`, `
`, ``, ``, text nodes)
- DOM tree: `Document`, `Element`, `Text`, `Comment` node types
- Basic block layout: stack blocks vertically, wrap text into lines
- Software renderer: paint text glyphs and block backgrounds into CG bitmap
- Display painted bitmap in the AppKit window
**Test milestone:** Pass html5lib tokenizer tests.
## Phase 4: CSS Parsing + Selector Matching + Cascade + Inline/Text Layout
**Goal:** Parse CSS, match selectors, resolve styles, lay out inline content.
- CSS tokenizer (per spec)
- CSS parser: selectors, declarations, `@`-rules (at least `@media`, `@import`)
- Selector matching: type, class, ID, attribute, combinators (descendant, child, sibling)
- Cascade: origin, specificity, source order
- Computed style resolution
- Inline layout: inline boxes, line boxes, text wrapping, vertical alignment
- Handle `<style>` elements and `style` attributes
**Test milestone:** Pass Acid1.
## Phase 5: Pure Rust Crypto
**Goal:** Implement the cryptographic primitives needed for TLS 1.3.
- SHA-256, SHA-384, SHA-512 (FIPS 180-4)
- HMAC (RFC 2104)
- HKDF (RFC 5869)
- AES-128-GCM, AES-256-GCM (NIST SP 800-38D)
- ChaCha20-Poly1305 (RFC 8439)
- X25519 key exchange (RFC 7748)
- RSA PKCS#1 v1.5 signature verification (RFC 8017)
- ECDSA signature verification (P-256, P-384) (FIPS 186-4)
- ASN.1 DER parser
- X.509 certificate parsing and chain validation
## Phase 6: Pure Rust TLS 1.3 + TCP + DNS + HTTP/1.1 + URL Parser
**Goal:** Fetch resources over HTTPS.
- WHATWG URL parser (full spec compliance)
- DNS stub resolver (UDP, A/AAAA records, system resolver config)
- TCP socket wrapper (std::net)
- TLS 1.3 client (RFC 8446): handshake, record layer, key schedule, certificate verification
- HTTP/1.1 client: request/response parsing, chunked transfer encoding, keep-alive
- Connection pooling
- Content-Length and Transfer-Encoding handling
## Phase 7: Image Decoders
**Goal:** Decode common image formats in pure Rust.
- DEFLATE decompressor (RFC 1951)
- zlib wrapper (RFC 1950)
- PNG decoder (RFC 2083): IHDR, IDAT, PLTE, tRNS, interlacing
- JPEG decoder: baseline DCT, Huffman, JFIF/EXIF markers
- GIF decoder: LZW, frames, transparency
- Pixel format conversion (RGBA8)
## Phase 8: Resource Loading + Character Encoding + Real Page Loading
**Goal:** Load and render real web pages.
- WHATWG Encoding Standard: UTF-8, UTF-16, ISO-8859-1, Windows-1252, and other legacy encodings
- Encoding sniffing (BOM, HTTP header, meta tag, prescan)
- Resource loader: fetch HTML, CSS, images via `net` crate
- `<link rel="stylesheet">` and `<img>` loading
- Data URLs
- about:blank
## Phase 9: Advanced Layout
**Goal:** Handle modern CSS layout modes.
- Positioned layout: relative, absolute, fixed, sticky
- Flexbox (CSS Flexible Box Layout Level 1)
- Floats and clear
- Overflow and scrolling (scroll bars, `overflow: auto/scroll/hidden`)
- `display: none`, `visibility: hidden`
- `box-sizing`, margin collapsing
- Viewport units, percentage resolution
**Test milestone:** Pass Acid2.
## Phase 10: JavaScript Engine
**Goal:** Execute JavaScript with a JIT-ready architecture.
- Lexer/tokenizer (ECMAScript 2024)
- Parser → AST
- Bytecode compiler: register-based bytecode format designed for JIT
- Register-based VM: instruction dispatch, operand stack
- Garbage collector: tri-color mark-and-sweep
- Core built-ins: Object, Array, String, Number, Boolean, Function, Math, Date, RegExp, JSON, Error, Map, Set, Promise, Symbol
- `typeof`, `instanceof`, prototype chain, closures, `this` binding
- `var`/`let`/`const` scoping
- Iterators, generators, async/await
**Test milestone:** Pass Test262 core language subset.
## Phase 11: DOM-JS Bindings + Events + Timers + Fetch API
**Goal:** Connect JavaScript to the DOM and web APIs.
- DOM bindings: `document.getElementById`, `querySelector`, `createElement`, `appendChild`, `textContent`, `innerHTML`
- Event system: `addEventListener`, `removeEventListener`, `dispatchEvent`, bubbling/capturing
- `setTimeout`, `setInterval`, `requestAnimationFrame`
- Fetch API (backed by `net` crate)
- Console API (`console.log`, `console.error`, `console.warn`)
- `<script>` element loading and execution (defer, async)
**Test milestone:** Begin WPT pass rate tracking.
## Phase 12: Metal GPU Compositor
**Goal:** GPU-accelerated rendering.
- Metal device/command queue setup via `platform` crate
- Texture atlas for glyph cache
- Display list → Metal render passes
- Compositing layers (for transforms, opacity, will-change)
- Double-buffered presentation
- Fallback to software rendering when Metal unavailable
## Phase 13: Advanced CSS
**Goal:** Modern CSS features.
- CSS Grid Layout (Level 1)
- CSS Animations (`@keyframes`, `animation-*`)
- CSS Transitions (`transition-*`)
- CSS Custom Properties (`--var`, `var()`)
- `@font-face` (load and parse web fonts via `text` + `net`)
- `calc()`, `min()`, `max()`, `clamp()`
- Media queries (screen width, prefers-color-scheme)
- SVG basics: `<svg>`, `<rect>`, `<circle>`, `<path>`, `<text>`
## Phase 14: Security + Storage
**Goal:** Web security model and client-side storage.
- Same-Origin Policy enforcement
- CORS (preflight, simple requests, credentialed requests)
- Content Security Policy (CSP Level 2)
- Cookie jar (`Set-Cookie` parsing, `Cookie` header, SameSite, Secure, HttpOnly)
- `localStorage` / `sessionStorage`
- IndexedDB (basic subset)
- `<iframe>` isolation and `postMessage`
- Referrer Policy
## Phase 15: Performance
**Goal:** Production-grade performance.
- Baseline JIT compiler: bytecode → AArch64 machine code
- Inline caches for property access
- Incremental layout (dirty bit propagation)
- HTTP/2 (HPACK, multiplexed streams, flow control)
- Speculative HTML parsing (off-main-thread tokenization)
- Style sharing cache
- Layer tree and damage tracking for minimal repaints
- Memory profiling and optimization pass
---
## Test Suites
| Suite | Crate(s) | Phase |
|-------|----------|-------|
| html5lib-tests (tokenizer) | `html` | 3 |
| Acid1 | `css`, `style`, `layout`, `render` | 4 |
| Acid2 | `layout`, `render` | 9 |
| Test262 (core language) | `js` | 10 |
| WPT (progressive) | all | 11+ |