Revert revision 33053

third_party/pkg/angular/lib/change_detection/ast.dart

-part of angular.watch_group;
-
-
-/**
- * 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;
-  AST(expression)
-      : expression = expression.startsWith('#.')
-          ? expression.substring(2)
-          : expression
-  {
-    assert(expression!=null);
-  }
-  WatchRecord<_Handler> setupWatch(WatchGroup watchGroup);
-  String toString() => expression;
-}
-
-/**
- * SYNTAX: _context_
- *
- * This represent the initial _context_ for evaluation.
- */
-class ContextReferenceAST extends AST {
-  ContextReferenceAST(): super(AST._CONTEXT);
-  WatchRecord<_Handler> setupWatch(WatchGroup watchGroup) =>
-      new _ConstantWatchRecord(watchGroup, 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);
-
-  WatchRecord<_Handler> setupWatch(WatchGroup watchGroup) =>
-      new _ConstantWatchRecord(watchGroup, expression, constant);
-}
-
-/**
- * SYNTAX: lhs.name.
- *
- * This is the '.' dot operator.
- */
-class FieldReadAST extends AST {
-  AST lhs;
-  final String name;
-
-  FieldReadAST(lhs, name)
-      : lhs = lhs,
-        name = name,
-        super('$lhs.$name');
-
-  WatchRecord<_Handler> setupWatch(WatchGroup watchGroup) =>
-      watchGroup.addFieldWatch(lhs, 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)
-      : super('$name(${_argList(argsAST)})'),
-        argsAST = argsAST,
-        name = name;
-
-  WatchRecord<_Handler> setupWatch(WatchGroup watchGroup) =>
-      watchGroup.addFunctionWatch(fn, argsAST, expression);
-}
-
-/**
- * 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;
-
-  MethodAST(lhsAST, name, argsAST)
-      : super('$lhsAST.$name(${_argList(argsAST)})'),
-        lhsAST = lhsAST,
-        name = name,
-        argsAST = argsAST;
-
-  WatchRecord<_Handler> setupWatch(WatchGroup watchGroup) =>
-      watchGroup.addMethodWatch(lhsAST, name, argsAST, expression);
-}
-
-
-class CollectionAST extends AST {
-  final AST valueAST;
-  CollectionAST(valueAST)
-      : valueAST = valueAST,
-        super('#collection($valueAST)');
-
-  WatchRecord<_Handler> setupWatch(WatchGroup watchGroup) =>
-      watchGroup.addCollectionWatch(valueAST);
-}
-
-String _argList(List<AST> items) => items.join(', ');
-
-/**
- * The name is a bit oxymoron, but it is essentially the NullObject pattern.
- *
- * This allows children to set a handler on this ChangeRecord and then let it write the initial
- * constant value to the forwarding ChangeRecord.
- */
-class _ConstantWatchRecord extends WatchRecord<_Handler> {
-  final currentValue;
-  final _Handler handler;
-
-  _ConstantWatchRecord(WatchGroup watchGroup, String expression, currentValue)
-      : currentValue = currentValue,
-        handler = new _ConstantHandler(watchGroup, expression, currentValue);
-
-  ChangeRecord<_Handler> check() => null;
-  void remove() => null;
-
-  get field => null;
-  get previousValue => null;
-  get object => null;
-  set object(_) => null;
-  get nextChange => null;
-}
-