feat(ChangeDetector): unified architecture

Author: vicb

lib/change_detector/ast.dart

@@ -0,0 +1,146 @@
+part of angular.change_detector;
+
+/**
+ * RULES:
+ *  - ASTs are reusable. Don't store scope/instance refs there
+ *  - Parent knows about children, not the other way around.
+ */
+abstract class AST {
+  static final String _CONTEXT = '#';
+  final String expression;
+  var parsedExp; // The parsed version of expression.
+
+  AST(expression)
+      : expression = expression.startsWith('#.')
+          ? expression.substring(2)
+          : expression
+  {
+    assert(expression != null);
+  }
+
+  Record setupRecord(WatchGroup watchGroup);
+
+  String toString() => expression;
+}
+
+/**
+ * SYNTAX: _context_
+ *
+ * This represent the initial _context_ for evaluation.
+ */
+class ContextReferenceAST extends AST {
+  ContextReferenceAST(): super(AST._CONTEXT);
+
+  Record setupRecord(WatchGroup watchGroup) =>
+      watchGroup.addConstantRecord(expression, watchGroup._context);
+}
+
+/**
+ * SYNTAX: _context_
+ *
+ * This represent the initial _context_ for evaluation.
+ */
+class ConstantAST extends AST {
+  final constant;
+
+  ConstantAST(constant, [String expression])
+      : constant = constant,
+        super(expression == null
+            ? constant is String ? '"$constant"' : '$constant'
+            : expression);
+
+  Record setupRecord(WatchGroup watchGroup) => watchGroup.addConstantRecord(expression, constant);
+}
+
+/**
+ * SYNTAX: lhs.name.
+ *
+ * This is the '.' dot operator.
+ */
+class FieldReadAST extends AST {
+  AST lhsAST;
+  final String name;
+
+  FieldReadAST(lhsAST, name)
+      : lhsAST = lhsAST,
+        name = name,
+        super('$lhsAST.$name');
+
+  Record setupRecord(WatchGroup watchGroup) =>
+      watchGroup.addFieldRecord(lhsAST, name, expression);
+}
+
+/**
+ * SYNTAX: fn(arg0, arg1, ...)
+ *
+ * Invoke a pure function. Pure means that the function has no state, and
+ * therefore it needs to be re-computed only if its args change.
+ */
+class PureFunctionAST extends AST {
+  final String name;
+  final /* dartbug.com/16401 Function */ fn;
+  final List<AST> argsAST;
+
+  PureFunctionAST(name, this.fn, argsAST)
+      : argsAST = argsAST,
+        name = name,
+        super(_fnToString(name, argsAST));
+
+  Record setupRecord(WatchGroup watchGroup) =>
+      watchGroup.addFunctionRecord(fn, argsAST, const {}, expression, true);
+}
+
+/**
+ * SYNTAX: fn(arg0, arg1, ...)
+ *
+ * Invoke a (non-pure) function.
+ */
+class ClosureAST extends AST {
+  final String name;
+  final /* dartbug.com/16401 Function */ fn;
+  final List<AST> argsAST;
+
+  ClosureAST(name, this.fn, argsAST)
+      : argsAST = argsAST,
+        name = name,
+        super(_fnToString(name, argsAST));
+
+  Record setupRecord(WatchGroup watchGroup) =>
+      watchGroup.addFunctionRecord(fn, argsAST, const {}, expression, false);
+}
+
+/**
+ * SYNTAX: lhs.method(arg0, arg1, ...)
+ *
+ * Invoke a method on [lhs] object.
+ */
+class MethodAST extends AST {
+  final AST lhsAST;
+  final String name;
+  final List<AST> argsAST;
+  final Map<Symbol, AST> namedArgsAST;
+
+  MethodAST(lhsAST, name, argsAST, [this.namedArgsAST = const {}])
+      : lhsAST = lhsAST,
+        name = name,
+        argsAST = argsAST,
+        super('$lhsAST.${_fnToString(name, argsAST)}');
+
+  Record setupRecord(WatchGroup watchGroup) =>
+      watchGroup.addMethodRecord(lhsAST, name, argsAST, namedArgsAST, expression);
+}
+
+class CollectionAST extends AST {
+  final AST valueAST;
+
+  CollectionAST(valueAST)
+      : valueAST = valueAST,
+        super('#collection($valueAST)');
+
+  Record setupRecord(WatchGroup watchGroup) => watchGroup.addCollectionRecord(this);
+}
+
+String _fnToString(String name, List<AST> items) => name + items.join(', ');
+
+
+