refactor: Clean up TxMeta (#5845)

This change:
* Simplifies the `TxMeta` constructors - both were setting the same set of fields, and to make it harder for future bugs to arise and keep the code DRY, we can combine those into one helper function.
* Removes an unused constructor.
* Renames the variables to avoid Hungarian naming.
* Removes a bunch of now-unnecessary helper functions.

include/xrpl/protocol/TxMeta.h

@@ -33,51 +33,35 @@ namespace ripple {
 
 class TxMeta
 {
-private:
-    struct CtorHelper
-    {
-        explicit CtorHelper() = default;
-    };
-    template <class T>
-    TxMeta(
-        uint256 const& txID,
-        std::uint32_t ledger,
-        T const& data,
-        CtorHelper);
-
 public:
-    TxMeta(
-        uint256 const& transactionID,
-        std::uint32_t ledger,
-        std::optional<uint256> parentBatchId = std::nullopt);
+    TxMeta(uint256 const& transactionID, std::uint32_t ledger);
     TxMeta(uint256 const& txID, std::uint32_t ledger, Blob const&);
-    TxMeta(uint256 const& txID, std::uint32_t ledger, std::string const&);
     TxMeta(uint256 const& txID, std::uint32_t ledger, STObject const&);
 
     uint256 const&
     getTxID() const
     {
-        return mTransactionID;
+        return transactionID_;
     }
     std::uint32_t
     getLgrSeq() const
     {
-        return mLedger;
+        return ledgerSeq_;
     }
     int
     getResult() const
     {
-        return mResult;
+        return result_;
     }
     TER
     getResultTER() const
     {
-        return TER::fromInt(mResult);
+        return TER::fromInt(result_);
     }
     std::uint32_t
     getIndex() const
     {
-        return mIndex;
+        return index_;
     }
 
     void
@@ -104,66 +88,52 @@ public:
     STArray&
     getNodes()
     {
-        return (mNodes);
+        return nodes_;
     }
     STArray const&
     getNodes() const
     {
-        return (mNodes);
+        return nodes_;
     }
 
     void
-    setDeliveredAmount(STAmount const& delivered)
+    setAdditionalFields(STObject const& obj)
     {
-        mDelivered = delivered;
+        if (obj.isFieldPresent(sfDeliveredAmount))
+            deliveredAmount_ = obj.getFieldAmount(sfDeliveredAmount);
+
+        if (obj.isFieldPresent(sfParentBatchID))
+            parentBatchID_ = obj.getFieldH256(sfParentBatchID);
     }
 
-    STAmount
+    std::optional<STAmount> const&
     getDeliveredAmount() const
     {
-        XRPL_ASSERT(
-            hasDeliveredAmount(),
-            "ripple::TxMeta::getDeliveredAmount : non-null delivered amount");
-        return *mDelivered;
-    }
-
-    bool
-    hasDeliveredAmount() const
-    {
-        return static_cast<bool>(mDelivered);
+        return deliveredAmount_;
     }
 
     void
-    setParentBatchId(uint256 const& parentBatchId)
+    setDeliveredAmount(std::optional<STAmount> const& amount)
     {
-        mParentBatchId = parentBatchId;
+        deliveredAmount_ = amount;
     }
 
-    uint256
-    getParentBatchId() const
+    void
+    setParentBatchID(std::optional<uint256> const& id)
     {
-        XRPL_ASSERT(
-            hasParentBatchId(),
-            "ripple::TxMeta::getParentBatchId : non-null batch id");
-        return *mParentBatchId;
-    }
-
-    bool
-    hasParentBatchId() const
-    {
-        return static_cast<bool>(mParentBatchId);
+        parentBatchID_ = id;
     }
 
 private:
-    uint256 mTransactionID;
-    std::uint32_t mLedger;
-    std::uint32_t mIndex;
-    int mResult;
+    uint256 transactionID_;
+    std::uint32_t ledgerSeq_;
+    std::uint32_t index_;
+    int result_;
 
-    std::optional<STAmount> mDelivered;
-    std::optional<uint256> mParentBatchId;
+    std::optional<STAmount> deliveredAmount_;
+    std::optional<uint256> parentBatchID_;
 
-    STArray mNodes;
+    STArray nodes_;
 };
 
 }  // namespace ripple