Luafmt

A small Lua formatter / pretty printer. Designed for 5.1, may support newer versions.

About

Luafmt is licensed under the MIT license and written by Lars Mueller alias appgurueu.

Features

• Fixes spacing & indentation
• Neat literal formatting
• Converts ({}) and ('')/("")/([[]]) calls to short forms
• Moves comments to reasonable scopes (blocks or table constructors)
• Table & function inlining
• Extra newlines around function declarations

API

Installation

Install the NPM package luafmt:

npm install @appguru/luafmt

And import it like this:

const { ast, formatChunk, formatter } = require("@appguru/luafmt")

ast

Abstract syntax tree methods.

fixRanges

Makes luaparse ranges be from if to end and not from if to then for all IfClauses of the AST.

insertComments(chunk)

Inserts comments into the top-level abstract syntax tree provided by luaparse.

formatter(conf)

Provides a formatter which returns a function format(ast, [indent]) taking a luaparse AST & optionally the base indentation as number. Note that you have to call [fixRanges] and [insertComments] on the AST yourself before using it:

const { ast } = require("@appguru/luafmt")
const { parse } = require("luaparse") 
const srcAST = parse(`-- hello world
if true then print'hello world!'
else _ = _ end`)
const formatter = ast.formatter()
ast.fixRanges(srcAST)
ast.insertComments(srcAST)
console.log(formatter(srcAST))

formatChunk(text)

Takes a Lua chunk (think file / function body) as string and returns a formatted version, also as string.

formatter(conf)

const configuredFormatChunk = formatter({
  // string
  indent: "\t",
  // string
  newline: "\n",
  // boolean
  extra_newlines: true,
  // object
	inline: {
    // object or false
		block: {
			max_exp_length // number, in characters
    },
    // object or false
		table: {
			max_field_count // number
			max_field_length // number, in characters
		}
	}
})

Versions

• v1.0.0
  • The initial release
• v1.0.7
  • Lots of fixes
• v1.0.8
  • Empty blocks are now just a single space, no space after #
  • Fixed dependency constraints
• v1.0.9
  • Fixed operator precedence
• v1.0.10
  • Fixed table index operators (adding parens around base)
• v1.1.0
  • Fixed double minus (- -x)
  • Added inline tables & blocks
• v1.1.1
  • Fixed if statement formatting
• v1.1.2
  • Fixed local declarations without initializers (local name)
  • Tweaked table inlining
• v1.2.0
  • Added extra newlines around function declarations feature
• v1.2.1
  • Fixed table constructors containing comments
• v1.2.2
  • Fixed repeat-until statement formatting
  • Bumped luon version to v1.2.6
• v1.2.3
  • Fixed extra newlines
  • Improved tests
• v1.2.4
  • Fixed extra newlines
• v1.3.0, v1.4.0
  • Added configuration
• v1.4.1
  • Fixed Readme
• v1.4.2
  • Fixed (removed) trailing commas after fields followed by comments
  • Fixed (removed) obsolete (possibly invalid) bracketing (precedencies)
• v1.4.3
  • Tweaked: Obsolete brackets are omitted in the case of concatenation, but not for exponentation
• v1.5.0
  • Exposed AST-functions fixRanges & insertComments as well as lower-level AST formatter