@hdml/hooks

This module is part of the HDML-Utilities monorepo and provides a set of I/O utility functions for reading from stdin and writing to stdout. It's designed to work in environments like WebAssembly (Javy) where standard I/O operations require special handling.

Features

This package provides the following I/O utility functions:

Reading Functions

1. readUint8Array: Reads raw bytes from stdin and returns them as a Uint8Array.
2. readString: Reads a string from stdin by decoding the input bytes using UTF-8 encoding.
3. readJson: Reads and parses a JSON object from stdin.

Writing Functions

1. writeUint8Array: Writes a Uint8Array to stdout and returns the number of bytes written.
2. writeString: Writes a string to stdout by encoding it as UTF-8 and returns the number of bytes written.
3. writeJson: Serializes a JSON object to a string and writes it to stdout, returning the number of bytes written.

Dependencies

This module depends on:

• @hdml/parser: For parsing HDML documents
• @hdml/schemas: FlatBuffers schema-based classes for serialization
• @hdml/types: TypeScript interface definitions for HDML components

Installation

To install this module, simply add it to your project:

npm install @hdml/hooks

Usage

Reading from stdin

import { readString, readJson, readUint8Array } from "@hdml/hooks";

// Read a string from stdin
const text = readString();
console.log(text);

// Read and parse JSON from stdin
const data = readJson<{ name: string; age: number }>();
console.log(data.name, data.age);

// Read raw bytes from stdin
const bytes = readUint8Array();
console.log(bytes.length);

Writing to stdout

import { writeString, writeJson, writeUint8Array } from "@hdml/hooks";

// Write a string to stdout
const bytesWritten = writeString("Hello, world!");
console.log(`Wrote ${bytesWritten} bytes`);

// Write a JSON object to stdout
const bytesWritten = writeJson({ name: "John", age: 30 });
console.log(`Wrote ${bytesWritten} bytes`);

// Write raw bytes to stdout
const bytesWritten = writeUint8Array(new Uint8Array([1, 2, 3]));
console.log(`Wrote ${bytesWritten} bytes`);

Complete Example

import { readJson, writeJson } from "@hdml/hooks";

// Read JSON input from stdin
const input = readJson<{ message: string }>();

// Process the data
const output = {
  response: `Received: ${input.message}`,
  timestamp: Date.now(),
};

// Write JSON output to stdout
writeJson(output);

Notes

• The functions use Javy.IO.readSync and Javy.IO.writeSync internally, making them suitable for WebAssembly environments like Javy.
• readUint8Array reads input in 1024-byte chunks and assembles them into a single array.
• All string operations use UTF-8 encoding/decoding.
• JSON operations use JSON.parse and JSON.stringify for parsing and serialization.

License

Apache License Version 2.0