>`.
### Variable dependency
The command for generating possible inputs can implicitly refer other variables by using the `<varname>` syntax:
```sh
# Should print /my/pictures/wallpapers
echo "<wallpaper_folder>"
$ pictures_folder: echo "/my/pictures"
$ wallpaper_folder: echo "<pictures_folder>/wallpapers"
```
If you want to make dependencies explicit, you can use the `$varname` syntax:
```sh
# If you select "hello" for <x>, the possible values of <y> will be "hello foo" and "hello bar"
echo <x> <y>
# If you want to ignore the contents of <x> and only print <y>
: <x>; echo <y>
$ x: echo "hello hi" | tr ' ' '\n'
$ y: echo "$x foo;$x bar" | tr ';' '\n'
```
### Extending cheatsheets
With the `@ same tags from other cheatsheet` syntax you can reuse the same variable in multiple cheatsheets.
```sh
% dirs, common
$ pictures_folder: echo "/my/pictures"
% wallpapers
@ dirs, common
# Should print /my/pictures/wallpapers
echo "<pictures_folder>/wallpapers"
% screenshots
@ dirs, common
# Should print /my/pictures/screenshots
echo "<pictures_folder>/screenshots"
```
### Multiline snippets
Commands may be multiline:
```sh
# This will output "foo\nyes"
echo foo
true \
&& echo yes \
|| echo no
```
### Variable as multiple arguments
```sh
# This will result into: cat "file1.json" "file2.json"
jsons=($(echo "<jsons>"))
cat "${jsons[@]}"
$ jsons: find . -iname '*.json' -type f -print --- --multi
```