Extend synthetic children to produce synthetic values (as in, those that GetValueAsUnsigned(), GetValueAsCString() would return)

The way to do this is to write a synthetic child provider for your type, and have it vend the (optional) get_value function.
If get_value is defined, and it returns a valid SBValue, that SBValue's value (as in lldb_private::Value) will be used as the synthetic ValueObject's Value

The rationale for doing things this way is twofold:

- there are many possible ways to define a "value" (SBData, a Python number, ...) but SBValue seems general enough as a thing that stores a "value", so we just trade values that way and that keeps our currency trivial
- we could introduce a new level of layering (ValueObjectSyntheticValue), a new kind of formatter (synthetic value producer), but that would complicate the model (can I have a dynamic with no synthetic children but synthetic value? synthetic value with synthetic children but no dynamic?), and I really couldn't see much benefit to be reaped from this added complexity in the matrix
On the other hand, just defining a synthetic child provider with a get_value but returning no actual children is easy enough that it's not a significant road-block to adoption of this feature

Comes with a test case

llvm-svn: 219330

1 files changed, 11 insertions, 5 deletions

diff --git a/lldb/source/Core/ValueObject.cpp b/lldb/source/Core/ValueObject.cpp
index 3b37de79234..f38b7c01565 100644
--- a/lldb/source/Core/ValueObject.cpp
+++ b/lldb/source/Core/ValueObject.cpp
@@ -1450,7 +1450,7 @@ ValueObject::GetValueAsCString ()
                     }
                     else
                     {
-                        my_format = GetClangType().GetFormat();
+                        my_format = GetValue().GetClangType().GetFormat();
                     }
                 }
             }
@@ -1482,7 +1482,7 @@ uint64_t
 ValueObject::GetValueAsUnsigned (uint64_t fail_value, bool *success)
 {
     // If our byte size is zero this is an aggregate type that has children
-    if (!GetClangType().IsAggregateType())
+    if (CanProvideValue())
     {
         Scalar scalar;
         if (ResolveValue (scalar))
@@ -1503,7 +1503,7 @@ int64_t
 ValueObject::GetValueAsSigned (int64_t fail_value, bool *success)
 {
     // If our byte size is zero this is an aggregate type that has children
-    if (!GetClangType().IsAggregateType())
+    if (CanProvideValue())
     {
         Scalar scalar;
         if (ResolveValue (scalar))
@@ -1751,7 +1751,7 @@ ValueObject::DumpPrintableRepresentation(Stream& s,
                 cstr = GetSummaryAsCString();
             else if (val_obj_display == eValueObjectRepresentationStyleSummary)
             {
-                if (GetClangType().IsAggregateType())
+                if (!CanProvideValue())
                 {
                     strm.Printf("%s @ %s", GetTypeName().AsCString(), GetLocationAsCString());
                     cstr = strm.GetString().c_str();
@@ -2805,7 +2805,7 @@ ValueObject::GetValueForExpressionPath_Impl(const char* expression_cstr,
                         if (root->IsSynthetic())
                         {
                             *first_unparsed = expression_cstr;
-                            *reason_to_stop = ValueObject::eExpressionPathScanEndReasonNoSuchChild;
+                            *reason_to_stop = ValueObject::eExpressionPathScanEndReasonNoSuchSyntheticChild;
                             *final_result = ValueObject::eExpressionPathEndResultTypeInvalid;
                             return ValueObjectSP();
                         }
@@ -4080,3 +4080,9 @@ ValueObject::GetFormat () const
     }
     return m_format;
 }
+
+bool
+ValueObject::CanProvideValue ()
+{
+    return (false == GetClangType().IsAggregateType());
+}