cue-ts

A lightweight TypeScript parser for a subset of the CUE configuration language. Produces a fully typed AST. Zero runtime dependencies. Works in the browser and Node.js.

Install

pnpm add cue-ts

Usage

import { parse } from "cue-ts";

const ast = parse(`
  name: string
  age:  int & >=0
  role: "admin" | "user"
`);

// ast.kind === "file"
// ast.declarations contains CueField nodes

Error handling

import { parse, CueParseError } from "cue-ts";

try {
  parse("invalid: {");
} catch (e) {
  if (e instanceof CueParseError) {
    console.log(e.line, e.column, e.message);
  }
}

Supported CUE subset

Construct	Example
Literals	"hello", 42, 3.14, true, false, null
Multi-line strings	""" ... """
Type keywords	string, int, float, bool, number, bytes
Top / Bottom	_, _|_
Structs	{ name: "Alice" }
Optional fields	name?: string
Definitions	#Name: { ... }
Lists	[1, 2, 3], [...string]
Constraints	int & >=0, string & =~"pattern"
Disjunctions	"a" | "b" | "c"
Comments	// single line
Quoted labels	"my-key": value

AST node types

Every node has a kind discriminant for exhaustive matching:

• CueFile -- top-level container
• CueField -- label: value (with optional flag)
• CueStruct -- { fields }
• CueList -- [elements]
• CueLiteral -- string, number, bool, or null
• CueIdent -- identifier reference
• CueType -- type keyword (string, int, top, etc.)
• CueUnaryExpr -- constraint operator (>=, <, =~, etc.)
• CueBinaryExpr -- conjunction (&)
• CueDisjunction -- alternatives (|)
• CueDefinition -- #Name: value
• CueComment -- // text
• CueEllipsis -- ... or ...type

All types are exported and available for import.

Not supported

This is a subset parser. It does not support:

• CUE evaluation or unification
• Import/package resolution
• Constraint solving
• Comprehensions
• Interpolation
• Parenthesized expressions

Development

pnpm install
pnpm test        # vitest
pnpm build       # tsup (dual CJS/ESM + types)
pnpm lint        # biome

Changelog

See CHANGELOG.md for release history.

This project uses Conventional Commits and git-cliff for automated changelog generation.

License

Apache 2.0