Base JavaScript code position computation on JavaScript tracer.

tests/compiler/dart2js/sourcemaps/js_tracer.dart

+// Copyright (c) 2016, 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.
+
+library sourcemap.js_tracer;
+
+import 'package:compiler/src/io/source_information.dart';
+import 'package:compiler/src/io/position_information.dart';
+import 'package:compiler/src/js/js.dart' as js;
+import 'sourcemap_helper.dart';
+import 'trace_graph.dart';
+
+/// Create a [TraceGraph] for [info] registering usage in [coverage].
+TraceGraph createTraceGraph(SourceMapInfo info, Coverage coverage) {

[Siggi Cherem (dart-lang), 2016/01/21 18:18:34]

should this function move to trace_graph.dart? Or merge that library here?

[Johnni Winther, 2016/01/22 15:12:38]

This for JS trace graphs, later we will have Dart trace graphs as well (for
quality test)

+  TraceGraph graph = new TraceGraph();
+  TraceListener listener = new StepTraceListener(graph);
+  CodePositionMap codePositions =
+      new CodePositionCoverage(info.jsCodePositions, coverage);
+  JavaScriptTracer tracer = new JavaScriptTracer(
+      codePositions, [new CoverageListener(coverage), listener]);
+  info.node.accept(tracer);
+  return graph;
+}
+
+class StepTraceListener extends TraceListener {
+  Map<js.Node, TraceStep> steppableMap = <js.Node, TraceStep>{};
+  final TraceGraph graph;
+
+  StepTraceListener(this.graph);
+
+  @override
+  void onStep(js.Node node, Offset offset, StepKind kind) {
+    SourceInformation sourceInformation = node.sourceInformation;
+    SourcePositionKind sourcePositionKind = SourcePositionKind.START;
+    List text = [node];
+    switch (kind) {
+      case StepKind.FUN:
+        sourcePositionKind = SourcePositionKind.CLOSING;
+        text = ['<exit>'];
+        break;
+      case StepKind.CALL:
+        CallPosition callPosition =
+            CallPosition.getSemanticPositionForCall(node);
+        sourcePositionKind = callPosition.sourcePositionKind;
+        break;
+      case StepKind.NEW:
+      case StepKind.RETURN:
+      case StepKind.BREAK:
+      case StepKind.CONTINUE:
+      case StepKind.THROW:
+      case StepKind.EXPRESSION_STATEMENT:
+        break;
+      case StepKind.IF_CONDITION:
+        js.If ifNode = node;
+        text = ['if(', ifNode.condition, ') ...'];
+        break;
+      case StepKind.FOR_INITIALIZER:
+        js.For forNode = node;
+        text = ['for(', forNode.init, '; ...) ...'];
+        break;
+      case StepKind.FOR_CONDITION:
+        js.For forNode = node;
+        text = ['for(...;', forNode.condition, '; ...) ...'];
+        break;
+      case StepKind.FOR_UPDATE:
+        js.For forNode = node;
+        text = ['for(...; ...', forNode.update, ') ...'];
+        break;
+      case StepKind.WHILE_CONDITION:
+        js.While whileNode = node;
+        text = ['while(', whileNode.condition, ') ...'];
+        break;
+      case StepKind.DO_CONDITION:
+        js.Do doNode = node;
+        text = ['do {... } (', doNode.condition, ')'];
+        break;
+      case StepKind.SWITCH_EXPRESSION:
+        js.Switch switchNode = node;
+        text = ['switch(', switchNode.key, ') ...'];
+        break;
+
+    }
+    createTraceStep(
+        node,
+        offset: offset,
+        sourceLocation: getSourceLocation(
+            node.sourceInformation, sourcePositionKind),
+        text: text);
+  }
+
+  void createTraceStep(
+      js.Node node,
+      {Offset offset,
+       List text,
+       String note,
+       SourceLocation sourceLocation}) {
+    int id = steppableMap.length;
+
+    if (text == null) {
+      text = [node];
+    }
+
+    TraceStep step = new TraceStep(
+        id, node,
+        offset,
+        text, sourceLocation);
+    graph.addStep(step);
+
+    steppableMap[node] = step;
+  }
+
+
+  void pushBranch(BranchKind kind, [value]) {
+    var branch;
+    switch (kind) {
+      case BranchKind.CONDITION:
+        branch = value ? 't' : 'f';
+        break;
+      case BranchKind.LOOP:
+        branch = 'l';
+        break;
+      case BranchKind.CATCH:
+        branch = 'c';
+        break;
+      case BranchKind.FINALLY:
+        branch = 'F';
+        break;
+      case BranchKind.CASE:
+        branch = '$value';
+        break;
+    }
+    graph.pushBranch(branch);
+  }
+
+  void popBranch() {
+    graph.popBranch();
+  }
+}
+
+SourceLocation getSourceLocation(

[Siggi Cherem (dart-lang), 2016/01/21 18:18:34]

seems you already agreed with my other suggestion ;-). Let's move this to the
source library then.

[Johnni Winther, 2016/01/22 15:12:38]

Done.

+    SourceInformation sourceInformation,
+    [SourcePositionKind sourcePositionKind = SourcePositionKind.START]) {
+  if (sourceInformation == null) return null;
+  switch (sourcePositionKind) {
+    case SourcePositionKind.START:
+      return sourceInformation.startPosition;
+    case SourcePositionKind.CLOSING:
+      return sourceInformation.closingPosition;
+    case SourcePositionKind.END:
+      return sourceInformation.endPosition;
+  }
+}