Add tool for viewing source maps.

tools/dart2js/sourceMapViewer/web/display.dart

Index: tools/dart2js/sourceMapViewer/web/display.dart
diff --git a/tools/dart2js/sourceMapViewer/web/display.dart b/tools/dart2js/sourceMapViewer/web/display.dart
new file mode 100644
index 0000000000000000000000000000000000000000..a6d02bec24852d68244abe8d3efb98fb3444cabb
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+++ b/tools/dart2js/sourceMapViewer/web/display.dart
@@ -0,0 +1,323 @@
+// Copyright (c) 2014, 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:html';
+import 'dart:convert';
+import 'dart:async';
+import 'package:source_maps/source_maps.dart';
+
+Element targetFileName = querySelector("#target_filename");
+Element sourceFileName = querySelector("#source_filename");
+DivElement generatedOutput = querySelector("#generated_output");
+DivElement selectedSource = querySelector("#selected_source");
+DivElement selectedOutputSpan = querySelector("#current_span");
+DivElement decodedMap = querySelector("#decoded_map");
+DivElement originalMap = querySelector("#original_map");
+
+Map<TargetEntry, List<SpanElement>> targetEntryMap = {};
+List<SpanElement> highlightedMapEntry = null;
+List<String> target;
+SingleMapping sourceMap;
+
+void adjustDivHeightsToWindow() {
+  generatedOutput.style.height = "${window.innerHeight / 3 - 50}px";
+  selectedSource.style.height = "${window.innerHeight / 3 - 50}px";
+  decodedMap.style.height = "${window.innerHeight / 3 - 50}px";
+  originalMap.style.height = "${window.innerHeight / 3 - 50}px";
+}
+
+Future getMap() {
+  Completer c = new Completer();
+  HttpRequest httpRequest = new HttpRequest();
+  httpRequest
+      ..open('GET', '/map')
+      ..onLoadEnd.listen((_) => c.complete(httpRequest.responseText))
+      ..send('');
+  return c.future;
+}
+
+Future fetchFile(String path) {
+  Completer c = new Completer();
+  HttpRequest httpRequest = new HttpRequest();
+  sourceFileName.text = path;
+  httpRequest
+      ..open('GET', path)
+      ..onLoadEnd.listen((_) => c.complete(httpRequest.responseText))
+      ..send('');
+  return c.future;
+}
+
+displaySource(String filename, List<String> source, TargetEntry entry) {
+  int line = entry.sourceLine;
+  int column = entry.sourceColumn;
+  int nameId = entry.sourceNameId;
+  String id = nameId == null ? null : sourceMap.names[nameId];
+  selectedSource.children.clear();
+  SpanElement marker = new SpanElement()
+      ..className = "marker"
+      ..appendText("*");
+  for (int pos = 0; pos < source.length; pos++) {
+    String l = source[pos];
+    if (pos != line) {
+      selectedSource.children.add(l.isEmpty ? new BRElement() : new DivElement()
+          ..appendText(l));
+    } else {
+      selectedSource.children.add(new DivElement()
+          ..appendText(l.substring(0, column))
+          ..children.add(marker)
+          ..appendText(l.substring(column)));
+    }
+  }
+  sourceFileName.text = filename;
+  marker.scrollIntoView();
+}
+
+void highlightSelectedSpan(TargetEntry entry, TargetLineEntry lineEntry) {
+  selectedOutputSpan.children.clear();
+  String spanEndCol;
+  TargetEntry spanEnd;
+  bool nextEntryIsSpanEnd = false;
+  for (TargetEntry e in lineEntry.entries) {
+    if (nextEntryIsSpanEnd) {
+      spanEnd = e;
+      break;
+    }
+    if (e == entry) {
+      nextEntryIsSpanEnd = true;
+    }
+  }
+  if (spanEnd == null) {
+    spanEndCol = '${target[lineEntry.line].length} (EOL).';
+  } else {
+    spanEndCol = '${spanEnd.column}.';
+  }
+
+  String targetSpan =
+      'Target:  Line ${lineEntry.line} Col. ${entry.column} - $spanEndCol';
+
+  if (entry.sourceUrlId == null) {
+    targetSpan += ' Source: unknown';
+    selectedOutputSpan.children.add(getTextElement(targetSpan));
+    return;
+  }
+
+  String source = sourceMap.urls[entry.sourceUrlId];
+  String sourceName = source.substring(source.lastIndexOf('/') + 1);
+  String sourcePoint =
+      'Source: Line ${entry.sourceLine} Col. ${entry.sourceColumn}';
+  sourcePoint +=
+      entry.sourceNameId == null ? ''
+      : ' (${sourceMap.names[entry.sourceNameId]})';
+  sourcePoint += ' in $sourceName';
+  selectedOutputSpan.children.add(getTextElement(targetSpan));
+  selectedOutputSpan.children.add(new BRElement());
+  selectedOutputSpan.children.add(getTextElement(sourcePoint));
+
+  if (highlightedMapEntry != null) {
+    highlightedMapEntry[0].style.background = 'white';
+    highlightedMapEntry[1].style.background = 'white';
+  }
+
+  String highlightColor = "#99ff99";
+  highlightedMapEntry = targetEntryMap[entry];
+  highlightedMapEntry[0]
+     ..scrollIntoView()
+     ..style.backgroundColor = highlightColor;
+  highlightedMapEntry[1]
+     ..scrollIntoView()
+     ..style.backgroundColor = highlightColor;
+  highlightedMapEntry[1].onMouseOver.listen((e) {
+    selectedOutputSpan.style.zIndex = "2";
+    selectedOutputSpan.style.visibility = "visible";
+    selectedOutputSpan.style.top = "${decodedMap.offsetTo(document.body).y +
+                                      decodedMap.clientHeight - 20}px";
+    selectedOutputSpan.style.left = "${decodedMap.offsetTo(document.body).x}px";
+    selectedOutputSpan.style.width= "${decodedMap.clientWidth}px";
+  });
+
+  highlightedMapEntry[1].onMouseOut.listen( (e) {
+    selectedOutputSpan.style.visibility = "hidden";
+  });
+
+  adjustDivHeightsToWindow();
+}
+
+void loadSource(TargetEntry entry) {
+  if (entry.sourceUrlId == null) {
+    return;
+  }
+
+  String source = sourceMap.urls[entry.sourceUrlId];
+  fetchFile(new Uri(path: "/file",
+                    queryParameters: {"path": source}).toString()).then((text)
+                        => displaySource(source, text.split("\n"), entry));
+  selectedSource.text = "loading";
+}
+
+SpanElement createSpan(String content, TargetEntry entry,
+                       TargetLineEntry lineEntry) {
+    return new SpanElement()
+    ..addEventListener('click', (e) {
+       loadSource(entry);
+       highlightSelectedSpan(entry, lineEntry);
+     }, false)
+    ..className = "range${entry.sourceUrlId % 4}"
+    ..appendText(content);
+}
+
+Element getLineNumberElement(int line) {
+  SpanElement result = new SpanElement();
+  result.style.fontFamily = "Courier";
+  result.style.fontSize = "10pt";
+  result.appendText("${line} ");
+  return result;
+}
+
+Element getTextElement(String text) {
+  SpanElement result = new SpanElement();
+  result.text = text;
+  return result;
+}
+
+addTargetLine(int lineNumber, String content, TargetLineEntry lineEntry) {
+  if (content.isEmpty) {
+    generatedOutput.children.add(new DivElement()
+        ..children.add(getLineNumberElement(lineNumber)));
+    return;
+  }
+  if (lineEntry == null) {
+    generatedOutput.children.add(new DivElement()
+        ..children.add(getLineNumberElement(lineNumber))
+        ..children.add(getTextElement(content)));
+    return;
+  }
+  DivElement div = new DivElement();
+  div.children.add(getLineNumberElement(lineNumber));
+
+  int pos = 0;
+  TargetEntry previous = null;
+  for (TargetEntry next in lineEntry.entries) {
+    if (previous == null) {
+      if (pos < next.column) {
+        div.appendText(content.substring(pos, next.column));
+      }
+      if (content.length == next.column) {
+        div.children.add(createSpan(" ", next, lineEntry));
+      }
+    } else {
+      if (next.column <= content.length) {
+        String token = content.substring(pos, next.column);
+        div.children.add(createSpan(token, previous, lineEntry));
+      }
+      if (content.length == next.column) {
+        div.children.add(createSpan(" ", next, lineEntry));
+      }
+    }
+    pos = next.column;
+    previous = next;
+  }
+  String token = content.substring(pos);
+  if (previous == null) {
+    div.appendText(token);
+  } else {
+    div..children.add(createSpan(token, previous, lineEntry));
+  }
+  generatedOutput.children.add(div);
+}
+
+// Display the target source in the HTML.
+void displayTargetSource() {
+  List<TargetLineEntry> targetLines = sourceMap.lines;
+  int linesIndex = 0;
+  for (int line = 0; line < target.length; line++) {
+    TargetLineEntry entry = null;
+    if (linesIndex < targetLines.length
+        && targetLines[linesIndex].line == line) {
+      entry = targetLines[linesIndex];
+      linesIndex++;
+    }
+    if (entry != null) {
+      addTargetLine(line, target[line], entry);
+    } else {
+      addTargetLine(line, target[line], null);
+    }
+  }
+}
+
+String getMappedData(String mapFileContent) {
+  // Source map contains mapping information in this format:
+  // "mappings": "A;A,yC;"
+  List<String> mapEntry = mapFileContent.split('mappings');
+  return mapEntry[mapEntry.length-1].split('"')[2];
+}
+
+SpanElement createMapSpan(String segment) {
+  return new SpanElement()..text = segment;
+}
+
+SpanElement createDecodedMapSpan(TargetEntry entry) {
+  return new SpanElement()..text = '(${entry.column}, ${entry.sourceUrlId},'
+                                   ' ${entry.sourceLine},'
+                                   ' ${entry.sourceColumn})';
+}
+
+displayMap(String mapFileContent) {
+  String mappedData = getMappedData(mapFileContent);
+  int sourceMapLine = 0;
+  for (String group in mappedData.split(';')) {
+    if (group.length == 0) continue;
+
+    List<String> segments = [];
+    if (!group.contains(',')) {
+      segments.add(group);
+    } else {
+      segments = group.split(',');
+    }
+
+    TargetLineEntry targetLineEntry = sourceMap.lines[sourceMapLine];
+    decodedMap.children.add(getLineNumberElement(targetLineEntry.line));
+    originalMap.children.add(getLineNumberElement(targetLineEntry.line));
+    bool first = true;
+    int entryNumber = 0;
+    for (String segment in segments) {
+      TargetEntry entry = targetLineEntry.entries[entryNumber];
+      SpanElement orignalMapSpan = createMapSpan(segment);
+      SpanElement decodedMapSpan = createDecodedMapSpan(entry);
+      if (first) {
+        first = false;
+      } else {
+        originalMap.children.add(getTextElement(', '));
+        decodedMap.children.add(getTextElement(', '));
+      }
+      originalMap.children.add(orignalMapSpan);
+      decodedMap.children.add(decodedMapSpan);
+      ++entryNumber;
+      targetEntryMap.putIfAbsent(entry, () => [orignalMapSpan, decodedMapSpan]);
+    }
+    originalMap.children.add(new BRElement());
+    decodedMap.children.add(new BRElement());
+    ++sourceMapLine;
+  }
+}
+
+void main() {
+  Future load(String q) => fetchFile(new Uri(path: "/file", queryParameters: {
+    "path": q
+  }).toString());
+
+  getMap().then((mapFileName) {
+    load(mapFileName).then((mapFileContent) {
+      sourceMap = new SingleMapping.fromJson(JSON.decode(mapFileContent));
+      displayMap(mapFileContent);
+      targetFileName.text = sourceMap.targetUrl;
+      load(targetFileName.text).then((targetFileContent) {
+        target = targetFileContent.split('\n');
+        displayTargetSource();
+        adjustDivHeightsToWindow();
+      });
+    });
+  });
+
+  sourceFileName.text = "<source not selected>";
+}