allow plugins to declare an interface for their settings (#58)

* allow plugins to declare an interface for their settings

* Adjust pluggable list to support different setting interfaces

* add example of implicitly typed plugin

* support a second generic settings parameter for plugins

types/index.d.ts

@@ -15,18 +15,33 @@ declare namespace unified {
      * Configure the processor to use a plugin and optionally configure that plugin with options.
      *
      * @param plugin unified plugin
-     * @param options Configuration for plugin]
+     * @param options Configuration for plugin
+     * @param extraOptions Additional configuration for plugin
      * @returns The processor on which use is invoked
      */
-    use(plugin: Plugin, options?: unknown): Processor
+    use<T = Settings, S = undefined>(
+      plugin: Plugin<T, S>,
+      options?: T,
+      extraOptions?: S
+    ): Processor
+
     /**
      * @param preset `Object` with an optional plugins (set to list), and/or an optional settings object
      */
     use(preset: Preset): Processor
+
     /**
      * @param pluginTuple pairs, plugin and options in an array
      */
-    use(pluginTuple: PluginTuple): Processor
+    use<T = Settings>(pluginTuple: PluginTuple<T>): Processor
+
+    /**
+     * @param pluginTriple plugin, options, and extraOptions in an array
+     */
+    use<T = Settings, S = undefined>(
+      pluginTriple: PluginTriple<T, S>
+    ): Processor
+
     /**
      * @param list List of plugins, presets, and pairs
      */
@@ -145,7 +160,7 @@ declare namespace unified {
     freeze(): Processor
   }
 
-  type Plugin = Attacher
+  type Plugin<T = Settings, S = undefined> = Attacher<T, S>
   type Settings = {
     [key: string]: unknown
   }
@@ -157,9 +172,14 @@ declare namespace unified {
     plugins?: PluggableList
     settings?: Settings
   }
-  type PluginTuple = [Plugin, Settings]
-  type Pluggable = Plugin | Preset | PluginTuple
-  type PluggableList = Pluggable[]
+  type PluginTuple<T = Settings> = [Plugin<T>, T]
+  type PluginTriple<T = Settings, S = undefined> = [Plugin<T, S>, T, S]
+  type Pluggable<T = Settings, S = undefined> =
+    | Plugin<T>
+    | Preset
+    | PluginTuple<T>
+    | PluginTriple<T, S>
+  type PluggableList = Array<Pluggable<any, any>>
 
   /**
    * An attacher is the thing passed to `use`.
@@ -169,10 +189,11 @@ declare namespace unified {
    *
    * @this Processor context object is set to the invoked on processor.
    * @param options Configuration
+   * @param extraOptions Secondary configuration
    * @returns Optional.
    */
-  interface Attacher {
-    (this: Processor, options?: unknown): Transformer | void
+  interface Attacher<T = Settings, S = undefined> {
+    (this: Processor, options?: T, extraOptions?: S): Transformer | void
   }
 
   /**

types/tslint.json

@@ -9,6 +9,7 @@
     "semicolon": false,
     "unified-signatures": false,
     "whitespace": false,
-    "interface-over-type-literal": false
+    "interface-over-type-literal": false,
+    "no-unnecessary-generics": false
   }
 }

types/unified-tests.ts

@@ -27,19 +27,97 @@ const settings = {
   random: 'option'
 }
 
+interface ExamplePluginSettings {
+  example: string
+}
+const typedPlugin: Plugin<ExamplePluginSettings> = function() {}
+const typedSetting = {example: 'example'}
+
+const implicitlyTypedPlugin = (settings?: ExamplePluginSettings) => {}
+
+const pluginWithTwoSettings = (
+  processor?: Processor,
+  settings?: ExamplePluginSettings
+) => {}
+
 processor.use(plugin)
 processor.use(plugin).use(plugin)
+processor.use(plugin, settings)
+processor.use([plugin, plugin])
+processor.use([plugin])
+processor.use([plugin, settings])
+processor.use([[plugin, settings], [plugin, settings]])
+
+processor.use(typedPlugin)
+processor.use(typedPlugin).use(typedPlugin)
+processor.use(typedPlugin, typedSetting)
+processor.use([typedPlugin, typedSetting])
+processor.use([[typedPlugin, typedSetting], [typedPlugin, typedSetting]])
+processor.use([[plugin, settings], [typedPlugin, typedSetting]])
+processor.use([typedPlugin])
+
+processor.use(implicitlyTypedPlugin)
+processor.use(implicitlyTypedPlugin).use(implicitlyTypedPlugin)
+processor.use(implicitlyTypedPlugin, typedSetting)
+processor.use([implicitlyTypedPlugin, typedSetting])
+processor.use([
+  [implicitlyTypedPlugin, typedSetting],
+  [implicitlyTypedPlugin, typedSetting]
+])
+processor.use([[plugin, settings], [implicitlyTypedPlugin, typedSetting]])
+processor.use([implicitlyTypedPlugin])
+
+// NOTE: settings overrides the generic undefined
+// settings value will be unused but TypeScript will not warn
+processor.use(implicitlyTypedPlugin, typedSetting, settings)
+processor.use([implicitlyTypedPlugin, typedSetting, settings])
+
+processor.use(pluginWithTwoSettings)
+processor.use(pluginWithTwoSettings).use(pluginWithTwoSettings)
+processor.use(pluginWithTwoSettings, processor, typedSetting)
+processor.use(pluginWithTwoSettings, processor)
+processor.use([pluginWithTwoSettings, processor, typedSetting])
+processor.use([pluginWithTwoSettings, processor])
+processor.use([
+  [pluginWithTwoSettings, processor, typedSetting],
+  [pluginWithTwoSettings, processor, typedSetting]
+])
+processor.use([
+  [plugin, settings],
+  [pluginWithTwoSettings, processor, typedSetting]
+])
+processor.use([pluginWithTwoSettings])
+
+// $ExpectError
+processor.use(typedPlugin, settings)
+// $ExpectError
+processor.use([typedPlugin, settings])
+// $ExpectError
+processor.use(typedPlugin, typedSetting, settings)
+// $ExpectError
+processor.use([typedPlugin, typedSetting, settings])
+
+// $ExpectError
+processor.use(implicitlyTypedPlugin, settings)
+// $ExpectError
+processor.use([implicitlyTypedPlugin, settings])
+
+// $ExpectError
+processor.use(pluginWithTwoSettings, typedSetting)
+// $ExpectError
+processor.use(pluginWithTwoSettings, typedSetting)
+
+// $ExpectError
+processor.use(pluginWithTwoSettings, processor, settings)
+// $ExpectError
+processor.use([pluginWithTwoSettings, processor, settings])
+
 // $ExpectError
 processor.use(false)
 // $ExpectError
 processor.use(true)
 // $ExpectError
 processor.use('alfred')
-processor.use(plugin, settings)
-processor.use([plugin, plugin])
-processor.use([plugin])
-processor.use([plugin, settings])
-processor.use([[plugin, settings], [plugin, settings]])
 // $ExpectError
 processor.use([false])
 // $ExpectError
@@ -54,6 +132,7 @@ processor.use({
   // $ExpectError
   plugins: {foo: true}
 })
+
 processor.use({})
 processor.use({
   plugins: []