added: initial pure implementation

riot.d.ts

@@ -22,6 +22,18 @@ export interface RiotCoreComponent<P = object, S = object> {
   $$(selector: string): [HTMLElement]
 }
 
+// Riot Pure Component interface that should be used together with riot.pure
+export interface RiotPureComponent<C = object> {
+  mount(
+    element: HTMLElement,
+    context?: C,
+  ): any
+  update(
+    context?: C,
+  ): any
+  unmount(keepRootElement: boolean): any
+}
+
 // This object interface is created anytime a riot file will be compiled into javascript
 export interface RiotComponentShell<P = object, S = object> {
   readonly css?: string
@@ -72,4 +84,7 @@ export function component<P , S>(shell: RiotComponentShell<P, S>):(
   initialProps?: P,
   meta?: { slots: any[]; attributes: any[]; }
 ) => RiotComponent<P, S>
+export function pure<
+  C = object,
+  F = ({ slots?: any[]; attributes?: any[]; props?: C; }) => RiotPureComponent<C>>(func: F): F
 export const version: string

src/core/component.js

@@ -2,6 +2,7 @@ import {
   ATTRIBUTES_KEY_SYMBOL,
   COMPONENTS_IMPLEMENTATION_MAP,
   DOM_COMPONENT_INSTANCE_PROPERTY,
+  IS_PURE_SYMBOL,
   PARENT_KEY_SYMBOL,
   PLUGINS_SET,
   TEMPLATE_KEY_SYMBOL
@@ -39,6 +40,12 @@ const COMPONENT_CORE_HELPERS = Object.freeze({
   $$(selector){ return $(selector, this.root) }
 })
 
+const PURE_COMPONENT_API = Object.freeze({
+  update: noop,
+  mount: noop,
+  unmount: noop
+})
+
 const COMPONENT_LIFECYCLE_METHODS = Object.freeze({
   shouldUpdate: noop,
   onBeforeMount: noop,
@@ -50,9 +57,7 @@ const COMPONENT_LIFECYCLE_METHODS = Object.freeze({
 })
 
 const MOCKED_TEMPLATE_INTERFACE = {
-  update: noop,
-  mount: noop,
-  unmount: noop,
+  ...PURE_COMPONENT_API,
   clone: noop,
   createDOM: noop
 }
@@ -89,6 +94,13 @@ export function createComponent({css, template, exports, name}) {
   ) : MOCKED_TEMPLATE_INTERFACE
 
   return ({slots, attributes, props}) => {
+    // pure components rendering will be managed by the end user
+    if (exports && exports[IS_PURE_SYMBOL])
+      return defineDefaults(
+        exports({ slots, attributes, props }),
+        PURE_COMPONENT_API
+      )
+
     const componentAPI = callOrAssign(exports) || {}
 
     const component = defineComponent({

src/globals.js

@@ -4,6 +4,7 @@ export const
   PLUGINS_SET = new Set(),
   IS_DIRECTIVE = 'is',
   VALUE_ATTRIBUTE = 'value',
+  IS_PURE_SYMBOL = Symbol.for('pure'),
   PARENT_KEY_SYMBOL = Symbol('parent'),
   ATTRIBUTES_KEY_SYMBOL = Symbol('attributes'),
   TEMPLATE_KEY_SYMBOL = Symbol('template')

src/riot.js

@@ -106,6 +106,17 @@ export function component(implementation) {
   )(implementation)
 }
 
+/**
+ * Lift a riot component Interface into a pure riot object
+ * @param   {Function} func - RiotPureComponent factory function
+ * @returns {Function} the lifted original function received as argument
+ */
+export function pure(func) {
+  if (!isFunction(func)) panic('riot.pure accepts only arguments of type "function"')
+  func[globals.IS_PURE_SYMBOL] = true
+  return func
+}
+
 /** @type {string} current riot version */
 export const version = 'WIP'
 

test/specs/compiler.spec.js

@@ -12,6 +12,7 @@ describe('Riot compiler api', () => {
       'install',
       'uninstall',
       'component',
+      'pure',
       'version',
       '__',
       // compiler API

test/specs/core.spec.js

@@ -42,6 +42,7 @@ describe('Riot core api', () => {
       'install',
       'uninstall',
       'component',
+      'pure',
       'version',
       '__'
     ])