From 726eea2896e4c8054f0e162c10399e4b930c1845 Mon Sep 17 00:00:00 2001
From: Vladimir Matveev <vladima@microsoft.com>
Date: Tue, 30 Jun 2015 16:11:09 -0700
Subject: [PATCH 1/3] dispose script snapshots from the old source file

---
 src/services/services.ts | 13 +++++++++++++
 src/services/shims.ts    |  9 +++++++++
 2 files changed, 22 insertions(+)

diff --git a/src/services/services.ts b/src/services/services.ts
index 521c6db155a..41996349fba 100644
--- a/src/services/services.ts
+++ b/src/services/services.ts
@@ -91,6 +91,9 @@ module ts {
          * not happen and the entire document will be re - parsed.
          */
         getChangeRange(oldSnapshot: IScriptSnapshot): TextChangeRange;
+
+        /** Releases all resources held by this script snapshot */
+        dispose?(): void;
     }
 
     export module ScriptSnapshot {
@@ -1873,6 +1876,16 @@ module ts {
                     // after incremental parsing nameTable might not be up-to-date
                     // drop it so it can be lazily recreated later
                     newSourceFile.nameTable = undefined;
+
+                    // dispose all resources held by old script snapshot
+                    if (sourceFile.scriptSnapshot) {
+                        if (sourceFile.scriptSnapshot.dispose) {
+                            sourceFile.scriptSnapshot.dispose();
+                        }
+
+                        sourceFile.scriptSnapshot = undefined;
+                    }
+
                     return newSourceFile;
                 }
             }
diff --git a/src/services/shims.ts b/src/services/shims.ts
index d6f9f7a968a..6743f48df1d 100644
--- a/src/services/shims.ts
+++ b/src/services/shims.ts
@@ -34,6 +34,9 @@ module ts {
          * Or undefined value if there was no change.
          */
         getChangeRange(oldSnapshot: ScriptSnapshotShim): string;
+
+        /** Releases all resources held by this script snapshot */
+        dispose?(): void;
     }
 
     export interface Logger {
@@ -242,6 +245,12 @@ module ts {
             return createTextChangeRange(
                 createTextSpan(decoded.span.start, decoded.span.length), decoded.newLength);
         }
+
+        public dispose(): void {
+            if ("dispose" in this.scriptSnapshotShim) {
+                this.scriptSnapshotShim.dispose();
+            }
+        }
     }
 
     export class LanguageServiceShimHostAdapter implements LanguageServiceHost {

From ee1350b40e6cdd4a49eb298f591ad62afb4f3993 Mon Sep 17 00:00:00 2001
From: Vladimir Matveev <vladima@microsoft.com>
Date: Wed, 1 Jul 2015 23:14:40 -0700
Subject: [PATCH 2/3] dispose snapshot only if new file differs from the old
 file

---
 src/services/services.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/services/services.ts b/src/services/services.ts
index 41996349fba..a446c45aa8f 100644
--- a/src/services/services.ts
+++ b/src/services/services.ts
@@ -1878,7 +1878,7 @@ module ts {
                     newSourceFile.nameTable = undefined;
 
                     // dispose all resources held by old script snapshot
-                    if (sourceFile.scriptSnapshot) {
+                    if (sourceFile !== newSourceFile && sourceFile.scriptSnapshot) {
                         if (sourceFile.scriptSnapshot.dispose) {
                             sourceFile.scriptSnapshot.dispose();
                         }

From e190761d96beaa0aa39e84de010695c63b05e64d Mon Sep 17 00:00:00 2001
From: Vladimir Matveev <vladima@microsoft.com>
Date: Thu, 9 Jul 2015 13:13:49 -0700
Subject: [PATCH 3/3] addressed PR feedback: added comments

---
 src/services/shims.ts | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/services/shims.ts b/src/services/shims.ts
index 6743f48df1d..e583a0d3d18 100644
--- a/src/services/shims.ts
+++ b/src/services/shims.ts
@@ -247,6 +247,8 @@ module ts {
         }
 
         public dispose(): void {
+            // if scriptSnapshotShim is a COM object then property check becomes method call with no arguments
+            // 'in' does not have this effect
             if ("dispose" in this.scriptSnapshotShim) {
                 this.scriptSnapshotShim.dispose();
             }