Implement modular compilation

lib/src/codegen/js_printer.dart

-// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-import 'dart:convert' show JSON, JsonEncoder;
-import 'dart:io' show Directory, File, Platform, Process;
-
-import 'package:analyzer/dart/ast/ast.dart';
-import 'package:path/path.dart' as path;
-import 'package:source_maps/source_maps.dart' as srcmaps show Printer;
-import 'package:source_maps/source_maps.dart' show SourceMapSpan;
-import 'package:source_span/source_span.dart' show SourceLocation;
-
-import '../js/js_ast.dart' as JS;
-import '../utils.dart' show FileSystem, computeHash, locationForOffset;
-
-import 'js_names.dart' show TemporaryNamer;
-
-void writeJsLibrary(JS.Program jsTree, String outputPath, String inputDir,
-    {bool emitSourceMaps: false,
-    bool emitTypes: false,
-    FileSystem fileSystem}) {
-  var outFilename = path.basename(outputPath);
-  var outDir = path.dirname(outputPath);
-
-  JS.JavaScriptPrintingContext context;
-  if (emitSourceMaps) {
-    var printer = new srcmaps.Printer(outFilename);
-    context = new SourceMapPrintingContext(printer, outDir, inputDir, null);
-  } else {
-    context = new JS.SimpleJavaScriptPrintingContext();
-  }
-
-  var opts = new JS.JavaScriptPrintingOptions(
-      emitTypes: emitTypes,
-      allowKeywordsInProperties: true,
-      allowSingleLineIfStatements: true);
-  var jsNamer = new TemporaryNamer(jsTree);
-  jsTree.accept(new JS.Printer(opts, context, localNamer: jsNamer));
-
-  String text;
-  if (context is SourceMapPrintingContext) {
-    var printer = context.printer;
-    printer.add('//# sourceMappingURL=$outFilename.map\n');
-    // Write output file and source map
-    text = printer.text;
-    var sourceMap = JSON.decode(printer.map);
-    // TODO(jmesserly): I'm not sure where this logic came from, but we should
-    // upstream this, rather than workaround source_map's formatting ourselves.
-    var sourceMapText = new JsonEncoder.withIndent('  ').convert(sourceMap);
-    // Convert:
-    //   "names": [
-    //     "state",
-    //     "print"
-    //   ]
-    // to:
-    //   "names": ["state","print"]
-    sourceMapText =
-        sourceMapText.replaceAll('\n    ', '').replaceAll('\n  ]', ']');
-    fileSystem.writeAsStringSync('$outputPath.map', '$sourceMapText\n');
-  } else {
-    text = (context as JS.SimpleJavaScriptPrintingContext).getText();
-  }
-  fileSystem.writeAsStringSync(outputPath, text);
-  if (jsTree.scriptTag != null) {
-    // Mark executable.
-    // TODO(jmesserly): should only do this if the input file was executable?
-    if (!Platform.isWindows) Process.runSync('chmod', ['+x', outputPath]);
-  }
-}
-
-class SourceMapPrintingContext extends JS.JavaScriptPrintingContext {
-  final srcmaps.Printer printer;
-  final String outputDir;
-  final String inputDir;
-
-  final Uri baseUri;
-
-  CompilationUnit unit;
-  Uri uri;
-
-  SourceMapPrintingContext(
-      this.printer, this.outputDir, this.inputDir, this.baseUri);
-
-  void emit(String string) {
-    printer.add(string);
-  }
-
-  AstNode _currentTopLevelDeclaration;
-
-  void enterNode(JS.Node jsNode) {
-    AstNode node = jsNode.sourceInformation;
-    if (node == null || node.offset == -1) return;
-    if (unit == null) {
-      // This is a top-level declaration.  Note: consecutive top-level
-      // declarations may come from different compilation units due to
-      // parts.
-      _currentTopLevelDeclaration = node;
-      unit = node.getAncestor((n) => n is CompilationUnit);
-      uri = _makeRelativeUri(unit.element.source.uri);
-    }
-    if (unit == null) return;
-
-    assert(unit != null);
-    var loc = _location(node.offset);
-    var name = _getIdentifier(node);
-    if (name != null) {
-      // TODO(jmesserly): mark only uses the beginning of the span, but
-      // we're required to pass this as a valid span.
-      var end = _location(node.end);
-      printer.mark(new SourceMapSpan(loc, end, name, isIdentifier: true));
-    } else {
-      printer.mark(loc);
-    }
-  }
-
-  SourceLocation _location(int offset) =>
-      locationForOffset(unit.lineInfo, uri, offset);
-
-  Uri _makeRelativeUri(Uri src) {
-    if (baseUri == null) {
-      return new Uri(path: path.relative(src.path, from: outputDir));
-    } else {
-      if (src.path.startsWith('/')) {
-        return baseUri.resolve(path.relative(src.path, from: inputDir));
-      } else {
-        return baseUri.resolve(path.join('packages', src.path));
-      }
-    }
-  }
-
-  void exitNode(JS.Node jsNode) {
-    AstNode node = jsNode.sourceInformation;
-    if (unit == null || node == null || node.offset == -1) return;
-
-    // TODO(jmesserly): in many cases marking the end will be unnecessary.
-    printer.mark(_location(node.end));
-
-    if (_currentTopLevelDeclaration == node) {
-      unit = null;
-      uri = null;
-      _currentTopLevelDeclaration == null;
-      return;
-    }
-  }
-
-  String _getIdentifier(AstNode node) {
-    if (node is SimpleIdentifier) return node.name;
-    return null;
-  }
-}