From d692a8f512522832b086ba7614147b72874c7620 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Juno=20Su=C3=A1rez?= <juno@scroll.com>
Date: Mon, 5 Oct 2020 15:37:30 -0700
Subject: [PATCH] Implement ChainExpression type and update MemberExpression

---
 src/values/expressions/ChainExpression.js  | 12 ++++++++++++
 src/values/expressions/MemberExpression.js |  6 ++++--
 src/values/expressions/index.js            |  2 ++
 3 files changed, 18 insertions(+), 2 deletions(-)
 create mode 100644 src/values/expressions/ChainExpression.js

diff --git a/src/values/expressions/ChainExpression.js b/src/values/expressions/ChainExpression.js
new file mode 100644
index 0000000..abe2b25
--- /dev/null
+++ b/src/values/expressions/ChainExpression.js
@@ -0,0 +1,12 @@
+/**
+ * Extractor function for a ChainExpression type value node.
+ * A member expression is accessing a property on an object `obj.property`.
+ *
+ * @param - value - AST Value object with type `ChainExpression`
+ * @returns - The extracted value converted to correct type
+ */
+export default function extractValueFromChainExpression(value) {
+  // eslint-disable-next-line global-require
+  const getValue = require('./index.js').default;
+  return getValue(value.expression);
+}
diff --git a/src/values/expressions/MemberExpression.js b/src/values/expressions/MemberExpression.js
index 38e31fe..1c7d933 100644
--- a/src/values/expressions/MemberExpression.js
+++ b/src/values/expressions/MemberExpression.js
@@ -4,10 +4,12 @@
  *
  * @param - value - AST Value object with type `MemberExpression`
  * @returns - The extracted value converted to correct type
- *  and maintaing `obj.property` convention.
+ *  and maintaing `obj.property` convention,
+ * or `obj?.property` if it occurs in a `ChainExpression`.
  */
 export default function extractValueFromMemberExpression(value) {
   // eslint-disable-next-line global-require
   const getValue = require('./index.js').default;
-  return `${getValue(value.object)}.${getValue(value.property)}`;
+  const separator = value.optional ? '?.' : '.';
+  return `${getValue(value.object)}${separator}${getValue(value.property)}`;
 }
diff --git a/src/values/expressions/index.js b/src/values/expressions/index.js
index d0cc0e3..fe255ee 100644
--- a/src/values/expressions/index.js
+++ b/src/values/expressions/index.js
@@ -6,6 +6,7 @@ import TemplateLiteral from './TemplateLiteral';
 import FunctionExpression from './FunctionExpression';
 import LogicalExpression from './LogicalExpression';
 import MemberExpression from './MemberExpression';
+import ChainExpression from './ChainExpression';
 import OptionalCallExpression from './OptionalCallExpression';
 import OptionalMemberExpression from './OptionalMemberExpression';
 import CallExpression from './CallExpression';
@@ -32,6 +33,7 @@ const TYPES = {
   FunctionExpression,
   LogicalExpression,
   MemberExpression,
+  ChainExpression,
   OptionalCallExpression,
   OptionalMemberExpression,
   CallExpression,