(fix) ignore html end-tag-like inside moustache (#671)

#309

packages/language-server/src/lib/documents/Document.ts

@@ -1,6 +1,7 @@
 import { urlToPath } from '../../utils';
 import { WritableDocument } from './DocumentBase';
-import { extractScriptTags, extractStyleTag, TagInformation, parseHtml } from './utils';
+import { extractScriptTags, extractStyleTag, TagInformation } from './utils';
+import { parseHtml } from './parseHtml';
 import { SvelteConfig, loadConfig } from './configLoader';
 import { HTMLDocument } from 'vscode-html-languageservice';
 

packages/language-server/src/lib/documents/parseHtml.ts

@@ -0,0 +1,85 @@
+import {
+    getLanguageService,
+    HTMLDocument,
+    TokenType,
+    ScannerState,
+    Scanner
+} from 'vscode-html-languageservice';
+import { isInsideMoustacheTag } from './utils';
+
+const parser = getLanguageService();
+
+/**
+ * Parses text as HTML
+ */
+export function parseHtml(text: string): HTMLDocument {
+    const preprocessed = preprocess(text);
+
+    // We can safely only set getText because only this is used for parsing
+    const parsedDoc = parser.parseHTMLDocument(<any>{ getText: () => preprocessed });
+
+    return parsedDoc;
+}
+
+const createScanner = parser.createScanner as (
+    input: string,
+    initialOffset?: number,
+    initialState?: ScannerState
+) => Scanner;
+
+/**
+ * scan the text and remove any `>` or `<` that cause the tag to end short,
+ */
+function preprocess(text: string) {
+    let scanner = createScanner(text);
+    let token = scanner.scan();
+    let currentStartTagStart: number | null = null;
+
+    while (token !== TokenType.EOS) {
+        const offset = scanner.getTokenOffset();
+
+        if (token === TokenType.StartTagOpen) {
+            currentStartTagStart = offset;
+        }
+
+        if (token === TokenType.StartTagClose) {
+            if (shouldBlankStartOrEndTagLike(offset)) {
+                blankStartOrEndTagLike(offset);
+            } else {
+                currentStartTagStart = null;
+            }
+        }
+
+        if (token === TokenType.StartTagSelfClose) {
+            currentStartTagStart = null;
+        }
+
+        // <Foo checked={a < 1}>
+        // https://github.com/microsoft/vscode-html-languageservice/blob/71806ef57be07e1068ee40900ef8b0899c80e68a/src/parser/htmlScanner.ts#L327
+        if (
+            token === TokenType.Unknown &&
+            scanner.getScannerState() === ScannerState.WithinTag &&
+            scanner.getTokenText() === '<' &&
+            shouldBlankStartOrEndTagLike(offset)
+        ) {
+            blankStartOrEndTagLike(offset);
+        }
+
+        token = scanner.scan();
+    }
+
+    return text;
+
+    function shouldBlankStartOrEndTagLike(offset: number) {
+        // not null rather than falsy, otherwise it won't work on first tag(0)
+        return (
+            currentStartTagStart !== null &&
+            isInsideMoustacheTag(text, currentStartTagStart, offset)
+        );
+    }
+
+    function blankStartOrEndTagLike(offset: number) {
+        text = text.substring(0, offset) + ' ' + text.substring(offset + 1);
+        scanner = createScanner(text, offset, ScannerState.WithinTag);
+    }
+}

packages/language-server/src/lib/documents/utils.ts

@@ -1,7 +1,8 @@
 import { clamp, isInRange, regexLastIndexOf } from '../../utils';
 import { Position, Range } from 'vscode-languageserver';
-import { Node, getLanguageService, HTMLDocument } from 'vscode-html-languageservice';
+import { Node, HTMLDocument } from 'vscode-html-languageservice';
 import * as path from 'path';
+import { parseHtml } from './parseHtml';
 
 export interface TagInformation {
     content: string;
@@ -38,16 +39,6 @@ function parseAttributes(
     }
 }
 
-const parser = getLanguageService();
-
-/**
- * Parses text as HTML
- */
-export function parseHtml(text: string): HTMLDocument {
-    // We can safely only set getText because only this is used for parsing
-    return parser.parseHTMLDocument(<any>{ getText: () => text });
-}
-
 const regexIf = new RegExp('{#if\\s.*?}', 'gms');
 const regexIfElseIf = new RegExp('{:else if\\s.*?}', 'gms');
 const regexIfEnd = new RegExp('{/if}', 'gms');
@@ -375,3 +366,8 @@ export function getLangAttribute(...tags: Array<TagInformation | null>): string
 
     return attribute.replace(/^text\//, '');
 }
+
+export function isInsideMoustacheTag(html: string, tagStart: number, position: number) {
+    const charactersInNode = html.substring(tagStart, position);
+    return charactersInNode.lastIndexOf('{') > charactersInNode.lastIndexOf('}');
+}

packages/language-server/src/plugins/html/HTMLPlugin.ts

@@ -22,6 +22,7 @@ import {
 import { LSConfigManager, LSHTMLConfig } from '../../ls-config';
 import { svelteHtmlDataProvider } from './dataProvider';
 import { HoverProvider, CompletionsProvider } from '../interfaces';
+import { isInsideMoustacheTag } from '../../lib/documents/utils';
 
 export class HTMLPlugin implements HoverProvider, CompletionsProvider {
     private configManager: LSConfigManager;
@@ -180,8 +181,7 @@ export class HTMLPlugin implements HoverProvider, CompletionsProvider {
     private isInsideMoustacheTag(html: HTMLDocument, document: Document, position: Position) {
         const offset = document.offsetAt(position);
         const node = html.findNodeAt(offset);
-        const charactersInNode = document.getText().substring(node.start, offset);
-        return charactersInNode.lastIndexOf('{') > charactersInNode.lastIndexOf('}');
+        return isInsideMoustacheTag(document.getText(), node.start, offset);
     }
 
     getDocumentSymbols(document: Document): SymbolInformation[] {

packages/language-server/test/lib/documents/parseHtml.test.ts

@@ -0,0 +1,76 @@
+import assert from 'assert';
+import { HTMLDocument } from 'vscode-html-languageservice';
+import { parseHtml } from '../../../src/lib/documents/parseHtml';
+
+describe('parseHtml', () => {
+    const testRootElements = (document: HTMLDocument) => {
+        assert.deepStrictEqual(
+            document.roots.map((r) => r.tag),
+            ['Foo', 'style']
+        );
+    };
+
+    it('ignore arrow inside moustache', () => {
+        testRootElements(
+            parseHtml(
+                `<Foo on:click={() => console.log('ya!!!')} />
+                <style></style>`
+            )
+        );
+    });
+
+    it('ignore greater than operator inside moustache', () => {
+        testRootElements(
+            parseHtml(
+                `<Foo checked={a > 1} />
+                <style></style>`
+            )
+        );
+    });
+
+    it('ignore less than operator inside moustache', () => {
+        testRootElements(
+            parseHtml(
+                `<Foo checked={a < 1} />
+                <style></style>`
+            )
+        );
+    });
+
+    it('ignore less than operator inside moustache with tag not self closed', () => {
+        testRootElements(
+            parseHtml(
+                `<Foo checked={a < 1}>
+                </Foo>
+                <style></style>`
+            )
+        );
+    });
+
+    it('parse baseline html', () => {
+        testRootElements(
+            parseHtml(
+                `<Foo checked />
+                <style></style>`
+            )
+        );
+    });
+
+    it('parse baseline html with moustache', () => {
+        testRootElements(
+            parseHtml(
+                `<Foo checked={a} />
+                <style></style>`
+            )
+        );
+    });
+
+    it('parse baseline html with possibly un-closed start tag', () => {
+        testRootElements(
+            parseHtml(
+                `<Foo checked={a}
+                <style></style>`
+            )
+        );
+    });
+});