Snap

A fast finder system for neovim >0.5.

Demo

The following shows finding files and grepping in the large gcc codebase.

Installation

With Packer

use { 'camspiers/snap' }

or with fzy:

use { 'camspiers/snap', rocks = {'fzy'}}

With vim-plug

Plug 'camspiers/snap'

With vim-plug you will need to use luarocks manually if you want to install fzy, probably best to just use fzf if you are using vim-plug.

Semi-Optional Dependencies

To use the following snap components you need the specified dependencies, however not all components are needed, for example you should probably choose between fzy and fzf as your primary consumer.

They are semi-optional because you can mix and match them depending on which technology you want to use.

Getting Started

There are three primary APIs to be aware of in order to set up your local nvim to use snap.

snap.maps

snap.maps and snap.map will map a function to a particular keybinding. Any function can be registered (e.g your own lua functions), however usually you will register functions that result in a call to snap.run.

snap.config

snap.config offers a terse API for creating functions that call snap.run with sensible configuration.

snap.run

Though used directly infrequently, snap.run is the API to start a snap.

Registering Global Keymaps

The following illustrates some basic usage of the snap.maps and snap.config APIs, we generate a variety of functions and register them as normal mode mappings:

local snap = require'snap'
snap.maps {
  {"<Leader><Leader>", snap.config.file {producer = "ripgrep.file"}},
  {"<Leader>fb", snap.config.file {producer = "vim.buffer"}},
  {"<Leader>fo", snap.config.file {producer = "vim.oldfile"}},
  {"<Leader>ff", snap.config.vimgrep {}},
}

This gives a basic example, however see the snap.config section for all options available.

Registering Global Keymaps With Defaults

Perhaps you want some default config to apply to all your snap.config.file usages, to do so you can generate your own version of snap.config.file or snap.config.vimgrep with applied defaults:

local snap = require'snap'
local file = snap.config.file:with {reverse = true, suffix = ">>", consumer = "fzy"}
local vimgrep = snap.config.vimgrep:with {reverse = true, suffix = ">>", limit = 50000}
snap.maps {
  {"<Leader><Leader>", file {producer = "ripgrep.file"}},
  {"<Leader>ff", vimgrep {}},
}

Registering Global Keymaps With Registered Commands

If you want to also make your function available via the :Snap myexamplefunction API, you can pass an optional third parameter to snap.map or an optional third table value to each table to snap.maps.

local snap = require'snap'
snap.maps {
  {"<Leader><Leader>", snap.config.file {producer = "ripgrep.file"}, {command = "mycommandname"}}
}

Config API

snap.run is designed to be a very general API used by composing different types of producers and consumers, instead of bundling defaults and configuration types into the general snap.run API, it is designed to be highly flexible and idempotent. So to ease the pain of creating your own functions that call snap.run with appropriate configuration, we instead provide snap.config for generating such functions with common configuration patterns.

snap.config.file

The full API:

{
  // One of either producer, try or combine are required

  // A required producer either by string identifier or a function
  producer: "ripgrep.file"
    | "fd.file"
    | "vim.oldfile"
    | "vim.buffer"
    | "git.file"
    | Producer,

  // A table of producers, the first that returns results is used
  try: table<
    "ripgrep.file"
    | "fd.file"
    | "vim.oldfile"
    | "vim.buffer"
    | "git.file"
    | Producer
  >,

  // A table of producers, combines returns from each
  combine: table<
    "ripgrep.file"
    | "fd.file"
    | "vim.oldfile"
    | "vim.buffer"
    | "git.file"
    | Producer
  >,

  // Optionals

  // An optional prompt string (without suffix e.g. ">")
  prompt?: string,

  // An optional suffix string e.g. ">>"
  suffix?: string,

  // An optional layout function, see layout API below
  layout?: function,

  // An optional table that passes args to producers that support it
  args?: table<string>,

  // An optional boolean that configures producers that suppport it
  hidden?: boolean,

  // An optional boolean that when true places the input at the top
  reverse?: boolean,

  // An optional number that chanes the minimun screen column width the preview should display at
  preview_min_width?: number,

  // An optional boolean or function that returning true displays the preview and when false hides
  preview?: boolean | function,

  // An optional table of custom input buffer mappings, see mappings section below for options
  mappings?: table

  // An optional string, if cword then filter using current word, if selection then use selection
  filter_with?: "cword" | "selection",

  // An optional string or function use as initial filter
  filter?: string | function
}

Examples

The following snap.config.file calls generate functions that run snap.run with various defaults.

Each of these example functions generated would usually be passed to snap.maps, but you could also use them with any other mapping registration API, e.g. which-key.

-- Basic ripgrep file producer
file {producer = "ripgrep.file"}

-- Ripgrep file producer with args
file {producer = "ripgrep.file", args = {'--hidden', '--iglob', '!.git/*'}}

-- Git file producer with ripgrep fallback
file {try = {"git.file", "ripgrep.file"}}

-- Basic file producer with previews off
file {producer = "ripgrep.file", preview = false}

-- Basic buffer producer
file {producer = "vim.buffer"}

-- Basic oldfile producer
file {producer = "vim.oldfile"}

-- A customized prompt
file {producer = "ripgrep.file", prompt = "MyFiles"}

-- A customized prompt suffix
file {producer = "ripgrep.file", suffix = ">>"}

-- Display input at top
file {producer = "ripgrep.file", reverse = true}

-- Custom layout function
file {producer = "ripgrep.file", layout = myCustomLayoutFunction}

Recipes

snap comes with inbuilt producers and consumers (see How Snap Works for what producers and consumers are) to enable easy creation of finders.

The following recipes illustrate direct usage of snap.run meaning calling the following examples will immediately run snap, but as illustrated above when registering a mapping you most often want to get a function that will invoke snap.run with a particular config, in that case the following examples can be replaced with invocations to snap.config.file to create the desired config.

Find Files

Uses built in fzy filter + score, and ripgrep for file finding.

snap.run {
  producer = snap.get'consumer.fzy'(snap.get'producer.ripgrep.file'),
  select = snap.get'select.file'.select,
  multiselect = snap.get'select.file'.multiselect,
  views = {snap.get'preview.file'}
}

or using fzf:

snap.run {
  producer = snap.get'consumer.fzf'(snap.get'producer.ripgrep.file'),
  select = snap.get'select.file'.select,
  multiselect = snap.get'select.file'.multiselect,
  views = {snap.get'preview.file'}
}

Live Ripgrep

snap.run {
  producer = snap.get'producer.ripgrep.vimgrep',
  select = snap.get'select.vimgrep'.select,
  multiselect = snap.get'select.vimgrep'.multiselect,
  views = {snap.get'preview.vimgrep'}
}

Or given this can easily create the ability to ripgrep your entire filesystem with a result for every character, you can set a reasonable upper limit to 10,000 matches:

snap.run {
  producer = snap.get'consumer.limit'(10000, snap.get'producer.ripgrep.vimgrep'),
  select = snap.get'select.vimgrep'.select,
  multiselect = snap.get'select.vimgrep'.multiselect,
  views = {snap.get'preview.vimgrep'}
}

Find Buffers

snap.run {
  producer = snap.get'consumer.fzy'(snap.get'producer.vim.buffer'),
  select = snap.get'select.file'.select,
  multiselect = snap.get'select.file'.multiselect,
  views = {snap.get'preview.file'}
}

Find Old Files

snap.run {
  producer = snap.get'consumer.fzy'(snap.get'producer.vim.oldfile'),
  select = snap.get'select.file'.select,
  multiselect = snap.get'select.file'.multiselect,
  views = {snap.get'preview.file'}
}

Find Git Files

snap.run {
  producer = snap.get'consumer.fzy'(snap.get'producer.git.file'),
  select = snap.get'select.file'.select,
  multiselect = snap.get'select.file'.multiselect,
  views = {snap.get'preview.file'}
}

or find git files with fallback to ripgrep:

snap.run {
  producer = snap.get'consumer.fzf'(
    snap.get'consumer.try'(
      snap.get'producer.git.file',
      snap.get'producer.ripgrep.file'
    ),
  ),
  select = snap.get'select.file'.select,
  multiselect = snap.get'select.file'.multiselect,
  views = {snap.get'preview.file'}
}

Find Help Tags

snap.run {
  prompt = "Help>",
  producer = snap.get'consumer.fzy'(snap.get'producer.vim.help'),
  select = snap.get'select.help'.select,
  views = {snap.get'preview.help'}
}

Grep with FZF as optional next step

The following will run the vimgrep producer and upon <C-q> will run fzf on the filtered results.

snap.run {
  producer = snap.get'producer.ripgrep.vimgrep',
  steps = {{
    consumer = snap.get'consumer.fzf',
    config = {prompt = "FZF>"}
  }},
  select = snap.get'select.file'.select,
  multiselect = snap.get'select.file'.multiselect,
  views = {snap.get'preview.file'}
}

Search files in multiple paths

The following will combine results from multiple paths using a producer for each path:

snap.run {
  producer = snap.get'consumer.fzf'(
    snap.get'consumer.combine'(
      snap.get'producer.ripgrep.file'.args({}, "/directory1"),
      snap.get'producer.ripgrep.file'.args({}, "/directory2"),
      snap.get'producer.ripgrep.file'.args({}, "/directory3"),
    ),
  ),
  select = snap.get'select.file'.select,
  multiselect = snap.get'select.file'.multiselect,
  views = {snap.get'preview.file'}
}

Key Bindings for Input Buffer

The following are what bindings are made for the input buffer while snap is open.

Select

When a single item is selected, calls the provided select function with the cursor result as the selection.

When multiple items are selection, calls the provider multiselect function.

• <CR>

Alternatives:

• <C-x> opens in new split
• <C-v> opens in new vsplit
• <C-t> opens in new tab

Exit

Closes snap

• <Esc>
• <C-c>

Next

Move cursor to the next selection.

• <Down>
• <C-n>
• <C-j>

Previous

Move cursor to the previous selection.

• <Up>
• <C-p>
• <C-k>

Multiselect (enabled when multiselect is provided)

Add current cursor result to selection list.

• <Tab>

Remove current cursor result from selection list.

• <S-Tab>

Select all

• <C-a>

Results Page Down

Moves the results cursor down a page.

• <C-b>

Results Page Up

Moves the results cursor up a page.

• <C-f>

View Page Down

Moves the cursor of the first view down a page (if more than one exists).

• <C-d>

View Page Up

Moves the cursor of the first view up a page (if more than one exists).

• <C-u>

Toggle Views

Toggles the views on and off.

• <C-h>

Customizing Default Input Buffer Mappings

The default mappings can be customized by providing a mappings key to your snap.run configs.

The following are the default mappings, each of which can be overridden:

{
  ["enter-split"] = {"<C-x>"},
  ["enter-tab"] = {"<C-t>"},
  ["enter-vsplit"] = {"<C-v>"},
  ["next-item"] = {"<C-n>"},
  ["next-page"] = {"<C-f>"},
  ["prev-item"] = {"<C-p>"},
  ["prev-page"] = {"<C-b>"},
  ["select-all"] = {"<C-a>"},
  ["view-page-down"] = {"<C-d>"},
  ["view-page-up"] = {"<C-u>"},
  ["view-toggle-hide"] = {"<C-h>"},
  enter = {"<CR>"},
  exit = {"<Esc>", "<C-c>"},
  next = {"<C-q>"},
  select = {"<Tab>"},
  unselect = {"<S-Tab>"}
}

Example:

snap.run {
  producer = snap.get'consumer.fzy'(snap.get'producer.ripgrep.file'),
  select = snap.get'select.file'.select,
  multiselect = snap.get'select.file'.multiselect,
  views = {snap.get'preview.file'},
  mappings = {
    enter = {"<CR>", "<C-o>"}, -- my custom mapping
  }
}

How Snap Works

snap uses a non-blocking design to ensure the UI is always responsive to user input.

To achieve this it employs coroutines, and while that might be a little daunting, the following walk-through illustrates the primary concepts.

Our example's goal is to run the ls command, filter the results in response to input, and print the selected value.

Producer

A producers API looks like this:

type Producer = (request: Request) => yield<Yieldable>;

The producer is a function that takes a request and yields results (see below for the range of Yieldable types).

In the following producer, we run the ls command and progressively yield its output.

local snap = require'snap'
local io = snap.get'common.io'

-- Runs ls and yields lua tables containing each line
local function producer (request)
  -- Runs the slow-mode getcwd function
  local cwd = snap.sync(vim.fn.getcwd)
  -- Iterates ls commands output using snap.io.spawn
  for data, err, kill in io.spawn("ls", {}, cwd) do
    -- If the filter updates while the command is still running
    -- then we kill the process and yield nil
    if request.canceled() then
      kill()
      coroutine.yield(nil)
    -- If there is an error we yield nil
    elseif (err ~= "") then
      coroutine.yield(nil)
    -- If the data is empty we yield an empty table
    elseif (data == "") then
      coroutine.yield({})
    -- If there is data we split it by newline
    else
      coroutine.yield(vim.split(data, "\n", true))
    end
  end
end

Consumer

A consumers type looks like this:

type Consumer = (producer: Producer) => Producer;

A consumer is a function that takes a producer and returns a producer.

As our goal here is to filter, we iterate over our passed producer and only yield values that match request.filter.

-- Takes in a producer and returns a producer
local function consumer (producer)
  -- Return producer
  return function (request)
    -- Iterates over the producers results
    for results in snap.consume(producer, request) do
      -- If we have a table then we want to filter it
      if type(results) == "table" then
        -- Yield the filtered table
        coroutine.yield(vim.tbl_filter(
          function (value)
            return string.find(value, request.filter, 0, true)
          end,
          results
        ))
      -- If we don't have a table we finish by yielding nil
      else
        coroutine.yield(nil)
      end
    end
  end
end

Producer + Consumer

The following combines our above consumer and producer, itself creating a new producer, and passes this to snap to run:

snap.run {
  producer = consumer(producer),
  select = print
}

From the above we have seen the following distinct concepts of snap:

• Producer + consumer pattern
• Yielding a lua table of strings
• Yielding nil to exit
• Using snap.io.spawn iterate over the data of a process
• Using snap.sync to run slow-mode nvim functions
• Using snap.consume to consume another producer
• Using the request.filter value
• Using the request.canceled() signal to kill processes

API

Meta Result

Results can be decorated with additional information (see with_meta), these results are represented by the MetaResult type.

// A table that tostrings as result

type MetaResult = {
  // The result string value
  result: string;

  // A metatable __tostring implementation
  __tostring: (result: MetaResult) => string;

  // More optional properties, e.g. score
  ...
};

Yieldable

Coroutines in snap can yield 4 different types, each with a distinct meaning outlined below.

type Yieldable = table<string> | table<MetaResult> | function | nil;

Yielding table<string>

For each table<string> yielded (or returned as the last value of producer) from a producer, snap will accumulate the values of the table and display them in the results buffer.

local function producer(message)
  coroutine.yield({"Result 1", "Result 1"})
  -- the nvim UI can respond to input between these yields
  coroutine.yield({"Result 3", "Result 4"})
end

This producer function results in a table of 4 values displayed, but given there are two yields, in between these yields nvim has an oppurtunity to process more input.

One can see how this functionality allows for results of spawned processes to progressively yield thier results while avoiding blocking user input, and enabling the cancelation of said spawned processes.

Yielding table<MetaResult>

Results at times need to be decorated with additional information, e.g. a sort score.

snap makes use of tables (with an attached metatable implementing __tostring) to represent results with meta data.

The following shows how to add results with additional information. And because snap automatically sorts results with score meta data, the following with be ordered accordingly.

local function producer(message)
  coroutine.yield({
    snap.with_meta("Higher rank", "score", 10),
    snap.with_meta("Lower rank", "score", 1),
    snap.with_meta("Mid rank", "score", 5)
  })
end

Yielding function

Given that producer is by design run when fast-mode is true. One needs an ability to at times get the result of a blocking nvim function, such as many of nvim basic functions, e.g. vim.fn.getcwd. As such snap provides the ability to yield a function, have its execution run with vim.schedule and its resulting value returned.

local function producer(message)
  -- Yield a function to get its result
  local cwd = snap.sync(vim.fn.getcwd)
  -- Now we have the cwd we can do something with it
end

Yielding nil

Yielding nil signals to snap that there are not more results, and the coroutine is dead. snap will finish processing the coroutine when nil is encounted.

local function producer(message)
  coroutine.yield({"Result 1", "Result 1"})
  coroutine.yield(nil)
  -- Doesn't proces this, as coroutine is dead
  coroutine.yield({"Result 3", "Result 4"})
end

Request

This is the request that is passed to a producer.

type Request = {
  filter: string;
  winnr: number;
  canceled: () => boolean;
};

ViewRequest

This is the request that is passed to view producers.

type ViewRequest = {
  selection: string;
  bufnr: number;
  winnr: number;
  canceled: () => boolean;
};

Producer

type Producer = (request: Request) => yield<Yieldable>;

The full type of producer is actually:

type ProducerWithDefault = {default: Producer} | Producer;

Because we support passing a table if it has a default field that is a producer. This enables producer modules to export a default producer, while also making orther related producers available, e.g. ones with additional configuration.

See: https://github.com/camspiers/snap/blob/main/fnl/snap/producer/ripgrep/file.fnl

Consumer

type Consumer = (producer: Producer) => Producer;

ViewProducer

type ViewProducer = (request: ViewRequest) => yield<function | nil>;

snap.run

{
  // Get the results to display
  producer: Producer;

  // Called on select
  select: (selection: string) => nil;

  // Optional prompt displayed to the user
  prompt?: string;

  // Optional function that enables multiselect
  multiselect?: (selections: table<string>) => nil;

  // Optional function configuring the results window
  layout?: () => {
    width: number;
    height: number;
    row: number;
    col: number;
  };

  // Optional initial filter
  initial_filter?: string;

  // Optional views
  views?: table<ViewProducer>
};

Advanced API (for developers)

snap.meta_result

Turns a result into a meta result.

(result: string | MetaResult) => MetaResult

snap.with_meta

Adds a meta field to a result.

(result: string | MetaResult, field: string, value: any) => MetaResult

snap.has_meta

Checks if a result has a meta field.

(result: string | MetaResult, field: string) => boolean

snap.resume

Resumes a passed coroutine while handling non-fast API requests.

TODO

snap.sync

Yield a slow-mode function and get it's result.

(fnc: () => T) => T

snap.consume

Consumes a producer providing an iterator of its yielded results

(producer: Producer, request: Request) => iterator<Yieldable>

Layouts

snap.layouts.centered

snap.layouts.bottom

snap.layouts.top

Producers

snap.producer.vim.buffer

Produces vim buffers.

snap.producer.vim.oldfiles

Produces vim oldfiles.

snap.producer.luv.file

Luv (vim.loop) based file producer.

NOTE: Requires no external dependencies.

snap.producer.luv.directory

Luv (vim.loop) based directory producer.

NOTE: Requires no external dependencies.

snap.producer.ripgrep.file

Ripgrep based file producer.

snap.producer.ripgrep.vimgrep

Ripgrep based grep producer in vimgrep format.

snap.producer.fd.file

Fd based file producer.

snap.producer.fd.directory

Fd based directory producer.

snap.producer.git.file

Git file producer.

Consumers

snap.consumer.cache

General cache for producers whose values don't change in response to request.

snap.consumer.limit

General limit, will stop consuming a producer when a specified limit is reached.

snap.consumer.fzy

The workhorse consume for filtering producers that don't themselves filter.

NOTE: Requests fzy, e.g. use_rocks 'fzy'

snap.consumer.fzy.filter

A component piece of fzy that only filters.

snap.consumer.fzy.score

A component piece of fzy that only attaches score meta data.

snap.consumer.fzy.positions

A component piece of fzy that only attaches position meta data.

snap.consumer.fzf

Runs filtering through fzf, only supports basic positions highlighting for now.

snap.consumer.try

Accepts and arbitrary number of producers and upon the first that yields results then use it and skip the rest:

snap.get'consumer.try'(
  snap.get'producer.git.file',
  snap.get'producer.ripgrep.file'
)

snap.consumer.combine

Accepts and arbitrary number of producers and combines their results:

snap.get'consumer.combine'(
  snap.get'producer.ripgrep.file'.args({}, "/directory1"),
  snap.get'producer.ripgrep.file'.args({}, "/directory2"),
)

Selectors

snap.select.file

Opens a file in a buffer in the last used window.

NOTE: Provides both `select` and `multiselect`.

snap.select.vimgrep

If a single file is selected then simply opens the file at appropriate position.

If multiple files are selected then it adds them to the quickfix list, and opens the first.

NOTE: Provides both `select` and `multiselect`.

snap.select.cwd

Changes directory in response to selection.

snap.select.insert

Inserts selection at cursor location.

NOTE: Only provides `select`.

Previewers

snap.preview.file

Creates a basic file previewer.

NOTE: Experimental, and relies on `file` program in path.

Contributing

Snap is written in fennel, a language that compiles to Lua. See https://fennel-lang.org/

To install build dependencies:

make deps

To compile lua:

make compile

Roadmap

• Lua file producer
• Preview system
• More configurable layout system, including arbitrary windows
• Configurable loading screen
• FZF score/filter consumer
• More producers for vim concepts
• Lua filter consumer
• Tests