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The Compiler

Overview​

The OpenCore Compiler is the heart of the CLI. It is a high-performance build engine specifically designed to handle the complexities of FiveM's three distinct runtime environments (Server, Client, and NUI).

Technology Stack​

The compiler is built using a hybrid approach for maximum efficiency:

  • Go (Core Engine): Handles the orchestration, file system watching, and parallel worker pool.
  • SWC (Transformation): A super-fast TypeScript/JavaScript transformer written in Rust. We use it to handle Decorators and Metadata Reflection.
  • esbuild (Bundling): The fastest JavaScript bundler available, used to link all dependencies into a single FiveM-compatible file.

Why it's different​

Most FiveM build systems use standard Webpack or Rollup configurations which are slow and don't understand FiveM's unique constraints. The OpenCore compiler provides:

1. Multi-Core Parallelism​

While standard tools compile resources one by one, our Go engine distributes the work across all available CPU cores. This reduces build times from several seconds to milliseconds.

2. FiveM-Specific Targeting​

The compiler automatically applies different rules depending on the target:

  • Server: Optimized for Node.js runtime.
  • Client: Strips all Node.js and Web APIs, ensuring the code is compatible with FiveM's restricted "neutral" JS environment.
  • NUI: Standard browser bundling.

3. Automated Asset Management​

Beyond code, the compiler manages your fxmanifest.lua generation, copies static assets, and ensures that the final dist/ folder is ready to be dropped into your server without manual tweaks.

Performance Metrics​

On a typical project with 10 resources:

  • Sequential Build: ~2.3 seconds
  • Parallel Build (8 cores): ~0.5 seconds