Finalize autobridging implementation (RIPD-179):

Autobridging uses XRP as a natural bridge currency to allow IOU-to-IOU orders
to be satisfied not only from the direct IOU-to-IOU books but also over the
combined IOU-to-XRP and XRP-to-IOU books.

This commit addresses the following issues:

* RIPD-486: Refactoring the taker into a unit-testable architecture
* RIPD-659: Asset-aware offer crossing
* RIPD-491: Unit tests for IOU to XRP, XRP to IOU and IOU to IOU
* RIPD-441: Handle case when autobridging over same owner offers
* RIPD-665: Handle case when autobridging over own offers
* RIPD-273: Groom order books while crossing

Builds/VisualStudio2013/RippleD.vcxproj

@@ -1779,6 +1779,9 @@
     <ClCompile Include="..\..\src\ripple\app\book\tests\Quality.test.cpp">
       <ExcludedFromBuild>True</ExcludedFromBuild>
     </ClCompile>
+    <ClCompile Include="..\..\src\ripple\app\book\tests\Taker.test.cpp">
+      <ExcludedFromBuild>True</ExcludedFromBuild>
+    </ClCompile>
     <ClInclude Include="..\..\src\ripple\app\book\Types.h">
     </ClInclude>
     <ClCompile Include="..\..\src\ripple\app\consensus\DisputedTx.cpp">
@@ -2119,14 +2122,6 @@
     <ClCompile Include="..\..\src\ripple\app\transactors\CreateOffer.cpp">
       <ExcludedFromBuild>True</ExcludedFromBuild>
     </ClCompile>
-    <ClInclude Include="..\..\src\ripple\app\transactors\CreateOffer.h">
-    </ClInclude>
-    <ClCompile Include="..\..\src\ripple\app\transactors\CreateOfferBridged.cpp">
-      <ExcludedFromBuild>True</ExcludedFromBuild>
-    </ClCompile>
-    <ClCompile Include="..\..\src\ripple\app\transactors\CreateOfferDirect.cpp">
-      <ExcludedFromBuild>True</ExcludedFromBuild>
-    </ClCompile>
     <ClCompile Include="..\..\src\ripple\app\transactors\CreateTicket.cpp">
       <ExcludedFromBuild>True</ExcludedFromBuild>
     </ClCompile>

Builds/VisualStudio2013/RippleD.vcxproj.filters

@@ -2709,6 +2709,9 @@
     <ClCompile Include="..\..\src\ripple\app\book\tests\Quality.test.cpp">
       <Filter>ripple\app\book\tests</Filter>
     </ClCompile>
+    <ClCompile Include="..\..\src\ripple\app\book\tests\Taker.test.cpp">
+      <Filter>ripple\app\book\tests</Filter>
+    </ClCompile>
     <ClInclude Include="..\..\src\ripple\app\book\Types.h">
       <Filter>ripple\app\book</Filter>
     </ClInclude>
@@ -3114,15 +3117,6 @@
     <ClCompile Include="..\..\src\ripple\app\transactors\CreateOffer.cpp">
       <Filter>ripple\app\transactors</Filter>
     </ClCompile>
-    <ClInclude Include="..\..\src\ripple\app\transactors\CreateOffer.h">
-      <Filter>ripple\app\transactors</Filter>
-    </ClInclude>
-    <ClCompile Include="..\..\src\ripple\app\transactors\CreateOfferBridged.cpp">
-      <Filter>ripple\app\transactors</Filter>
-    </ClCompile>
-    <ClCompile Include="..\..\src\ripple\app\transactors\CreateOfferDirect.cpp">
-      <Filter>ripple\app\transactors</Filter>
-    </ClCompile>
     <ClCompile Include="..\..\src\ripple\app\transactors\CreateTicket.cpp">
       <Filter>ripple\app\transactors</Filter>
     </ClCompile>

src/BeastConfig.h

@@ -186,7 +186,7 @@
     This determines whether ripple implements offer autobridging via XRP.
 */
 #ifndef RIPPLE_ENABLE_AUTOBRIDGING
-#define RIPPLE_ENABLE_AUTOBRIDGING 0
+#define RIPPLE_ENABLE_AUTOBRIDGING 1
 #endif
 
 /** Config: RIPPLE_SINGLE_IO_SERVICE_THREAD

src/ripple/app/book/Offer.h

@@ -30,6 +30,7 @@
 #include <beast/utility/noexcept.h>
 
 #include <ostream>
+#include <stdexcept>
 
 namespace ripple {
 namespace core {
@@ -42,13 +43,20 @@ class Offer
 private:
     SLE::pointer m_entry;
     Quality m_quality;
+    Account m_account;
+
+    mutable Amounts m_amounts;
 
 public:
     Offer() = default;
 
     Offer (SLE::pointer const& entry, Quality quality)
         : m_entry (entry)
         , m_quality (quality)
+        , m_account (m_entry->getFieldAccount160 (sfAccount))
+        , m_amounts (
+            m_entry->getFieldAmount (sfTakerPays),
+            m_entry->getFieldAmount (sfTakerGets))
     {
     }
 
@@ -62,54 +70,68 @@ class Offer
         original quality.
     */
     Quality const
-    quality() const noexcept
+    quality () const noexcept
     {
         return m_quality;
     }
 
     /** Returns the account id of the offer's owner. */
-    Account const
-    account() const
+    Account const&
+    owner () const
     {
-        return m_entry->getFieldAccount160 (sfAccount);
+        return m_account;
     }
 
     /** Returns the in and out amounts.
         Some or all of the out amount may be unfunded.
     */
-    Amounts const
-    amount() const
+    Amounts const&
+    amount () const
     {
-        return Amounts (
-            m_entry->getFieldAmount (sfTakerPays),
-            m_entry->getFieldAmount (sfTakerGets));
+        return m_amounts;
     }
 
     /** Returns `true` if no more funds can flow through this offer. */
     bool
-    fully_consumed() const
+    fully_consumed () const
     {
-        if (m_entry->getFieldAmount (sfTakerPays) <= zero)
+        if (m_amounts.in <= zero)
             return true;
-        if (m_entry->getFieldAmount (sfTakerGets) <= zero)
+        if (m_amounts.out <= zero)
             return true;
         return false;
     }
 
-    /** Returns the ledger entry underlying the offer. */
-    // AVOID USING THIS
-    SLE::pointer
-    entry() const noexcept
+    /** Adjusts the offer to indicate that we consumed some (or all) of it. */
+    void
+    consume (LedgerView& view, Amounts const& consumed) const
+    {
+        if (consumed.in > m_amounts.in)
+            throw std::logic_error ("can't consume more than is available.");
+
+        if (consumed.out > m_amounts.out)
+            throw std::logic_error ("can't produce more than is available.");
+
+        m_amounts.in -= consumed.in;
+        m_amounts.out -= consumed.out;
+
+        m_entry->setFieldAmount (sfTakerPays, m_amounts.in);
+        m_entry->setFieldAmount (sfTakerGets, m_amounts.out);
+
+        view.entryModify (m_entry);
+    }
+
+    std::string id () const
     {
-        return m_entry;
+        return to_string (m_entry->getIndex());
     }
 };
 
 inline
 std::ostream&
 operator<< (std::ostream& os, Offer const& offer)
 {
-    return os << offer.entry()->getIndex();
+    return os << offer.id ();
 }
 
 }

src/ripple/app/book/OfferStream.h

@@ -104,17 +104,6 @@ class OfferStream
     */
     bool
     step ();
-
-    /** Advance to the next valid offer that is not from the specified account.
-        This automatically removes:
-            - Offers with missing ledger entries
-            - Offers found unfunded
-            - Offers from the same account
-            - Expired offers
-        @return `true` if there is a valid offer.
-    */
-    bool
-    step_account (Account const& account);
 };
 
 }