Add TypedFieldAmount to declare Amount fields.

Remove VT template parameter. Deduce value type from ValueType alias.

include/xrpl/protocol/SField.h

@@ -304,15 +304,8 @@ class SField
 
 enum class SFieldMPT { None, Yes, No };
 
-// clang-format off
-template <typename T, SFieldMPT F>
-concept ValidFields = (std::is_same_v<T, STEitherAmount> &&
-                       (F == SFieldMPT::No || F == SFieldMPT::Yes)) ||
-    (!std::is_same_v<T, STEitherAmount> && F == SFieldMPT::None);
-
 /** A field with a type known at compile time. */
-template <class T, SFieldMPT M = SFieldMPT::None>
-    requires ValidFields<T, M>
+template <class T>
 struct TypedField : SField
 {
     using type = T;
@@ -322,25 +315,49 @@ struct TypedField : SField
 };
 
 /** Indicate std::optional field semantics. */
-template <class T, SFieldMPT M = SFieldMPT::None>
-    requires ValidFields<T, M>
+template <class T>
 struct OptionaledField
 {
-    TypedField<T, M> const* f;
+    TypedField<T> const* f;
+
+    explicit OptionaledField(TypedField<T> const& f_) : f(&f_)
+    {
+    }
+};
+
+template <class T>
+inline OptionaledField<T>
+operator~(TypedField<T> const& f)
+{
+    return OptionaledField<T>(f);
+}
+
+// Amount fields
+
+/** A field with a type known at compile time. */
+template <SFieldMPT>
+struct TypedFieldAmount : public TypedField<STEitherAmount>
+{
+    template <class... Args>
+    explicit TypedFieldAmount(private_access_tag_t pat, Args&&... args);
+};
 
-    explicit OptionaledField(TypedField<T, M> const& f_) : f(&f_)
+/** Indicate std::optional field semantics. */
+template <SFieldMPT M>
+struct OptionaledFieldAmount : public OptionaledField<STEitherAmount>
+{
+    explicit OptionaledFieldAmount(TypedFieldAmount<M> const& f_)
+        : OptionaledField<STEitherAmount>(f_)
     {
     }
 };
 
-template <class T, SFieldMPT M = SFieldMPT::None>
-    requires ValidFields<T, M>
-inline OptionaledField<T, M>
-operator~(TypedField<T, M> const& f)
+template <SFieldMPT M>
+inline OptionaledFieldAmount<M>
+operator~(TypedFieldAmount<M> const& f)
 {
-    return OptionaledField<T, M>(f);
+    return OptionaledFieldAmount<M>(f);
 }
-// clang-format on
 
 //------------------------------------------------------------------------------
 
@@ -359,8 +376,8 @@ using SF_UINT384 = TypedField<STBitString<384>>;
 using SF_UINT512 = TypedField<STBitString<512>>;
 
 using SF_ACCOUNT = TypedField<STAccount>;
-using SF_AMOUNT = TypedField<STEitherAmount, SFieldMPT::No>;
-using SF_EITHER_AMOUNT = TypedField<STEitherAmount, SFieldMPT::Yes>;
+using SF_AMOUNT = TypedFieldAmount<SFieldMPT::No>;
+using SF_EITHER_AMOUNT = TypedFieldAmount<SFieldMPT::Yes>;
 using SF_ISSUE = TypedField<STIssue>;
 using SF_CURRENCY = TypedField<STCurrency>;
 using SF_VL = TypedField<STBlob>;

include/xrpl/protocol/SOTemplate.h

@@ -75,10 +75,15 @@ class SOElement
     {
         init(fieldName);
     }
+    SOElement(TypedFieldAmount<SFieldMPT::No> const& fieldName, SOEStyle style)
+        : sField_(fieldName), style_(style), supportMpt_(soeMPTNotSupported)
+    {
+        init(fieldName);
+    }
     SOElement(
-        TypedField<STEitherAmount, SFieldMPT::Yes> const& fieldName,
+        TypedFieldAmount<SFieldMPT::Yes> const& fieldName,
         SOEStyle style,
-        SOETxMPTAmount supportMpt = SOETxMPTAmount::soeMPTNotSupported)
+        SOETxMPTAmount supportMpt = soeMPTNotSupported)
         : sField_(fieldName), style_(style), supportMpt_(supportMpt)
     {
         init(fieldName);
@@ -99,7 +104,7 @@ class SOElement
     bool
     supportMPT() const
     {
-        return supportMpt_ == SOETxMPTAmount::soeMPTSupported;
+        return supportMpt_ == soeMPTSupported;
     }
 };