1 files changed, 26 insertions, 0 deletions
diff --git a/plugin/src/extension.js b/plugin/src/extension.js
index a7b4834..bfc51a1 100644
--- a/plugin/src/extension.js
+++ b/plugin/src/extension.js
@@ -3,6 +3,7 @@
 const vscode = require('vscode');
 const { indentationEdits } = require('./indentation');
 const { codeOnly } = require('./lexical');
+const { unmatchedBrackets } = require('./brackets');
 const languageId = 'cie-pseudocode';
 
 function formatLines(document, startLine, endLine, keepBlankIndent = false) {
@@ -12,7 +13,31 @@ function formatLines(document, startLine, endLine, keepBlankIndent = false) {
 }
 
 function activate(context) {
+	const invalidBracket = vscode.window.createTextEditorDecorationType({
+		dark: { color: '#F44747' }
+	});
+	function refreshBrackets(document) {
+		const rangesByDocument = new Map();
+		for (const editor of vscode.window.visibleTextEditors) {
+			if (document && editor.document !== document) continue;
+			if (editor.document.languageId !== languageId) {
+				editor.setDecorations(invalidBracket, []);
+				continue;
+			}
+			if (!rangesByDocument.has(editor.document)) {
+				const ranges = unmatchedBrackets(editor.document.getText()).map(offset =>
+					new vscode.Range(editor.document.positionAt(offset), editor.document.positionAt(offset + 1)));
+				rangesByDocument.set(editor.document, ranges);
+			}
+			editor.setDecorations(invalidBracket, rangesByDocument.get(editor.document));
+		}
+	}
 	context.subscriptions.push(
+		invalidBracket,
+		vscode.workspace.onDidChangeTextDocument(event => refreshBrackets(event.document)),
+		// Changing a document's language closes/reopens it without a text edit.
+		vscode.workspace.onDidOpenTextDocument(() => refreshBrackets()),
+		vscode.window.onDidChangeVisibleTextEditors(() => refreshBrackets()),
 		vscode.languages.registerDocumentRangeFormattingEditProvider(languageId, {
 			provideDocumentRangeFormattingEdits(document, range) {
 				const endLine = range.end.character === 0 && range.end.line > range.start.line
@@ -28,6 +53,7 @@ function activate(context) {
 			}
 		}, '\n', 'E', 'F', 'L', 'T', 'N')
 	);
+	refreshBrackets();
 }
 
 module.exports = { activate };