From 8a986d4642a82734cda9624934ff96da86e42aa9 Mon Sep 17 00:00:00 2001
From: Alex Rickabaugh <alx+alxhub@alxandria.net>
Date: Mon, 9 Jul 2018 11:39:15 -0700
Subject: [PATCH] feat(ivy): statically resolve template expressions (#24862)

This commit adds support for template substitution expressions for
ngtsc static resolution.

PR Close #24862
---
 .../src/ngtsc/metadata/src/resolver.ts         | 18 ++++++++++++++++++
 .../src/ngtsc/metadata/test/resolver_spec.ts   |  3 +++
 packages/compiler-cli/test/ngtsc/ngtsc_spec.ts |  2 +-
 3 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/packages/compiler-cli/src/ngtsc/metadata/src/resolver.ts b/packages/compiler-cli/src/ngtsc/metadata/src/resolver.ts
index 9c3f7891f7..a63ec59081 100644
--- a/packages/compiler-cli/src/ngtsc/metadata/src/resolver.ts
+++ b/packages/compiler-cli/src/ngtsc/metadata/src/resolver.ts
@@ -258,6 +258,8 @@ class StaticInterpreter {
       return node.text;
     } else if (ts.isNoSubstitutionTemplateLiteral(node)) {
       return node.text;
+    } else if (ts.isTemplateExpression(node)) {
+      return this.visitTemplateExpression(node, context);
     } else if (ts.isNumericLiteral(node)) {
       return parseFloat(node.text);
     } else if (ts.isObjectLiteralExpression(node)) {
@@ -362,6 +364,22 @@ class StaticInterpreter {
     return this.visitSymbol(symbol, context);
   }
 
+  private visitTemplateExpression(node: ts.TemplateExpression, context: Context): ResolvedValue {
+    const pieces: string[] = [node.head.text];
+    for (let i = 0; i < node.templateSpans.length; i++) {
+      const span = node.templateSpans[i];
+      const value = this.visit(span.expression, context);
+      if (typeof value === 'string' || typeof value === 'number' || typeof value === 'boolean' ||
+          value == null) {
+        pieces.push(`${value}`);
+      } else {
+        return DYNAMIC_VALUE;
+      }
+      pieces.push(span.literal.text);
+    }
+    return pieces.join('');
+  }
+
   private visitSymbol(symbol: ts.Symbol, context: Context): ResolvedValue {
     let absoluteModuleName = context.absoluteModuleName;
     if (symbol.declarations !== undefined && symbol.declarations.length > 0) {
diff --git a/packages/compiler-cli/src/ngtsc/metadata/test/resolver_spec.ts b/packages/compiler-cli/src/ngtsc/metadata/test/resolver_spec.ts
index 7a41ad3595..740dd1ea0c 100644
--- a/packages/compiler-cli/src/ngtsc/metadata/test/resolver_spec.ts
+++ b/packages/compiler-cli/src/ngtsc/metadata/test/resolver_spec.ts
@@ -249,4 +249,7 @@ describe('ngtsc metadata', () => {
                'obj.fn("test")'))
         .toEqual('test');
   });
+
+  it('template expressions work',
+     () => { expect(evaluate('const a = 2, b = 4;', '`1${a}3${b}5`')).toEqual('12345'); });
 });
diff --git a/packages/compiler-cli/test/ngtsc/ngtsc_spec.ts b/packages/compiler-cli/test/ngtsc/ngtsc_spec.ts
index 3046f5dbc6..7ad4cf2ffa 100644
--- a/packages/compiler-cli/test/ngtsc/ngtsc_spec.ts
+++ b/packages/compiler-cli/test/ngtsc/ngtsc_spec.ts
@@ -345,7 +345,7 @@ describe('ngtsc behavioral tests', () => {
     expect(dtsContents).toContain('i0.ɵNgModuleDef<TestModule, [TestPipe,TestCmp], [], []>');
   });
 
-  it('should unwrap a ModuleWithProviders functoin if a generic type is provided for it', () => {
+  it('should unwrap a ModuleWithProviders function if a generic type is provided for it', () => {
     writeConfig();
     write(`test.ts`, `
         import {NgModule} from '@angular/core';