fix for #16 with MagicString (not Bundle)

src/Bundle/index.js

@@ -93,7 +93,7 @@ class Bundle {
 					mappings = getSemis( source.content.toString() );
 				} else {
 					const sourceIndex = this.uniqueSourceIndexByFilename[ source.filename ];
-					mappings = source.content.getMappings( options.hires, sourceIndex, offsets );
+					mappings = source.content.getMappings( options.hires, sourceIndex, offsets, [], {} ); // TODO names and nameLocations
 				}
 
 				return prefix + mappings;

src/MagicString/encodeMappings.js

@@ -1,6 +1,6 @@
 import { encode } from 'vlq';
 
-export default function encodeMappings ( original, str, mappings, hires, sourcemapLocations, sourceIndex, offsets ) {
+export default function encodeMappings ( original, str, mappings, hires, sourcemapLocations, sourceIndex, offsets, names, nameLocations ) {
 	// store locations, for fast lookup
 	let lineStart = 0;
 	const locations = original.split( '\n' ).map( line => {
@@ -20,6 +20,7 @@ export default function encodeMappings ( original, str, mappings, hires, sourcem
 		let origin;
 		let lastOrigin = -1;
 		let location;
+		let nameIndex;
 
 		let i;
 
@@ -28,28 +29,29 @@ export default function encodeMappings ( original, str, mappings, hires, sourcem
 			char = i + charOffset;
 			origin = inverseMappings[ char ];
 
-			location = ( !~origin && ~lastOrigin ) ?
+			nameIndex = -1;
+			location = null;
 
-				// if this character has no mapping, but the last one did,
-				// create a new segment
-				getLocation( locations, lastOrigin + 1 ) :
+			// if this character has no mapping, but the last one did,
+			// create a new segment
+			if ( !~origin && ~lastOrigin ) {
+				origin = lastOrigin + 1;
+				location = getLocation( locations, lastOrigin + 1 );
 
-				// otherwise create a new segment if this character is mapped to an origin and
-				//   a) we're in hires mode
-				//   b) the origin isn't just lastOrigin + 1
-				//   c) there's a marked sourcemapLocation
-				( ~origin && ( hires || ( ~lastOrigin && origin !== lastOrigin + 1 ) || sourcemapLocations[ origin ] ) ) ?
-					getLocation( locations, origin ) :
+				if ( origin in nameLocations ) nameIndex = names.indexOf( nameLocations[ origin ] );
+			}
 
-					// otherwise skip it
-					null;
+			else if ( ~origin && ( hires || ( ~lastOrigin && origin !== lastOrigin + 1 ) || sourcemapLocations[ origin ] ) ) {
+				location = getLocation( locations, origin );
+			}
 
 			if ( location ) {
 				segments.push({
 					generatedCodeColumn: i,
 					sourceIndex: sourceIndex,
 					sourceCodeLine: location.line,
-					sourceCodeColumn: location.column
+					sourceCodeColumn: location.column,
+					sourceCodeName: nameIndex
 				});
 			}
 
@@ -60,17 +62,16 @@ export default function encodeMappings ( original, str, mappings, hires, sourcem
 		return segments;
 	});
 
-	offsets = offsets || {};
-
 	offsets.sourceIndex = offsets.sourceIndex || 0;
 	offsets.sourceCodeLine = offsets.sourceCodeLine || 0;
 	offsets.sourceCodeColumn = offsets.sourceCodeColumn || 0;
+	offsets.sourceCodeName = offsets.sourceCodeName || 0;
 
 	const encoded = lines.map( segments => {
 		var generatedCodeColumn = 0;
 
 		return segments.map( segment => {
-			const arr = [
+			let arr = [
 				segment.generatedCodeColumn - generatedCodeColumn,
 				segment.sourceIndex - offsets.sourceIndex,
 				segment.sourceCodeLine - offsets.sourceCodeLine,
@@ -82,6 +83,11 @@ export default function encodeMappings ( original, str, mappings, hires, sourcem
 			offsets.sourceCodeLine = segment.sourceCodeLine;
 			offsets.sourceCodeColumn = segment.sourceCodeColumn;
 
+			if ( ~segment.sourceCodeName ) {
+				arr.push( segment.sourceCodeName - offsets.sourceCodeName );
+				offsets.sourceCodeName = segment.sourceCodeName;
+			}
+
 			return encode( arr );
 		}).join( ',' );
 	}).join( ';' );

src/MagicString/index.js

@@ -14,6 +14,7 @@ class MagicString {
 		this.indentExclusionRanges = options.indentExclusionRanges;
 
 		this.sourcemapLocations = {};
+		this.nameLocations = {};
 
 		this.indentStr = guessIndent( string );
 	}
@@ -58,21 +59,27 @@ class MagicString {
 	generateMap ( options ) {
 		options = options || {};
 
+		let names = [];
+		Object.keys( this.nameLocations ).forEach( location => {
+			const name = this.nameLocations[ location ];
+			if ( !~names.indexOf( name ) ) names.push( name );
+		});
+
 		return new SourceMap({
 			file: ( options.file ? options.file.split( /[\/\\]/ ).pop() : null ),
 			sources: [ options.source ? getRelativePath( options.file || '', options.source ) : null ],
 			sourcesContent: options.includeContent ? [ this.original ] : [ null ],
-			names: [],
-			mappings: this.getMappings( options.hires, 0 )
+			names,
+			mappings: this.getMappings( options.hires, 0, {}, names, this.nameLocations )
 		});
 	}
 
 	getIndentString () {
 		return this.indentStr === null ? '\t' : this.indentStr;
 	}
 
-	getMappings ( hires, sourceIndex, offsets ) {
-		return encodeMappings( this.original, this.str, this.mappings, hires, this.sourcemapLocations, sourceIndex, offsets );
+	getMappings ( hires, sourceIndex, offsets, names, nameLocations ) {
+		return encodeMappings( this.original, this.str, this.mappings, hires, this.sourcemapLocations, sourceIndex, offsets, names, nameLocations );
 	}
 
 	indent ( indentStr, options ) {
@@ -238,7 +245,7 @@ class MagicString {
 		return null;
 	}
 
-	overwrite ( start, end, content ) {
+	overwrite ( start, end, content, storeName ) {
 		if ( typeof content !== 'string' ) {
 			throw new TypeError( 'replacement content must be a string' );
 		}
@@ -259,6 +266,10 @@ class MagicString {
 			);
 		}
 
+		if ( storeName ) {
+			this.nameLocations[ start ] = this.original.slice( start, end );
+		}
+
 		this.str = this.str.substr( 0, firstChar ) + content + this.str.substring( lastChar + 1 );
 
 		d = content.length - ( lastChar + 1 - firstChar );