print awaits

Author: bakkot

src/coderep.js

@@ -120,6 +120,7 @@ export function getPrecedence(node) {
       return node.arguments.length === 0 ? Precedence.New : Precedence.Member;
     case 'UpdateExpression':
       return node.isPrefix ? Precedence.Prefix : Precedence.Postfix;
+    case 'AwaitExpression':
     case 'UnaryExpression':
       return Precedence.Prefix;
     default:

src/formatted-codegen.js

@@ -43,6 +43,7 @@ const separatorNames = [
   'ARRAY_BEFORE_COMMA',
   'ARRAY_AFTER_COMMA',
   'SPREAD',
+  'AWAIT',
   'BEFORE_DEFAULT_EQUALS',
   'AFTER_DEFAULT_EQUALS',
   'REST',
@@ -421,6 +422,10 @@ export class ExtensibleCodeGen {
     return this.bracket(content, Sep.ARRAY_INITIAL, Sep.ARRAY_FINAL);
   }
 
+  reduceAwaitExpression(node, { expression }) {
+    return seq(this.t('await'), this.sep(Sep.AWAIT), this.p(node.expression, getPrecedence(node), expression));
+  }
+
   reduceSpreadElement(node, { expression }) {
     return seq(this.t('...'), this.sep(Sep.SPREAD), this.p(node.expression, Precedence.Assignment, expression));
   }
@@ -1190,6 +1195,7 @@ export class FormattedCodeGen extends ExtensibleCodeGen {
 
   sep(separator) {
     switch (separator.type) {
+      case 'AWAIT':
       case 'ARRAY_AFTER_COMMA':
       case 'OBJECT_AFTER_COMMA':
       case 'ARGS_AFTER_COMMA':

src/minimal-codegen.js

@@ -82,6 +82,10 @@ export default class MinimalCodeGen {
     return bracket(content);
   }
 
+  reduceAwaitExpression(node, { expression }) {
+    return seq(t('await'), p(node.expression, getPrecedence(node), expression));
+  }
+
   reduceSpreadElement(node, { expression }) {
     return seq(t('...'), p(node.expression, Precedence.Assignment, expression));
   }

test/simple.js

@@ -241,6 +241,11 @@ describe('Code generator', () => {
       testModule('({async a(){}})');
     });
 
+    it('AwaitExpression', () => {
+      testModule('async function f(){await 0}');
+      testModule('async function f(){await(a+b)}');
+    });
+
     it('ArrayAssignmentTarget', () => {
       testModule('[]=0');
       testModule('[...a]=0');