MonoRail/Castle.MonoRail.Views.Brail/FixTryGetParameterConditionalChecks.cs

   1 // Copyright 2004-2008 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
  20         /// <summary>
  21         /// We need to handle the following code:
  22         /// if ?Error:
  23         /// end
  24         ///
  25         /// However, because ?Op will return an IgnoreNull object, we can't just
  26         /// use the default boo behavior, but need to fix it up
  27         /// </summary>
  28         public class FixTryGetParameterConditionalChecks : AbstractNamespaceSensitiveTransformerCompilerStep
  29         {
  30                 public override void Run()
  31                 {
  32                         Visit(CompileUnit);
  33                 }
  34
  35                 public override void OnBinaryExpression(BinaryExpression node)
  36                 {
  37                         if (node.Operator != BinaryOperatorType.Equality)
  38                                 return;
  39
  40                         if (IsTryGetParameterInvocation(node.Left) == false &&
  41                             IsTryGetParameterInvocation(node.Right) == false)
  42                                 return;
  43
  44                         MethodInvocationExpression mie = new MethodInvocationExpression();
  45                         ReferenceExpression expression = AstUtil.CreateReferenceExpression("Castle.MonoRail.Views.Brail.IgnoreNull.AreEqual");
  46                         mie.Target = expression;
  47                         mie.Arguments.Add(node.Left);
  48                         mie.Arguments.Add(node.Right);
  49
  50                         ReplaceCurrentNode(mie);
  51                 }
  52
  53
  54                 public override void OnIfStatement(IfStatement node)
  55                 {
  56                         base.OnIfStatement(node);
  57                         node.Condition = FixCondition(node.Condition);
  58                 }
  59
  60                 public override void OnUnlessStatement(UnlessStatement node)
  61                 {
  62                         base.OnUnlessStatement(node);
  63                         node.Condition = FixCondition(node.Condition);
  64                 }
  65
  66                 private Expression FixCondition(Expression condition)
  67                 {
  68                         if (IsTryGetParameterInvocation(condition) == false)
  69                                 return condition;
  70
  71                         string name = ((ReferenceExpression) condition).Name.Substring(1);
  72                         condition = new MethodInvocationExpression(
  73                                 new MemberReferenceExpression(new SuperLiteralExpression(), "TryGetParameter"),
  74                                 new StringLiteralExpression(name)
  75                                 );
  76
  77                         MemberReferenceExpression isNull =
  78                                 new MemberReferenceExpression(condition, "_IsIgnoreNullReferencingNotNullObject_");
  79
  80                         return isNull;
  81                 }
  82
  83                 private static bool IsTryGetParameterInvocation(Expression condition)
  84                 {
  85                         ReferenceExpression expression = condition as ReferenceExpression;
  86                         if (expression == null)
  87                                 return false;
  88
  89                         return expression.Name.StartsWith("?");
  90                 }
  91         }
  92 }