Stream isolates.

sdk/lib/isolate/mangler.dart

+// 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.
+
+class _IsolateEncoder {
+  final manglingToken;
+  // TODO(floitsch): switch to identity set.
+  final Map _encoded = new Map();

[Anton Muhin, 2012/11/25 10:23:16]

why not = {}?

[floitsch, 2012/11/28 14:13:18]

If I'm not wrong that would be a Map<String, dynamic> and not Map<dynamic,
dynamic>.

+  final Map _visiting = new Map();
+  final Function _mangle;
+  static const int _REFERENCE = 0;
+  static const int _DECLARATION = 1;
+  static const int _ESCAPED = 2;
+  static const int _MANGLED = 3;
+
+  _IsolateEncoder(this.manglingToken, mangle(data))

[Anton Muhin, 2012/11/25 10:23:16]

why not this._mangle here?

[floitsch, 2012/11/28 14:13:18]

This way I get a little bit of typing. The field is just declared as Function,
whereas the parameter is defined as a function that takes exactly one argument.

+      : this._mangle = mangle;
+
+  encode(var data) {
+    if (data is num || data is String || data is bool || data == null) {
+      return data;
+    }
+
+    if (_encoded.containsKey(data)) return _encoded[data];
+    if (_visiting.containsKey(data)) {
+      // Self reference.
+      var selfReference = _visiting[data];
+      if (selfReference == data) {
+        // Nobody used the self-reference yet.
+        selfReference = _createReference();
+        _visiting[data] = selfReference;
+      }
+      return selfReference;
+    }
+    _visiting[data] = data;
+
+    var result;
+
+    if (data is List) {
+      bool hasBeenDuplicated = false;
+      result = data;
+      for (int i = 0; i < data.length; i++) {
+        var mangled = encode(data[i]);
+        if (mangled != data[i] && !hasBeenDuplicated) {
+          result = new List(data.length);
+          for (int j = 0; j < i; j++) {
+            result[j] = data[j];
+          }
+          hasBeenDuplicated = true;
+        }
+        if (hasBeenDuplicated) {
+          result[i] = mangled;
+        }
+      }
+      result = _escapeIfNecessary(result);
+    } else if (data is Set) {
+      // TODO(floitsch): should we accept sets?
+      bool needsCopy = false;
+      for (var entry in data) {
+        var encoded = encode(entry);
+        if (encoded != entry) {
+          needsCopy = true;
+          break;
+        }
+      }
+      result = data;
+      if (needsCopy) {
+        result = new Set();
+        data.forEach((entry) {
+          result.add(encode(entry));
+        });
+      }
+    } else if (data is Map) {
+      bool needsCopy = false;
+      data.forEach((key, value) {
+        var encodedKey = encode(key);
+        var encodedValue = encode(value);
+        if (encodedKey != key) needsCopy = true;
+        if (encodedValue != value) needsCopy = true;
+      });
+      result = data;
+      if (needsCopy) {
+        result = new Map();
+        data.forEach((key, value) {
+          result[encode(key)] = encode(value);
+        });
+      }
+    } else {
+      // We don't handle self-references for user data.
+      // TODO(floitsch): we could keep the reference and throw when we see it
+      // again. However now the user has at least the possibility to do
+      // cyclic data-structures.
+      _visiting.remove(data);
+      result = _mangle(data);
+      if (result != data) {
+        result = _wrapMangled(encode(result));
+      }
+    }
+
+    var selfReference = _visiting[data];
+    if (selfReference != null && selfReference != data) {
+      // A self-reference has been used.
+      result = _declareReference(selfReference, result);
+    }
+    _encoded[data] = result;
+
+    _visiting.remove(data);
+    return result;
+  }
+
+  _createReference() => [manglingToken, _REFERENCE];
+  _declareReference(reference, data) {
+    return [manglingToken, _DECLARATION, reference, data];
+  }
+
+  _wrapMangled(data) => [manglingToken, _MANGLED, data];
+  _escapeIfNecessary(List list) {
+    if (!list.isEmpty && list[0] == manglingToken) {
+      return [manglingToken, _ESCAPED, list];
+    } else {
+      return list;
+    }
+  }
+}
+
+class _IsolateDecoder {
+  final manglingToken;
+  final Map _decoded = new Map();
+  final Function _unmangle;
+  static const int _REFERENCE = _IsolateEncoder._REFERENCE;
+  static const int _DECLARATION = _IsolateEncoder._DECLARATION;
+  static const int _ESCAPED = _IsolateEncoder._ESCAPED;
+  static const int _MANGLED = _IsolateEncoder._MANGLED;
+
+  _IsolateDecoder(this.manglingToken, unmangle(data))
+      : this._unmangle = unmangle;
+
+  decode(var data) {
+    if (data is num || data is String || data is bool || data == null) {
+      return data;
+    }
+
+    if (_decoded.containsKey(data)) return _decoded[data];
+
+    if (_isDeclaration(data)) {
+      var reference = _extractReference(data);
+      var declared = _extractDeclared(data);
+      return _decodeObject(declared, reference);
+    } else {
+      return _decodeObject(data, null);
+    }
+  }
+
+  _decodeObject(data, reference) {
+    if (_decoded.containsKey(data)) {
+      assert(reference == null);
+      return _decoded[data];
+    }
+
+    // If the data was a reference then we would have found it in the _decoded
+    // map.
+    assert(!_isReference(data));
+
+    var result;
+    if (_isMangled(data)) {
+      assert(reference == null);
+      List mangled = _extractMangled(data);
+      var decoded = decode(mangled);
+      result = _unmangle(decoded);
+    } else if (data is List) {
+      if (_isEscaped(data)) data = _extractEscaped(data);
+      assert(!_isMarked(data));
+      result = data;
+      bool hasBeenDuplicated = false;
+      List duplicate() {
+        assert(!hasBeenDuplicated);
+        result = new List();
+        result.length = data.length;
+        if (reference != null) _decoded[reference] = result;
+        hasBeenDuplicated = true;
+      }
+
+      if (reference != null) duplicate();
+      for (int i = 0; i < data.length; i++) {
+        var decoded = decode(data[i]);
+        if (decoded != data[i] && !hasBeenDuplicated) {
+          duplicate();
+          for (int j = 0; j < i; j++) {
+            result[j] = data[j];
+          }
+        }
+        if (hasBeenDuplicated) {
+          result[i] = decoded;
+        }
+      }
+    } else if (data is Set) {
+      bool needsCopy = reference != null;
+      if (!needsCopy) {
+        for (var entry in data) {
+          var decoded = decode(entry);
+          if (decoded != entry) {
+            needsCopy = true;
+            break;
+          }
+        }
+      }
+      result = data;
+      if (needsCopy) {
+        result = new Set();
+        if (reference != null) _decoded[reference] = result;
+        for (var entry in data) {
+          result.add(decode(entry));
+        }
+      }
+    } else if (data is Map) {
+      bool needsCopy = reference != null;
+      if (!needsCopy) {
+        data.forEach((key, value) {
+          var decodedKey = decode(key);
+          var decodedValue = decode(value);
+          if (decodedKey != key) needsCopy = true;
+          if (decodedValue != value) needsCopy = true;
+        });
+      }
+      result = data;
+      if (needsCopy) {
+        result = new Map();
+        if (reference != null) _decoded[reference] = result;
+        data.forEach((key, value) {
+          result[decode(key)] = decode(value);
+        });
+      }
+    } else {
+      result = data;
+    }
+    _decoded[data] = result;
+    return result;
+  }
+
+  _isMarked(data) {
+    if (data is List && !data.isEmpty && data[0] == manglingToken) {
+      assert(data.length > 1);
+      return true;
+    }
+    return false;
+  }
+  _isReference(data) => _isMarked(data) && data[1] == _REFERENCE;
+  _isDeclaration(data) => _isMarked(data) && data[1] == _DECLARATION;
+  _isMangled(data) => _isMarked(data) && data[1] == _MANGLED;
+  _isEscaped(data) => _isMarked(data) && data[1] == _ESCAPED;
+
+  _extractReference(declaration) {
+    assert(_isDeclaration(declaration));
+    return declaration[2];
+  }
+  _extractDeclared(declaration) {
+    assert(_isDeclaration(declaration));
+    return declaration[3];
+  }
+  _extractMangled(wrappedMangled) {
+    assert(_isMangled(wrappedMangled));
+    return wrappedMangled[2];
+  }
+  _extractEscaped(data) {
+    assert(_isEscaped(data));
+    return data[2];
+  }
+}