feat(plugin): highlight exception keywords with C++ scopes

Reuse C++ try, catch and throw scopes for exception keywords, with ENDTRY
sharing the TRY scope. Add an example and verify keyword boundaries,
case sensitivity, comments and strings with TextMate tokenization.

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

4 files changed, 38 insertions, 1 deletions

diff --git a/plugin/ThirdPartyNotices.md b/plugin/ThirdPartyNotices.md
index d21d67a..72c3190 100644
--- a/plugin/ThirdPartyNotices.md
+++ b/plugin/ThirdPartyNotices.md
@@ -1,7 +1,10 @@
 # Third-party notices
 
 Language configuration and comment/string grammar structures are adapted from
-Microsoft VS Code’s built-in C++ extension:
+Microsoft VS Code’s built-in C++ extension. Exception keywords reuse its
+`keyword.control.try.cpp`, `keyword.control.catch.cpp` and
+`keyword.control.throw.cpp` scopes; ENDTRY uses the TRY scope.
+
 https://github.com/microsoft/vscode/tree/main/extensions/cpp
 
 MIT License
diff --git a/plugin/examples/highlighting.cps b/plugin/examples/highlighting.cps
index 9925bf3..7b30bb7 100644
--- a/plugin/examples/highlighting.cps
+++ b/plugin/examples/highlighting.cps
@@ -39,3 +39,9 @@ ENDPROCEDURE
 OPENFILE "example.txt" FOR WRITE
 WRITEFILE "example.txt", Text
 CLOSEFILE "example.txt"
+
+TRY
+	THROW
+CATCH
+	OUTPUT "Caught an exception"
+ENDTRY
diff --git a/plugin/syntaxes/cie-pseudocode.tmLanguage.json b/plugin/syntaxes/cie-pseudocode.tmLanguage.json
index cf1957f..fe3582c 100644
--- a/plugin/syntaxes/cie-pseudocode.tmLanguage.json
+++ b/plugin/syntaxes/cie-pseudocode.tmLanguage.json
@@ -9,6 +9,18 @@
       "include": "#strings"
     },
     {
+      "match": "(?<!\\w)(?:TRY|ENDTRY)(?!\\w)",
+      "name": "keyword.control.try.cpp"
+    },
+    {
+      "match": "(?<!\\w)CATCH(?!\\w)",
+      "name": "keyword.control.catch.cpp"
+    },
+    {
+      "match": "(?<!\\w)THROW(?!\\w)",
+      "name": "keyword.control.throw.cpp"
+    },
+    {
       "match": "(?<!\\w)(?:IF|THEN|ELSE|ENDIF|WHILE|DO|ENDWHILE|REPEAT|UNTIL|FOR|TO|STEP|NEXT|RETURN|CALL)(?!\\w)",
       "name": "keyword.control.cie-pseudocode"
     },
diff --git a/plugin/test/highlighting.test.js b/plugin/test/highlighting.test.js
index 24751bf..0f677a3 100644
--- a/plugin/test/highlighting.test.js
+++ b/plugin/test/highlighting.test.js
@@ -53,6 +53,22 @@ test('both assignment characters share the C++ assignment scope', () => {
 	assert.ok(!scopesAt('X - 1', '-').includes('keyword.operator.assignment.cpp'));
 });
 
+test('exception keywords reuse C++ scopes and ignore non-keyword occurrences', () => {
+	for (const [word, scope] of [
+		['TRY', 'keyword.control.try.cpp'],
+		['CATCH', 'keyword.control.catch.cpp'],
+		['THROW', 'keyword.control.throw.cpp'],
+		['ENDTRY', 'keyword.control.try.cpp']
+	]) {
+		assert.ok(scopesAt(word, word).includes(scope));
+		assert.ok(scopesAt(`// ${word}`, word).some(s => s.startsWith('comment.')));
+		assert.ok(scopesAt(`OUTPUT "${word}"`, word).some(s => s.startsWith('string.')));
+		for (const text of [word.toLowerCase(), `${word}Value`, `My${word}`, `${word}_1`]) {
+			assert.ok(!scopesAt(text, text).some(s => s.startsWith('keyword.')), text);
+		}
+	}
+});
+
 test('comments, strings, lowercase and keyword prefixes cannot become keywords', () => {
 	assert.ok(scopesAt('// IF [(', 'IF').some(s => s.startsWith('comment.')));
 	assert.ok(scopesAt('OUTPUT "IF // ["', 'IF').some(s => s.startsWith('string.')));