# decodal-wasm

WebAssembly runtime package for Decodal.

This package exposes the Decodal evaluator and shared language service to browsers and other JavaScript runtimes that can load WebAssembly modules.
It is generated from the Rust crate in `crates/decodal-wasm` with `wasm-pack` and is used by the official playground.

Use `decodal-codemirror` separately when you need CodeMirror 6 language support.

## Install

```sh
npm install decodal-wasm
```

JSR:

```sh
deno add jsr:@hare/decodal-wasm
```

## Usage

```js
import init, { DecodalLanguageService } from 'decodal-wasm';

await init();

const files = {
  'main.dcdl': 'let schema = import "./schema.dcdl"; in schema.Server',
  'schema.dcdl': 'Server = { port = 8080; } as App.Server;',
};

const service = new DecodalLanguageService({
  globals: {
    App: {
      Server: {
        port: { $decodal: 'Int' },
      },
    },
  },
  loadImport(_currentKey, specifier) {
    const key = specifier.startsWith('./') ? specifier.slice(2) : specifier;
    return { kind: 'source', key, name: key, source: files[key] };
  },
  completeImport() {
    return ['./schema.dcdl'];
  },
});

const result = service.evaluate('main.dcdl', 'main.dcdl', files['main.dcdl']);

console.log(JSON.parse(result));

const completion = service.complete(
  'main.dcdl',
  'App.Server.po',
  'App.Server.po'.length,
  false,
);

console.log(JSON.parse(completion));
```

`globals`, `loadImport`, and `completeImport` are host-owned. The package does not assume a filesystem or virtual project model. Import callbacks are synchronous; preload or cache remote content before evaluation.

Plain strings, numbers, booleans, arrays, and objects are concrete values. Use `{ $decodal: 'String' | 'Int' | 'Float' | 'Bool' }` for primitive ranges, `{ $decodal: 'Unknown' }` for the top range, `{ $decodal: 'Array', item: value }` for array ranges, and `{ $decodal: 'Map', value: value }` for associative-array ranges. Primitive, unknown, array, and map descriptors also accept `constraints` and `default`.

Use `{ $decodal: 'Range', constraints, default }` when constructing a general range directly.

An object with named fields and an open rest range uses `{ $decodal: 'Object', fields, rest }`. The `fields` property is a record of values and `rest` is the range applied to every other field.

Methods return JSON strings so callers can handle diagnostics and successful results without depending on Rust data structures.