fix range source mapping for semantic tokens (#784)

Author: jasonlyu123

packages/language-server/src/plugins/typescript/features/SemanticTokensProvider.ts

@@ -1,6 +1,6 @@
 import ts from 'typescript';
 import { Range, SemanticTokens, SemanticTokensBuilder } from 'vscode-languageserver';
-import { Document } from '../../../lib/documents';
+import { Document, mapRangeToOriginal } from '../../../lib/documents';
 import { SemanticTokensProvider } from '../../interfaces';
 import { SnapshotFragment } from '../DocumentSnapshot';
 import { LSAndTSDocResolver } from '../LSAndTSDocResolver';
@@ -81,15 +81,16 @@ export class SemanticTokensProviderImpl implements SemanticTokensProvider {
         generatedOffset: number,
         generatedLength: number
     ): [line: number, character: number, length: number] | undefined {
-        const startPosition = fragment.getOriginalPosition(fragment.positionAt(generatedOffset));
+        const range = {
+            start: fragment.positionAt(generatedOffset),
+            end: fragment.positionAt(generatedOffset + generatedLength)
+        };
+        const { start: startPosition, end: endPosition } = mapRangeToOriginal(fragment, range);
 
-        if (startPosition.line < 0) {
+        if (startPosition.line < 0 || endPosition.line < 0) {
             return;
         }
 
-        const endPosition = fragment.getOriginalPosition(
-            fragment.positionAt(generatedOffset + generatedLength)
-        );
         const startOffset = document.offsetAt(startPosition);
         const endOffset = document.offsetAt(endPosition);
 

packages/language-server/test/plugins/typescript/features/SemanticTokensProvider.test.ts

@@ -140,6 +140,20 @@ describe('SemanticTokensProvider', () => {
                 length: 'text'.length,
                 type: TokenType.property,
                 modifiers: []
+            },
+            {
+                line: 13,
+                character: 16,
+                length: 1,
+                type: TokenType.parameter,
+                modifiers: [TokenModifier.declaration]
+            },
+            {
+                line: 14,
+                character: 5,
+                length: 1,
+                type: TokenType.parameter,
+                modifiers: []
             }
         ];
 

packages/language-server/test/plugins/typescript/testfiles/semantic-tokens/tokens.svelte

@@ -11,3 +11,6 @@
 {#await textPromise then text}
     <textarea on:blur={blurHandler} value={text.text} />
 {/await}
+{#each ['a'] as a}
+    {a}
+{/each}