work in progress: observable implementation using detailed change records

lib/src/dart_parser.dart

Index: lib/src/dart_parser.dart
diff --git a/lib/src/dart_parser.dart b/lib/src/dart_parser.dart
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+// Copyright (c) 2012, 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.
+
+/**
+ * Parser for Dart code based on the dart2js parser.
+ *
+ * Use [DartCodeParser.parse] to parse top-level code, and the returned
+ * instance to parse additonal structures such as classes.
+ */
+library dart_parser;
+
+import 'dart:uri';
+import 'dart:utf';
+import 'package:compiler_unsupported/implementation/dart2jslib.dart' as dart2js;
+import 'package:compiler_unsupported/implementation/elements/elements.dart';
+import 'package:compiler_unsupported/implementation/elements/modelx.dart';
+import 'package:compiler_unsupported/implementation/scanner/scannerlib.dart';
+import 'package:compiler_unsupported/implementation/source_file.dart';
+import 'package:compiler_unsupported/implementation/tree/tree.dart';
+import 'package:compiler_unsupported/implementation/util/util.dart';
+import 'package:compiler_unsupported/implementation/util/characters.dart';
+import 'package:compiler_unsupported/compiler.dart' as api;
+import 'package:html5lib/dom_parsing.dart' as dom_parsing;
+import 'messages.dart' show Messages;
+import 'file_system/path.dart' as fs;
+
+// TODO(jmesserly): reconcile this with DartCodeInfo
+class DartCodeParser {
+  final DiagnosticListener diagnostics;
+  final CompilationUnitElement unit;
+  final String code;
+  bool _success;
+
+  bool get success => _success;
+
+  Messages get messages => diagnostics.messages;
+
+  DartCodeParser._parse(this.diagnostics, this.unit, this.code) {
+    _success = _parseCompilationUnit();
+  }
+
+  /**
+   * Performs a partial parse of Dart code and returns the parser.
+   * From their you can determine if the parse was a [success] and get the
+   * compilation [unit].
+   *
+   * The partial parse only parses the top-level structure. Futher parsing can
+   * then be performed using the parser, such as [parseClass].
+   *
+   * You can provide a object to receive warning and error [messages] from the
+   * parser, otherwise [this.messages] will be a new messages instance that is
+   * silent (does not print).
+   */
+  factory DartCodeParser.parse(String path, String code, {Messages messages}) {
+    if (messages == null) messages = new Messages.silent();
+    var uri = new Uri.fromComponents(path: path);
+    var script = new dart2js.Script(uri, new SourceFile(uri.toString(), code));
+    var unit = new LibraryElementX(script, uri).entryCompilationUnit;
+    var fileSpanInfo = _createSourceFileInfo(code);
+    var diagnostics = new DiagnosticListener(fileSpanInfo, unit, messages);
+    return new DartCodeParser._parse(diagnostics, unit, code);
+  }
+
+  bool _parseCompilationUnit() {
+    int nextFreeClassId = 0;
+    var idGenerator = () => nextFreeClassId++;
+    var listener = new ElementListener(diagnostics, unit, idGenerator);
+
+    // Try parsing the code. Note that the parser can throw an exception to bail
+    // out of the call stack.
+    try {
+      var tokens = new StringScanner(code).tokenize();
+      new PartialParser(listener).parseUnit(tokens);
+      return true;
+    } on dart2js.CompilerCancelledException catch (e) {
+      return false;
+    }
+  }
+
+  ClassNode parseClass(PartialClassElement element) {
+    if (element.cachedNode != null) return element.cachedNode;
+    var listener = new MemberListener(diagnostics, element);
+    var parser = new ClassElementParser(listener);
+    var token = parser.parseTopLevelDeclaration(element.beginToken);
+    assert(identical(token, element.endToken.next));
+    var classNode = listener.popNode();
+    assert(listener.nodes.isEmpty);
+    return element.cachedNode = classNode;
+  }
+}
+
+
+/**
+ * DiagnosticListener for dart2js. Figures out warning/error spans, and adapts
+ * them to the [Messages] format used in web_ui.
+ *
+ * This class is madness. It has to deal with spans/messages/paths/uris from
+ * 3+ compilers colliding (for those keeping score: dart2js, frog remnants
+ * inside dart2js, html5lib, and web_ui ...). Also a lot of this code had to be
+ * copied from the dart2js Compiler class to make DiagnosticListener actually
+ * work.
+ *
+ * Avert your eyes!
+ */
+class DiagnosticListener implements dart2js.DiagnosticListener {
+  final dom_parsing.SourceFileInfo fileInfo;
+  final CompilationUnitElement currentElement;
+  final Messages messages;
+
+  DiagnosticListener(this.fileInfo, this.currentElement, this.messages);
+
+  void cancel(String reason, {node, token, instruction, element}) {
+    SourceSpan span = null;
+    if (node != null) {
+      span = spanFromNode(node);
+    } else if (token != null) {
+      span = spanFromTokens(token, token);
+    } else if (instruction != null) {
+      span = spanFromHInstruction(instruction);
+    } else if (element != null) {
+      span = spanFromElement(element);
+    } else {
+      throw 'No error location for error: $reason';
+    }
+    reportMessageString(span, reason, api.Diagnostic.ERROR);
+    throw new CompilerCancelledException(reason);
+  }
+
+  SourceSpan spanFromTokens(Token begin, Token end, [Uri uri]) {
+    if (begin == null || end == null) {
+      // TODO(ahe): We can almost always do better. Often it is only
+      // end that is null. Otherwise, we probably know the current
+      // URI.
+      throw 'Cannot find tokens to produce error message.';
+    }
+    if (uri == null && currentElement != null) {
+      uri = currentElement.getCompilationUnit().script.uri;
+    }
+    return SourceSpan.withCharacterOffsets(begin, end,
+      (beginOffset, endOffset) => new SourceSpan(uri, beginOffset, endOffset));
+  }
+
+  SourceSpan spanFromNode(Node node, [Uri uri]) {
+    return spanFromTokens(node.getBeginToken(), node.getEndToken(), uri);
+  }
+
+  SourceSpan spanFromElement(Element element) {
+    if (Elements.isErroneousElement(element)) {
+      element = element.enclosingElement;
+    }
+    if (element.position() == null && !element.isCompilationUnit()) {
+      // Sometimes, the backend fakes up elements that have no
+      // position. So we use the enclosing element instead. It is
+      // not a good error location, but cancel really is "internal
+      // error" or "not implemented yet", so the vicinity is good
+      // enough for now.
+      element = element.enclosingElement;
+      // TODO(ahe): I plan to overhaul this infrastructure anyways.
+    }
+    if (element == null) {
+      element = currentElement;
+    }
+    Token position = element.position();
+    Uri uri = element.getCompilationUnit().script.uri;
+    return (position == null)
+        ? new SourceSpan(uri, 0, 0)
+        : spanFromTokens(position, position, uri);
+  }
+
+  SourceSpan spanFromHInstruction(HInstruction instruction) {
+    Element element = instruction.sourceElement;
+    if (element == null) element = currentElement;
+    var position = instruction.sourcePosition;
+    if (position == null) return spanFromElement(element);
+    Token token = position.token;
+    if (token == null) return spanFromElement(element);
+    Uri uri = element.getCompilationUnit().script.uri;
+    return spanFromTokens(token, token, uri);
+  }
+
+  void log(message) {
+    print(message);
+  }
+
+  void internalError(String message,
+                     {Node node, Token token, HInstruction instruction,
+                      Element element}) {
+    cancel('Internal error: $message', node: node, token: token,
+           instruction: instruction, element: element);
+  }
+
+  void internalErrorOnElement(Element element, String message) {
+    internalError(message, element: element);
+  }
+
+  // What you say? One kind of "Diagnostic" isn't enough? Well, have two!
+  void reportMessage(SourceSpan span, Diagnostic message, api.Diagnostic kind) {
+    reportMessageString(span, "$message", kind);
+  }
+
+  // Note: renamed this, because otherwise you had "reportDiagnostic" reporting
+  // message strings and "reportMessage" reporting Diagnostics...
+  void reportMessageString(SourceSpan span, String message,
+      api.Diagnostic kind) {
+
+    // TODO(jmesserly): we should validate that the Uri is what we expected.
+    var msg = message.toString();
+    var ourSpan = convertToOurSpan(span);
+    var file = new fs.Path(span.uri.toString());
+
+    switch (kind) {
+      case api.Diagnostic.ERROR:
+      case api.Diagnostic.CRASH:
+        messages.error(msg, ourSpan, file: file);
+        return;
+      case api.Diagnostic.WARNING:
+        messages.error(msg, ourSpan, file: file);
+        return;
+      case api.Diagnostic.LINT:
+      case api.Diagnostic.INFO:
+      case api.Diagnostic.VERBOSE_INFO:
+        messages.info(msg, ourSpan, file: file);
+        return;
+    }
+  }
+
+  bool onDeprecatedFeature(Spannable span, String feature) {
+    // Not our job to warn about deprecated Dart features
+    return false;
+  }
+
+  dom_parsing.SourceSpan convertToOurSpan(SourceSpan span) {
+    // TODO(jmesserly): make html5lib spans less crazy.
+    return new dom_parsing.SourceSpan(fileInfo, span.begin, span.end);
+  }
+}
+
+
+// TODO(jmesserly): fix dom_parsing.SourceFileInfo. It should compute line
+// locations itself on demand and caching. At the very least this function
+// should move into that class.
+dom_parsing.SourceFileInfo _createSourceFileInfo(String text) {
+  var lineStarts = <int>[0];
+  var chars = stringToCodepoints(text);
+
+  for (int i = 0; i < chars.length; i++) {
+    var c = chars[i];
+
+    if (c == $CR) {
+      // Return not followed by newline is treated as a newline
+      int j = i + 1;
+      if (j >= chars.length || chars[j] != $LF) {
+        c = $LF;
+      }
+    }
+
+    if (c == $LF) lineStarts.add(i + 1);
+  }
+
+  return new dom_parsing.SourceFileInfo(lineStarts, chars);
+}