inline-schema

A TypeScript library for parsing and validating inline schemas with a TypeScript-like syntax using ; instead of ,.

Installation

npm install inline-schema

Usage

Basic Example

import { defineSchema } from 'inline-schema';

// Define a schema
const stringSchema = defineSchema('string');
const numberSchema = defineSchema('number');
const booleanSchema = defineSchema('boolean');

// Parse values
const name = stringSchema.parse('hello');        // "hello"
const age = numberSchema.parse('42');            // 42
const active = booleanSchema.parse('true');      // true

// Validate parsed values
stringSchema.validator(name);    // true
numberSchema.validator(name);    // false

Tuples

const tupleSchema = defineSchema('[string; number; boolean]');

// With brackets
const value1 = tupleSchema.parse('[hello; 42; true]');
// ["hello", 42, true]

// Without brackets (outermost brackets are optional)
const value2 = tupleSchema.parse('hello; 42; true');
// ["hello", 42, true]

tupleSchema.validator(value1);    // true
tupleSchema.validator(['a', 'b', true]);  // false (second element should be number)

Arrays

// Array syntax: Type[] or [Type][]
const stringArray = defineSchema('string[]');
const numberArray = defineSchema('[number][]');

// With brackets
const names1 = stringArray.parse('[alice; bob; charlie]');
// ["alice", "bob", "charlie"]

// Without brackets (outermost brackets are optional)
const names2 = stringArray.parse('alice; bob; charlie');
// ["alice", "bob", "charlie"]

const numbers = numberArray.parse('[1; 2; 3; 4; 5]');
// [1, 2, 3, 4, 5]

Array of Tuples

const schema = defineSchema('[string; number][]');

// With outer brackets
const data1 = schema.parse('[[a; 1]; [b; 2]; [c; 3]]');
// [["a", 1], ["b", 2], ["c", 3]]

// Without outer brackets
const data2 = schema.parse('[a; 1]; [b; 2]; [c; 3]');
// [["a", 1], ["b", 2], ["c", 3]]

Escaping Special Characters

Use \ to escape special characters ;, [, ], and \ in string values:

const schema = defineSchema('string');

const value1 = schema.parse('hello\\;world');    // "hello;world"
const value2 = schema.parse('hello\\[world');    // "hello[world"
const value3 = schema.parse('hello\\\\world');   // "hello\\world"

// In tuples
const tupleSchema = defineSchema('[string; string]');
const tuple = tupleSchema.parse('hello\\;world; test');
// ["hello;world", "test"]

String Identifiers

Any identifier (including hyphens) is treated as a string schema:

const schema = defineSchema('word-smith');
const value = schema.parse('word-smith');
// "word-smith"

API

defineSchema(schemaString: string): ParsedSchema

Parses a schema string and returns an object with:

• schema: The parsed schema AST
• validator: A function to validate values against the schema
• parse: A function to parse value strings

parseSchema(schemaString: string): Schema

Parses a schema string and returns the schema AST.

parseValue(schema: Schema, valueString: string): unknown

Parses a value string according to the given schema.

createValidator(schema: Schema): (value: unknown) => boolean

Creates a validation function for the given schema.

Schema Syntax

Type	Schema	Example Value
String	string or identifier	hello
Number	number	42
Boolean	boolean	true or false
Tuple	[Type1; Type2; ...]	[hello; 42; true] or hello; 42; true
Array	Type[] or [Type][]	[1; 2; 3] or 1; 2; 3
Array of Tuples	[Type1; Type2][]	[[a; 1]; [b; 2]] or [a; 1]; [b; 2]

Notes

• Semicolons ; are used as separators instead of commas ,
• Outermost brackets [] are optional for tuple and array values
• Special characters can be escaped with backslash: \;, \[, \], \\
• Empty arrays/tuples are not allowed

CSV Loader

For loading CSV files with schema validation in rspack, see csv-loader.md.

// rspack.config.js
module.exports = {
  module: {
    rules: [
      {
        test: /\.schema\.csv$/,
        use: 'inline-schema/csv-loader',
      },
    ],
  },
};

License

ISC