Fixes microsoft#75494: do not break between surrogate pairs

alexdima · alexdima · commit 78ddcdcd5cf3 · 2019-08-07T17:26:23.000+02:00
diff --git a/src/vs/editor/common/viewModel/characterHardWrappingLineMapper.ts b/src/vs/editor/common/viewModel/characterHardWrappingLineMapper.ts
@@ -136,6 +136,13 @@ export class CharacterHardWrappingLineMapperFactory implements ILineMapperFactor
 			let charCodeIsTab = (charCode === CharCode.Tab);
 			let charCodeClass = classifier.get(charCode);
 
+			if (strings.isLowSurrogate(charCode)/*  && i + 1 < len */) {
+				// A surrogate pair must always be considered as a single unit, so it is never to be broken
+				// => advance visibleColumn by 1 and advance to next char code...
+				visibleColumn = visibleColumn + 1;
+				continue;
+			}
+
 			if (charCodeClass === CharacterClass.BREAK_BEFORE) {
 				// This is a character that indicates that a break should happen before it
 				// Since we are certain the character before `i` fits, there's no extra checking needed,
diff --git a/src/vs/editor/test/common/viewModel/characterHardWrappingLineMapper.test.ts b/src/vs/editor/test/common/viewModel/characterHardWrappingLineMapper.test.ts
@@ -114,6 +114,11 @@ suite('Editor ViewModel - CharacterHardWrappingLineMapper', () => {
 		assert.equal(mapper!.getWrappedLinesIndent(), '                \t');
 	});
 
+	test('issue #75494: surrogate pairs', () => {
+		let factory = new CharacterHardWrappingLineMapperFactory('', ' ', '');
+		assertLineMapping(factory, 4, 49, '🐇👬🌖🌞🏇🍼🐇👬🌖🌞🏇🍼🐇👬🌖🌞🏇🍼🐇👬🌖🌞🏇🍼🐇|👬🌖🌞🏇🍼🐇👬🌖🌞🏇🍼🐇👬🌖🌞🏇🍼🐇👬🌖🌞🏇🍼🐇👬', WrappingIndent.Same);
+	});
+
 	test('CharacterHardWrappingLineMapper - WrappingIndent.DeepIndent', () => {
 		let factory = new CharacterHardWrappingLineMapperFactory('', ' ', '');
 		let mapper = assertLineMapping(factory, 4, 26, '        W e A r e T e s t |i n g D e |e p I n d |e n t a t |i o n', WrappingIndent.DeepIndent);
