From cf8c9f0982fb5d384503f28f05f87fe2b156ed90 Mon Sep 17 00:00:00 2001
From: Wojtek Figat <wojtek@figat.pl>
Date: Mon, 30 Sep 2024 12:20:34 +0200
Subject: [PATCH] Add basic Variant parsing from text

---
 Source/Engine/Core/Types/StringView.cpp |  2 +-
 Source/Engine/Core/Types/Variant.cpp    | 67 ++++++++++++++++++++++++-
 Source/Engine/Core/Types/Variant.h      |  3 ++
 3 files changed, 70 insertions(+), 2 deletions(-)

diff --git a/Source/Engine/Core/Types/StringView.cpp b/Source/Engine/Core/Types/StringView.cpp
index 39404179b..24a3978f8 100644
--- a/Source/Engine/Core/Types/StringView.cpp
+++ b/Source/Engine/Core/Types/StringView.cpp
@@ -35,7 +35,7 @@ StringView StringView::Left(int32 count) const
 StringView StringView::Right(int32 count) const
 {
     const int32 countClamped = count < 0 ? 0 : count < Length() ? count : Length();
-    return StringView(**this + Length() - countClamped);
+    return StringView(**this + countClamped, Length() - countClamped);
 }
 
 StringView StringView::Substring(int32 startIndex) const
diff --git a/Source/Engine/Core/Types/Variant.cpp b/Source/Engine/Core/Types/Variant.cpp
index 3dd403d5f..3aea34368 100644
--- a/Source/Engine/Core/Types/Variant.cpp
+++ b/Source/Engine/Core/Types/Variant.cpp
@@ -2449,7 +2449,9 @@ void Variant::SetType(const VariantType& type)
     case VariantType::Structure:
         AllocStructure();
         break;
-    default: ;
+    default:
+        AsUint64 = 0;
+        break;
     }
 }
 
@@ -3065,6 +3067,69 @@ void Variant::DeleteValue()
     SetType(VariantType(VariantType::Null));
 }
 
+Variant Variant::Parse(const StringView& text, const VariantType& type)
+{
+    Variant result;
+    result.SetType(type);
+    if (text.IsEmpty())
+        return result;
+    if (type != VariantType())
+    {
+        switch (type.Type)
+        {
+        case VariantType::Bool:
+            if (text == TEXT("1") || text.Compare(StringView(TEXT("true"), 4), StringSearchCase::IgnoreCase) == 0)
+                result.AsBool = true;
+            break;
+        case VariantType::Int16:
+            StringUtils::Parse(text.Get(), &result.AsInt16);
+            break;
+        case VariantType::Uint16:
+            StringUtils::Parse(text.Get(), &result.AsUint16);
+            break;
+        case VariantType::Int:
+            StringUtils::Parse(text.Get(), &result.AsInt);
+            break;
+        case VariantType::Uint:
+            StringUtils::Parse(text.Get(), &result.AsUint);
+            break;
+        case VariantType::Int64:
+            StringUtils::Parse(text.Get(), &result.AsInt64);
+            break;
+        case VariantType::Uint64:
+        case VariantType::Enum:
+            StringUtils::Parse(text.Get(), &result.AsUint64);
+            break;
+        case VariantType::Float:
+            StringUtils::Parse(text.Get(), &result.AsFloat);
+            break;
+        case VariantType::Double:
+            StringUtils::Parse(text.Get(), &result.AsFloat);
+            result.AsDouble = (float)result.AsFloat;
+            break;
+        case VariantType::String:
+            result.SetString(text);
+        default:
+            break;
+        }
+    }
+    else
+    {
+        // Parse as number
+        int32 valueInt;
+        if (!StringUtils::Parse(text.Get(), text.Length(), &valueInt))
+        {
+            result = valueInt;
+        }
+        else
+        {
+            // Fallback to string
+            result.SetString(text);
+        }
+    }
+    return result;
+}
+
 bool Variant::CanCast(const Variant& v, const VariantType& to)
 {
     if (v.Type == to)
diff --git a/Source/Engine/Core/Types/Variant.h b/Source/Engine/Core/Types/Variant.h
index fa7f748fe..cd05fc038 100644
--- a/Source/Engine/Core/Types/Variant.h
+++ b/Source/Engine/Core/Types/Variant.h
@@ -381,6 +381,9 @@ public:
     // Frees the object or data owned by this Variant container (eg. structure or object).
     void DeleteValue();
 
+    // Parses the text into the Variant value. Allows to specify explicit value type.
+    static Variant Parse(const StringView& text, const VariantType& type = VariantType());
+
     FORCE_INLINE Variant Cast(const VariantType& to) const
     {
         return Cast(*this, to);