From 6d82a2010997f6706c60b089e028d2552cbd5745 Mon Sep 17 00:00:00 2001
From: Andy <anhans@microsoft.com>
Date: Thu, 22 Mar 2018 09:32:05 -0700
Subject: [PATCH] Combine getLastChild helpers (#22418)

---
 src/compiler/parser.ts    | 16 +++-------------
 src/compiler/utilities.ts | 18 ++++++++++++++++++
 src/services/utilities.ts | 13 -------------
 3 files changed, 21 insertions(+), 26 deletions(-)

diff --git a/src/compiler/parser.ts b/src/compiler/parser.ts
index b22906540aa..12177f8545b 100644
--- a/src/compiler/parser.ts
+++ b/src/compiler/parser.ts
@@ -7243,7 +7243,7 @@ namespace ts {
             forEachChild(sourceFile, visit);
 
             if (lastNodeEntirelyBeforePosition) {
-                const lastChildOfLastEntireNodeBeforePosition = getLastChild(lastNodeEntirelyBeforePosition);
+                const lastChildOfLastEntireNodeBeforePosition = getLastDescendant(lastNodeEntirelyBeforePosition);
                 if (lastChildOfLastEntireNodeBeforePosition.pos > bestResult.pos) {
                     bestResult = lastChildOfLastEntireNodeBeforePosition;
                 }
@@ -7251,9 +7251,9 @@ namespace ts {
 
             return bestResult;
 
-            function getLastChild(node: Node): Node {
+            function getLastDescendant(node: Node): Node {
                 while (true) {
-                    const lastChild = getLastChildWorker(node);
+                    const lastChild = getLastChild(node);
                     if (lastChild) {
                         node = lastChild;
                     }
@@ -7263,16 +7263,6 @@ namespace ts {
                 }
             }
 
-            function getLastChildWorker(node: Node): Node | undefined {
-                let last: Node;
-                forEachChild(node, child => {
-                    if (nodeIsPresent(child)) {
-                        last = child;
-                    }
-                });
-                return last;
-            }
-
             function visit(child: Node) {
                 if (nodeIsMissing(child)) {
                     // Missing nodes are effectively invisible to us.  We never even consider them
diff --git a/src/compiler/utilities.ts b/src/compiler/utilities.ts
index 69249952166..236177ea6ff 100644
--- a/src/compiler/utilities.ts
+++ b/src/compiler/utilities.ts
@@ -3883,6 +3883,24 @@ namespace ts {
         return isStringLiteral(moduleSpecifier) ? moduleSpecifier.text : getTextOfNode(moduleSpecifier);
     }
 
+    export function getLastChild(node: Node): Node | undefined {
+        let lastChild: Node | undefined;
+        forEachChild(node,
+            child => {
+                if (nodeIsPresent(child)) lastChild = child;
+            },
+            children => {
+                // As an optimization, jump straight to the end of the list.
+                for (let i = children.length - 1; i >= 0; i--) {
+                    if (nodeIsPresent(children[i])) {
+                        lastChild = children[i];
+                        break;
+                    }
+                }
+            });
+        return lastChild;
+    }
+
     /** Add a value to a set, and return true if it wasn't already present. */
     export function addToSeen(seen: Map<true>, key: string | number): boolean {
         key = String(key);
diff --git a/src/services/utilities.ts b/src/services/utilities.ts
index 09887d9dffa..2772b8920e7 100644
--- a/src/services/utilities.ts
+++ b/src/services/utilities.ts
@@ -1499,17 +1499,4 @@ namespace ts {
     function getFirstChild(node: Node): Node | undefined {
         return node.forEachChild(child => child);
     }
-
-    function getLastChild(node: Node): Node | undefined {
-        let lastChild: Node | undefined;
-        node.forEachChild(
-            child => { lastChild = child; },
-            children => {
-                // As an optimization, jump straight to the end of the list.
-                if (children.length) {
-                    lastChild = last(children);
-                }
-            });
-        return lastChild;
-    }
 }