Implement enhanced Ticket support:

Tickets are a mechanism to allow for the "out-of-order" execution of
transactions on the XRP Ledger.

This commit, if merged, reworks the existing support for tickets and
introduces support for 'ticket batching', completing the feature set
needed for tickets.

The code is gated under the newly-introduced `TicketBatch` amendment
and the `Tickets` amendment, which is not presently active on the
network, is being removed.

The specification for this change can be found at:
https://github.com/xrp-community/standards-drafts/issues/16

src/test/jtx/Env_test.cpp

@@ -480,20 +480,15 @@ public:
     {
         using namespace jtx;
         // create syntax
-        ticket::create("alice", "bob");
-        ticket::create("alice", 60);
-        ticket::create("alice", "bob", 60);
-        ticket::create("alice", 60, "bob");
+        ticket::create("alice", 1);
 
         {
-            Env env(*this, supported_amendments().set(featureTickets));
+            Env env(*this, supported_amendments() | featureTicketBatch);
             env.fund(XRP(10000), "alice");
             env(noop("alice"),
                 require(owners("alice", 0), tickets("alice", 0)));
-            env(ticket::create("alice"),
+            env(ticket::create("alice", 1),
                 require(owners("alice", 1), tickets("alice", 1)));
-            env(ticket::create("alice"),
-                require(owners("alice", 2), tickets("alice", 2)));
         }
     }
 

src/test/jtx/impl/ticket.cpp

@@ -26,34 +26,22 @@ namespace jtx {
 
 namespace ticket {
 
-namespace detail {
-
 Json::Value
-create(
-    Account const& account,
-    boost::optional<Account> const& target,
-    boost::optional<std::uint32_t> const& expire)
+create(Account const& account, std::uint32_t count)
 {
     Json::Value jv;
     jv[jss::Account] = account.human();
     jv[jss::TransactionType] = jss::TicketCreate;
-    if (expire)
-        jv["Expiration"] = *expire;
-    if (target)
-        jv["Target"] = target->human();
+    jv[sfTicketCount.jsonName] = count;
     return jv;
 }
 
-}  // namespace detail
-
-Json::Value
-cancel(Account const& account, std::string const& ticketId)
+void
+use::operator()(Env&, JTx& jt) const
 {
-    Json::Value jv;
-    jv[jss::TransactionType] = jss::TicketCancel;
-    jv[jss::Account] = account.human();
-    jv["TicketID"] = ticketId;
-    return jv;
+    jt.fill_seq = false;
+    jt[sfSequence.jsonName] = 0u;
+    jt[sfTicketSequence.jsonName] = ticketSeq_;
 }
 
 }  // namespace ticket

src/test/jtx/ticket.h

@@ -39,62 +39,24 @@ namespace jtx {
 /** Ticket operations */
 namespace ticket {
 
-namespace detail {
-
+/** Create one of more tickets */
 Json::Value
-create(
-    Account const& account,
-    boost::optional<Account> const& target,
-    boost::optional<std::uint32_t> const& expire);
+create(Account const& account, std::uint32_t count);
 
-inline void
-create_arg(
-    boost::optional<Account>& opt,
-    boost::optional<std::uint32_t>&,
-    Account const& value)
+/** Set a ticket sequence on a JTx. */
+class use
 {
-    opt = value;
-}
+private:
+    std::uint32_t ticketSeq_;
 
-inline void
-create_arg(
-    boost::optional<Account>&,
-    boost::optional<std::uint32_t>& opt,
-    std::uint32_t value)
-{
-    opt = value;
-}
+public:
+    use(std::uint32_t ticketSeq) : ticketSeq_{ticketSeq}
+    {
+    }
 
-template <class Arg, class... Args>
-void
-create_args(
-    boost::optional<Account>& account_opt,
-    boost::optional<std::uint32_t>& expire_opt,
-    Arg const& arg,
-    Args const&... args)
-{
-    create_arg(account_opt, expire_opt, arg);
-    if constexpr (sizeof...(args))
-        create_args(account_opt, expire_opt, args...);
-}
-
-}  // namespace detail
-
-/** Create a ticket */
-template <class... Args>
-Json::Value
-create(Account const& account, Args const&... args)
-{
-    boost::optional<Account> target;
-    boost::optional<std::uint32_t> expire;
-    if constexpr (sizeof...(args) > 0)
-        detail::create_args(target, expire, args...);
-    return detail::create(account, target, expire);
-}
-
-/** Cancel a ticket */
-Json::Value
-cancel(Account const& account, std::string const& ticketId);
+    void
+    operator()(Env&, JTx& jt) const;
+};
 
 }  // namespace ticket