feat: support defineExpose (#40)

Author: chearon

src/core/macros.ts

@@ -40,6 +40,7 @@ export function applyMacros(nodes: Statement[]) {
   | TSInterfaceBody
   | undefined
   let emitsTypeDeclRaw: Node | undefined
+  let exposeDecl: CallExpression['arguments'][number] | undefined
 
   // props/emits declared via types
   const typeDeclaredProps: Record<string, PropTypeData> = {}
@@ -190,9 +191,18 @@ export function applyMacros(nodes: Statement[]) {
   }
 
   function processDefineExpose(node: Node): boolean {
-    if (isCallOf(node, DEFINE_EXPOSE))
-      error(`Vue 2 does not support ${DEFINE_EXPOSE}()`, node)
-    return false
+    if (!isCallOf(node, DEFINE_EXPOSE))
+      return false
+
+    if (exposeDecl)
+      error(`duplicate ${DEFINE_EXPOSE}() call`, node)
+
+    if (node.arguments.length !== 1)
+      error(`${DEFINE_EXPOSE}() requires one argument`, node)
+
+    exposeDecl = node.arguments[0]
+
+    return true
   }
 
   function genRuntimeProps(props: Record<string, PropTypeData>) {
@@ -285,6 +295,7 @@ export function applyMacros(nodes: Statement[]) {
   return {
     nodes,
     props: getProps(),
+    expose: exposeDecl,
   }
 }
 

src/core/transformScriptSetup.ts

@@ -10,7 +10,7 @@ import { getIdentifierDeclarations } from './identifiers'
 export function transformScriptSetup(sfc: ParsedSFC, options?: ScriptSetupTransformOptions) {
   const { scriptSetup, script, template } = sfc
 
-  const { nodes: body, props } = applyMacros(scriptSetup.ast.body)
+  const { nodes: body, props, expose } = applyMacros(scriptSetup.ast.body)
 
   const [hoisted, setupBody] = partition(
     body,
@@ -25,9 +25,14 @@ export function transformScriptSetup(sfc: ParsedSFC, options?: ScriptSetupTransf
   getIdentifierDeclarations(setupBody, declarations)
 
   // filter out identifiers that are used in `<template>`
-  const returns = Array.from(declarations)
+  const returns: t.ObjectExpression['properties'] = Array.from(declarations)
     .filter(Boolean)
     .filter(i => template.identifiers.has(i))
+    .map((i) => {
+      const id = t.identifier(i)
+      return t.objectProperty(id, id, false, true)
+    })
+
   const components = Array.from(declarations)
     .filter(Boolean)
     .filter(i => template.components.has(i)
@@ -92,14 +97,13 @@ export function transformScriptSetup(sfc: ParsedSFC, options?: ScriptSetupTransf
   // `__sfc_main.setup = () => {}`
   if (body.length) {
     hasBody = true
-    const returnStatement = t.returnStatement(
-      t.objectExpression(
-        returns.map((i) => {
-          const id = t.identifier(i)
-          return t.objectProperty(id, id, false, true)
-        }),
-      ),
-    )
+    const returnExpr = expose
+      ? t.callExpression(
+        t.memberExpression(t.identifier('Object'), t.identifier('assign')),
+        [t.objectExpression(returns), expose],
+      )
+      : t.objectExpression(returns)
+    const returnStatement = t.returnStatement(returnExpr)
 
     ast.body.push(
       t.expressionStatement(

test/__snapshots__/transform.test.ts.snap

@@ -215,6 +215,29 @@ export default __sfc_main;
 "
 `;
 
+exports[`transform fixtures test/fixtures/MacrosDefineExpose.vue 1`] = `
+"<template>
+  <div>{{a}}</div>
+</template>
+
+<script lang=\\"js\\">
+const __sfc_main = {};
+
+__sfc_main.setup = (__props, __ctx) => {
+  const a = ref(1);
+  const b = 1;
+  return Object.assign({
+    a
+  }, {
+    b
+  });
+};
+
+export default __sfc_main;
+</script>
+"
+`;
+
 exports[`transform fixtures test/fixtures/MacrosPure.vue 1`] = `
 "<template>
   <div>{{ msg }}</div>

test/fixtures/MacrosDefineExpose.vue

@@ -0,0 +1,9 @@
+<template>
+  <div>{{a}}</div>
+</template>
+
+<script setup lang="js">
+const a = ref(1);
+const b = 1;
+defineExpose({b});
+</script>