Generate source maps during transpilation.

Also refactor the interface to ts2dart to pass an options object,
for better readability of the call sites.

Author: mprobst

lib/main.ts

@@ -1,22 +1,45 @@
-/// <reference path="../typings/node/node.d.ts" />
+/// <reference path='../typings/node/node.d.ts' />
+/// <reference path='../typings/source-map/source-map.d.ts' />
 // Use HEAD version of typescript, installed by npm
-/// <reference path="../node_modules/typescript/bin/typescript.d.ts" />
+/// <reference path='../node_modules/typescript/bin/typescript.d.ts' />
 require('source-map-support').install();
-import ts = require("typescript");
-import fs = require("fs");
+import fs = require('fs');
+import SourceMap = require('source-map');
+import ts = require('typescript');
 
 export type ClassLike = ts.ClassDeclaration | ts.InterfaceDeclaration;
 
+export interface TranspilerOptions {
+  failFast?: boolean;
+  generateLibraryName?: boolean;
+  generateSourceMap?: boolean;
+}
+
 export class Transpiler {
+  // Position information.
+  generateSourceMap: boolean;
+  sourceMap: SourceMap.SourceMapGenerator;
+
+  generateLibraryName: boolean;
+  relativeFileName: string;
+  currentFile: ts.SourceFile;
+
   result: string = '';
+  column: number = 1;
+  line: number = 1;
+
   // Comments attach to all following AST nodes before the next 'physical' token. Track the earliest
   // offset to avoid printing comments multiple times.
   lastCommentIdx: number = -1;
-  currentFile: ts.SourceFile;
-  relativeFileName: string;
+
+  failFast: boolean;
   errors: string[] = [];
 
-  constructor(private failFast: boolean = false, private generateLibraryName: boolean = false) {}
+  constructor(opts: TranspilerOptions = {}) {
+    this.failFast = !!opts.failFast;
+    this.generateLibraryName = !!opts.generateLibraryName;
+    this.generateSourceMap = !!opts.generateSourceMap;
+  }
 
   static OPTIONS: ts.CompilerOptions = {
     target: ts.ScriptTarget.ES6,
@@ -26,11 +49,18 @@ export class Transpiler {
 
   translateProgram(program: ts.Program, relativeFileName: string): string {
     this.relativeFileName = relativeFileName;
-    return program.getSourceFiles()
-        .filter((sourceFile: ts.SourceFile) => !sourceFile.fileName.match(/\.d\.ts$/) &&
-                                               !!sourceFile.fileName.match(/\.[jt]s$/))
-        .map((f) => this.translate(f))
-        .join('\n');
+    var src = program.getSourceFiles()
+                  .filter((sourceFile: ts.SourceFile) => !sourceFile.fileName.match(/\.d\.ts$/) &&
+                                                         !!sourceFile.fileName.match(/\.[jt]s$/))
+                  .map((f) => this.translate(f))
+                  .join('\n');
+    if (this.sourceMap) src += this.generateSourceMapComment();
+    return src;
+  }
+
+  generateSourceMapComment() {
+    var base64map = new Buffer(JSON.stringify(this.sourceMap)).toString('base64');
+    return '\n\n//# sourceMappingURL=data:application/json;base64,' + base64map;
   }
 
   createCompilerHost(files: string[]): ts.CompilerHost {
@@ -80,19 +110,51 @@ export class Transpiler {
     this.result = '';
     this.errors = [];
     this.lastCommentIdx = -1;
-    this.currentFile = sourceFile.getSourceFile();
+    this.currentFile = sourceFile;
+    if (this.generateSourceMap) {
+      this.sourceMap = new SourceMap.SourceMapGenerator({file: this.relativeFileName + '.dart'});
+      this.sourceMap.setSourceContent(this.relativeFileName, this.currentFile.text);
+    }
     this.visit(sourceFile);
     if (this.errors.length) {
       var e = new Error(this.errors.join('\n'));
       e.name = 'TS2DartError';
       throw e;
     }
+
     return this.result;
   }
 
+  enterNode(n: ts.Node) {
+    if (!this.sourceMap) return; // source maps disabled.
+    var file = n.getSourceFile() || this.currentFile;
+    var start = n.getStart(file);
+    var pos = file.getLineAndCharacterOfPosition(start);
+
+    var mapping: SourceMap.Mapping = {
+      original: {line: pos.line + 1, column: pos.character},
+      generated: {line: this.line, column: this.column},
+      source: this.relativeFileName,
+    };
+
+    this.sourceMap.addMapping(mapping);
+  }
+
   emit(str: string) {
-    this.result += ' ';
+    this.emitNoSpace(' ');
+    this.emitNoSpace(str);
+  }
+
+  emitNoSpace(str: string) {
     this.result += str;
+    for (var i = 0; i < str.length; i++) {
+      if (str[i] === '\n') {
+        this.line++;
+        this.column = 0;
+      } else {
+        this.column++;
+      }
+    }
   }
 
   visitEach(nodes: ts.Node[]) { nodes.forEach((n) => this.visit(n)); }
@@ -144,7 +206,7 @@ export class Transpiler {
       this.visitParameters(fn);
     } else {
       if (fn.parameters && fn.parameters.length > 0) {
-        this.reportError(fn, "getter should not accept parameters");
+        this.reportError(fn, 'getter should not accept parameters');
       }
     }
     if (fn.body) {
@@ -583,14 +645,15 @@ export class Transpiler {
   }
 
   visit(node: ts.Node) {
+    this.enterNode(node);
     var comments = ts.getLeadingCommentRanges(this.currentFile.text, node.getFullStart());
     if (comments) {
       comments.forEach((c) => {
         if (c.pos <= this.lastCommentIdx) return;
         this.lastCommentIdx = c.pos;
         var text = this.currentFile.text.substring(c.pos, c.end);
         this.emit(text);
-        if (c.hasTrailingNewLine) this.result += '\n';
+        if (c.hasTrailingNewLine) this.emitNoSpace('\n');
       });
     }
 
@@ -773,7 +836,7 @@ export class Transpiler {
         this.emit(`'''${this.escapeTextForTemplateString(node)}'''`);
         break;
       case ts.SyntaxKind.TemplateMiddle:
-        this.result += this.escapeTextForTemplateString(node);
+        this.emitNoSpace(this.escapeTextForTemplateString(node));
         break;
       case ts.SyntaxKind.TemplateExpression:
         var tmpl = <ts.TemplateExpression>node;
@@ -784,16 +847,16 @@ export class Transpiler {
         this.emit(`'''${this.escapeTextForTemplateString(node)}`); //highlighting bug:'
         break;
       case ts.SyntaxKind.TemplateTail:
-        this.result += this.escapeTextForTemplateString(node);
-        this.result += `'''`;
+        this.emitNoSpace(this.escapeTextForTemplateString(node));
+        this.emitNoSpace(`'''`);
         break;
       case ts.SyntaxKind.TemplateSpan:
         var span = <ts.TemplateSpan>node;
         if (span.expression) {
           // Do not emit extra whitespace inside the string template
-          this.result += '${';
+          this.emitNoSpace('${');
           this.visit(span.expression);
-          this.result += '}';
+          this.emitNoSpace('}');
         }
         if (span.literal) this.visit(span.literal);
         break;
@@ -813,9 +876,9 @@ export class Transpiler {
         var propAssign = <ts.PropertyAssignment>node;
         if (propAssign.name.kind === ts.SyntaxKind.Identifier) {
           // Dart identifiers in Map literals need quoting.
-          this.result += ' "';
-          this.result += (<ts.Identifier>propAssign.name).text;
-          this.result += '"';
+          this.emitNoSpace(' "');
+          this.emitNoSpace((<ts.Identifier>propAssign.name).text);
+          this.emitNoSpace('"');
         } else {
           this.visit(propAssign.name);
         }
@@ -824,9 +887,9 @@ export class Transpiler {
         break;
       case ts.SyntaxKind.ShorthandPropertyAssignment:
         var shorthand = <ts.ShorthandPropertyAssignment>node;
-        this.result += ' "';
-        this.result += shorthand.name.text;
-        this.result += '"';
+        this.emitNoSpace(' "');
+        this.emitNoSpace(shorthand.name.text);
+        this.emitNoSpace('"');
         this.emit(':');
         this.visit(shorthand.name);
         break;

package.json

@@ -7,6 +7,7 @@
     "test": "test"
   },
   "dependencies": {
+    "source-map": "^0.4.2",
     "source-map-support": "^0.2.9",
     "typescript": "Microsoft/TypeScript#cebe42b81fbeeaf68c8e228dda5e602ab94e151b"
   },

test/DartTest.ts

@@ -1,12 +1,13 @@
 /// <reference path="../typings/chai/chai.d.ts"/>
 /// <reference path="../typings/mocha/mocha.d.ts"/>
+/// <reference path="../typings/source-map/source-map.d.ts"/>
 /// <reference path="../typings/source-map-support/source-map-support.d.ts"/>
 
-import sms = require('source-map-support');
-sms.install();
+require('source-map-support').install();
 
 import chai = require('chai');
 import main = require('../lib/main');
+import SourceMap = require('source-map');
 import ts = require('typescript');
 
 describe('transpile to dart', () => {
@@ -573,7 +574,7 @@ describe('transpile to dart', () => {
 
   describe('library name', () => {
     var transpiler;
-    beforeEach(() => transpiler = new main.Transpiler(true, /* generateLibraryName */ true));
+    beforeEach(() => transpiler = new main.Transpiler({failFast: true, generateLibraryName: true}));
     it('adds a library name', () => {
       var program = parseProgram('var x;', '/a/b/c.ts');
       var res = transpiler.translateProgram(program, 'a/b/c.ts');
@@ -592,6 +593,28 @@ describe('transpile to dart', () => {
     it('handles non word characters',
        () => { chai.expect(transpiler.getLibraryName('a/%x.ts')).to.equal('a._x'); });
   });
+
+  describe('source maps', () => {
+    var transpiler: main.Transpiler;
+    beforeEach(() => transpiler = new main.Transpiler({failFast: true, generateSourceMap: true}));
+    function expectTranslateMap(source) {
+      var program = parseProgram(source, '/absolute/path/test.ts');
+      var res = transpiler.translateProgram(program, 'path/test.ts');
+      return chai.expect(res);
+    }
+    it('generates a source map', () => {
+      expectTranslateMap('var x;').to.contain('//# sourceMappingURL=data:application/json;base64,');
+    });
+    it('maps locations', () => {
+      expectTranslateMap('var xVar: number;\nvar yVar: string;')
+          .to.contain(' num xVar ; String yVar ;');
+      var consumer = new SourceMap.SourceMapConsumer(<any>transpiler.sourceMap.toString());
+      var expectedColumn = ' num xVar ; String yVar ;'.indexOf('yVar') + 1;
+      var pos = consumer.originalPositionFor({line: 1, column: expectedColumn});
+      chai.expect(pos).to.include({line: 2, column: 4});
+      chai.expect(consumer.sourceContentFor('path/test.ts')).to.contain('yVar: string');
+    });
+  });
 });
 
 function parseProgram(contents: string, fileName = 'file.ts'): ts.Program {
@@ -629,6 +652,6 @@ function parseProgram(contents: string, fileName = 'file.ts'): ts.Program {
 
 function translateSource(contents: string, failFast = true): string {
   var program = parseProgram(contents);
-  var transpiler = new main.Transpiler(failFast, /* generateLibraryName */ false);
-  return transpiler.translateProgram(program, null);
+  var transpiler = new main.Transpiler({failFast});
+  return transpiler.translateProgram(program, 'test.ts');
 }

tsd.json

@@ -16,6 +16,9 @@
     },
     "source-map-support/source-map-support.d.ts": {
       "commit": "69bdfb0884020e41f17a1dd80ad4c77de2636874"
+    },
+    "source-map/source-map.d.ts": {
+      "commit": "2520bce9a8a71b66e67487cbd5b33fec880b0c55"
     }
   }
 }