[Lldb-commits] [lldb] r339014 - Add ConstString::IsNull() to tell between null vs. empty strings and fix usage in Mangled::GetDemangledName()

[Stefan Granitz via lldb-commits]

Author: stefan.graenitz
Date: Mon Aug  6 07:15:17 2018
New Revision: 339014

URL: http://llvm.org/viewvc/llvm-project?rev=339014&view=rev
Log:
Add ConstString::IsNull() to tell between null vs. empty strings and fix usage in Mangled::GetDemangledName()

Summary: `IsEmpty()` and `operator bool() == false` have equal semantics. Usage in Mangled::GetDemangledName() was incorrect. What it actually wants is a check for null-string. Split this off of D50071 and added a test to clarify usage.

Reviewers: labath, jingham

Subscribers: erik.pilkington, lldb-commits

Differential Revision: https://reviews.llvm.org/D50327

Modified:
    lldb/trunk/include/lldb/Utility/ConstString.h
    lldb/trunk/source/Core/Mangled.cpp
    lldb/trunk/unittests/Utility/ConstStringTest.cpp

Modified: lldb/trunk/include/lldb/Utility/ConstString.h
URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/include/lldb/Utility/ConstString.h?rev=339014&r1=339013&r2=339014&view=diff
==============================================================================
--- lldb/trunk/include/lldb/Utility/ConstString.h (original)
+++ lldb/trunk/include/lldb/Utility/ConstString.h Mon Aug  6 07:15:17 2018
@@ -346,6 +346,15 @@ public:
   bool IsEmpty() const { return m_string == nullptr || m_string[0] == '\0'; }
 
   //------------------------------------------------------------------
+  /// Test for null string.
+  ///
+  /// @return
+  ///     @li \b true if there is no string associated with this instance.
+  ///     @li \b false if there is a string associated with this instance.
+  //------------------------------------------------------------------
+  bool IsNull() const { return m_string == nullptr; }
+
+  //------------------------------------------------------------------
   /// Set the C string value.
   ///
   /// Set the string value in the object by uniquing the \a cstr string value

Modified: lldb/trunk/source/Core/Mangled.cpp
URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Core/Mangled.cpp?rev=339014&r1=339013&r2=339014&view=diff
==============================================================================
--- lldb/trunk/source/Core/Mangled.cpp (original)
+++ lldb/trunk/source/Core/Mangled.cpp Mon Aug  6 07:15:17 2018
@@ -242,7 +242,7 @@ const ConstString &
 Mangled::GetDemangledName(lldb::LanguageType language) const {
   // Check to make sure we have a valid mangled name and that we haven't
   // already decoded our mangled name.
-  if (m_mangled && !m_demangled) {
+  if (m_mangled && m_demangled.IsNull()) {
     // We need to generate and cache the demangled name.
     static Timer::Category func_cat(LLVM_PRETTY_FUNCTION);
     Timer scoped_timer(func_cat, "Mangled::GetDemangledName (m_mangled = %s)",
@@ -312,7 +312,7 @@ Mangled::GetDemangledName(lldb::Language
         free(demangled_name);
       }
     }
-    if (!m_demangled) {
+    if (m_demangled.IsNull()) {
       // Set the demangled string to the empty string to indicate we tried to
       // parse it once and failed.
       m_demangled.SetCString("");

Modified: lldb/trunk/unittests/Utility/ConstStringTest.cpp
URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/unittests/Utility/ConstStringTest.cpp?rev=339014&r1=339013&r2=339014&view=diff
==============================================================================
--- lldb/trunk/unittests/Utility/ConstStringTest.cpp (original)
+++ lldb/trunk/unittests/Utility/ConstStringTest.cpp Mon Aug  6 07:15:17 2018
@@ -33,3 +33,20 @@ TEST(ConstStringTest, MangledCounterpart
   EXPECT_TRUE(foo.GetMangledCounterpart(counterpart));
   EXPECT_EQ("bar", counterpart.GetStringRef());
 }
+
+TEST(ConstStringTest, NullAndEmptyStates) {
+  ConstString foo("foo");
+  EXPECT_FALSE(!foo);
+  EXPECT_FALSE(foo.IsEmpty());
+  EXPECT_FALSE(foo.IsNull());
+
+  ConstString empty("");
+  EXPECT_TRUE(!empty);
+  EXPECT_TRUE(empty.IsEmpty());
+  EXPECT_FALSE(empty.IsNull());
+
+  ConstString null;
+  EXPECT_TRUE(!null);
+  EXPECT_TRUE(null.IsEmpty());
+  EXPECT_TRUE(null.IsNull());
+}