MonoRail/Castle.MonoRail.Views.Brail/ReturnValueVisitor.cs

   1 // Copyright 2004-2007 Castle Project - http://www.castleproject.org/
   2 //
   3 // Licensed under the Apache License, Version 2.0 (the "License");
   4 // you may not use this file except in compliance with the License.
   5 // You may obtain a copy of the License at
   6 //
   7 //     http://www.apache.org/licenses/LICENSE-2.0
   8 //
   9 // Unless required by applicable law or agreed to in writing, software
  10 // distributed under the License is distributed on an "AS IS" BASIS,
  11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12 // See the License for the specific language governing permissions and
  13 // limitations under the License.
  14
  15 namespace Castle.MonoRail.Views.Brail
  16 {
  17         using Boo.Lang.Compiler.Ast;
  18         using Boo.Lang.Compiler.Steps;
  19         using Castle.MonoRail.Framework;
  20
  21         //This will search for all return statements in a method
  22         //and will replace them with a method call (only a marker)
  23         //called transform, later, the output attribute will replace it
  24         //with the correct method call.
  25         public class ReturnValueVisitor : DepthFirstVisitor
  26         {
  27                 private NormalizeStatementModifiers normalizer;
  28                 private MethodInvocationExpression mie;
  29                 private bool found = false;
  30
  31                 public bool Found
  32                 {
  33                         get { return found; }
  34                 }
  35
  36                 public ReturnValueVisitor()
  37                 {
  38                         normalizer = new NormalizeStatementModifiers();
  39                         mie = new MethodInvocationExpression();
  40                         mie.Target = AstUtil.CreateReferenceExpression("transform");
  41                 }
  42
  43                 public override void OnReturnStatement(ReturnStatement stmt)
  44                 {
  45                         // First normalize the statement
  46                         normalizer.Visit(stmt);
  47                         //empty return, so error
  48                         if (stmt.Expression == null)
  49                                 throw new RailsException("An empty return statement on a method with output attribute");
  50                         found = true;
  51                         Block block = (Block) stmt.ParentNode;
  52                         int index = 0;
  53                         while(block.Statements[index] != stmt)
  54                         {
  55                                 index ++;
  56                         }
  57
  58                         MethodInvocationExpression invocation = mie.CloneNode();
  59                         invocation.Arguments.Add(stmt.Expression);
  60
  61                         stmt.Expression = invocation;
  62                 }
  63         }
  64 }