From 0dd1facc3292aec6b0ca6fd65fc73efae2c194fc Mon Sep 17 00:00:00 2001
From: Andrew Scott <atscott@google.com>
Date: Mon, 22 Feb 2021 15:29:28 -0800
Subject: [PATCH] perf(language-service): Skip Angular analysis when quick info
 requested outside a template (#40956)

The Angular LS does not provide quick info when the given position is not
inside a template. As an optimization, we can quickly look at the
file and determine if we are at a position that is part of an Angular
template. If not, we bail before asking the compiler for any more
information. Note that the Angular LS _already_ provides no quick info
when outside a template file, but currently asks the compiler to analyze
the program before it determines that information.

PR Close #40956
---
 .../language-service/ivy/language_service.ts  | 39 ++++++++++---------
 1 file changed, 21 insertions(+), 18 deletions(-)

diff --git a/packages/language-service/ivy/language_service.ts b/packages/language-service/ivy/language_service.ts
index 8ce646acafe..dad897a2b82 100644
--- a/packages/language-service/ivy/language_service.ts
+++ b/packages/language-service/ivy/language_service.ts
@@ -94,25 +94,28 @@ export class LanguageService {
   }
 
   getQuickInfoAtPosition(fileName: string, position: number): ts.QuickInfo|undefined {
-    const compiler = this.compilerFactory.getOrCreate();
-    const templateInfo = getTemplateInfoAtPosition(fileName, position, compiler);
-    if (templateInfo === undefined) {
-      return undefined;
-    }
-    const positionDetails = getTargetAtPosition(templateInfo.template, position);
-    if (positionDetails === null) {
-      return undefined;
-    }
+    return this.withCompiler((compiler) => {
+      if (!isTemplateContext(compiler.getNextProgram(), fileName, position)) {
+        return undefined;
+      }
 
-    // Because we can only show 1 quick info, just use the bound attribute if the target is a two
-    // way binding. We may consider concatenating additional display parts from the other target
-    // nodes or representing the two way binding in some other manner in the future.
-    const node = positionDetails.context.kind === TargetNodeKind.TwoWayBindingContext ?
-        positionDetails.context.nodes[0] :
-        positionDetails.context.node;
-    const results = new QuickInfoBuilder(this.tsLS, compiler, templateInfo.component, node).get();
-    this.compilerFactory.registerLastKnownProgram();
-    return results;
+      const templateInfo = getTemplateInfoAtPosition(fileName, position, compiler);
+      if (templateInfo === undefined) {
+        return undefined;
+      }
+      const positionDetails = getTargetAtPosition(templateInfo.template, position);
+      if (positionDetails === null) {
+        return undefined;
+      }
+
+      // Because we can only show 1 quick info, just use the bound attribute if the target is a two
+      // way binding. We may consider concatenating additional display parts from the other target
+      // nodes or representing the two way binding in some other manner in the future.
+      const node = positionDetails.context.kind === TargetNodeKind.TwoWayBindingContext ?
+          positionDetails.context.nodes[0] :
+          positionDetails.context.node;
+      return new QuickInfoBuilder(this.tsLS, compiler, templateInfo.component, node).get();
+    });
   }
 
   getReferencesAtPosition(fileName: string, position: number): ts.ReferenceEntry[]|undefined {