regex-railroad.nvim

regex-railroad.nvim generates useful text and diagrams to help explain regular expressions in your code.

Getting started

Required dependencies

• nvim-treesitter/nvim-treesitter to extract the regular expression text

Installation

lazy.nvim

-- plugins/regex-railroad.lua:
return {
    "rclawlor/regex-railroad.nvim",
    tag = "0.0.3",
    dependencies = { "nvim-treesitter/nvim-treesitter" }
}

Usage

Use :RegexText to generate a text description of the regular expression under your cursor, or :RegexRailroad to instead generate a railroad diagram!

To remap the functions to something more convenient, use the following:

vim.api.nvim_set_keymap("n", "<C-x>", "<cmd>RegexText<CR>", {noremap = true, silent = true})
vim.api.nvim_set_keymap("n", "<C-s>", "<cmd>RegexRailroad<CR>", {noremap = true, silent = true})

Customisation

This section explains the available options for configuring regex-railroad.nvim

Setup function

require("regex-railroad").setup({
    --- Github release of plugin
    tag = "v0.0.3",
    --- Highlight group used in :RegexText
    highlight = {
        bold = true,
        fg = "fg",
        bg = "bg"
    }})

Supported Features

Character classes

Feature	Example	Supported
Character set	[ABC]	✓
Negated set	[^ABC]	✓
Range	[A-Z]	✓
Dot	.	✓
Word	\w	✓
Non-word	\W	✓
Digit	\d	✓
Non-digit	\D	✓
Whitespace	\s	✓
Non-whitespace	\S	✓
Unicode category	\p{L}	✗
Non-unicode category	\p{L}	✗
Unicode script	\p{Han}	✗
Non-unicode script	\P{Han}	✗

Anchors

Feature	Example	Supported
Beginning	^	✓
End	$	✓
Word boundary	\b	✗
Non-word boundary	\B	✗

Groups & References

Feature	Example	Supported
Capturing group	(ABC)	✓
Named capturing group	(?ABC)	✓
Numeric reference	\1	✗
Non-capturing group	(?:ABC)	✓

Lookaround

Feature	Example	Supported
Positive lookahead	(?=ABC)	✗
Negative lookahead	(?!ABC)	✗
Positive lookbehind	(?<=ABC)	✗
Negative lookbehind	(?<!ABC)	✗

Qualifiers & Alternation

Feature	Example	Supported
Plus	+	✓
Star	*	✗
Quantifier	{1,3}	✓
Optional	?	✓
Lazy	?	✗
Alternation	|	✓