rules_web

Bazel toolchain types and rules for W3C / WHATWG web-standards specs — WebIDL, HTML, CSS, JS. Consumers depend on this module for the interface (rule names, toolchain types, providers); the implementation comes from a separate module that registers the toolchain.

Toolchain types

Path	Toolchain type	Status	First implementation
//web/webidl/...	webidl_toolchain_type	v0	firefox_webidl_parser (WebIDL.py)
//web/html/...	html_parser_toolchain_type	stub	(planned: firefox_html_parser)
//web/css/...	css_toolchain_type	stub	(planned: firefox_css_specs)
//web/js/...	js_engine_toolchain_type	stub	(planned: firefox_spidermonkey)

Multiple implementations of the same toolchain type can coexist — Bazel's toolchain resolution picks whichever is registered. This mirrors how rules_cc lets you swap between LLVM, Xcode clang, MSVC, etc., without touching the consumer.

Consumer usage (WebIDL — v0 shape)

# MODULE.bazel
bazel_dep(name = "rules_web", version = "0.0.1")
bazel_dep(name = "firefox_webidl_parser", version = "0.0.1")
register_toolchains("@firefox_webidl_parser//:webidl_toolchain")

# BUILD.bazel
load("@rules_web//web/webidl:rules.bzl", "webidl_library", "webidl_parse")

webidl_library(
    name = "html_details",
    srcs = ["HTMLDetailsElement.webidl"],
)

webidl_parse(
    name = "html_details_ast",
    src = ":html_details",
)

webidl_parse invokes the registered parser toolchain via ctx.actions.run. The output is a JSON AST consumable by downstream codegen (the polyglot AST HTML emitter is the v0 consumer).

Why split rules from impl

• Consumers only pull in the narrowest closure (rules_web + the registered toolchain — not the whole Firefox source).
• Implementations can be swapped without changing consumer BUILD files (Mozilla's parser today, a Rust port tomorrow).
• The same pattern scales to html / css / js — rules_web owns the vocabulary; implementations live elsewhere.

Status

v0 scaffold. WebIDL toolchain type + minimal webidl_library / webidl_parse rules; html / css / js subdirs are stubs awaiting first real consumer.

PRIVATE / NDA. Published in fastverk/bazel-registry-premium.