From 8c3ef44ae6d273562f6e03cb890726d2cc02f9b2 Mon Sep 17 00:00:00 2001
From: David Bonnet <david@bonnet.cc>
Date: Sat, 2 Jan 2021 11:34:50 +0100
Subject: [PATCH] feat: add optional chaining support

Closes #424
---
 package-lock.json                   |  2 +-
 package.json                        |  4 ++--
 src/astring.js                      | 16 +++++++++++++++-
 src/tests/fixtures/syntax/object.js |  1 +
 4 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/package-lock.json b/package-lock.json
index 6abe5809..612fe4c7 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,6 +1,6 @@
 {
   "name": "astring",
-  "version": "1.4.3",
+  "version": "1.4.4",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {
diff --git a/package.json b/package.json
index 7438b29d..6ba03c3f 100644
--- a/package.json
+++ b/package.json
@@ -1,11 +1,11 @@
 {
   "name": "astring",
-  "version": "1.4.3",
+  "version": "1.4.4",
   "description": "JavaScript code generator from an ESTree-compliant AST.",
   "main": "./dist/astring.js",
   "module": "./src/astring.js",
   "bin": {
-    "astring": "./bin/astring"
+    "astring": "bin/astring"
   },
   "scripts": {
     "build": "babel src/astring.js --out-file dist/astring.js --source-maps --no-comments",
diff --git a/src/astring.js b/src/astring.js
index f5d68374..9fa75832 100644
--- a/src/astring.js
+++ b/src/astring.js
@@ -68,6 +68,7 @@ const EXPRESSIONS_PRECEDENCE = {
   SequenceExpression: 20,
   // Operations
   MemberExpression: 19,
+  ChainExpression: 19,
   CallExpression: 19,
   NewExpression: 19,
   // Other definitions
@@ -918,8 +919,14 @@ export const baseGenerator = {
     } else {
       this[node.callee.type](node.callee, state)
     }
+    if (node.optional) {
+      state.write('?.')
+    }
     formatSequence(state, node['arguments'])
   },
+  ChainExpression(node, state) {
+    this[node.expression.type](node.expression, state)
+  },
   MemberExpression(node, state) {
     if (
       EXPRESSIONS_PRECEDENCE[node.object.type] <
@@ -932,11 +939,18 @@ export const baseGenerator = {
       this[node.object.type](node.object, state)
     }
     if (node.computed) {
+      if (node.optional) {
+        state.write('?.')
+      }
       state.write('[')
       this[node.property.type](node.property, state)
       state.write(']')
     } else {
-      state.write('.')
+      if (node.optional) {
+        state.write('?.')
+      } else {
+        state.write('.')
+      }
       this[node.property.type](node.property, state)
     }
   },
diff --git a/src/tests/fixtures/syntax/object.js b/src/tests/fixtures/syntax/object.js
index 017db9b8..c1c6731a 100644
--- a/src/tests/fixtures/syntax/object.js
+++ b/src/tests/fixtures/syntax/object.js
@@ -27,3 +27,4 @@ let i = {
   ...d,
   a
 };
+a?.['b']?.[0]?.(1);