Create docs

docs/05-plugin-development.md

@@ -102,7 +102,7 @@ Notifies a plugin when watcher process closes and all open resources should be c
 
 #### `load`
 
-**Type:** `(id: string) => string | null | {code: string, map?: string | SourceMap, ast? : ESTree.Program, moduleSideEffects?: boolean | "no-treeshake" | null, syntheticNamedExports?: boolean | string | null, meta?: {[plugin: string]: any} | null}`<br> **Kind:** `async, first`<br> **Previous Hook:** [`resolveId`](guide/en/#resolveid) or [`resolveDynamicImport`](guide/en/#resolvedynamicimport) where the loaded id was resolved. Additionally, this hook can be triggered at any time from plugin hooks by calling [`this.load`](guide/en/#thisload) to preload the module corresponding to an id.<br> **Next Hook:** [`transform`](guide/en/#transform) to transform the loaded file.
+**Type:** `(id: string) => string | null | {code: string, map?: string | SourceMap, ast? : ESTree.Program, moduleSideEffects?: boolean | "no-treeshake" | null, syntheticNamedExports?: boolean | string | null, meta?: {[plugin: string]: any} | null}`<br> **Kind:** `async, first`<br> **Previous Hook:** [`resolveId`](guide/en/#resolveid) or [`resolveDynamicImport`](guide/en/#resolvedynamicimport) where the loaded id was resolved. Additionally, this hook can be triggered at any time from plugin hooks by calling [`this.load`](guide/en/#thisload) to preload the module corresponding to an id.<br> **Next Hook:** [`transform`](guide/en/#transform) to transform the loaded file if no cache was used, or there was no cached copy with the same `code`, otherwise [`shouldTransformCachedModule`](guide/en/#shouldtransformcachedmodule).
 
 Defines a custom loader. Returning `null` defers to other `load` functions (and eventually the default behavior of loading from the file system). To prevent additional parsing overhead in case e.g. this hook already used `this.parse` to generate an AST for some reason, this hook can optionally return a `{ code, ast, map }` object. The `ast` must be a standard ESTree AST with `start` and `end` properties for each node. If the transformation does not move code, you can preserve existing sourcemaps by setting `map` to `null`. Otherwise you might need to generate the source map. See [the section on source code transformations](#source-code-transformations).
 
@@ -222,9 +222,19 @@ Note that while `resolveId` will be called for each import of a module and can t
 
 When triggering this hook from a plugin via [`this.resolve`](guide/en/#thisresolve), it is possible to pass a custom options object to this hook. While this object will be passed unmodified, plugins should follow the convention of adding a `custom` property with an object where the keys correspond to the names of the plugins that the options are intended for. For details see [custom resolver options](guide/en/#custom-resolver-options).
 
+#### `shouldTransformCachedModule`
+
+**Type:** `({id: string, code: string, ast: ESTree.Program, meta: {[plugin: string]: any}, moduleSideEffects: boolean | "no-treeshake", syntheticNamedExports: string | boolean}) => boolean`<br> **Kind:** `sync, first`<br> **Previous Hook:** [`load`](guide/en/#load) where the cached file was loaded to compare its code with the cached version.<br> NextHook: [`moduleParsed`](guide/en/#moduleparsed) if no plugin returns `true`, otherwise [`transform`](guide/en/#transform).
+
+If Rollup cache is used (e.g. in watch mode or explicitly via the JavaScript API), Rollup will usually skip the transform hook of a module if after the load hook, the loaded `code` is identical to the code of the cached copy. To prevent this and instead transform a module, plugins can implement this hook and return `true`.
+
+This hook can also be used to find out which modules were cached and access their cached meta information.
+
+If a plugin does not return `true`, Rollup will trigger this hook for other plugins, otherwise all other plugins will be skipped.
+
 #### `transform`
 
-**Type:** `(code: string, id: string) => string | null | {code?: string, map?: string | SourceMap, ast? : ESTree.Program, moduleSideEffects?: boolean | "no-treeshake" | null, syntheticNamedExports?: boolean | string | null, meta?: {[plugin: string]: any} | null}`<br> **Kind:** `async, sequential`<br> **Previous Hook:** [`load`](guide/en/#load) where the currently handled file was loaded.<br> NextHook: [`moduleParsed`](guide/en/#moduleparsed) once the file has been processed and parsed.
+**Type:** `(code: string, id: string) => string | null | {code?: string, map?: string | SourceMap, ast? : ESTree.Program, moduleSideEffects?: boolean | "no-treeshake" | null, syntheticNamedExports?: boolean | string | null, meta?: {[plugin: string]: any} | null}`<br> **Kind:** `async, sequential`<br> **Previous Hook:** [`load`](guide/en/#load) where the currently handled file was loaded. If caching is used and there was a cached copy of that module, [`shouldTransformCachedModule`](guide/en/#shouldtransformcachedmodule) if a plugin returned `true` for that hook.<br> NextHook: [`moduleParsed`](guide/en/#moduleparsed) once the file has been processed and parsed.
 
 Can be used to transform individual modules. To prevent additional parsing overhead in case e.g. this hook already used `this.parse` to generate an AST for some reason, this hook can optionally return a `{ code, ast, map }` object. The `ast` must be a standard ESTree AST with `start` and `end` properties for each node. If the transformation does not move code, you can preserve existing sourcemaps by setting `map` to `null`. Otherwise you might need to generate the source map. See [the section on source code transformations](#source-code-transformations).
 

docs/build-hooks.mmd

@@ -3,6 +3,7 @@ flowchart TB
     classDef hook-sequential fill:#ffd2b3,stroke:#000;
     classDef hook-first fill:#fff2b3,stroke:#000;
     classDef hook-sequential-sync fill:#ffd2b3,stroke:#f00;
+    classDef hook-first-sync fill:#fff2b3,stroke:#f00;
 
 	buildend("buildEnd"):::hook-parallel
 	click buildend "/guide/en/#buildend" _parent
@@ -25,6 +26,9 @@ flowchart TB
 	resolveid("resolveId"):::hook-first
 	click resolveid "/guide/en/#resolveid" _parent
 
+	shouldtransformcachedmodule("shouldTransformCachedModule"):::hook-sequential-sync
+	click shouldtransformcachedmodule "/guide/en/#shouldtransformcachedmodule" _parent
+
 	transform("transform"):::hook-sequential
 	click transform "/guide/en/#transform" _parent
 
@@ -41,10 +45,17 @@ flowchart TB
 
     resolveid
     --> |non-external|load
-    --> transform
+    --> |not cached|transform
     --> moduleparsed
     .-> |no imports|buildend
 
+    load
+    --> |cached|shouldtransformcachedmodule
+    --> |false|moduleparsed
+
+    shouldtransformcachedmodule
+    --> |true|transform
+
     moduleparsed
     --> |"each import()"|resolvedynamicimport
     --> |non-external|load