Overhaul tree IR visitor and rename IR classes.

pkg/compiler/lib/src/tree_ir/optimization/statement_rewriter.dart

 // 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.
 
 part of tree_ir.optimization;
 
 /**
  * Performs the following transformations on the tree:
  * - Assignment propagation
  * - If-to-conditional conversion
@@ skipping 73 matching lines @@
  * to their label are redirected.
  * For example, where 'jump' is either break or continue:
  *
  *   L0: {... break L0 ...}; jump L1
  *     ==>
  *   {... jump L1 ...}
  *
  * This may trigger a flattening of nested ifs in case the eliminated label
  * separated two ifs.
  */
-class StatementRewriter extends Visitor<Statement, Expression> with PassMixin {
+class StatementRewriter extends Transformer implements Pass {
   String get passName => 'Statement rewriter';
 
+  @override
+  void rewrite(RootNode node) {
+    node.replaceEachBody(visitStatement);
+  }
+
   // The binding environment.  The rightmost element of the list is the nearest
   // available enclosing binding.
-  List<Assign> environment;
+  List<Assign> environment = <Assign>[];
 
   /// Binding environment for variables that are assigned to effectively
   /// constant expressions (see [isEffectivelyConstant]).
   final Map<Variable, Expression> constantEnvironment;
 
   /// Substitution map for labels. Any break to a label L should be substituted
   /// for a break to L' if L maps to L'.
   Map<Label, Jump> labelRedirects = <Label, Jump>{};
 
   /// Rewriter for methods.
@@ skipping 11 matching lines @@
   /// handler (i.e., if the code would be moved into a try from outside it).
   Set<Label> safeForInlining = new Set<Label>();
 
   /// Returns the redirect target of [jump] or [jump] itself if it should not
   /// be redirected.
   Jump redirect(Jump jump) {
     Jump newJump = labelRedirects[jump.target];
     return newJump != null ? newJump : jump;
   }
 
-  rewriteExecutableDefinition(ExecutableDefinition definition) {
-    inEmptyEnvironment(() {
-      definition.body = visitStatement(definition.body);
-    });
-  }
-
-  void rewriteConstructorDefinition(ConstructorDefinition definition) {
-    if (definition.isAbstract) return;
-    definition.initializers.forEach(visitExpression);
-    rewriteExecutableDefinition(definition);
-  }
-
   void inEmptyEnvironment(void action()) {
     List<Assign> oldEnvironment = environment;
     environment = <Assign>[];
     action();
     assert(environment.isEmpty);
     environment = oldEnvironment;
   }
 
-  Expression visitFieldInitializer(FieldInitializer node) {
-    inEmptyEnvironment(() {
-      node.body = visitStatement(node.body);
-    });
-    return node;
-  }
-
-  Expression visitSuperInitializer(SuperInitializer node) {
-    inEmptyEnvironment(() {
-      for (int i = node.arguments.length - 1; i >= 0; --i) {
-        node.arguments[i] = visitStatement(node.arguments[i]);
-        assert(environment.isEmpty);
-      }
-    });
-    return node;
-  }
-
   Expression visitExpression(Expression e) => e.processed ? e : e.accept(this);
 
   @override
   Expression visitVariableUse(VariableUse node) {
     // Propagate constant to use site.
     Expression constant = constantEnvironment[node.variable];
     if (constant != null) {
       --node.variable.readCount;
       return constant;
     }
@@ skipping 518 matching lines @@
   }
 
   Expression makeCondition(Expression e, bool polarity) {
     return polarity ? e : new Not(e);
   }
 
   Statement getBranch(If node, bool polarity) {
     return polarity ? node.thenStatement : node.elseStatement;
   }
 }