Demonstrate how strongly typed ledger objects work

Signed-off-by: JCW <a1q123456@users.noreply.github.com>

# Conflicts:
#	include/xrpl/protocol/Keylet.h
#	src/libxrpl/protocol/Indexes.cpp
#	src/xrpld/rpc/handlers/VaultInfo.cpp

src/xrpld/app/ledger/detail/LocalTxs.cpp

@@ -157,7 +157,7 @@ public:
                 return false;
 
             SeqProxy const acctSeq =
-                SeqProxy::sequence(sleAcct->getFieldU32(sfSequence));
+                SeqProxy::sequence(sleAcct.fsfSequence());
             SeqProxy const seqProx = txn.getSeqProxy();
 
             if (seqProx.isSeq())

src/xrpld/app/misc/CredentialHelpers.cpp

@@ -245,7 +245,7 @@ authorizedDepositPreauth(
             return tefINTERNAL;  // LCOV_EXCL_LINE
 
         auto [it, ins] =
-            sorted.emplace((*sleCred)[sfIssuer], (*sleCred)[sfCredentialType]);
+            sorted.emplace(sleCred.fsfIssuer(), sleCred.fsfCredentialType());
         if (!ins)
             return tefINTERNAL;  // LCOV_EXCL_LINE
         lifeExtender.push_back(std::move(sleCred));

src/xrpld/app/misc/PermissionedDEXHelpers.cpp

@@ -34,10 +34,10 @@ accountInDomain(
         return false;
 
     // domain owner is in the domain
-    if (sleDomain->getAccountID(sfOwner) == account)
+    if (sleDomain.fsfOwner() == account)
         return true;
 
-    auto const& credentials = sleDomain->getFieldArray(sfAcceptedCredentials);
+    auto const& credentials = sleDomain.fsfAcceptedCredentials();
 
     bool const inDomain = std::any_of(
         credentials.begin(), credentials.end(), [&](auto const& credential) {
@@ -67,20 +67,20 @@ offerInDomain(
     // have any of the following wrong behavior
     if (!sleOffer)
         return false;  // LCOV_EXCL_LINE
-    if (!sleOffer->isFieldPresent(sfDomainID))
+    if (!sleOffer.fsfDomainID().has_value())
         return false;  // LCOV_EXCL_LINE
-    if (sleOffer->getFieldH256(sfDomainID) != domainID)
+    if (sleOffer.fsfDomainID() != domainID)
         return false;  // LCOV_EXCL_LINE
 
     if (sleOffer->isFlag(lsfHybrid) &&
-        !sleOffer->isFieldPresent(sfAdditionalBooks))
+        !sleOffer.fsfAdditionalBooks())
     {
         JLOG(j.error()) << "Hybrid offer " << offerID
                         << " missing AdditionalBooks field";
         return false;  // LCOV_EXCL_LINE
     }
 
-    return accountInDomain(view, sleOffer->getAccountID(sfAccount), domainID);
+    return accountInDomain(view, sleOffer.fsfAccount(), domainID);
 }
 
 }  // namespace permissioned_dex

src/xrpld/app/misc/detail/AMMUtils.cpp

@@ -215,14 +215,14 @@ ammAccountHolds(
     if (isXRP(issue))
     {
         if (auto const sle = view.read(keylet::account(ammAccountID)))
-            return (*sle)[sfBalance];
+            return sle.fsfBalance();
     }
     else if (auto const sle = view.read(
                  keylet::line(ammAccountID, issue.account, issue.currency));
              sle &&
              !isFrozen(view, ammAccountID, issue.currency, issue.account))
     {
-        auto amount = (*sle)[sfBalance];
+        auto amount = sle.fsfBalance();
         if (ammAccountID > issue.account)
             amount.negate();
         amount.setIssuer(issue.account);

src/xrpld/app/paths/detail/BookStep.cpp

@@ -104,7 +104,7 @@ public:
             ammSle && ammSle->getFieldAmount(sfLPTokenBalance) != beast::zero)
             ammLiquidity_.emplace(
                 ctx.view,
-                (*ammSle)[sfAccount],
+                ammSle.fsfAccount(),
                 getTradingFee(ctx.view, *ammSle, ctx.ammContext.account()),
                 in,
                 out,
@@ -1392,7 +1392,7 @@ BookStep<TIn, TOut, TDerived>::check(StrandContext const& ctx) const
             auto sle = view.read(keylet::line(*prev, cur, book_.in.currency));
             if (!sle)
                 return terNO_LINE;
-            if ((*sle)[sfFlags] &
+            if ((*sle.getObject())[sfFlags] &
                 ((cur > *prev) ? lsfHighNoRipple : lsfLowNoRipple))
                 return terNO_RIPPLE;
         }

src/xrpld/app/paths/detail/DirectStep.cpp

@@ -421,7 +421,7 @@ DirectIPaymentStep::check(
 
         if (((*sleSrc)[sfFlags] & lsfRequireAuth) &&
             !((*sleLine)[sfFlags] & authField) &&
-            (*sleLine)[sfBalance] == beast::zero)
+            sleLine.fsfBalance() == beast::zero)
         {
             JLOG(j_.warn())
                 << "DirectStepI: can't receive IOUs from issuer without auth."

src/xrpld/app/paths/detail/StepChecks.h

@@ -65,17 +65,17 @@ checkFreeze(
     if (view.rules().enabled(fixFrozenLPTokenTransfer))
     {
         if (auto const sleDst = view.read(keylet::account(dst));
-            sleDst && sleDst->isFieldPresent(sfAMMID))
+            sleDst && sleDst.fsfAMMID().has_value())
         {
-            auto const sleAmm = view.read(keylet::amm((*sleDst)[sfAMMID]));
+            auto const sleAmm = view.read(keylet::amm(sleDst.fsfAMMID().value()));
             if (!sleAmm)
                 return tecINTERNAL;  // LCOV_EXCL_LINE
 
             if (isLPTokenFrozen(
                     view,
                     src,
-                    (*sleAmm)[sfAsset].get<Issue>(),
+                    sleAmm.fsfAsset().get<Issue>(),
-                    (*sleAmm)[sfAsset2].get<Issue>()))
+                    sleAmm.fsfAsset2().get<Issue>()))
             {
                 return terNO_LINE;
             }

src/xrpld/app/tx/detail/AMMBid.cpp

@@ -109,7 +109,7 @@ AMMBid::preclaim(PreclaimContext const& ctx)
         return terNO_AMM;
     }
 
-    auto const lpTokensBalance = (*ammSle)[sfLPTokenBalance];
+    auto const lpTokensBalance = ammSle.fsfLPTokenBalance();
     if (lpTokensBalance == beast::zero)
         return tecAMM_EMPTY;
 

src/xrpld/app/tx/detail/AMMDelete.cpp

@@ -56,7 +56,7 @@ AMMDelete::preclaim(PreclaimContext const& ctx)
         return terNO_AMM;
     }
 
-    auto const lpTokensBalance = (*ammSle)[sfLPTokenBalance];
+    auto const lpTokensBalance = ammSle.fsfLPTokenBalance();
     if (lpTokensBalance != beast::zero)
         return tecAMM_NOT_EMPTY;
 

src/xrpld/app/tx/detail/AMMDeposit.cpp

@@ -220,7 +220,7 @@ AMMDeposit::preclaim(PreclaimContext const& ctx)
     auto balance = [&](auto const& deposit) -> TER {
         if (isXRP(deposit))
         {
-            auto const lpIssue = (*ammSle)[sfLPTokenBalance].issue();
+            auto const lpIssue = ammSle.fsfLPTokenBalance().issue();
             // Adjust the reserve if LP doesn't have LPToken trustline
             auto const sle = ctx.view.read(
                 keylet::line(accountID, lpIssue.account, lpIssue.currency));

src/xrpld/app/tx/detail/CancelCheck.cpp

@@ -61,7 +61,7 @@ CancelCheck::preclaim(PreclaimContext const& ctx)
 
     using duration = NetClock::duration;
     using timepoint = NetClock::time_point;
-    auto const optExpiry = (*sleCheck)[~sfExpiration];
+    auto const optExpiry = sleCheck.fsfExpiration();
 
     // Expiration is defined in terms of the close time of the parent
     // ledger, because we definitively know the time that it closed but
@@ -73,8 +73,8 @@ CancelCheck::preclaim(PreclaimContext const& ctx)
         // If the check is not yet expired, then only the creator or the
         // destination may cancel the check.
         AccountID const acctId{ctx.tx[sfAccount]};
-        if (acctId != (*sleCheck)[sfAccount] &&
+        if (acctId != sleCheck.fsfAccount() &&
-            acctId != (*sleCheck)[sfDestination])
+            acctId != sleCheck.fsfDestination())
         {
             JLOG(ctx.j.warn()) << "Check is not expired and canceler is "
                                   "neither check source nor destination.";

src/xrpld/app/tx/detail/CancelOffer.cpp

@@ -61,7 +61,7 @@ CancelOffer::preclaim(PreclaimContext const& ctx)
     if (!sle)
         return terNO_ACCOUNT;
 
-    if ((*sle)[sfSequence] <= offerSequence)
+    if (sle.fsfSequence() <= offerSequence)
     {
         JLOG(ctx.j.trace()) << "Malformed transaction: "
                             << "Sequence " << offerSequence << " is invalid.";

src/xrpld/ledger/ReadView.h

@@ -33,6 +33,7 @@
 #include <xrpl/protocol/STAmount.h>
 #include <xrpl/protocol/STLedgerEntry.h>
 #include <xrpl/protocol/STTx.h>
+#include <xrpl/protocol/TypedLedgerEntries.h>
 
 #include <cstdint>
 #include <optional>
@@ -170,6 +171,13 @@ public:
     virtual std::shared_ptr<SLE const>
     read(Keylet const& k) const = 0;
 
+    template<LedgerEntryType Type>
+    ConstLedgerObjectType<Type>
+    read(TypedKeylet<Type> const& k) const
+    {
+        return ConstLedgerObjectType<Type>::fromObject(read(k));
+    }
+
     // Accounts in a payment are not allowed to use assets acquired during that
     // payment. The PaymentSandbox tracks the debits, credits, and owner count
     // changes that accounts make during a payment. `balanceHook` adjusts

src/xrpld/ledger/detail/View.cpp

@@ -36,6 +36,7 @@
 #include <xrpl/protocol/TxFlags.h>
 #include <xrpl/protocol/digest.h>
 #include <xrpl/protocol/st.h>
+#include <xrpl/protocol/TypedLedgerEntries.h>
 
 #include <type_traits>
 #include <variant>
@@ -260,9 +261,9 @@ isFrozen(
     if (issuer != account)
     {
         // Check if the issuer froze the line
-        sle = view.read(keylet::line(account, issuer, currency));
+        auto sleLine = view.read(keylet::line(account, issuer, currency));
-        if (sle &&
+        if (sleLine &&
-            sle->isFlag((issuer > account) ? lsfHighFreeze : lsfLowFreeze))
+            sleLine->isFlag((issuer > account) ? lsfHighFreeze : lsfLowFreeze))
             return true;
     }
     return false;
@@ -319,30 +320,34 @@ isVaultPseudoAccountFrozen(
         return true;  // LCOV_EXCL_LINE
 
     auto const mptIssuance =
-        view.read(keylet::mptIssuance(mptShare.getMptID()));
+        ConstLedgerObjectType<ltMPTOKEN_ISSUANCE>::fromObject(
-    if (mptIssuance == nullptr)
+            view.read(keylet::mptIssuance(mptShare.getMptID())));
+    if (mptIssuance.isValid())
         return false;  // zero MPToken won't block deletion of MPTokenIssuance
 
-    auto const issuer = mptIssuance->getAccountID(sfIssuer);
+    auto const issuer = mptIssuance.fsfIssuer();
-    auto const mptIssuer = view.read(keylet::account(issuer));
+    auto const mptIssuer =
-    if (mptIssuer == nullptr)
+        ConstLedgerObjectType<ltACCOUNT_ROOT>::fromObject(
+            view.read(keylet::account(issuer)));
+    if (mptIssuer.isValid())
     {  // LCOV_EXCL_START
         UNREACHABLE("ripple::isVaultPseudoAccountFrozen : null MPToken issuer");
         return false;
     }  // LCOV_EXCL_STOP
 
-    if (!mptIssuer->isFieldPresent(sfVaultID))
+    if (!mptIssuer.fsfVaultID().has_value())
         return false;  // not a Vault pseudo-account, common case
 
     auto const vault =
-        view.read(keylet::vault(mptIssuer->getFieldH256(sfVaultID)));
+        ConstLedgerObjectType<ltVAULT>::fromObject(
-    if (vault == nullptr)
+            view.read(keylet::vault(*mptIssuer.fsfVaultID())));
+    if (vault.isValid())
     {  // LCOV_EXCL_START
         UNREACHABLE("ripple::isVaultPseudoAccountFrozen : null vault");
         return false;
     }  // LCOV_EXCL_STOP
 
-    return isAnyFrozen(view, {issuer, account}, vault->at(sfAsset), depth + 1);
+    return isAnyFrozen(view, {issuer, account}, vault.fsfAsset(), depth + 1);
 }
 
 bool