prettier-plugin-acme

A Prettier plugin for ACME assembly sources (*.asm, *.a).

What it does

• registers *.asm and *.a as ACME source extensions
• keeps ACME directives, labels, and comments readable
• normalizes indentation and comma spacing
• preserves quoted strings and semicolons inside them
• supports ACME-specific forms like anonymous labels (+, ++, ---) and force-bit symbol assignments (label+3 = $ff)
• aligns = in contiguous variable-assignment blocks by default

Files of interest

• index.js — Prettier plugin entry point
• parser.js — AST parser for ACME source lines
• printer.js — AST printer/formatter logic
• tests/acme-plugin.test.js — node-based integration tests against Prettier
• tests/fixtures.test.js and tests/fixtures/*.asm — golden fixture tests (input/expected pairs)

Usage

Install the plugin in a project that already uses Prettier 3:

npm install --save-dev /path/to/prettier-plugin-acme

Then format ACME files with Prettier:

npx prettier --write src/example.asm --plugin prettier-plugin-acme

Or use the included prettier.config.cjs style:

npx prettier --write "**/*.asm"

Or include both default ACME extensions:

npx prettier --write "**/*.{asm,a}"

A CommonJS prettier.config.js example is also included as prettier.config.js.

If your Prettier config loads plugins automatically, running Prettier on an *.asm file is enough.

Options

• acmeAlignAssignments (default: true)

  • Aligns equal signs in contiguous blocks of variable assignments.
  • Set to false to keep normalized assignment spacing without block alignment.

• acmeAlignAssignmentsMinLines (default: 2)

  • Minimum number of contiguous variable-assignment lines required before alignment is applied.
  • Example: set to 3 to only align blocks with 3 or more assignment lines.

Example prettier.config.cjs snippet:

"use strict";

module.exports = {
  plugins: ["./index.js"],
  overrides: [
	{
	  files: ["*.asm", "*.a"],
	  options: {
		parser: "acme",
		acmeAlignAssignments: false,
		acmeAlignAssignmentsMinLines: 2,
	  },
	},
  ],
};

Notes

• The plugin now uses AST parsing (Program with typed line nodes) before printing.
• Expression-level AST nodes are also generated for assignments/operands (ExpressionList, Expression, BinaryExpression, UnaryExpression, etc.).
• Parser includes grouped expression forms for (...) and [...], plus current-PC symbol expressions like * + 2.
• Unsupported expression forms are kept non-fatal: parser stores parseError while formatter remains stable.
• The formatter is conservative: it does not rewrite expressions or mnemonics.
• It is aimed at ACME-style assembly files, especially the *.asm files in this repo.
• Package metadata includes exports in package.json for modern Node/Prettier loading.

Testing

Run both unit/integration and fixture golden tests:

npm test