Fifty parts of Gosub Browser Progress

Part 50 went up this week, which felt like a good moment to look back at the whole series. Three years, from "I don't know Rust and I don't know how browsers work" to a modular engine with a multi-process proof-of-concept.

Here is the whole thing, one line per part. It reads a bit like a changelog of the project, and a bit like a changelog of me learning Rust.

It started here: The one where he is writing a browser... - the announcement, including the tiny issue that I didn't know Rust yet.

Tokenizer (pt1-pt9)

1. pt1 - First days with Rust, and how much less explicit it is than Go.
2. pt2 - Fighting Rust over how to structure the thing. Unclear who won.
3. pt3 - Named character references, finally done. They took far too long.
4. pt4 - Character entities complete, so whole strings tokenize correctly.
5. pt5 - More data states filled in, plus generated testcases to check them.
6. pt6 - A test harness that runs the tokenizer against the html5 testsuite.
7. pt7 - Over 5000 of 6000 token tests passing, with utf-8 as the sticking point.
8. pt8 - The tokenizer passes all html5lib-tests and lands in main.
9. pt9 - Tokenizer done, so on to tree construction.

Tree construction and the borrow checker (pt10-pt23)

10. pt10 - Starting to get the hang of Rust. The borrow checker yells less.
11. pt11 - Document tree generation runs straight into ownership problems.
12. pt12 - An arena holding all nodes, referenced by node_id.
13. pt13 - Still wrestling the borrow checker, with an LLM as a second pair of eyes.
14. pt14 - First attempts at the adoption agency algorithm.
15. pt15 - Something snapped and the borrow checker finally made sense.
16. pt16 - A blog post on why this project exists, which blew up on Hacker News.
17. pt17 - Still stuck on test 23 of the tree-construction tests.
18. pt18 - Contributions start coming in, and my long-lived branch gets out of sync.
19. pt19 - Test 23 defeated. The adoption agency works.
20. pt20 - Filling in more tests, and struggling with Rust while doing it.
21. pt21 - All 112 tests in test1.dat pass. Many files to go.
22. pt22 - Parsing live documents from the actual web.
23. pt23 - 99.89% of the tree-construction tests pass.

Network stack and CSS (pt24-pt30)

24. pt24 - Designing the whole flow, and realising how much is still unwritten.
25. pt25 - The DNS component is finished.
26. pt26 - A week of yak shaving on the way to a http-to-rendertree pipeline.
27. pt27 - A working css3 parser, at the cost of the previous one.
28. pt28 - Porting csstree from JavaScript to Rust, which goes better than expected.
29. pt29 - Real-life CSS parses, at the cost of ignoring the rest of the engine.
30. pt30 - Tying the html parser and the css3 parser together.

First pixels (pt31-pt43)

31. pt31 - "dive", a text-based user agent built with ratatui.
32. pt32 - Tree-walking to get rudimentary text on screen.
33. pt33 - Turning a CST into stylesheet structures usable for selectors.
34. pt34 - Slower going, with the CSS system still far from finished.
35. pt35 - Refactoring to break the cyclic dependency between html5 and css3.
36. pt36 - The CSS3 and HTML5 crates finally work together.
37. pt37 - Taking stock of the components, and thinking about event loops and async.
38. pt38 - The v2 engine proof-of-concept merges into main.
39. pt39 - We've got a browser: a standalone useragent that loads tabs and renders them.
40. pt40 - Typography work, after the planning went sideways as usual.
41. pt41 - Font manager setbacks: the font libraries are not interchangeable.
42. pt42 - The render pipeline split into separate phases, tiling and painting included.
43. pt43 - The rendering pipeline PoC turns html and css into actual pixels.

Putting it together (pt44-pt50)

44. pt44 - Back at it after a quiet stretch, now with AI in the toolbox.
45. pt45 - The big three merged: network stack, rendering pipeline and engine api.
46. pt46 - Modularity pays off, with several browsers built on the same engine.
47. pt47 - A new gosub.io, with a nautical theme.
48. pt48 - The engine back in a useful state, with ModuleConfig and RenderConfig.
49. pt49 - A refurbished Mac M1 to build and test on real hardware.
50. pt50 - Cleanup, and a multi-process proof-of-concept.

On to the next fifty.