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Parser and Lexer.md

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LayerScript Compiler: Parser, Lexer & OS Lower-Ring Target

this document explains how we turn raw text into a working program and why we made certain choices.

1. syntax choices

we use the function (or fn) keyword to keep things clear.

// layerscript style: no confusion
function foo() -> i32 { return 32; }

in old languages like C, it's hard to tell if something is a function or a variable. by using a keyword, the Lexer and Parser can move way faster because they always know what's coming next.

2. implementation: why rust?

we chose Rust for the compiler because:

  • speed: it compiles code almost instantly.
  • safety: the "Ring System" (0-3) is enforced by Rust's crate system, so we don't accidentally make a mess of the dependencies.
  • PascalCase: we use a specific coding style in the Rust code to keep things organized.

3. low-level targets

layerscript is built to replace assembly for kernels and bootloaders.

flowchart TD
    Ring4[Ring 4: User Apps] --> Ring3[Ring 3: CLI Commands]
    Ring3 --> Ring2[Ring 2: Device Drivers]
    Ring2 --> Ring1[Ring 1: Hypervisor]
    Ring1 --> Ring0[Ring 0: LayerScript Kernel]
    
    style Ring0 fill:#f44,stroke:#d32,color:#fff
Loading

bare metal features

  • No-Std: the compiler doesn't need an OS to run.
  • Direct Addressing: you can map a struct directly to a memory address (like 0x7C00 for boot sectors).
  • Havoc: you have total control over when the compiler should forget what's in a CPU register.