Introduction

MoonTemplate is a highly extensible text templating engine built from scratch in MoonBit. It provides developers with a robust tool to generate dynamic content, ranging from HTML pages and emails to source code generation.

Key Features

• Zero Dependencies: Pure MoonBit implementation.
• Robust Parsing: Custom-built Lexer and AST (Abstract Syntax Tree) Parser ensuring safety and speed.
• Variable Interpolation: Easily inject data into templates using {{ variable }}.
• Control Flow (If/Else): Conditional rendering logic with {% if cond %}.
• Iteration (For Loops): Support for rendering lists and arrays using {% for item in iterable %}.
• Filter System: Extensible architecture via pipes {{ name | uppercase }}.
• CLI Ready: Includes a scaffolding for a Command Line Interface.

Architecture

MoonTemplate is divided into 4 core modules to maintain high cohesion and low coupling:

1. lexer: Tokenizes the raw template string into a stream of semantic tokens.
2. parser: Consumes the token stream to build an Abstract Syntax Tree (AST).
3. ast: Defines the node structures (Text, Variable, If, For).
4. engine: The rendering runtime that traverses the AST and interpolates context data.

Quick Start

1. Basic Variable Rendering

let template = "Hello, {{ user }}! Welcome to MoonBit."
let engine = Engine::new(template).unwrap()
let ctx = Map::new()
ctx.set("user", "Hero001")

let output = engine.render(ctx)
println(output) // Hello, Hero001! Welcome to MoonBit.

2. Using Conditionals

let template = "{% if is_admin %}Admin Panel{% endif %}"
let engine = Engine::new(template).unwrap()
let ctx = Map::new()
ctx.set("is_admin", "true")
println(engine.render(ctx)) // Admin Panel

3. Filters

let template = "Current status: {{ status | uppercase }}"
let engine = Engine::new(template).unwrap()
engine.register_filter("uppercase", fn(s) { s.to_upper() })
// ... render with ctx

CLI Usage

MoonTemplate includes a CLI tool for rendering templates directly from your terminal.

moon run src/cli -- template.txt

Contributing

Please see CONTRIBUTING.md for details on how to contribute, build, and test the project.

License

This project is licensed under the Apache 2.0 License - see the LICENSE file for details.