observatory/vm: add support for computing/passing end tokens on classes

runtime/bin/vmservice/client/lib/src/service/object.dart

Index: runtime/bin/vmservice/client/lib/src/service/object.dart
diff --git a/runtime/bin/vmservice/client/lib/src/service/object.dart b/runtime/bin/vmservice/client/lib/src/service/object.dart
index 09b0de853ab1bc0a891d5aa9d999b71d3a811573..5fe97e6bec5e4ae4ffe1f92348e401c653972e5e 100644
--- a/runtime/bin/vmservice/client/lib/src/service/object.dart
+++ b/runtime/bin/vmservice/client/lib/src/service/object.dart
@@ -1103,6 +1103,146 @@ class Allocations {
   bool get empty => accumulated.empty && current.empty;
 }
 
+class ClassParser {

[hausner, 2014/07/01 23:49:07]

When we spoke offline I was under the impression that you had access to the
tokenized script and would not have to parse text. This one-off parser looks
incorrect to me, e.g. does not handle all whitespace, does not handle string
interpolation etc. Writing a full tokenizer in Dart is not what I expected you'd
have to do.

Can you have native functions here? If so, you could write a native function
that computes the end token position of a class using the token stream of the VM
Script object.

+  List<ScriptLine> _source;
+  int _offset;
+
+  ClassParser(this._source) {
+    assert(_source != null && _source.length > 0);
+    _offset = this._source.first.line;
+  }
+
+  // Internal state for parsing the class.
+  var _line;
+  var _col;
+  int _currentToken;
+
+  int _char(String str) => str.codeUnitAt(0);
+
+  void _initTokens() {
+    _line = 0;
+    _col = 0;
+    _currentToken = _source[_line].text.codeUnitAt(_col);
+  }
+
+  int _advanceToken([int num, stripWhite=true]) {
+    _col++;
+    if (_col >= _source[_line].text.codeUnits.length) {
+      var col = _col;
+      _col = 0;
+      _line++;
+      if (_line == _source.length) {
+        _line--;
+        _col = col;
+        _currentToken = 0;
+        return 0;
+      }
+    }
+
+    while (_source[_line].text.length == 0) { _line++; }
+    _currentToken = _source[_line].text.codeUnitAt(_col);
+    if (stripWhite && _currentToken == _char(' ')) {
+      _advanceToken();
+    }
+    if (num != null) {
+      for (int i = 1; i < num; i++) {
+        _advanceToken();
+      }
+    }
+    return _currentToken;
+  }
+
+  int _peek(int len, [stripWhite=true]) {
+    int saved_line = _line;
+    int saved_col = _col;
+    int c = _advanceToken(len,stripWhite);
+    _line = saved_line;
+    _col = saved_col;
+    return c;
+  }
+
+  void _consumeMultilineString(int quote) {
+    _advanceToken(3);
+    for (int c = _currentToken; c != 0; c = _advanceToken()) {
+      if (c == quote && _peek(1) == quote && _peek(2) == quote) {
+        _advanceToken(3);
+        break;
+      }
+    }
+  }
+
+  void _consumeString(int quote) {
+    _advanceToken();
+    for (int c = _currentToken; c != 0; c = _advanceToken()) {
+      if (c == _char('\\')) {
+        _advanceToken();
+      }
+      if (c == quote) {
+        _advanceToken();
+        break;
+      }
+    }
+  }
+
+  void _consumeComment() {
+    _col = _source[_line].text.codeUnits.length;
+  }
+
+  void _consumeMultilineComment() {
+    _advanceToken(2);
+    int commentLevel = 1;
+    for (int c = _currentToken; c != 0; c = _advanceToken()) {
+      if (c == _char('/') && _peek(1, false) == _char('*')) {
+        commentLevel++;
+        _advanceToken();
+      } else if (c == _char('*') && _peek(1, false) == _char('/')) {
+        commentLevel--;
+        _advanceToken();
+        if (commentLevel == 0) {
+          _advanceToken();
+          break;
+        }
+      }
+    }
+  }
+
+  /// Finds the end position, i.e., the closing curly brackets of the given
+  /// class.
+  /// Returns a tuple [line, col].
+  List findEndPos() {
+    int level = 0;
+    _initTokens();
+    for (int c = _currentToken; c != 0; c=_currentToken) {
+      if ((c == _char("'") &&
+           _peek(1) == _char("'") &&
+           _peek(2) == _char("'")) ||
+          (c == _char('"') &&
+           _peek(1) == _char('"') &&
+           _peek(2) == _char('"'))) {
+        _consumeMultilineString(c);
+        continue;
+      } else if (c == _char("'") || c == _char('"')) {
+        _consumeString(c);
+        continue;
+      } else if (c == _char('/') && _peek(1, false) == _char('/')) {
+        _consumeComment();
+        continue;
+      } else if (c == _char('/') && _peek(1, false) == _char('*')) {
+        _consumeMultilineComment();
+        continue;
+      } else if (c == _char('{')) {
+        level++;
+      } else if (c == _char('}')) {
+        if (--level == 0) {
+          break;
+        }
+      }
+      c = _advanceToken();
+    }
+    return [_line + _offset, _col + 1];
+  }
+}
+
 class Class extends ServiceObject with Coverage {
   @observable Library library;
   @observable Script script;
@@ -1116,6 +1256,14 @@ class Class extends ServiceObject with Coverage {
 
   @observable int tokenPos;
 
+  int _endTokenPos = null;
+  @observable int get endTokenPos {
+    if (_endTokenPos == null) {
+      _computeEndTokenPos();
+    }
+    return _endTokenPos;
+  }
+
   @observable ServiceMap error;
 
   final Allocations newSpace = new Allocations();
@@ -1201,6 +1349,26 @@ class Class extends ServiceObject with Coverage {
   Future<ServiceObject> get(String command) {
     return isolate.get(id + "/$command");
   }
+
+  void _computeEndTokenPos() {
+    script.load().whenComplete(() {
+      int line = script.tokenToLine(tokenPos); // Lines are 1-based.
+      ClassParser clsp = new ClassParser(script.lines.sublist(line - 1));
+      List posTuple = clsp.findEndPos();
+      // Search for the token one this line and column.
+      List tokenCandidates = [];
+      script._tokenToLine.forEach((k,v) {
+        if (script._tokenToLine[k] == posTuple[0]) {
+          tokenCandidates.add(k);
+        }
+      });
+      Iterable tokenIndex =
+          tokenCandidates.where((e) => script._tokenToCol[e] == posTuple[1]);
+      assert(tokenIndex.length == 1);
+      _endTokenPos = tokenIndex.first;
+      notifyPropertyChange(#endTokenPos, null, _endTokenPos);
+    });
+  }
 }
 
 class ScriptLine extends Observable {