Add libc++ data formatters for std::optional.

Patch by Shafik Yaghmour!

This reapplies an earlier version after addressing some post-commit feedback.

Differential Revision: https://reviews.llvm.org/D49271

llvm-svn: 339828

5 files changed, 132 insertions, 7 deletions

diff --git a/lldb/source/Plugins/Language/CPlusPlus/CMakeLists.txt b/lldb/source/Plugins/Language/CPlusPlus/CMakeLists.txt
index e7faee84988..eb0d880c641 100644
--- a/lldb/source/Plugins/Language/CPlusPlus/CMakeLists.txt
+++ b/lldb/source/Plugins/Language/CPlusPlus/CMakeLists.txt
@@ -9,6 +9,7 @@ add_lldb_library(lldbPluginCPlusPlusLanguage PLUGIN
   LibCxxInitializerList.cpp
   LibCxxList.cpp
   LibCxxMap.cpp
+  LibCxxOptional.cpp
   LibCxxQueue.cpp
   LibCxxTuple.cpp
   LibCxxUnorderedMap.cpp
diff --git a/lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.cpp b/lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.cpp
index 46c9c40885f..12da953e878 100644
--- a/lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.cpp
+++ b/lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.cpp
@@ -251,14 +251,14 @@ std::string CPlusPlusLanguage::MethodName::GetScopeQualifiedName() {
 bool CPlusPlusLanguage::IsCPPMangledName(const char *name) {
   // FIXME!! we should really run through all the known C++ Language plugins
   // and ask each one if this is a C++ mangled name
-  
+
   if (name == nullptr)
     return false;
-  
-  // MSVC style mangling 
+
+  // MSVC style mangling
   if (name[0] == '?')
     return true;
-  
+
   return (name[0] != '\0' && name[0] == '_' && name[1] == 'Z');
 }
 
@@ -512,6 +512,10 @@ static void LoadLibCxxFormatters(lldb::TypeCategoryImplSP cpp_category_sp) {
                   "libc++ std::tuple synthetic children",
                   ConstString("^std::__(ndk)?1::tuple<.*>(( )?&)?$"), stl_synth_flags,
                   true);
+  AddCXXSynthetic(cpp_category_sp, LibcxxOptionalFrontEndCreator,
+                  "libc++ std::optional synthetic children",
+                  ConstString("^std::__(ndk)?1::optional<.+>(( )?&)?$"),
+                  stl_synth_flags, true);
   AddCXXSynthetic(
       cpp_category_sp,
       lldb_private::formatters::LibcxxAtomicSyntheticFrontEndCreator,
@@ -603,6 +607,11 @@ static void LoadLibCxxFormatters(lldb::TypeCategoryImplSP cpp_category_sp) {
       cpp_category_sp, lldb_private::formatters::LibCxxAtomicSummaryProvider,
       "libc++ std::atomic summary provider",
       ConstString("^std::__(ndk)?1::atomic<.+>$"), stl_summary_flags, true);
+  AddCXXSummary(cpp_category_sp,
+                lldb_private::formatters::LibcxxOptionalSummaryProvider,
+                "libc++ std::optional summary provider",
+                ConstString("^std::__(ndk)?1::optional<.+>(( )?&)?$"),
+                stl_summary_flags, true);
 
   stl_summary_flags.SetSkipPointers(true);
 
diff --git a/lldb/source/Plugins/Language/CPlusPlus/LibCxx.cpp b/lldb/source/Plugins/Language/CPlusPlus/LibCxx.cpp
index 95e02a473cd..56dce5cbc1d 100644
--- a/lldb/source/Plugins/Language/CPlusPlus/LibCxx.cpp
+++ b/lldb/source/Plugins/Language/CPlusPlus/LibCxx.cpp
@@ -33,6 +33,28 @@ using namespace lldb;
 using namespace lldb_private;
 using namespace lldb_private::formatters;
 
+bool lldb_private::formatters::LibcxxOptionalSummaryProvider(
+    ValueObject &valobj, Stream &stream, const TypeSummaryOptions &options) {
+  ValueObjectSP valobj_sp(valobj.GetNonSyntheticValue());
+  if (!valobj_sp)
+    return false;
+
+  // An optional either contains a value or not, the member __engaged_ is
+  // a bool flag, it is true if the optional has a value and false otherwise.
+  ValueObjectSP engaged_sp(
+      valobj_sp->GetChildMemberWithName(ConstString("__engaged_"), true));
+
+  if (!engaged_sp)
+    return false;
+
+  llvm::StringRef engaged_as_cstring(
+      engaged_sp->GetValueAsUnsigned(0) == 1 ? "true" : "false");
+
+  stream.Printf(" Has Value=%s ", engaged_as_cstring.data());
+
+  return true;
+}
+
 bool lldb_private::formatters::LibcxxSmartPointerSummaryProvider(
     ValueObject &valobj, Stream &stream, const TypeSummaryOptions &options) {
   ValueObjectSP valobj_sp(valobj.GetNonSyntheticValue());
@@ -120,9 +142,9 @@ bool lldb_private::formatters::LibCxxMapIteratorSyntheticFrontEnd::Update() {
 
   if (!valobj_sp)
     return false;
-  
+
   static ConstString g___i_("__i_");
-  
+
   // this must be a ValueObject* because it is a child of the ValueObject we
   // are producing children for it if were a ValueObjectSP, we would end up
   // with a loop (iterator -> synthetic -> child -> parent == iterator) and
@@ -163,7 +185,7 @@ bool lldb_private::formatters::LibCxxMapIteratorSyntheticFrontEnd::Update() {
         m_pair_ptr = nullptr;
         return false;
       }
-      
+
       auto addr(m_pair_ptr->GetValueAsUnsigned(LLDB_INVALID_ADDRESS));
       m_pair_ptr = nullptr;
       if (addr && addr!=LLDB_INVALID_ADDRESS) {
diff --git a/lldb/source/Plugins/Language/CPlusPlus/LibCxx.h b/lldb/source/Plugins/Language/CPlusPlus/LibCxx.h
index 3f6e0d6e14d..0a45504cf76 100644
--- a/lldb/source/Plugins/Language/CPlusPlus/LibCxx.h
+++ b/lldb/source/Plugins/Language/CPlusPlus/LibCxx.h
@@ -27,6 +27,10 @@ bool LibcxxWStringSummaryProvider(
     ValueObject &valobj, Stream &stream,
     const TypeSummaryOptions &options); // libc++ std::wstring
 
+bool LibcxxOptionalSummaryProvider(
+    ValueObject &valobj, Stream &stream,
+    const TypeSummaryOptions &options); // libc++ std::optional<>
+
 bool LibcxxSmartPointerSummaryProvider(
     ValueObject &valobj, Stream &stream,
     const TypeSummaryOptions
@@ -133,6 +137,10 @@ SyntheticChildrenFrontEnd *LibcxxQueueFrontEndCreator(CXXSyntheticChildren *,
 SyntheticChildrenFrontEnd *LibcxxTupleFrontEndCreator(CXXSyntheticChildren *,
                                                       lldb::ValueObjectSP);
 
+SyntheticChildrenFrontEnd *
+LibcxxOptionalFrontEndCreator(CXXSyntheticChildren *,
+                              lldb::ValueObjectSP valobj_sp);
+
 } // namespace formatters
 } // namespace lldb_private
 
diff --git a/lldb/source/Plugins/Language/CPlusPlus/LibCxxOptional.cpp b/lldb/source/Plugins/Language/CPlusPlus/LibCxxOptional.cpp
new file mode 100644
index 00000000000..762b824f262
--- /dev/null
+++ b/lldb/source/Plugins/Language/CPlusPlus/LibCxxOptional.cpp
@@ -0,0 +1,85 @@
+//===-- LibCxxOptional.cpp --------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "LibCxx.h"
+#include "lldb/DataFormatters/FormattersHelpers.h"
+
+using namespace lldb;
+using namespace lldb_private;
+
+namespace {
+
+class OptionalFrontEnd : public SyntheticChildrenFrontEnd {
+public:
+  OptionalFrontEnd(ValueObject &valobj) : SyntheticChildrenFrontEnd(valobj) {
+    Update();
+  }
+
+  size_t GetIndexOfChildWithName(const ConstString &name) override {
+    return formatters::ExtractIndexFromString(name.GetCString());
+  }
+
+  bool MightHaveChildren() override { return true; }
+  bool Update() override;
+  size_t CalculateNumChildren() override { return m_size; }
+  ValueObjectSP GetChildAtIndex(size_t idx) override;
+
+private:
+  size_t m_size = 0;
+  ValueObjectSP m_base_sp;
+};
+} // namespace
+
+bool OptionalFrontEnd::Update() {
+  ValueObjectSP engaged_sp(
+      m_backend.GetChildMemberWithName(ConstString("__engaged_"), true));
+
+  if (!engaged_sp)
+    return false;
+
+  // __engaged_ is a bool flag and is true if the optional contains a value.
+  // Converting it to unsigned gives us a size of 1 if it contains a value
+  // and 0 if not.
+  m_size = engaged_sp->GetValueAsUnsigned(0);
+
+  return false;
+}
+
+ValueObjectSP OptionalFrontEnd::GetChildAtIndex(size_t idx) {
+  if (idx >= m_size)
+    return ValueObjectSP();
+
+  // __val_ contains the underlying value of an optional if it has one.
+  // Currently because it is part of an anonymous union GetChildMemberWithName()
+  // does not peer through and find it unless we are at the parent itself.
+  // We can obtain the parent through __engaged_.
+  ValueObjectSP val_sp(
+      m_backend.GetChildMemberWithName(ConstString("__engaged_"), true)
+          ->GetParent()
+          ->GetChildAtIndex(0, true)
+          ->GetChildMemberWithName(ConstString("__val_"), true));
+
+  if (!val_sp)
+    return ValueObjectSP();
+
+  CompilerType holder_type = val_sp->GetCompilerType();
+
+  if (!holder_type)
+    return ValueObjectSP();
+
+  return val_sp->Clone(ConstString(llvm::formatv("Value").str()));
+}
+
+SyntheticChildrenFrontEnd *
+formatters::LibcxxOptionalFrontEndCreator(CXXSyntheticChildren *,
+                                          lldb::ValueObjectSP valobj_sp) {
+  if (valobj_sp)
+    return new OptionalFrontEnd(*valobj_sp);
+  return nullptr;
+}