From 6409e7828112ddf28ef7144b1a0a3af4180f3370 Mon Sep 17 00:00:00 2001
From: Daniel Holbert <dholbert@cs.stanford.edu>
Date: Fri, 29 Jan 2010 12:18:50 -0800
Subject: [PATCH] Bug 542731, Patch A: Clean up nsSMILValue class. r=roc

---
 content/smil/nsSMILValue.cpp | 84 ++++++++++++++++++++++--------------
 content/smil/nsSMILValue.h   |  5 +++
 2 files changed, 56 insertions(+), 33 deletions(-)

diff --git a/content/smil/nsSMILValue.cpp b/content/smil/nsSMILValue.cpp
index e50da0cb4307..3266ccbd9b3d 100644
--- a/content/smil/nsSMILValue.cpp
+++ b/content/smil/nsSMILValue.cpp
@@ -39,26 +39,27 @@
 #include "nsSMILValue.h"
 #include "nsDebug.h"
 
-nsSMILValue::nsSMILValue(const nsISMILType* aType)
-: mU(),
-  mType(&nsSMILNullType::sSingleton)
-{
-  if (!aType) return;
+//----------------------------------------------------------------------
+// Public methods
 
-  nsresult rv = aType->Init(*this);
-  NS_POSTCONDITION(mType == aType || (NS_FAILED(rv) && IsNull()),
-    "Post-condition of Init failed. nsSMILValue is invalid");
+nsSMILValue::nsSMILValue(const nsISMILType* aType)
+  : mType(&nsSMILNullType::sSingleton)
+{
+  if (!aType) {
+    NS_ERROR("Trying to construct nsSMILValue with null mType pointer");
+    return;
+  }
+
+  InitAndCheckPostcondition(aType);
 }
 
 nsSMILValue::nsSMILValue(const nsSMILValue& aVal)
-:
-  mU(),
-  mType(&nsSMILNullType::sSingleton)
+  : mType(&nsSMILNullType::sSingleton)
 {
-  nsresult rv = aVal.mType->Init(*this);
-  NS_POSTCONDITION(mType == aVal.mType || (NS_FAILED(rv) && IsNull()),
-    "Post-condition of Init failed. nsSMILValue is invalid");
-  if (NS_FAILED(rv)) return;
+  nsresult rv = InitAndCheckPostcondition(aVal.mType);
+  if (NS_FAILED(rv))
+    return;
+
   mType->Assign(*this, aVal);
 }
 
@@ -69,12 +70,9 @@ nsSMILValue::operator=(const nsSMILValue& aVal)
     return *this;
 
   if (mType != aVal.mType) {
-    mType->Destroy(*this);
-    NS_POSTCONDITION(IsNull(), "nsSMILValue not null after destroying");
-    nsresult rv = aVal.mType->Init(*this);
-    NS_POSTCONDITION(mType == aVal.mType || (NS_FAILED(rv) && IsNull()),
-      "Post-condition of Init failed. nsSMILValue is invalid");
-    if (NS_FAILED(rv)) return *this;
+    nsresult rv = DestroyAndReinit(aVal.mType);
+    if (NS_FAILED(rv))
+      return *this; // Initialization failed; return early
   }
 
   mType->Assign(*this, aVal);
@@ -85,8 +83,6 @@ nsSMILValue::operator=(const nsSMILValue& aVal)
 nsresult
 nsSMILValue::Add(const nsSMILValue& aValueToAdd, PRUint32 aCount)
 {
-  if (aValueToAdd.IsNull()) return NS_OK;
-
   if (aValueToAdd.mType != mType) {
     NS_ERROR("Trying to add incompatible types");
     return NS_ERROR_FAILURE;
@@ -98,9 +94,6 @@ nsSMILValue::Add(const nsSMILValue& aValueToAdd, PRUint32 aCount)
 nsresult
 nsSMILValue::SandwichAdd(const nsSMILValue& aValueToAdd)
 {
-  if (aValueToAdd.IsNull())
-    return NS_OK;
-
   if (aValueToAdd.mType != mType) {
     NS_ERROR("Trying to add incompatible types");
     return NS_ERROR_FAILURE;
@@ -131,14 +124,39 @@ nsSMILValue::Interpolate(const nsSMILValue& aEndVal,
   }
 
   if (aResult.mType != mType) {
-    aResult.mType->Destroy(aResult);
-    NS_POSTCONDITION(aResult.IsNull(), "nsSMILValue not null after destroying");
-    nsresult rv = mType->Init(aResult);
-    NS_POSTCONDITION(aResult.mType == mType
-      || (NS_FAILED(rv) && aResult.IsNull()),
-      "Post-condition of Init failed. nsSMILValue is invalid");
-    if (NS_FAILED(rv)) return rv;
+    // Outparam has wrong type
+    nsresult rv = aResult.DestroyAndReinit(mType);
+    if (NS_FAILED(rv))
+      return rv;
   }
 
   return mType->Interpolate(*this, aEndVal, aUnitDistance, aResult);
 }
+
+//----------------------------------------------------------------------
+// Helper methods
+
+// Wrappers for nsISMILType::Init & ::Destroy that verify their postconditions
+nsresult
+nsSMILValue::InitAndCheckPostcondition(const nsISMILType* aNewType)
+{
+  nsresult rv = aNewType->Init(*this);
+  NS_ABORT_IF_FALSE(mType == aNewType || (NS_FAILED(rv) && IsNull()),
+                    "Post-condition of Init failed. nsSMILValue is invalid");
+  return rv;
+}
+                
+void
+nsSMILValue::DestroyAndCheckPostcondition()
+{
+  mType->Destroy(*this);
+  NS_ABORT_IF_FALSE(IsNull(), "Post-condition of Destroy failed. "
+                    "nsSMILValue not null after destroying");
+}
+
+nsresult
+nsSMILValue::DestroyAndReinit(const nsISMILType* aNewType)
+{
+  DestroyAndCheckPostcondition();
+  return InitAndCheckPostcondition(aNewType);
+}
diff --git a/content/smil/nsSMILValue.h b/content/smil/nsSMILValue.h
index 218e20226042..a2ab8e3144d1 100644
--- a/content/smil/nsSMILValue.h
+++ b/content/smil/nsSMILValue.h
@@ -76,6 +76,11 @@ public:
     void* mPtr;
   } mU;
   const nsISMILType* mType;
+
+protected:
+  nsresult InitAndCheckPostcondition(const nsISMILType* aNewType);
+  void     DestroyAndCheckPostcondition();
+  nsresult DestroyAndReinit(const nsISMILType* aNewType);
 };
 
 #endif  // NS_SMILVALUE_H_