diff --git a/.oxlintrc.json b/.oxlintrc.json index e0bae8b..31a9152 100644 --- a/.oxlintrc.json +++ b/.oxlintrc.json @@ -34,7 +34,9 @@ "no-unused-expressions": "off", "no-empty-file": "off", "import/no-nodejs-modules": "off", - "eslint/no-magic-numbers": "off" + "eslint/no-magic-numbers": "off", + "unicorn/no-null": "off", + "typescript/no-floating-promises": "off" } }, { diff --git a/AGENTS.md b/AGENTS.md index 89d3d4e..3dadddd 100644 --- a/AGENTS.md +++ b/AGENTS.md @@ -25,10 +25,11 @@ first-action facts. Do not restate evolving prose here — it will drift. Don't silence the type system to force a green run. As an agent these are forbidden: - `// @ts-nocheck`, `// @ts-ignore`, `// @ts-expect-error` -- `// oxlint-disable` / `// oxlint-disable-next-line` — the sole exception is the fixed file-level `typescript/no-floating-promises` header at the top of a `*.test.ts` file, spelled exactly as [CONTRIBUTING.md § Rules the tools don't enforce](./CONTRIBUTING.md#rules-the-tools-dont-enforce) prescribes +- `// oxlint-disable` / `// oxlint-disable-next-line` +- editing `.oxlintrc.json` to silence a finding (e.g. turning `typescript/no-floating-promises` off) - `as` casts used to push an expression through (type-aware oxlint already flags unsafe assertions) -Fix the root cause with the type system instead — narrowing, generics, `satisfies`, conditional / mapped types, utility types (`NonNullable`, `Exclude`, …). TypeScript can express it; that's the intended tool. The `oxlint-disable`-location rule in [CONTRIBUTING.md § Rules the tools don't enforce](./CONTRIBUTING.md#rules-the-tools-dont-enforce) is a **human** last-resort convention (so a reviewer can spot a deliberate suppression) — it is not permission for you to add one, except the one fixed `*.test.ts` file-level header named there. If the types genuinely cannot express something, stop and surface the conflict (commit message / handover) rather than suppress it. +Fix the root cause with the type system instead — narrowing, generics, `satisfies`, conditional / mapped types, utility types (`NonNullable`, `Exclude`, …). TypeScript can express it; that's the intended tool. Suppressions — a source `oxlint-disable` **or** a `.oxlintrc.json` entry — are a **human** last resort, not a tool for you. If the types genuinely cannot express something, stop and surface the conflict (commit message / handover) rather than suppress it. The same applies to the checks themselves: **never `git commit --no-verify`** (or otherwise skip a pre-commit / pre-push hook). The checks are fast and offline, so a redundant run is fine — bypassing a hook to get green is the identical anti-pattern. If a commit already skipped a hook, redo it through one: `git reset --soft HEAD~1 && git commit -C `. diff --git a/CHANGELOG.md b/CHANGELOG.md index fc485b4..2ae113d 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -8,6 +8,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0 ## [Unreleased] - reject a fallback when the handler map already covers the universe +- allow boolean, null and undefined in the matcher universe ## [0.4.0] - 2026-09-20 diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md index c9a882c..52c1928 100644 --- a/CONTRIBUTING.md +++ b/CONTRIBUTING.md @@ -155,12 +155,9 @@ reaches for by default: [Script prefix convention](#script-prefix-convention). - **`oxlint-disable` directives live in source, not `.oxlintrc.json`.** The trade-off must sit next to the code it silences. This is a _human_ last-resort - convention; agents must not add these — see - [AGENTS.md § Never do](./AGENTS.md#never-do). The sole agent exception is the - fixed file-level header at the top of a `*.test.ts` file, spelled exactly: - `/* oxlint-disable typescript/no-floating-promises -- expectTypeOf() is a sync -type-assertion library that the type-aware linter misidentifies as a promise -*/` — any other suppression stays human-last-resort. (why: + convention; agents must not add one, nor edit `.oxlintrc.json` to silence a + finding (e.g. `typescript/no-floating-promises`) — see + [AGENTS.md § Never do](./AGENTS.md#never-do). (why: [development/tooling.md](./development/tooling.md#oxlint-disable-directives-live-next-to-the-code)) - **Don't put slow / network / whole-project scans in `check` or pre-commit.** Advisory scans are not correctness gates; they belong under `maintain:`. (why: diff --git a/README.md b/README.md index 5e86b41..f6b20e4 100644 --- a/README.md +++ b/README.md @@ -9,7 +9,7 @@ ordinary objects whose `matches` method is a TypeScript type guard, so narrowing composes the way any other guard does. It is deliberately not a regex engine and not a macro: there is no transpiler and no DSL to learn, and the type-level contract is the feature — see [development/library.md](./development/library.md) -for the design decisions and the known limitations. +for the design decisions and [Caveats](#caveats) for the limits. ## Requirements @@ -23,6 +23,18 @@ for the design decisions and the known limitations. Yet to be implemented +## Caveats + +- **A value and its stringification collide.** Object keys stringify, so a + universe that mixes a member with the string it stringifies to — `1 | "1"`, + `true | "true"`, `null | "null"` — collapses to a single handler key and both + members are routed to it. Use one form or the other. +- **`symbol` and `bigint` are not supported.** A `symbol` brand is a + compile-time phantom with nothing to match at runtime, and a `bigint` is not a + valid property key; neither satisfies the matcher's universe constraint. +- **`NaN` and `-0` cannot be matched specifically.** They have no literal type, + so both stay part of `number`. + ## License MIT © 2025 tmu. See [LICENSE](./LICENSE). diff --git a/backlog.tasks b/backlog.tasks index e409cd7..e17212f 100644 --- a/backlog.tasks +++ b/backlog.tasks @@ -52,8 +52,9 @@ Bugs: → `handleExit` returns `io.EOF`, cancelling the background context while `Session.updateWatches` is still in flight; the bare error is flushed to stderr and the server exits 1 → close stdin after `shutdown` instead of sending `exit`; the server exits cleanly (code 0, no output), kill kept as a fallback Enhancements: -☐ Allow boolean literals in primitive union patterns (e.g. `true: () => "yes"`) @medium -☐ Are there other primitive types that should be supported in union patterns? (e.g. `bigint`, `symbol`) @medium +✔ Allow boolean literals in primitive union patterns (e.g. `true: () => "yes"`) @medium @done + ✔ Are there other primitive types that should be supported in union patterns? (e.g. `bigint`, `symbol`) @medium @done + → added boolean, null and undefined; rejected `symbol` (compile-time brand, nothing at runtime) and `bigint` (not a property key) Documentation: ☐ Bring README.md back to its previous form — synopsis and examples restored, in the correct place diff --git a/development/library.md b/development/library.md index f8650b9..7c6b5fe 100644 --- a/development/library.md +++ b/development/library.md @@ -91,3 +91,26 @@ Each factory is two overloads whose order is load-bearing: - `Parameters[0]` resolves only the **last** overload, so it is not a sound "rejected" oracle for a factory. Factory-negative tests use `@ts-expect-error` call sites (the test file only — the general ban stands). + +## Primitive universe + +#### Decision (2026-09) + +The universe (`Matchable`) is `string | number | boolean | null | undefined`, +with `boolean` admitted as `true | false`. + +`boolean`/`null`/`undefined` are not property keys, so handler-map keys are a +projection (`PatternKey`: each member stringified) and `PatternParam` inverts +it, so callbacks receive the real member (`true`, not `"true"`). The popup +offers `true`, `false`, `null`, `undefined` by name (verified over LSP). + +#### Why + +- Runtime dispatch indexes with the raw `shape`; `handlers[true]` coerces to + `"true"` at runtime exactly as `String` would. The `shape as string | number` + assertion only placates `TS2538` and buys the number fast path (an explicit + `String()` defeats V8's numeric-key path: measured ~2× on number-keyed + dispatch). +- `symbol`/`bigint`/`NaN`/`-0` are rejected, and a member colliding with its + stringification is unguarded: user-facing, stated once in + [README § Caveats](../README.md#caveats). diff --git a/development/testing.md b/development/testing.md index edcd407..0a2926f 100644 --- a/development/testing.md +++ b/development/testing.md @@ -167,8 +167,8 @@ the CLI is for manual inspection. ## Known issues -- The type-aware linter misidentifies `expectTypeOf()` as a floating promise, so - test files that use it (`src/primitive.test.ts`) carry a file-level - `oxlint-disable typescript/no-floating-promises` with an explanatory comment. - It is a known false positive, not a rule worth disabling project-wide (see +- The type-aware linter misidentifies `expectTypeOf()` as a floating promise. + It is a known false positive, so `typescript/no-floating-promises` is off for + `**/*.test.ts` in the `.oxlintrc.json` override rather than repeated as a + file-level header (see [tooling.md § oxlint-disable directives live next to the code](./tooling.md#oxlint-disable-directives-live-next-to-the-code)). diff --git a/development/tooling.md b/development/tooling.md index 53d3637..7bc39bd 100644 --- a/development/tooling.md +++ b/development/tooling.md @@ -106,26 +106,34 @@ Type-aware oxlint is enabled via `options.typeAware: true` in `.oxlintrc.json` #### Decision (2026-09) -A type-aware rule that false-positives is silenced with a source-level -`oxlint-disable` directive (see `src/primitive.ts`, -`src/primitive.test.ts`), not by turning the rule off in `.oxlintrc.json`. +A type-aware rule that false-positives **at one site** is silenced with a +source-level `oxlint-disable` directive (see `src/primitive.ts`). A rule that is +wrong for a whole **file class** is turned off in a `.oxlintrc.json` `overrides` +entry instead — e.g. `typescript/no-floating-promises` (synchronous +`expectTypeOf` reads as an unhandled promise) and `unicorn/no-null` (intentional +`null` inputs) for `**/*.test.ts`. The same exemption is not repeated as a +file-level header in every affected file. #### Why -- The disable sits next to the code it silences, visible to anyone reading the - source. -- The rule stays on everywhere else, so only the mis-firing line is exempted. +- A one-site disable sits next to the code it silences, visible to anyone + reading the source, and the rule stays on everywhere else. +- A file-class rule is a property of the file class, not of one line; the + override states it once, where the rest of the file-class config lives. #### Rejected -- A project-wide disable in `.oxlintrc.json` for a false positive: it hides the - exemption from the reader of the affected code and switches the rule off - repo-wide for a one-site problem. +- A project-wide disable in `.oxlintrc.json` for a one-site false positive: it + hides the exemption from the reader of the affected code and switches the rule + off repo-wide for a one-site problem. +- A repeated file-level `oxlint-disable` header for a file-class false positive: + the copies drift and scatter one config decision across the tree. #### Known issue -- A source-level disable is a _human_ last resort. AI agents must not add one; - they fix the type at its root (see [AGENTS.md § Never do](../AGENTS.md#never-do)). +- Both placements are _human_ last resorts. AI agents must neither add a source + disable nor edit `.oxlintrc.json`; they fix the type at its root (see + [AGENTS.md § Never do](../AGENTS.md#never-do)). ### Unwanted stylistic rules are turned off in the config diff --git a/src/primitive.test.ts b/src/primitive.test.ts index 2953883..7045094 100644 --- a/src/primitive.test.ts +++ b/src/primitive.test.ts @@ -1,4 +1,3 @@ -/* oxlint-disable typescript/no-floating-promises -- expectTypeOf() is a sync type-assertion library that the type-aware linter misidentifies as a promise */ import { strict as assert } from "node:assert"; import path from "node:path"; import { test } from "node:test"; @@ -95,6 +94,50 @@ test("getMatcher: dispatches on mixed string and numeric keys", () => { assert.equal(matcher(2), 20); }); +test("getMatcher: dispatches on boolean literals", () => { + // Arrange + const factory = getMatcher(); + + // Act + const matcher = factory({ + true: (s) => { + expectTypeOf(s).toEqualTypeOf(); + return 1; + }, + false: (s) => { + expectTypeOf(s).toEqualTypeOf(); + return 2; + }, + }); + + // Assert + expectTypeOf(matcher).toEqualTypeOf<(shape: boolean) => number>(); + assert.equal(matcher(true), 1); + assert.equal(matcher(false), 2); +}); + +test("getMatcher: dispatches on null and undefined", () => { + // Arrange + const factory = getMatcher(); + + // Act + const matcher = factory({ + null: (s) => { + expectTypeOf(s).toEqualTypeOf(); + return "null"; + }, + undefined: (s) => { + expectTypeOf(s).toEqualTypeOf(); + return "undefined"; + }, + }); + + // Assert + expectTypeOf(matcher).toEqualTypeOf<(shape: null | undefined) => string>(); + assert.equal(matcher(null), "null"); + assert.equal(matcher(undefined), "undefined"); +}); + // ============================================================================ // API: getMatcher — ❌ Exhaustive (fallback) / ✔️ ReturnsStrict // ============================================================================ @@ -157,6 +200,41 @@ test("getMatcher: a `_` fallback routes mixed string and numeric gaps", () => { assert.equal(matcher(2), "fallback"); }); +test("getMatcher: a `_` fallback receives unhandled boolean and nullish keys", () => { + // Arrange + const factory = getMatcher<"a" | true | false | null | undefined>(); + + // Act + const matcher = factory( + { + a: (s) => { + expectTypeOf(s).toEqualTypeOf<"a">(); + return 1 as const; + }, + null: (s) => { + expectTypeOf(s).toEqualTypeOf(); + return 2 as const; + }, + }, + (s) => { + // `true` and `false` are keyed as `"true"`/`"false"` but the + // fallback still sees them as booleans. + expectTypeOf(s).toEqualTypeOf(); + return 3 as const; + }, + ); + + // Assert + expectTypeOf(matcher).toEqualTypeOf< + (shape: "a" | true | false | null | undefined) => 1 | 2 | 3 + >(); + assert.equal(matcher("a"), 1); + assert.equal(matcher(true), 3); + assert.equal(matcher(false), 3); + assert.equal(matcher(null), 2); + assert.equal(matcher(undefined), 3); +}); + // ============================================================================ // API: getMatcherW — ✔️ Exhaustive / ❌ ReturnsStrict // ============================================================================ @@ -220,6 +298,40 @@ test("getMatcherW: dispatches on mixed string and numeric keys", () => { assert.equal(matcher(2), 20); }); +test("getMatcherW: exhaustive boolean and nullish widen to the union", () => { + // Arrange + const factory = getMatcherW(); + + // Act + const matcher = factory({ + true: (s) => { + expectTypeOf(s).toEqualTypeOf(); + return "yes" as const; + }, + false: (s) => { + expectTypeOf(s).toEqualTypeOf(); + return "no" as const; + }, + null: (s) => { + expectTypeOf(s).toEqualTypeOf(); + return 0 as const; + }, + undefined: (s) => { + expectTypeOf(s).toEqualTypeOf(); + return 1 as const; + }, + }); + + // Assert + expectTypeOf(matcher).toEqualTypeOf< + (shape: boolean | null | undefined) => "yes" | "no" | 0 | 1 + >(); + assert.equal(matcher(true), "yes"); + assert.equal(matcher(false), "no"); + assert.equal(matcher(null), 0); + assert.equal(matcher(undefined), 1); +}); + // ============================================================================ // API: getMatcherW — ❌ Exhaustive (fallback) / ❌ ReturnsStrict // ============================================================================ @@ -313,6 +425,27 @@ test("getMatcher factory rejects patterns outside its contract", () => { factory({ a: () => 1, b: () => 2 }, () => 0); }); +test("getMatcher factory rejects non-exhaustive boolean and nullish maps", () => { + // Arrange + const factory = getMatcher(); + + // Act / Assert — the calls below must not compile + // @ts-expect-error only `true` is handled; `false`, `null`, `undefined` are not + factory({ true: () => 1 }); + // @ts-expect-error `null` and `undefined` are not handled + factory({ true: () => 1, false: () => 2 }); + factory( + // @ts-expect-error a fallback is redundant once the map covers the universe + { + true: () => 1, + false: () => 2, + null: () => 3, + undefined: () => 4, + }, + () => 0, + ); +}); + test("getMatcher: an open universe keeps the fallback's remainder open", () => { // Arrange const factory = getMatcher(); @@ -363,6 +496,17 @@ test("getMatcher: an unhandled shape throws without a fallback", () => { assert.throws(() => matcher("b"), /Unhandled shape: b/); }); +test("getMatcher: an unhandled boolean shape throws without a fallback", () => { + // Arrange — an `string | boolean` universe widens its handler map to an + // index signature, so the runtime map's exhaustiveness is not provable. + const handlers: Record number> = { true: () => 1 }; + const matcher = getMatcher()(handlers); + + // Act / Assert + assert.equal(matcher(true), 1); + assert.throws(() => matcher(false), /Unhandled shape: false/); +}); + // ============================================================================ // Autocomplete — the language server is the oracle, not the type system // ============================================================================ @@ -381,6 +525,7 @@ interface LabelsProbe { readonly name: string; readonly factory: "getMatcher" | "getMatcherW"; readonly body: string; + readonly universe?: string; readonly tail?: string; } @@ -388,6 +533,7 @@ const labelsFor = ({ name, factory, body, + universe = UNIVERSE, tail = "", }: LabelsProbe): Promise => { const session = new LspSession(REPO_ROOT); @@ -395,7 +541,7 @@ const labelsFor = ({ file: `src/__autocomplete_${name}.ts`, source: [ `import { ${factory} } from "./index.ts";`, - `const m = ${factory}<${UNIVERSE}>()({`, + `const m = ${factory}<${universe}>()({`, body, `}${tail});`, "", @@ -511,3 +657,39 @@ test("autocomplete: `getMatcherW` also offers optional keys with a fallback", () assert.deepEqual([...result], ["a?", "b?", "c?"]); }); }); + +test("autocomplete: boolean and nullish keys are offered by name", () => { + // Arrange + const name = "getMatcher_boolean_nullish"; + + // Act + const labels = labelsFor({ + name, + factory: "getMatcher", + universe: "boolean | null | undefined", + body: " /*COMPLETE*/", + }); + + // Assert + return labels.then((result) => { + assert.deepEqual([...result], ["false", "null", "true", "undefined"]); + }); +}); + +test("autocomplete: a handled boolean literal drops out of the popup", () => { + // Arrange + const name = "getMatcher_boolean_after_key"; + + // Act + const labels = labelsFor({ + name, + factory: "getMatcher", + universe: "boolean | null | undefined", + body: " true: () => 1,\n /*COMPLETE*/", + }); + + // Assert + return labels.then((result) => { + assert.deepEqual([...result], ["false", "null", "undefined"]); + }); +}); diff --git a/src/primitive.ts b/src/primitive.ts index b23c5c3..7919d2c 100644 --- a/src/primitive.ts +++ b/src/primitive.ts @@ -2,13 +2,42 @@ import type { Exact, ValueOf } from "type-fest"; type UnaryFn = (shape: T) => R; +// The primitive universe a matcher can discriminate. `boolean` is admitted as +// the pair `true | false`; see README § Caveats for the unsupported members. +type Matchable = string | number | boolean | null | undefined; + +// `boolean`, `null` and `undefined` cannot be property keys, so a mapped type +// over the universe keys each non-key member by its stringification. `Param` +// inverts that projection, so a handler callback still receives the *real* +// member (`true`, not `"true"`) — see README § Caveats for the limits. +type PatternKey = T extends boolean + ? T extends true + ? "true" + : "false" + : T extends null + ? "null" + : T extends undefined + ? "undefined" + : T; +type PatternParam = K extends "true" + ? true + : K extends "false" + ? false + : K extends "null" + ? null + : K extends "undefined" + ? undefined + : K; + // `Extract` drops optional handlers (`undefined`) so `PatternReturns` also works // when `P`'s constraint has optional keys. type PatternReturns

= ReturnType< Extract, (...args: never[]) => unknown> >; -type Handlers = { [K in T]: UnaryFn }; +type Handlers = { + [K in PatternKey]: UnaryFn, R>; +}; // The fallback is a *second argument*, not a property of the handler map, // because its parameter is the remainder `Exclude` and TypeScript @@ -16,8 +45,8 @@ type Handlers = { [K in T]: UnaryFn }; // argument, by contrast, is contextually typed from inference on an earlier // one, so the split is what makes the remainder expressible at all. // See development/library.md. -type Fallback = UnaryFn< - Exclude, +type Fallback = UnaryFn< + Exclude>, R >; @@ -32,9 +61,8 @@ type Fallback = UnaryFn< interface RedundantFallback { readonly "every case is already handled, so the fallback is redundant": never; } -type MustBePartial = T extends keyof Handled - ? RedundantFallback - : unknown; +type MustBePartial = + PatternKey extends keyof Handled ? RedundantFallback : unknown; // TypeScript does not apply the excess-property check to a generic constraint, // so `Exact` restores it for the generic forms: a handler map can otherwise @@ -44,7 +72,7 @@ type MustBePartial = T extends keyof Handled // Strict returns: one common `R`. Overload order is load-bearing: // #1 Handlers (first) -> the exhaustive form and the autocomplete popup // #2 Fallback (last) -> accepts a partial handler map plus a fallback -interface MatcherStrict { +interface MatcherStrict { (handlers: Handlers): UnaryFn; < R, @@ -61,7 +89,7 @@ interface MatcherStrict { // from the whole handler map, whose closed constraint supplies the // contextual/autocomplete type. // oxlint-disable typescript/unified-signatures -interface MatcherWidening { +interface MatcherWidening {

, P>>( handlers: P, ): UnaryFn>; @@ -80,19 +108,27 @@ type HandlerMap = Record | undefined>; const dispatch = (handlers: HandlerMap, fallback?: UnaryFn) => - (shape: string | number): unknown => + (shape: Matchable): unknown => + // `handlers[true]` already coerces to the `"true"` property at runtime, + // identical to `handlers[String(shape)]`, so indexing with `shape` + // directly is sound: `shape` is a facade-checked universe member and + // `PatternKey` only ever produces valid property keys. The assertion is + // needed solely because TypeScript forbids indexing with + // `boolean`/`null`/`undefined` (TS2538); it buys the number fast path. ( - handlers[shape] ?? + handlers[ + // oxlint-disable-next-line typescript/no-unsafe-type-assertion + shape as string | number + ] ?? fallback ?? (() => { - throw new Error(`Unhandled shape: ${shape}`); + throw new Error(`Unhandled shape: ${String(shape)}`); }) )( // oxlint-disable-next-line typescript/no-unsafe-type-assertion shape as never, ); -export const getMatcher = (): MatcherStrict => - dispatch; -export const getMatcherW = (): MatcherWidening => +export const getMatcher = (): MatcherStrict => dispatch; +export const getMatcherW = (): MatcherWidening => dispatch; diff --git a/src/util/__tests__/lsp-completion.test.ts b/src/util/__tests__/lsp-completion.test.ts index c02f74e..f632a53 100644 --- a/src/util/__tests__/lsp-completion.test.ts +++ b/src/util/__tests__/lsp-completion.test.ts @@ -1,4 +1,3 @@ -/* oxlint-disable typescript/no-floating-promises -- expectTypeOf() is a sync type-assertion library that the type-aware linter misidentifies as a promise */ import { strict as assert } from "node:assert"; import path from "node:path"; import { test } from "node:test";