nvim-chainsaw 🪚

Speed up log creation. Create various kinds of language-specific log statements, such as logs of variables, assertions, or time-measuring.

demo.mp4

Installation
Built-in language support
Usage
- List of commands
- Smart variable identification
Configuration
Similar Lua Plugins
About the developer

Installation

Requirements

nvim 0.10 or higher.
Optional for smart variable identification: Treesitter parser for the respective languages.

-- lazy.nvim
{ "chrisgrieser/nvim-chainsaw" },

-- packer
use { "chrisgrieser/nvim-chainsaw" }

Built-in language support

JavaScript (and supersets)
Python
Lua (with special considerations for nvim_lua)
Shell (and supersets)
AppleScript
Ruby
Rust
CSS (and supersets)

Not every language supports every type of log statement. For details on what is supported, see log-statements-data.lua.

Note

For non-scripting languages like CSS, nvim-chainsaw uses statements such as outline: 2px solid red !important; that are the closest thing to logging you have.

Usage

The plugin offers various types of log statements. Bind keymaps for the ones you want to use.

All operations are dot-repeatable.

List of commands

-- log the name & value of the variable under the cursor
require("chainsaw").variableLog()

-- like variableLog, but with syntax specific to inspect an object such as
-- `console.log(JSON.stringify(foobar))` in javascript
require("chainsaw").objectLog()

-- inspect the type of the variable under cursor, such as `typeof foo` in js
require("chainsaw").typeLog()

-- assertion statement for variable under cursor
require("chainsaw").assertLog()

-- Minimal log statement, with an emoji for differentiation. Intended for
-- control flow inspection, i.e. to quickly glance whether a condition was
-- triggered or not. (Inspired by AppleScript's `beep` command.)
require("chainsaw").beepLog()

-- create log statement, and position the cursor to enter a message
require("chainsaw").messageLog()

-- 1st call: start measuring the time
-- 2nd call: logs the time duration since
require("chainsaw").timeLog()

-- debug statements like `debugger` in javascript or `breakpoint()` in python
require("chainsaw").debugLog()

-- prints the stacktrace of the current call
require("chainsaw").stacktraceLog()

-- clearing statement, such as `console.clear()`
require("chainsaw").clearLog()

---------------------------------------------------

-- remove all log statements created by chainsaw
require("chainsaw").removeLogs()

These features can also be accessed with the user command :ChainSaw. Each option corresponds to the commands above. For example, :ChainSaw variableLog is same as :lua require("chainsaw").variableLog().

When using lua functions, variableLog, objectLog, typeLog, and assertLog can also be used in visual mode to use the visual selection instead of the word under the cursor.

Smart variable identification

When the variable under the cursor is an object with fields, chainsaw attempts to automatically select the correct field. Note that this feature requires the Treesitter parser of the respective language to be installed.

myVariable.myF[i]eld = "foobar"
-- prints: myVariable.myField

myVa[r]iable.myField = "foobar"
-- prints: myVariable

Filetypes currently supporting this feature:

Lua
Python
JavaScript (and supersets)

PRs adding support for more languages are welcome.

Configuration

Basic Configuration

-- default settings
require("chainsaw").setup {
	-- The marker should be a unique string, since lines with it are highlighted
	-- and since `removeLogs` will remove any line with it. Thus, emojis or
	-- strings like "[Chainsaw]" are recommended.
	marker = "🪚",

	-- Highlight lines with the marker.
	-- lazy.nvim users:, you need to add `event = VeryLazy` to the plugin spec to
	-- have existing log statements highlighted as well.
	---@type string|false -- false to disable
	logHighlightGroup = "Visual",

	-- emojis used for `beepLog`
	beepEmojis = { "🔵", "🟩", "⭐", "⭕", "💜", "🔲" },
}

Add your own log statements

Custom log statements are added in the setup() call. The values are formatted lua strings, meaning %s is a placeholder that is dynamically replaced with the actual value. See log-statements-data.lua for examples.

PRs adding log statements for more languages are welcome.

require("chainsaw").setup ({
	logStatements = {
		variableLog = {
			javascript = 'console.log("%s %s:", %s);',
			otherFiletype = … -- <-- add the statement for your filetype here
		},
		-- the same way for the other log statement operations
	},
})

Have your formatter ignore the log statements

A common problem is that formatters like prettier break up the log statements, making them hard to read and also breaking removeLogs(), which relies on each line containing the marker emoji.

The simplest method to deal with this is to customize the log statement in your configuration to include /* prettier-ignore */:

require("chainsaw").setup {
	logStatements = {
		variableLog = {
			javascript = {
				"/* prettier-ignore */ // %s", -- adding this line
				'console.log("%s %s:", %s);',
			},
		},
	},
}

Similar Lua Plugins

The other plugins are more feature-rich, while nvim-chainsaw tries to achieve the core functionality in a far more lightweight manner to keep maintenance minimal.

About the developer

In my day job, I am a sociologist studying the social mechanisms underlying the digital economy. For my PhD project, I investigate the governance of the app economy and how software ecosystems manage the tension between innovation and compatibility. If you are interested in this subject, feel free to get in touch.

I also occasionally blog about vim: Nano Tips for Vim