From bf31ef29f65f2654218b55608c0f9be26d5d5481 Mon Sep 17 00:00:00 2001
From: Pete Bacon Darwin <pete@bacondarwin.com>
Date: Mon, 31 Aug 2020 16:19:11 +0100
Subject: [PATCH] refactor(compiler): capture interpolation source-spans in
 expression parser (#38645)

The expression parser will split the expression up at the interpolation markers
into expressions and static strings. This commit also captures the positions of
these strings in the expression to be used in source-mapping later.

PR Close #38645
---
 packages/compiler/src/expression_parser/parser.ts | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/packages/compiler/src/expression_parser/parser.ts b/packages/compiler/src/expression_parser/parser.ts
index f71fa40f57..090e236135 100644
--- a/packages/compiler/src/expression_parser/parser.ts
+++ b/packages/compiler/src/expression_parser/parser.ts
@@ -14,7 +14,10 @@ import {AbsoluteSourceSpan, AST, AstVisitor, ASTWithSource, Binary, BindingPipe,
 import {EOF, isIdentifier, isQuote, Lexer, Token, TokenType} from './lexer';
 
 export class SplitInterpolation {
-  constructor(public strings: string[], public expressions: string[], public offsets: number[]) {}
+  constructor(
+      public strings: string[], public stringSpans: {start: number, end: number}[],
+      public expressions: string[], public expressionsSpans: {start: number, end: number}[],
+      public offsets: number[]) {}
 }
 
 export class TemplateBindingParseResult {
@@ -194,18 +197,24 @@ export class Parser {
     const strings: string[] = [];
     const expressions: string[] = [];
     const offsets: number[] = [];
+    const stringSpans: {start: number, end: number}[] = [];
+    const expressionSpans: {start: number, end: number}[] = [];
     let offset = 0;
     for (let i = 0; i < parts.length; i++) {
       const part: string = parts[i];
       if (i % 2 === 0) {
         // fixed string
         strings.push(part);
+        const start = offset;
         offset += part.length;
+        stringSpans.push({start, end: offset});
       } else if (part.trim().length > 0) {
+        const start = offset;
         offset += interpolationConfig.start.length;
         expressions.push(part);
         offsets.push(offset);
         offset += part.length + interpolationConfig.end.length;
+        expressionSpans.push({start, end: offset});
       } else {
         this._reportError(
             'Blank expressions are not allowed in interpolated strings', input,
@@ -213,9 +222,10 @@ export class Parser {
             location);
         expressions.push('$implicit');
         offsets.push(offset);
+        expressionSpans.push({start: offset, end: offset});
       }
     }
-    return new SplitInterpolation(strings, expressions, offsets);
+    return new SplitInterpolation(strings, stringSpans, expressions, expressionSpans, offsets);
   }
 
   wrapLiteralPrimitive(input: string|null, location: any, absoluteOffset: number): ASTWithSource {