Decode mappings

package.json

@@ -18,14 +18,16 @@
     "eslint": "^2.11.1",
     "istanbul": "^0.4.3",
     "mocha": "^3.0.1",
+    "object-assign": "^4.1.0",
     "remap-istanbul": "^0.6.4",
     "resolve": "^1.1.7",
     "rollup": "^0.34.5",
     "rollup-plugin-buble": "^0.12.1",
     "rollup-plugin-node-resolve": "^2.0.0",
     "rollup-plugin-replace": "^1.1.0",
     "source-map": "^0.5.6",
-    "source-map-support": "^0.4.0"
+    "source-map-support": "^0.4.0",
+    "sourcemap-codec": "^1.3.0"
   },
   "keywords": [
     "string",

src/Bundle.js

@@ -103,23 +103,36 @@ Bundle.prototype = {
 	getMappings ( options, names ) {
 		const offsets = {};
 
-		return (
-			getSemis( this.intro ) +
-			this.sources.map( ( source, i ) => {
-				const prefix = ( i > 0 ) ? ( getSemis( source.separator ) || ',' ) : '';
-				let mappings;
-
-				// we don't bother encoding sources without a filename
-				if ( !source.filename ) {
-					mappings = getSemis( source.content.toString() );
-				} else {
+		if (options.encodeMappings === false) {
+			return Array.prototype.concat.apply(
+				this.intro.split( '\n' ).map( () => [] ).slice( 1 ),
+				this.sources.map( ( source, i ) => {
+					if ( !source.filename ) {
+						return source.content.toString().split( '\n' ).map( () => [] ).slice( 1 );
+					}
 					const sourceIndex = this.uniqueSourceIndexByFilename[ source.filename ];
-					mappings = source.content.getMappings( options, sourceIndex, offsets, names );
-				}
-
-				return prefix + mappings;
-			}).join( '' )
-		);
+					return source.content.getMappings( options, sourceIndex, offsets, names );
+				})
+			);
+		} else {
+			return (
+				getSemis( this.intro ) +
+				this.sources.map( ( source, i ) => {
+					const prefix = ( i > 0 ) ? ( getSemis( source.separator ) || ',' ) : '';
+					let mappings;
+
+					// we don't bother encoding sources without a filename
+					if ( !source.filename ) {
+						mappings = getSemis( source.content.toString() );
+					} else {
+						const sourceIndex = this.uniqueSourceIndexByFilename[ source.filename ];
+						mappings = source.content.getMappings( options, sourceIndex, offsets, names );
+					}
+
+					return prefix + mappings;
+				}).join( '' )
+			);
+		}
 	},
 
 	getIndentString () {

src/MagicString.js

@@ -1,6 +1,7 @@
 import Chunk from './Chunk.js';
 import SourceMap from './utils/SourceMap.js';
 import guessIndent from './utils/guessIndent.js';
+import generateMappings from './utils/generateMappings.js';
 import encodeMappings from './utils/encodeMappings.js';
 import getRelativePath from './utils/getRelativePath.js';
 import isObject from './utils/isObject.js';
@@ -84,9 +85,7 @@ MagicString.prototype = {
 		return cloned;
 	},
 
-	generateMap ( options ) {
-		options = options || {};
-
+	generateMap ( options = {} ) {
 		const names = Object.keys( this.storedNames );
 
 		if ( DEBUG ) this.stats.time( 'generateMap' );
@@ -107,7 +106,11 @@ MagicString.prototype = {
 	},
 
 	getMappings ( options, sourceIndex, offsets, names ) {
-		return encodeMappings( this.original, this.intro, this.outro, this.firstChunk, options.hires, this.sourcemapLocations, sourceIndex, offsets, names );
+		if ( options.encodeMappings === false ) {
+			return generateMappings( this.original, this.intro, this.outro, this.firstChunk, options.hires, this.sourcemapLocations, sourceIndex, names );
+		} else  {
+			return encodeMappings( this.original, this.intro, this.outro, this.firstChunk, options.hires, this.sourcemapLocations, sourceIndex, offsets, names );
+		}
 	},
 
 	indent ( indentStr, options ) {

src/utils/generateMappings.js

@@ -0,0 +1,124 @@
+import { encode } from 'vlq';
+import getSemis from './getSemis.js';
+import getLocator from './getLocator.js';
+
+const nonWhitespace = /\S/;
+
+export default function generateMappings ( original, intro, outro, chunk, hires, sourcemapLocations, sourceIndex, names ) {
+	const rawLines = intro.split( '\n' ).map( () => [] );
+	let generatedCodeLine = rawLines.length - 1;
+
+	let rawSegments = rawLines[ generatedCodeLine ];
+
+	let generatedCodeColumn = 0;
+
+	const locate = getLocator( original );
+
+	function addEdit ( content, original, loc, nameIndex, i ) {
+		if ( i || ( content.length && nonWhitespace.test( content ) ) ) {
+			rawSegments.push({
+				generatedCodeLine,
+				generatedCodeColumn,
+				sourceCodeLine: loc.line,
+				sourceCodeColumn: loc.column,
+				sourceCodeName: nameIndex,
+				sourceIndex
+			});
+		}
+
+		let lines = content.split( '\n' );
+		let lastLine = lines.pop();
+
+		if ( lines.length ) {
+			generatedCodeLine += lines.length;
+			rawLines[ generatedCodeLine ] = rawSegments = [];
+			generatedCodeColumn = lastLine.length;
+		} else {
+			generatedCodeColumn += lastLine.length;
+		}
+
+		lines = original.split( '\n' );
+		lastLine = lines.pop();
+
+		if ( lines.length ) {
+			loc.line += lines.length;
+			loc.column = lastLine.length;
+		} else {
+			loc.column += lastLine.length;
+		}
+	}
+
+	function addUneditedChunk ( chunk, loc ) {
+		let originalCharIndex = chunk.start;
+		let first = true;
+
+		while ( originalCharIndex < chunk.end ) {
+			if ( hires || first || sourcemapLocations[ originalCharIndex ] ) {
+				rawSegments.push({
+					generatedCodeLine,
+					generatedCodeColumn,
+					sourceCodeLine: loc.line,
+					sourceCodeColumn: loc.column,
+					sourceCodeName: -1,
+					sourceIndex
+				});
+			}
+
+			if ( original[ originalCharIndex ] === '\n' ) {
+				loc.line += 1;
+				loc.column = 0;
+				generatedCodeLine += 1;
+				rawLines[ generatedCodeLine ] = rawSegments = [];
+				generatedCodeColumn = 0;
+			} else {
+				loc.column += 1;
+				generatedCodeColumn += 1;
+			}
+
+			originalCharIndex += 1;
+			first = false;
+		}
+	}
+
+	let hasContent = false;
+
+	while ( chunk ) {
+		const loc = locate( chunk.start );
+
+		if ( chunk.intro.length ) {
+			addEdit( chunk.intro, '', loc, -1, hasContent );
+		}
+
+		if ( chunk.edited ) {
+			addEdit( chunk.content, chunk.original, loc, chunk.storeName ? names.indexOf( chunk.original ) : -1, hasContent );
+		} else {
+			addUneditedChunk( chunk, loc );
+		}
+
+		if ( chunk.outro.length ) {
+			addEdit( chunk.outro, '', loc, -1, hasContent );
+		}
+
+		if ( chunk.content || chunk.intro || chunk.outro ) hasContent = true;
+
+		const nextChunk = chunk.next;
+		chunk = nextChunk;
+	}
+
+	return rawLines.map( segments => {
+		return segments.map( segment => {
+			const arr = [
+				segment.generatedCodeColumn,
+				segment.sourceIndex,
+				segment.sourceCodeLine,
+				segment.sourceCodeColumn
+			];
+
+			if ( ~segment.sourceCodeName ) {
+				arr.push( segment.sourceCodeName );
+			}
+
+			return arr;
+		});
+	}).concat( outro.split( '\n' ).map( () => [] ).slice( 1 ) );
+}

test/MagicString.Bundle.js

@@ -1,10 +1,19 @@
 const assert = require( 'assert' );
+const assign = require('object-assign');
+const decodeMappings = require( 'sourcemap-codec' ).decode;
 const SourceMapConsumer = require( 'source-map' ).SourceMapConsumer;
 const MagicString = require( '../' );
 
 require( 'source-map-support' ).install();
 require( 'console-group' ).install();
 
+function generateMap( b, options ) {
+	const map = b.generateMap( options );
+	const decodedMap = b.generateMap( assign( {}, options || {}, { encodeMappings: false } ) );
+	assert.deepEqual( decodedMap.mappings, decodeMappings( map.mappings ) );
+	return map;
+}
+
 describe( 'MagicString.Bundle', () => {
 	describe( 'addSource', () => {
 		it( 'should return this', () => {
@@ -87,7 +96,7 @@ describe( 'MagicString.Bundle', () => {
 		});
 	});
 
-	describe( 'generateMap', () => {
+	describe.only( 'generateMap', () => {
 		it( 'should generate a sourcemap', () => {
 			const b = new MagicString.Bundle()
 				.addSource({
@@ -100,7 +109,7 @@ describe( 'MagicString.Bundle', () => {
 				});
 
 
-			const map = b.generateMap({
+			const map = generateMap(b, {
 				file: 'bundle.js',
 				includeContent: true,
 				hires: true
@@ -149,7 +158,7 @@ describe( 'MagicString.Bundle', () => {
 					content: new MagicString( 'console.log( answer );' )
 				});
 
-			const map = b.generateMap({
+			const map = generateMap(b, {
 				file: 'bundle.js',
 				includeContent: true,
 				hires: true
@@ -198,7 +207,7 @@ describe( 'MagicString.Bundle', () => {
 				})
 				.indent().prepend( '(function () {\n' ).append( '\n}());' );
 
-			const map = b.generateMap({
+			const map = generateMap(b, {
 				file: 'bundle.js',
 				includeContent: true,
 				hires: true
@@ -229,15 +238,16 @@ describe( 'MagicString.Bundle', () => {
 		});
 
 		it( 'should allow missing file option when generating map', () => {
-			new MagicString.Bundle()
+			const m = new MagicString.Bundle()
 				.addSource({
 					filename: 'foo.js',
 					content: new MagicString( 'var answer = 42;' )
-				})
-				.generateMap({
-					includeContent: true,
-					hires: true
 				});
+
+			generateMap(m, {
+				includeContent: true,
+				hires: true
+			});
 		});
 
 		it( 'should handle repeated sources', () => {
@@ -259,7 +269,7 @@ describe( 'MagicString.Bundle', () => {
 			const code = b.toString();
 			assert.equal( code, 'var one = 1;\nvar two = 2;\nvar three = 3;\nvar four = 4;' );
 
-			const map = b.generateMap({
+			const map = generateMap(b, {
 				includeContent: true,
 				hires: true
 			});
@@ -303,7 +313,7 @@ describe( 'MagicString.Bundle', () => {
 			b.addSource( one );
 			b.addSource( two );
 
-			const map = b.generateMap({
+			const map = generateMap(b, {
 				file: 'output.js',
 				source: 'input.js',
 				includeContent: true
@@ -330,7 +340,7 @@ describe( 'MagicString.Bundle', () => {
 			b.addSource( two );
 			b.addSource( three );
 
-			const map = b.generateMap({
+			const map = generateMap(b, {
 				file: 'output.js',
 				source: 'input.js',
 				includeContent: true
@@ -359,7 +369,7 @@ describe( 'MagicString.Bundle', () => {
 			b.addSource( one );
 			b.addSource( two );
 
-			const map = b.generateMap({
+			const map = generateMap(b, {
 				file: 'output.js',
 				source: 'input.js',
 				includeContent: true
@@ -385,7 +395,7 @@ describe( 'MagicString.Bundle', () => {
 			b.addSource( one );
 			b.addSource( two );
 
-			const map = b.generateMap({
+			const map = generateMap(b, {
 				file: 'output.js',
 				source: 'input.js',
 				includeContent: true