Initial cut for a development server

lib/src/dependency_graph.dart

Index: lib/src/dependency_graph.dart
diff --git a/lib/src/dependency_graph.dart b/lib/src/dependency_graph.dart
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+/// Tracks the shape of the import/export graph and dependencies between files.

[Jennifer Messerly, 2015/03/03 02:24:21]

copyright?

[Siggi Cherem (dart-lang), 2015/03/04 04:44:23]

Done.

+library ddc.src.dependency_graph;
+
+import 'package:analyzer/analyzer.dart' show parseDirectives;
+import 'package:analyzer/src/generated/ast.dart'
+    show
+        LibraryDirective,
+        ImportDirective,
+        ExportDirective,
+        PartDirective,
+        CompilationUnit,
+        Identifier;
+import 'package:analyzer/src/generated/engine.dart'
+    show ParseDartTask, AnalysisContext;
+import 'package:analyzer/src/generated/source.dart' show Source, SourceKind;
+import 'package:html5lib/dom.dart' show Document;
+import 'package:html5lib/parser.dart' as html;
+import 'package:logging/logging.dart' show Logger;
+import 'package:path/path.dart' as path;
+
+import 'info.dart';
+import 'options.dart';
+import 'utils.dart';
+
+/// Holds references to all source nodes in the import graph. This is mainly
+/// used as a level of indirection to ensure that each source has a canonical
+/// representation.
+class SourceGraph {
+  /// All nodes in the source graph. Used to get a canonical representation for
+  /// any node.
+  Map<Uri, SourceNode> nodes = {};
+
+  /// Analyzer used to resolve source files.
+  AnalysisContext _context;

[Jennifer Messerly, 2015/03/03 02:24:22]

final?

[Siggi Cherem (dart-lang), 2015/03/04 04:44:23]

Done.

+  CompilerOptions _options;
+
+  SourceGraph(this._context, this._options);
+
+  /// Node associated with a resolved [uri].
+  SourceNode nodeFromUri(Uri uri, [bool isPart = false]) {
+    var uriString = Uri.encodeFull('$uri');
+    var kind = uriString.endsWith('.html')
+        ? SourceKind.HTML
+        : isPart ? SourceKind.PART : SourceKind.LIBRARY;
+    return nodeFor(uri, _context.sourceFactory.forUri(uriString), kind);
+  }
+
+  /// Construct the node of the given [kind] with the given [uri] and [source].
+  SourceNode nodeFor(Uri uri, Source source, SourceKind kind) {
+    // TODO(sigmund): validate canonicalization?
+    // TODO(sigmund): add support for changing a file from one kind to another
+    // (e.g.  converting a file from a part to a library).
+    return nodes.putIfAbsent(uri, () {
+      if (kind == SourceKind.HTML) {
+        return new HtmlSourceNode(uri, source);
+      } else if (kind == SourceKind.LIBRARY) {
+        return new LibrarySourceNode(uri, source);
+      } else if (kind == SourceKind.PART) {
+        return new PartSourceNode(uri, source);
+      } else {
+        assert(false); // unreachable
+      }
+    });
+  }
+}
+
+/// A node in the import graph representing a source file.
+abstract class SourceNode {
+  /// Resolved URI for this node.
+  final Uri uri;
+
+  /// Resolved source from the analyzer. We let the analyzer internally track
+  /// for modifications to the source files.
+  final Source source;
+
+  /// Last stamp read from `source.modificationStamp`.
+  int _lastStamp = 0;
+
+  /// Whether we need to rebuild this source file.
+  bool needsRebuild = false;
+
+  /// Whether the structure of dependencies from this node (scripts, imports,
+  /// exports, or parts) changed after we reparsed its contents.
+  bool structureChanged = false;
+
+  /// Direct dependencies (script tags for HtmlSourceNodes; imports, exports and
+  /// parts for LibrarySourceNodes).
+  Iterable<SourceNode> get directDeps;
+
+  SourceNode(this.uri, this.source);
+
+  /// Check for whether the file has changed and, if so, mark [needsRebuild] and
+  /// [structureChanged] as necessary.
+  void update(SourceGraph graph) {
+    int newStamp = source.modificationStamp;
+    if (newStamp > _lastStamp) {
+      _lastStamp = newStamp;
+      needsRebuild = true;
+    }
+  }
+
+  String toString() {
+    var simpleUri = uri.scheme == 'file' ? path.relative(uri.path) : "$uri";
+    return '[$runtimeType: $simpleUri]';
+  }
+}
+
+/// A node representing an entry HTML source file.
+class HtmlSourceNode extends SourceNode {
+  /// Libraries referred to via script tags.
+  Set<LibrarySourceNode> scripts = new Set<LibrarySourceNode>();

[Jennifer Messerly, 2015/03/03 02:24:21]

final?

also, we are officially Java :)

[Siggi Cherem (dart-lang), 2015/03/04 04:44:24]

In this case no, we update the entire list every time we detect a structural
change in the file. We could replace the contents of the list, or make the field
read-only from outside this library, but I'm not sure that's worth it.
sigh...

+
+  @override
+  Iterable<SourceNode> get directDeps => scripts;
+
+  /// Parsed document, updated whenever [update] is invoked.
+  Document document;
+
+  HtmlSourceNode(uri, source) : super(uri, source);
+
+  void update(SourceGraph graph) {
+    super.update(graph);
+    if (needsRebuild) {
+      document = html.parse(source.contents.data, generateSpans: true);
+      var newScripts = new Set<LibrarySourceNode>();
+      var tags = document.querySelectorAll('script[type="application/dart"]');
+      for (var script in tags) {
+        var src = script.attributes['src'];
+        if (src == null) {
+          // TODO(sigmund): expose these as compile-time failures
+          _log.severe(script.sourceSpan.message(
+              'inlined script tags not supported at this time '
+              '(see https://github.com/dart-lang/dart-dev-compiler/issues/54).',
+              color: graph._options.useColors ? colorOf('error') : false));
+          continue;
+        }
+        var node = graph.nodeFromUri(uri.resolve(src));
+        if (!node.source.exists()) {
+          _log.severe(script.sourceSpan.message('Script file $src not found',
+              color: graph._options.useColors ? colorOf('error') : false));
+        }
+        newScripts.add(node);
+      }
+
+      if (!_same(newScripts, scripts)) {
+        structureChanged = true;
+        scripts = newScripts;
+      }
+    }
+  }
+}
+
+/// A node representing a Dart part.
+class PartSourceNode extends SourceNode {
+  final Iterable<SourceNode> directDeps = const [];
+  PartSourceNode(uri, source) : super(uri, source);
+}
+
+/// A node representing a Dart library.
+class LibrarySourceNode extends SourceNode {
+  LibrarySourceNode(uri, source) : super(uri, source);
+
+  Set<LibrarySourceNode> imports = new Set<LibrarySourceNode>();
+  Set<LibrarySourceNode> exports = new Set<LibrarySourceNode>();
+  Set<PartSourceNode> parts = new Set<PartSourceNode>();
+
+  Iterable<SourceNode> get directDeps =>
+      [imports, exports, parts].expand((e) => e);
+
+  LibraryInfo info;
+
+  void update(SourceGraph graph) {
+    super.update(graph);
+    if (needsRebuild && source.contents.data != null) {
+      // If the defining compilation-unit changed, the structure might have
+      // changed.
+      var unit = parseDirectives(source.contents.data, name: source.fullName);
+      var newImports = new Set<LibrarySourceNode>();
+      var newExports = new Set<LibrarySourceNode>();
+      var newParts = new Set<PartSourceNode>();
+      for (var d in unit.directives) {
+        if (d is LibraryDirective) continue;
+        var target =
+            ParseDartTask.resolveDirective(graph._context, source, d, null);
+        var uri = target.uri;
+        var node = graph.nodeFor(uri, target,
+            d is PartDirective ? SourceKind.PART : SourceKind.LIBRARY);
+        if (!node.source.exists()) {
+          _log.severe(spanFor(unit, source.uri, d).message(
+              'File $uri not found',
+              color: graph._options.useColors ? colorOf('error') : false));
+        }
+
+        if (d is ImportDirective) {
+          newImports.add(node);
+        } else if (d is ExportDirective) {
+          newExports.add(node);
+        } else if (d is PartDirective) {
+          newParts.add(node);
+        }
+      }
+
+      if (!_same(newImports, imports)) {
+        structureChanged = true;
+        imports = newImports;
+      }
+
+      if (!_same(newExports, exports)) {
+        structureChanged = true;
+        exports = newExports;
+      }
+
+      if (!_same(newParts, parts)) {
+        structureChanged = true;
+        parts = newParts;
+      }
+    }
+
+    // The library should be marked as needing rebuild if a part changed
+    // internally:
+    for (var p in parts) {
+      p.update(graph);
+      if (p.needsRebuild) needsRebuild = true;
+    }
+  }
+}
+
+/// Updates the structure and `needsRebuild` marks in nodes of [graph] reachable
+/// from [start].
+///
+/// That is, staring from [start], we update the graph by detecting file changes
+/// and rebuilding the structure of the graph wherever it changed (an import was
+/// added or removed, etc).
+///
+/// After calling this function a node is marked with `needsRebuild` only if it
+/// contained local changes. Rebuild decisions that derive from transitive
+/// changes (e.g. when the API of a dependency changed) are handled later in
+/// [rebuild].
+void refreshStructureAndMarks(SourceNode start, SourceGraph graph) {
+  visitInPreOrder(start, (n) => n.update(graph));
+}
+
+/// Clears all the `needsRebuild` and `structureChanged` marks in nodes
+/// reachable from [start].
+void clearMarks(SourceNode start) {
+  visitInPreOrder(start, (n) => n.needsRebuild = n.structureChanged = false);
+}
+
+/// Traverses from [start] with the purpose of building any source that needs to
+/// be rebuilt.
+///
+/// This function will call [build] in a post-order fashion, on a subset of the
+/// reachable nodes. There are four rules used to decide when to rebuild a node
+/// (call [build] on a node):
+///
+///   * Only rebuild Dart libraries ([LibrarySourceNode]) or HTML files
+///     ([HtmlSourceNode]), but never part files ([PartSourceNode]). That is
+///     because those are built as part of some library.
+///
+///   * Always rebuild [LibrarySourceNode]s and [HtmlSourceNode]s with local
+///     changes or changes in a part of the library. Internally this function
+///     calls [refreshStructureAndMarks] to ensure that the graph structure is
+///     up-to-date and that these nodes with local changes contain the
+///     `needsRebuild` bit.
+///
+///   * Rebuild [HtmlSourceNode]s if there were structural changes somewhere
+///     down its reachable subgraph. This is done because HTML files embed the
+///     transitive closure of the import graph in their output.
+///
+///   * Rebuild [LibrarySourceNode]s that depend on other [LibrarySourceNode]s
+///     whose API may have changed. The result of [build] is used to determine
+///     whether other nodes need to be rebuilt. The function [build] is expected
+///     to return `true` on a node `n` if it detemines other nodes that import
+///     `n` may need to be rebuilt as well.
+rebuild(SourceNode start, SourceGraph graph, bool build(SourceNode node)) {
+  refreshStructureAndMarks(start, graph);
+  // Hold which source nodes may have changed their public API, this includes
+  // libraries that were modified or libraries that export other modified APIs.
+  // TODO(sigmund): consider removing this special support for exports? Many
+  // cases anways require using summaries to understand what parts of the public
+  // API may be affected by transitive changes. The re-export case is just one
+  // of those transitive cases, but is not sufficient. See
+  // https://github.com/dart-lang/dev_compiler/issues/76
+  var apiChangeDetected = new Set<SourceNode>();

[Jennifer Messerly, 2015/03/03 02:24:22]

by default Set is LinkedHashSet, which preserves iteration order as insertion
order. Are you exploiting that in here? If not, it might be worth switching to
`new HashSet` throughout.

[Siggi Cherem (dart-lang), 2015/03/04 04:44:23]

I'm not depending on it, so I went ahead and did the change, but I sort of like
how the code reads by just doing `new Set`. Maybe because it feels odd to
specify a specific implementation if I don't rely on the implementation
internals?

+  bool structureHasChanged = false;
+
+  bool shouldBuildNode(SourceNode n) {
+    if (n is PartSourceNode) return false;
+    if (n.needsRebuild) return true;
+    if (n is HtmlSourceNode) return structureHasChanged;
+    return (n as LibrarySourceNode).imports
+        .any((i) => apiChangeDetected.contains(i));
+  }
+
+  visitInPostOrder(start, (n) {
+    if (n.structureChanged) structureHasChanged = true;
+    if (shouldBuildNode(n)) {
+      if (build(n)) apiChangeDetected.add(n);
+    } else if (n is LibrarySourceNode &&
+        n.exports.any((e) => apiChangeDetected.contains(e))) {
+      apiChangeDetected.add(n);
+    }
+    n.needsRebuild = false;
+    n.structureChanged = false;
+  });
+}
+
+/// Helper that runs [action] on nodes reachable from [node] in pre-order.
+visitInPreOrder(SourceNode node, void action(SourceNode node),
+    {Set<SourceNode> seen}) {
+  if (seen == null) seen = new Set<SourceNode>();

[Jennifer Messerly, 2015/03/03 02:24:21]

same comment on HashSet vs LinkedHashSet

[Siggi Cherem (dart-lang), 2015/03/04 04:44:24]

Done.

+  if (seen.contains(node)) return;

[Jennifer Messerly, 2015/03/03 02:24:22]

you can combine the `contains` and `add` in one hash operation:

if (seen.add(node)) {
  ... we found a new item ...
}

(add returns `true` if it was added, false otherwise)

[Siggi Cherem (dart-lang), 2015/03/04 04:44:24]

thx, Done

+  seen.add(node);
+  action(node);
+  node.directDeps.forEach((d) => visitInPreOrder(d, action, seen: seen));
+}
+
+/// Helper that runs [action] on nodes reachable from [node] in post-order.
+visitInPostOrder(SourceNode node, void action(SourceNode node),
+    {Set<SourceNode> seen}) {
+  if (seen == null) seen = new Set<SourceNode>();
+  if (seen.contains(node)) return;
+  seen.add(node);
+  node.directDeps.forEach((d) => visitInPostOrder(d, action, seen: seen));
+  action(node);
+}
+
+bool _same(Set a, Set b) => a.length == b.length && a.containsAll(b);
+final _log = new Logger('ddc.graph');