fix: correct mappings for update containing new line (#261)

Author: sapphi-red

src/utils/Mappings.js

@@ -12,16 +12,35 @@ export default class Mappings {
 
 	addEdit(sourceIndex, content, loc, nameIndex) {
 		if (content.length) {
+			let contentLineEnd = content.indexOf('\n', 0);
+			let previousContentLineEnd = -1;
+			while (contentLineEnd >= 0) {
+				const segment = [this.generatedCodeColumn, sourceIndex, loc.line, loc.column];
+				if (nameIndex >= 0) {
+					segment.push(nameIndex);
+				}
+				this.rawSegments.push(segment);
+
+				this.generatedCodeLine += 1;
+				this.raw[this.generatedCodeLine] = this.rawSegments = [];
+				this.generatedCodeColumn = 0;
+
+				previousContentLineEnd = contentLineEnd;
+				contentLineEnd = content.indexOf('\n', contentLineEnd + 1);
+			}
+
 			const segment = [this.generatedCodeColumn, sourceIndex, loc.line, loc.column];
 			if (nameIndex >= 0) {
 				segment.push(nameIndex);
 			}
 			this.rawSegments.push(segment);
+
+			this.advance(content.slice(previousContentLineEnd + 1));
 		} else if (this.pending) {
 			this.rawSegments.push(this.pending);
+			this.advance(content);
 		}
 
-		this.advance(content);
 		this.pending = null;
 	}
 

test/MagicString.js

@@ -447,7 +447,7 @@ describe('MagicString', () => {
 				includeContent: true,
 				hires: 'boundary'
 			});
-			
+
 			assert.equal(map.mappings, 'AAAA,QAAQ,CAAC,GAAG,CAAC,CAAC,CAAC,CAAC,OAAO,CAAC,GAAG,CAAC,CAAC,KAAG,CAAC,CAAC,CAAC');
 
 			const smc = new SourceMapConsumer(map);
@@ -469,6 +469,28 @@ describe('MagicString', () => {
 			assert.equal(loc.line, 1);
 			assert.equal(loc.column, 33);
 		});
+
+		it('generates a correct source map with update using a content containing a new line', () => {
+			const s = new MagicString('foobar');
+			s.update(3, 4, '\nbb');
+			assert.equal(s.toString(), 'foo\nbbar');
+
+			const map = s.generateMap({ hires: true });
+
+			const smc = new SourceMapConsumer(map);
+			const loc = smc.originalPositionFor({ line: 1, column: 3 });
+			assert.equal(loc.line, 1);
+			assert.equal(loc.column, 3);
+			const loc2 = smc.originalPositionFor({ line: 2, column: 0 });
+			assert.equal(loc2.line, 1);
+			assert.equal(loc2.column, 3);
+			const loc3 = smc.originalPositionFor({ line: 2, column: 1 });
+			assert.equal(loc3.line, 1);
+			assert.equal(loc3.column, 3);
+			const loc4 = smc.originalPositionFor({ line: 2, column: 2 });
+			assert.equal(loc4.line, 1);
+			assert.equal(loc4.column, 4);
+		});
 	});
 
 	describe('getIndentString', () => {
@@ -1490,7 +1512,7 @@ describe('MagicString', () => {
 			const s = new MagicString(' abcde   fghijkl ');
 
 			assert.ok(!s.hasChanged());
-		
+
 			assert.ok(s.clone().prepend('  ').hasChanged());
 			assert.ok(s.clone().overwrite(1, 2, 'b').hasChanged());
 			assert.ok(s.clone().remove(1, 6).hasChanged());
@@ -1504,7 +1526,7 @@ describe('MagicString', () => {
 			assert.ok(clone.hasChanged());
 		});
 	});
-  
+
 	describe('replace', () => {
 		it('works with string replace', () => {
 			const code = '1 2 1 2';
@@ -1575,7 +1597,7 @@ describe('MagicString', () => {
 			);
 		});
 	});
-  
+
 	describe('replaceAll', () => {
 		it('works with string replace', () => {
 			assert.strictEqual(