Who am I？ Daiki Nishikawa (GitHub: @nissy-dev X: @nissy_dev) Frontend engineer at Cybozu, Inc. Replace frontend using Next.js App Router I like coding rust 🦀 (also like eating 🦀) Core contributor of Biome
What is Biome? Provide toolchains for web development Currently, focus on linter and formatter Language support: JS, TS, JSON and JSONC Biome is the fork of Rome by community The members of Rome are laid off Rome isn’t maintained anymore
Governance Welcome to more contributors Join three new maintainers Collect funds from community Open Collective GitHub Sponsor Start thinking about roadmap
Red-Green Tree (lossless syntax tree) Great error resilience Fully recoverable Created by C# compiler team rust-analyzer and swift also use Biome use the forked Rowan Rowan: A library for red-green tree used in rust-analyzer
Example: enforce-foo-bar All const variables named "foo" are assigned the string literal "bar" This is covered in ESLint’s custom rule tutorial // show error! const foo = "foo123"; ↓ // expected const foo = "bar";
ESLint implementation create(context) { return { // Performs action in the function on every variable declarator VariableDeclarator(node) { // Check if a `const` variable declaration if (node.parent.kind === "const") { // Check if variable name is `foo` if (node.id.type === "Identifier" && node.id.name === "foo") { // Check if value of variable is "bar" if (node.init && node.init.type === "Literal" && node.init.value !== "bar") { // report error context.report({ ... }); } } } } } }
Biome implementation impl Rule for EnforceFooBar { // define the AST node which visitor enter type Query = Ast; type State = (); // The main logic for linter // - return Some(()) when to report error // - return None **when not** to report error fn run(ctx: &RuleContext) -> Option { let node = ctx.query(); let parent = node .parent::()? .parent::()?; ... } }
Biome implementation // define the AST node which visitor enter type Query = Ast; impl Rule for EnforceFooBar { type State = (); // The main logic for linter // - return Some(()) when to report error // - return None **when not** to report error fn run(ctx: &RuleContext) -> Option { let node = ctx.query(); let parent = node .parent::()? .parent::()?; ... } }
Biome implementation // The main logic for linter // - return Some(()) when to report error // - return None **when not** to report error fn run(ctx: &RuleContext) -> Option { let node = ctx.query(); let parent = node .parent::()? .parent::()?; ... } } impl Rule for EnforceFooBar { // define the AST node which visitor enter type Query = Ast; type State = ();
Biome implementation impl Rule for EnforceFooBar { // define the AST node which visitor enter type Query = Ast; type State = (); // The main logic for linter // - return Some(()) when to report error // - return None **when not** to report error fn run(ctx: &RuleContext) -> Option { let node = ctx.query(); let parent = node .parent::()? .parent::()?; ... } }
Biome implementation fn run(ctx: &RuleContext) -> Option { ... // check if a `const` variable declaration if parent.is_const() { // Check if variable name is `foo` if node.id().ok()?.text() == "foo" { // Check if value of variable is "bar" let init_exp = node.initializer()?.expression().ok()?; let literal_exp = init_exp.as_any_js_literal_expression()?; if literal_exp.as_static_value()?.text() != "bar" { // Report error to Biome // The details of error message is implemented by "diagnostic" method return Some(()); } } } None }
Biome implementation // check if a `const` variable declaration if parent.is_const() { // Check if variable name is `foo` if node.id().ok()?.text() == "foo" { fn run(ctx: &RuleContext) -> Option { ... // Check if value of variable is "bar" let init_exp = node.initializer()?.expression().ok()?; let literal_exp = init_exp.as_any_js_literal_expression()?; if literal_exp.as_static_value()?.text() != "bar" { // Report error to Biome // The details of error message is implemented by "diagnostic" method return Some(()); } } } None }
Biome implementation // Check if value of variable is "bar" let init_exp = node.initializer()?.expression().ok()?; let literal_exp = init_exp.as_any_js_literal_expression()?; if literal_exp.as_static_value()?.text() != "bar" { // Report error to Biome // The details of error message is implemented by "diagnostic" method return Some(()); } fn run(ctx: &RuleContext) -> Option { ... // check if a `const` variable declaration if parent.is_const() { // Check if variable name is `foo` if node.id().ok()?.text() == "foo" { } } None }
Biome implementation fn run(ctx: &RuleContext) -> Option { ... // check if a `const` variable declaration if parent.is_const() { // Check if variable name is `foo` if node.id().ok()?.text() == "foo" { // Check if value of variable is "bar" let init_exp = node.initializer()?.expression().ok()?; let literal_exp = init_exp.as_any_js_literal_expression()?; if literal_exp.as_static_value()?.text() != "bar" { // Report error to Biome // The details of error message is implemented by "diagnostic" method return Some(()); } } } None }
References biomejs.dev Announcing Biome Announcing Rome v10 Rowan Syntax in rust-analyzer Rome will be written in Rust 🦀 Rust Dublin October 2023 - Biome
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