(fix) split tscheck-regex to avoid heavy compution (#367)

#337

Author: dummdidumm

packages/language-server/src/plugins/typescript/DocumentSnapshot.ts

@@ -14,7 +14,12 @@ import {
 } from '../../lib/documents';
 import { pathToUrl } from '../../utils';
 import { ConsumerDocumentMapper } from './DocumentMapper';
-import { getScriptKindFromAttributes, getScriptKindFromFileName, isSvelteFilePath } from './utils';
+import {
+    getScriptKindFromAttributes,
+    getScriptKindFromFileName,
+    isSvelteFilePath,
+    getTsCheckComment,
+} from './utils';
 
 /**
  * An error which occured while trying to parse/preprocess the svelte file contents.
@@ -120,10 +125,9 @@ function preprocessSvelteFile(document: Document, options: SvelteSnapshotOptions
         if (tsxMap) {
             tsxMap.sources = [document.uri];
 
-            const tsCheck = document.scriptInfo?.content.match(tsCheckRegex);
+            const tsCheck = getTsCheckComment(document.scriptInfo?.content);
             if (tsCheck) {
-                // second-last entry is the capturing group with the exact ts-check wording
-                text = `//${tsCheck[tsCheck.length - 3]}${ts.sys.newLine}` + text;
+                text = tsCheck + text;
                 nrPrependedLines = 1;
             }
         }
@@ -330,13 +334,3 @@ export class SvelteSnapshotFragment implements SnapshotFragment {
         }
     }
 }
-
-// The following regex matches @ts-check or @ts-nocheck if:
-// - it is before the first line of code (so other lines with comments before it are ok)
-// - must be @ts-(no)check
-// - the comment which has @ts-(no)check can have any type of whitespace before it, but not other characters
-// - what's coming after @ts-(no)check is irrelevant as long there is any kind of whitespace or line break, so this would be picked up, too: // @ts-check asdasd
-// [ \t\u00a0\u1680\u2000-\u200a\u2028\u2029\u202f\u205f\u3000\ufeff]
-// is just \s (a.k.a any whitespace character) without linebreak and vertical tab
-// eslint-disable-next-line
-const tsCheckRegex = /^(\s*(\/\/[ \t\u00a0\u1680\u2000-\u200a\u2028\u2029\u202f\u205f\u3000\ufeff\S]*)*\s*)*(\/\/[ \t\u00a0\u1680\u2000-\u200a\u2028\u2029\u202f\u205f\u3000\ufeff]*(@ts-(no)?check)($|\s))/;

packages/language-server/src/plugins/typescript/utils.ts

@@ -260,3 +260,29 @@ export function mapSeverity(category: ts.DiagnosticCategory): DiagnosticSeverity
 
     return DiagnosticSeverity.Error;
 }
+
+// Matches comments that come before any non-comment content
+const commentsRegex = /^(\s*\/\/.*\s*)*/;
+// The following regex matches @ts-check or @ts-nocheck if:
+// - must be @ts-(no)check
+// - the comment which has @ts-(no)check can have any type of whitespace before it, but not other characters
+// - what's coming after @ts-(no)check is irrelevant as long there is any kind of whitespace or line break, so this would be picked up, too: // @ts-check asdasd
+// [ \t\u00a0\u1680\u2000-\u200a\u2028\u2029\u202f\u205f\u3000\ufeff]
+// is just \s (a.k.a any whitespace character) without linebreak and vertical tab
+// eslint-disable-next-line max-len
+const tsCheckRegex = /\/\/[ \t\u00a0\u1680\u2000-\u200a\u2028\u2029\u202f\u205f\u3000\ufeff]*(@ts-(no)?check)($|\s)/;
+
+/**
+ * Returns `// @ts-check` or `// @ts-nocheck` if content starts with comments and has one of these
+ * in its comments.
+ */
+export function getTsCheckComment(str = ''): string | undefined {
+    const comments = str.match(commentsRegex)?.[0];
+    if (comments) {
+        const tsCheck = comments.match(tsCheckRegex);
+        if (tsCheck) {
+            // second-last entry is the capturing group with the exact ts-check wording
+            return `// ${tsCheck[tsCheck.length - 3]}${ts.sys.newLine}`;
+        }
+    }
+}

packages/language-server/test/plugins/typescript/utils.test.ts

@@ -0,0 +1,57 @@
+import { getTsCheckComment } from '../../../src/plugins/typescript/utils';
+import ts from 'typescript';
+import * as assert from 'assert';
+
+describe('TypeScriptPlugin utils', () => {
+    describe('#getTsCheckComment', () => {
+        const tsCheckComment = `// @ts-check${ts.sys.newLine}`;
+        const tsNocheckComment = `// @ts-nocheck${ts.sys.newLine}`;
+
+        it('should not return if ts-check is after non-comment-code', () => {
+            assert.deepStrictEqual(
+                getTsCheckComment(`qwd
+            // @ts-check`),
+                undefined,
+            );
+        });
+
+        it('should return @ts-check', () => {
+            assert.deepStrictEqual(
+                getTsCheckComment(`
+            // @ts-check`),
+                tsCheckComment,
+            );
+        });
+
+        it('should return @ts-nocheck', () => {
+            assert.deepStrictEqual(
+                getTsCheckComment(`
+            // @ts-nocheck`),
+                tsNocheckComment,
+            );
+        });
+
+        it('should return if ts-check is after some comments', () => {
+            assert.deepStrictEqual(
+                getTsCheckComment(`
+            // hello
+            
+            ///
+            // @ts-check`),
+                tsCheckComment,
+            );
+        });
+
+        it('should not return if there are comments but without ts-check', () => {
+            assert.deepStrictEqual(
+                getTsCheckComment(`
+            // nope
+            // almost@ts-check
+            // @ts-almostcheck
+            ///
+            `),
+                undefined,
+            );
+        });
+    });
+});