Initial commit of Dart transformer to generate constructor stubs, see https://github.com/angular/an…

modules/angular2/src/transform/codegen.dart

+library angular2.transformer;
+
+import 'package:analyzer/src/generated/ast.dart';
+import 'package:analyzer/src/generated/element.dart';
+import 'package:analyzer/src/generated/java_core.dart';
+import 'package:barback/barback.dart' show AssetId, TransformLogger;
+import 'package:dart_style/dart_style.dart';
+import 'package:path/path.dart' as path;
+
+import 'annotation_processor.dart';
+
+/// Base class that maintains codegen state.
+class Context {
+  final TransformLogger _logger;
+  /// Maps libraries to the import prefixes we will use in the newly
+  /// generated code.
+  final Map<LibraryElement, String> _libraryPrefixes;
+
+  DirectiveRegistry _directiveRegistry;

[jakemac, 2015/02/18 16:18:50]

might be nice to have a comment here

[tjblasi, 2015/02/18 21:18:25]

Done.

+  DirectiveRegistry get directiveRegistry => _directiveRegistry;
+
+  Context({TransformLogger logger})
+      : _logger = logger,
+        _libraryPrefixes = {} {
+    _directiveRegistry = new _DirectiveRegistryImpl(this);
+  }
+
+  void error(String errorString) {
+    if (_logger != null) {

[jakemac, 2015/02/17 23:46:45]

nit, you could rewrite this:

if (_logger == null) throw new Error(errorString);
_logger.error(errorString);

[tjblasi, 2015/02/18 21:18:25]

Done.

+      _logger.error(errorString);
+    } else {
+      throw new Error(errorString);
+    }
+  }
+
+  /// If elements in [lib] should be prefixed in our generated code, returns
+  /// the appropriate prefix followed by a `.`. Future items from the same
+  /// library will use the same prefix.
+  /// If [lib] does not need a prefix, returns the empty string.
+  String _getPrefixDot(LibraryElement lib) {
+    var prefix = lib != null && !lib.isInSdk

[jakemac, 2015/02/18 16:18:50]

I might reorganize this a little bit to return early for the null case:

if (lib == null || lib.isInSdk) return '';
return _libraryPrefixes.putIfAbsent(
    lib, () => '$i{_libraryPrefixes.length}');

[tjblasi, 2015/02/18 21:18:25]

Done.

+        ? _libraryPrefixes.putIfAbsent(lib, () => 'i${_libraryPrefixes.length}')
+        : null;
+    return prefix == null ? '' : '${prefix}.';
+  }
+}
+
+abstract class DirectiveRegistry {

[jakemac, 2015/02/18 16:18:50]

A comment here would be good

[tjblasi, 2015/02/18 21:18:25]

Done.

+  // Adds [entry] to the `registerType` calls which will be generated.
+  void register(AnnotationMatch entry);
+}
+
+const _reflectorImport =

[jakemac, 2015/02/18 16:18:50]

You might just want to use ''' here

[tjblasi, 2015/02/18 21:18:25]

Done.

+    'import \'package:angular2/src/reflection/reflection.dart\' '
+    'show reflector;';
+
+/// Default implementation to map from [LibraryElement] to [AssetId]. This
+/// assumes that [el.source] has a getter called [assetId].
+AssetId _assetIdFromLibraryElement(LibraryElement el) {
+  return (el.source as dynamic).assetId;
+}
+
+String codegenEntryPoint(Context context,
+    {LibraryElement entryPoint, AssetId newEntryPoint}) {
+  // This must be called prior to [codegenImports] or the entry point
+  // library will not be imported.
+  var entryPointPrefix = context._getPrefixDot(entryPoint);
+  // TODO(jakemac): copyright and library declaration
+  var outBuffer = new StringBuffer(_reflectorImport);
+  _codegenImports(context, newEntryPoint, outBuffer);
+  outBuffer
+    ..write('main() {')
+    ..write(context.directiveRegistry.toString())
+    ..write('${entryPointPrefix}main();}');
+
+  return new DartFormatter().format(outBuffer.toString());
+}
+
+String _codegenImports(
+    Context context, AssetId newEntryPoint, StringBuffer buffer) {
+  context._libraryPrefixes.forEach((lib, prefix) {
+    buffer
+      ..write(_codegenImport(
+          context, _assetIdFromLibraryElement(lib), newEntryPoint))
+      ..writeln('as ${prefix};');
+  });
+}
+
+_codegenImport(Context context, AssetId libraryId, AssetId entryPoint) {
+  if (libraryId.path.startsWith('lib/')) {
+    var packagePath = libraryId.path.replaceFirst('lib/', '');
+    return "import 'package:${libraryId.package}/${packagePath}'";
+  } else if (libraryId.package != entryPoint.package) {
+    context._error("Can't import `${libraryId}` from `${entryPoint}`");
+  } else if (path.url.split(libraryId.path)[0] ==
+      path.url.split(entryPoint.path)[0]) {
+    var relativePath =
+        path.relative(libraryId.path, from: path.dirname(entryPoint.path));
+    return "import '${relativePath}'";
+  } else {
+    context._error("Can't import `${libraryId}` from `${entryPoint}`");
+  }
+}
+
+class _DirectiveRegistryImpl implements DirectiveRegistry {
+  final Context _context;
+  final StringBuffer _buffer = new StringBuffer();
+
+  _DirectiveRegistryImpl(this._context);
+
+  @override
+  String toString() {
+    return _buffer.isEmpty ? '' : 'reflector${_buffer};';
+  }
+
+  // Adds [entry] to the `registerType` calls which will be generated.
+  void register(AnnotationMatch entry) {
+    var element = entry.element;
+    var annotation = entry.annotation;
+
+    if (annotation.element is! ConstructorElement) {
+      _context._error('Unsupported annotation type. '
+          'Only constructors are supported as Directives.');
+      return;
+    }
+    if (element is! ClassElement) {
+      _context._error('Directives can only be applied to classes.');
+      return;
+    }
+    if (element.node is! ClassDeclaration) {

[jakemac, 2015/02/17 23:46:46]

Just fyi, any call to `.node` is potentially pretty expensive. You probably want
to store these in a variable that gets cached. I recenty did this do the
InitializerData class in the initialize transformer,
https://github.com/dart-lang/initialize/blob/master/lib/transformer.dart#L461. I
don't have a good idea of exactly how much of an issue this is, so I will leave
it up to your best judgment as to whether its worth updating now, but I would at
least put in a TODO.

[tjblasi, 2015/02/18 21:18:25]

Added an issue [https://github.com/kegluneq/angular/issues/4] & TODO.

+      _context._error('Unsupported annotation type. '
+          'Only class declarations are supported as Directives.');
+      return;
+    }
+    final ConstructorElement ctor = element.unnamedConstructor;
+    if (ctor == null) {
+      _context._error('No default constructor found for ${element.name}');
+      return;
+    }
+
+    _buffer.writeln('..registerType(${_codegenClassTypeString(element)}, {'
+        '"factory": ${_codegenFactoryProp(ctor)},'
+        '"parameters": ${_codegenParametersProp(ctor)},'
+        '"annotations": ${_codegenAnnotationsProp(element)}'
+        '})');
+  }
+
+  String _codegenClassTypeString(ClassElement el) {
+    return '${_context._getPrefixDot(el.library)}${el.name}';
+  }
+
+  /// Creates the 'annotations' property for the Angular2 [registerType] call
+  /// for [el].
+  String _codegenAnnotationsProp(ClassElement el) {
+    var writer = new PrintStringWriter();
+    var visitor = new _AnnotationsTransformVisitor(writer, _context);
+    el.node.accept(visitor);
+    return writer.toString();
+  }
+
+  /// Creates the 'factory' property for the Angular2 [registerType] call
+  /// for [ctor].
+  String _codegenFactoryProp(ConstructorElement ctor) {
+    if (ctor.node == null) {
+      // This occurs when the class does not declare a constructor.
+      var prefix = _context._getPrefixDot(ctor.type.element.library);
+      return '() => new ${prefix}${ctor.enclosingElement.displayName}()';
+    } else {
+      var writer = new PrintStringWriter();
+      var visitor = new _FactoryTransformVisitor(writer, _context);
+      ctor.node.accept(visitor);
+      return writer.toString();
+    }
+  }
+
+  /// Creates the 'parameters' property for the Angular2 [registerType] call
+  /// for [ctor].
+  String _codegenParametersProp(ConstructorElement ctor) {
+    if (ctor.node == null) {
+      // This occurs when the class does not declare a constructor.
+      return 'const [const []]';
+    } else {
+      var writer = new PrintStringWriter();
+      var visitor = new _ParameterTransformVisitor(writer, _context);
+      ctor.node.accept(visitor);
+      return writer.toString();
+    }
+  }
+}
+
+/// Visitor providing common methods for concrete implementations.
+abstract class _TransformVisitor extends ToSourceVisitor {
+  final Context _context;
+  final PrintWriter _writer;
+
+  _TransformVisitor(PrintWriter writer, this._context)
+      : this._writer = writer,
+        super(writer);
+
+  /// Safely visit the given node.
+  /// @param node the node to be visited

[jakemac, 2015/02/17 23:46:45]

I haven't really seen us use these JavaDoc style comments, does the doc
generator support them?

[tjblasi, 2015/02/18 21:18:25]

Ah, I stole this code from analyzer, which was generated from Java code. Fixed.

+  void _visitNode(AstNode node) {
+    if (node != null) {
+      node.accept(this);
+    }
+  }
+
+  /**

[jakemac, 2015/02/17 23:46:46]

Usually we just do the /// style comments, not sure if this is against style
guides or not.

[tjblasi, 2015/02/18 21:18:25]

Done.

+   * Safely visit the given node, printing the prefix before the node if it is non-`null`.
+   *
+   * @param prefix the prefix to be printed if there is a node to visit
+   * @param node the node to be visited
+   */
+  void _visitNodeWithPrefix(String prefix, AstNode node) {
+    if (node != null) {
+      _writer.print(prefix);
+      node.accept(this);
+    }
+  }
+
+  /**
+   * Safely visit the given node, printing the suffix after the node if it is non-`null`.
+   *
+   * @param suffix the suffix to be printed if there is a node to visit
+   * @param node the node to be visited
+   */
+  void _visitNodeWithSuffix(AstNode node, String suffix) {
+    if (node != null) {
+      node.accept(this);
+      _writer.print(suffix);
+    }
+  }
+
+  @override
+  Object visitSimpleIdentifier(SimpleIdentifier node) {
+    // Make sure the identifier is prefixed if necessary.
+    if (node.bestElement is ClassElementImpl ||
+        node.bestElement is PropertyAccessorElement) {
+      _writer
+        ..print(_context._getPrefixDot(node.bestElement.library))
+        ..print(node.token.lexeme);
+    } else {
+      return super.visitSimpleIdentifier(node);
+    }
+    return null;
+  }
+}
+
+/// SourceVisitor designed to accept [ConstructorDeclaration] nodes.
+class _CtorTransformVisitor extends _TransformVisitor {
+  bool _withParameterTypes = true;
+  bool _withParameterNames = true;
+
+  _CtorTransformVisitor(PrintWriter writer, Context _context)
+      : super(writer, _context);
+
+  /// If [_withParameterTypes] is true, this method outputs [node]'s type
+  /// (appropriately prefixed based on [_libraryPrefixes]. If
+  /// [_withParameterNames] is true, this method outputs [node]'s identifier.
+  Object _visitNormalFormalParameter(NormalFormalParameter node) {
+    if (_withParameterTypes) {
+      var paramType = node.element.type;
+      var prefix = _context._getPrefixDot(paramType.element.library);
+      _writer.print('${prefix}${paramType.displayName}');
+      if (_withParameterNames) {
+        _visitNodeWithPrefix(' ', node.identifier);
+      }
+    } else if (_withParameterNames) {
+      _visitNode(node.identifier);
+    }
+    return null;
+  }
+
+  @override
+  Object visitSimpleFormalParameter(SimpleFormalParameter node) {
+    return _visitNormalFormalParameter(node);
+  }
+
+  @override
+  Object visitFieldFormalParameter(FieldFormalParameter node) {
+    if (node.parameters != null) {
+      _context.error('Parameters in ctor not supported '
+          '(${super.visitFormalParameterList(node)}');
+    }
+    return _visitNormalFormalParameter(node);
+  }
+
+  @override
+  Object visitDefaultFormalParameter(DefaultFormalParameter node) {
+    _visitNode(node.parameter);
+    return null;
+  }
+
+  @override
+  /// Overridden to avoid outputting grouping operators for default parameters.
+  Object visitFormalParameterList(FormalParameterList node) {
+    _writer.print('(');
+    NodeList<FormalParameter> parameters = node.parameters;
+    int size = parameters.length;
+    for (int i = 0; i < size; i++) {
+      if (i > 0) {
+        _writer.print(', ');
+      }
+      parameters[i].accept(this);
+    }
+    _writer.print(')');
+    return null;
+  }
+}
+
+/// ToSourceVisitor designed to print 'parameters' values for Angular2's
+/// [registerType] calls.
+class _ParameterTransformVisitor extends _CtorTransformVisitor {
+  _ParameterTransformVisitor(PrintWriter writer, Context _context)
+      : super(writer, _context);
+
+  @override
+  Object visitConstructorDeclaration(ConstructorDeclaration node) {
+    _withParameterNames = false;
+    _withParameterTypes = true;
+    _writer.print('const [const [');
+    _visitNode(node.parameters);
+    _writer.print(']]');
+    return null;
+  }
+
+  @override
+  Object visitFormalParameterList(FormalParameterList node) {
+    NodeList<FormalParameter> parameters = node.parameters;
+    int size = parameters.length;
+    for (int i = 0; i < size; i++) {
+      if (i > 0) {
+        _writer.print(', ');
+      }
+      parameters[i].accept(this);
+    }
+    return null;
+  }
+}
+
+/// ToSourceVisitor designed to print 'factory' values for Angular2's
+/// [registerType] calls.
+class _FactoryTransformVisitor extends _CtorTransformVisitor {
+  _FactoryTransformVisitor(PrintWriter writer, Context _context)
+      : super(writer, _context);
+
+  @override
+  Object visitConstructorDeclaration(ConstructorDeclaration node) {
+    _withParameterNames = true;
+    _withParameterTypes = true;
+    _visitNode(node.parameters);
+    _writer.print(' => new ');
+    _visitNode(node.returnType);
+    _visitNodeWithPrefix(".", node.name);
+    _withParameterTypes = false;
+    _visitNode(node.parameters);
+    return null;
+  }
+}
+
+/// ToSourceVisitor designed to print a [ClassDeclaration] node as a
+/// 'annotations' value for Angular2's [registerType] calls.
+class _AnnotationsTransformVisitor extends _TransformVisitor {
+  _AnnotationsTransformVisitor(PrintWriter writer, Context _context)
+      : super(writer, _context);
+
+  @override
+  Object visitClassDeclaration(ClassDeclaration node) {
+    _writer.print('const [');
+    var size = node.metadata.length;
+    for (var i = 0; i < size; ++i) {
+      if (i > 0) {
+        _writer.print(', ');
+      }
+      node.metadata[i].accept(this);
+    }
+    _writer.print(']');
+    return null;
+  }
+
+  @override
+  Object visitAnnotation(Annotation node) {
+    _writer.print('const ');
+    _visitNode(node.name);
+//     TODO(tjblasi): Do we need to handle named constructors for annotations?
+//    _visitNodeWithPrefix(".", node.constructorName);
+    _visitNode(node.arguments);
+    return null;
+  }
+}