feat(plugin): color bracket pairs and mark unmatched brackets red

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

7 files changed, 122 insertions, 15 deletions

diff --git a/plugin/package.json b/plugin/package.json
index 003a866..60cf9da 100644
--- a/plugin/package.json
+++ b/plugin/package.json
@@ -10,20 +10,32 @@
     "url": "https://github.com/ovfor4/cie-pseudocode-compiler.git",
     "directory": "plugin"
   },
-  "engines": { "vscode": "^1.85.0" },
+  "engines": {
+    "vscode": "^1.85.0"
+  },
   "main": "./src/extension.js",
-  "categories": ["Programming Languages", "Formatters"],
+  "categories": [
+    "Programming Languages",
+    "Formatters"
+  ],
   "scripts": {
-    "check": "node --check src/extension.js && node --check src/indentation.js && node --check src/lexical.js",
+    "check": "node --check src/extension.js && node --check src/indentation.js && node --check src/lexical.js && node --check src/brackets.js",
     "test": "node --test test/*.test.js"
   },
   "contributes": {
-    "languages": [{
-      "id": "cie-pseudocode",
-      "aliases": ["CIE Pseudocode", "cie-pseudocode"],
-      "extensions": [".cps"],
-      "configuration": "./language-configuration.json"
-    }],
+    "languages": [
+      {
+        "id": "cie-pseudocode",
+        "aliases": [
+          "CIE Pseudocode",
+          "cie-pseudocode"
+        ],
+        "extensions": [
+          ".cps"
+        ],
+        "configuration": "./language-configuration.json"
+      }
+    ],
     "configurationDefaults": {
       "[cie-pseudocode]": {
         "editor.insertSpaces": false,
@@ -31,14 +43,18 @@
         "editor.detectIndentation": false,
         "editor.autoIndent": "full",
         "editor.formatOnType": true,
-        "editor.defaultFormatter": "ovfor4.cie-pseudocode"
+        "editor.defaultFormatter": "ovfor4.cie-pseudocode",
+        "editor.bracketPairColorization.enabled": true,
+        "editor.bracketPairColorization.independentColorPoolPerBracketType": false
       }
     },
-    "grammars": [{
-      "language": "cie-pseudocode",
-      "scopeName": "source.cie-pseudocode",
-      "path": "./syntaxes/cie-pseudocode.tmLanguage.json"
-    }]
+    "grammars": [
+      {
+        "language": "cie-pseudocode",
+        "scopeName": "source.cie-pseudocode",
+        "path": "./syntaxes/cie-pseudocode.tmLanguage.json"
+      }
+    ]
   },
   "devDependencies": {
     "vscode-oniguruma": "^2.0.1",
diff --git a/plugin/src/brackets.js b/plugin/src/brackets.js
new file mode 100644
index 0000000..ad79ea5
--- /dev/null
+++ b/plugin/src/brackets.js
@@ -0,0 +1,25 @@
+'use strict';
+
+const { codeOnly } = require('./lexical');
+const pairs = { ')': '(', ']': '[' };
+
+function unmatchedBrackets(text) {
+	const code = codeOnly(text);
+	const stack = [];
+	const unmatched = [];
+	for (let offset = 0; offset < code.length; offset++) {
+		const char = code[offset];
+		if (char === '(' || char === '[') {
+			stack.push({ char, offset });
+		} else if (pairs[char]) {
+			const opening = stack.pop();
+			if (!opening || opening.char !== pairs[char]) {
+				if (opening) unmatched.push(opening.offset);
+				unmatched.push(offset);
+			}
+		}
+	}
+	return unmatched.concat(stack.map(opening => opening.offset)).sort((a, b) => a - b);
+}
+
+module.exports = { unmatchedBrackets };
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 };
diff --git a/plugin/src/lexical.js b/plugin/src/lexical.js
index 3fc856a..ff01166 100644
--- a/plugin/src/lexical.js
+++ b/plugin/src/lexical.js
@@ -17,6 +17,10 @@ function codeOnly(text) {
 		} else if (quote) {
 			if (char === quote) quote = null;
 			result.push(' ');
+		} else if (text.slice(i, i + 3) === "'''") {
+			// The compiler accepts a quote character as a three-quote CHAR literal.
+			result.push(' ', ' ', ' ');
+			i += 2;
 		} else if (char === '"' || char === "'") {
 			quote = char;
 			result.push(' ');
diff --git a/plugin/syntaxes/cie-pseudocode.tmLanguage.json b/plugin/syntaxes/cie-pseudocode.tmLanguage.json
index 40a67df..cb7d401 100644
--- a/plugin/syntaxes/cie-pseudocode.tmLanguage.json
+++ b/plugin/syntaxes/cie-pseudocode.tmLanguage.json
@@ -81,6 +81,10 @@
     "strings": {
       "patterns": [
         {
+          "match": "'''",
+          "name": "string.quoted.single.cie-pseudocode"
+        },
+        {
           "begin": "\"",
           "end": "\"|$",
           "beginCaptures": {
diff --git a/plugin/test/brackets.test.js b/plugin/test/brackets.test.js
new file mode 100644
index 0000000..acb18d0
--- /dev/null
+++ b/plugin/test/brackets.test.js
@@ -0,0 +1,31 @@
+'use strict';
+
+const assert = require('node:assert/strict');
+const { test } = require('node:test');
+const { unmatchedBrackets } = require('../src/brackets');
+
+test('mixed nesting matches across lines and repaired brackets stop being errors', () => {
+	assert.deepEqual(unmatchedBrackets('A[(B + C)\n + D[1]]'), []);
+	assert.deepEqual(unmatchedBrackets('A['), [1]);
+	assert.deepEqual(unmatchedBrackets('A[1]'), []);
+	assert.deepEqual(unmatchedBrackets('(\n)'), []);
+});
+
+test('unpaired opening, closing and crossed bracket types are all reported', () => {
+	assert.deepEqual(unmatchedBrackets('(['), [0, 1]);
+	assert.deepEqual(unmatchedBrackets(')]'), [0, 1]);
+	assert.deepEqual(unmatchedBrackets('([)]'), [0, 1, 2, 3]);
+	assert.deepEqual(unmatchedBrackets('(]'), [0, 1]);
+});
+
+test('comments and quotes are ignored with correct UTF-16 offsets after Unicode and CRLF', () => {
+	assert.deepEqual(unmatchedBrackets('OUTPUT "[( //" // )]\nOUTPUT \'[\''), []);
+	const unfinished = 'OUTPUT "unfinished [\r\nA[';
+	assert.deepEqual(unmatchedBrackets(unfinished), [unfinished.length - 1]);
+	const unicode = 'OUTPUT "你好😀"\r\nA[';
+	assert.deepEqual(unmatchedBrackets(unicode), [unicode.length - 1]);
+	// Backslashes do not escape CIE quotes.
+	assert.deepEqual(unmatchedBrackets('"x\\"['), [4]);
+	const quoteChar = "OUTPUT ''' [";
+	assert.deepEqual(unmatchedBrackets(quoteChar), [quoteChar.length - 1]);
+});
diff --git a/plugin/test/highlighting.test.js b/plugin/test/highlighting.test.js
index df18f6a..89e031a 100644
--- a/plugin/test/highlighting.test.js
+++ b/plugin/test/highlighting.test.js
@@ -58,4 +58,5 @@ test('comments, strings, lowercase and keyword prefixes cannot become keywords',
 	assert.ok(grammar.tokenizeLine('IF X THEN', state).tokens[0].scopes.includes(
 		'keyword.control.cie-pseudocode'));
 	assert.ok(scopesAt('OUTPUT "x\\" + 1', '+').includes('keyword.operator.cie-pseudocode'));
+	assert.ok(scopesAt("OUTPUT ''' + 1", '+').includes('keyword.operator.cie-pseudocode'));
 });