text: //------------------------------------------------------------------------------
  /*
      
      Copyright (c) 2012, 2013 Ripple Labs Inc.
  
      Permission to use, copy, modify, and/or distribute this software for any
      purpose  with  or without fee is hereby granted, provided that the above
      copyright notice and this permission notice appear in all copies.
  
      THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
      WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
      MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
      ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
      WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
      ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
      OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
  //==============================================================================
  
  #ifndef RIPPLE_PROTOCOL_STPATHSET_H_INCLUDED
  #define RIPPLE_PROTOCOL_STPATHSET_H_INCLUDED
  
  #include <ripple/json/json_value.h>
  #include <ripple/protocol/SField.h>
  #include <ripple/protocol/STBase.h>
  #include <ripple/protocol/UintTypes.h>
  #include <boost/optional.hpp>
  #include <cassert>
  #include <cstddef>
  
  namespace ripple {
  
  class STPathElement
  {
  public:
      enum Type
      {
          typeNone        = 0x00,
          typeAccount     = 0x01, // Rippling through an account (vs taking an offer).
          typeCurrency    = 0x10, // Currency follows.
          typeIssuer      = 0x20, // Issuer follows.
          typeBoundary    = 0xFF, // Boundary between alternate paths.
          typeAll = typeAccount | typeCurrency | typeIssuer,
                                  // Combination of all types.
      };
  
  private:
      static
      std::size_t
      get_hash (STPathElement const& element);
  
  public:
      STPathElement(
          boost::optional<AccountID> const& account,
          boost::optional<Currency> const& currency,
          boost::optional<AccountID> const& issuer)
          : mType (typeNone)
      {
          if (! account)
          {
              is_offer_ = true;
          }
          else
          {
              is_offer_ = false;
              mAccountID = *account;
              mType |= typeAccount;
              assert(mAccountID != noAccount());
          }
  
          if (currency)
          {
              mCurrencyID = *currency;
              mType |= typeCurrency;
          }
  
          if (issuer)
          {
              mIssuerID = *issuer;
              mType |= typeIssuer;
              assert(mIssuerID != noAccount());
          }
  
          hash_value_ = get_hash (*this);
      }
  
      STPathElement (
          AccountID const& account, Currency const& currency,
          AccountID const& issuer, bool forceCurrency = false)
          : mType (typeNone), mAccountID (account), mCurrencyID (currency)
          , mIssuerID (issuer), is_offer_ (isXRP(mAccountID))
      {
          if (!is_offer_)
              mType |= typeAccount;
  
          if (forceCurrency || !isXRP(currency))
              mType |= typeCurrency;
  
          if (!isXRP(issuer))
              mType |= typeIssuer;
  
          hash_value_ = get_hash (*this);
      }
  
      STPathElement (
          unsigned int uType, AccountID const& account, Currency const& currency,
          AccountID const& issuer)
          : mType (uType), mAccountID (account), mCurrencyID (currency)
          , mIssuerID (issuer), is_offer_ (isXRP(mAccountID))
      {
          hash_value_ = get_hash (*this);
      }
  
      STPathElement ()
          : mType (typeNone), is_offer_ (true)
      {
          hash_value_ = get_hash (*this);
      }
  
      STPathElement(STPathElement const&) = default;
      STPathElement& operator=(STPathElement const&) = default;
  
      auto
      getNodeType () const
      {
          return mType;
      }
  
      bool
      isOffer () const
      {
          return is_offer_;
      }
  
      bool
      isAccount () const
      {
          return !isOffer ();
      }
  
      bool
      hasIssuer () const
      {
          return getNodeType () & STPathElement::typeIssuer;
      }
  
      bool
      hasCurrency () const
      {
          return getNodeType () & STPathElement::typeCurrency;
      }
  
      bool
      isNone () const
      {
          return getNodeType () == STPathElement::typeNone;
      }
  
      // Nodes are either an account ID or a offer prefix. Offer prefixs denote a
      // class of offers.
      AccountID const&
      getAccountID () const
      {
          return mAccountID;
      }
  
      Currency const&
      getCurrency () const
      {
          return mCurrencyID;
      }
  
      AccountID const&
      getIssuerID () const
      {
          return mIssuerID;
      }
  
      bool
      operator== (const STPathElement& t) const
      {
          return (mType & typeAccount) == (t.mType & typeAccount) &&
              hash_value_ == t.hash_value_ &&
              mAccountID == t.mAccountID &&
              mCurrencyID == t.mCurrencyID &&
              mIssuerID == t.mIssuerID;
      }
  
      bool
      operator!= (const STPathElement& t) const
      {
          return !operator==(t);
      }
  
  private:
      unsigned int mType;
      AccountID mAccountID;
      Currency mCurrencyID;
      AccountID mIssuerID;
  
      bool is_offer_;
      std::size_t hash_value_;
  };
  
  class STPath
  {
  public:
      STPath () = default;
  
      STPath (std::vector<STPathElement> p)
          : mPath (std::move(p))
      { }
  
      std::vector<STPathElement>::size_type
      size () const
      {
          return mPath.size ();
      }
  
      bool empty() const
      {
          return mPath.empty ();
      }
  
      void
      push_back (STPathElement const& e)
      {
          mPath.push_back (e);
      }
  
      template <typename ...Args>
      void
      emplace_back (Args&&... args)
      {
          mPath.emplace_back (std::forward<Args> (args)...);
      }
  
      bool
      hasSeen (
          AccountID const& account, Currency const& currency,
          AccountID const& issuer) const;
  
      Json::Value
      getJson (JsonOptions) const;
  
      std::vector<STPathElement>::const_iterator
      begin () const
      {
          return mPath.begin ();
      }
  
      std::vector<STPathElement>::const_iterator
      end () const
      {
          return mPath.end ();
      }
  
      bool
      operator== (STPath const& t) const
      {
          return mPath == t.mPath;
      }
  
      std::vector<STPathElement>::const_reference
      back () const
      {
          return mPath.back ();
      }
  
      std::vector<STPathElement>::const_reference
      front () const
      {
          return mPath.front ();
      }
  
      STPathElement& operator[](int i)
      {
          return mPath[i];
      }
  
      const STPathElement& operator[](int i) const
      {
          return mPath[i];
      }
  
      void reserve(size_t s)
      {
          mPath.reserve(s);
      }
  private:
      std::vector<STPathElement> mPath;
  };
  
  //------------------------------------------------------------------------------
  
  // A set of zero or more payment paths
  class STPathSet final
      : public STBase
  {
  public:
      STPathSet () = default;
  
      STPathSet (SField const& n)
          : STBase (n)
      { }
  
      STPathSet (SerialIter& sit, SField const& name);
  
      STBase*
      copy (std::size_t n, void* buf) const override
      {
          return emplace(n, buf, *this);
      }
  
      STBase*
      move (std::size_t n, void* buf) override
      {
          return emplace(n, buf, std::move(*this));
      }
  
      void
      add (Serializer& s) const override;
  
      Json::Value
      getJson (JsonOptions) const override;
  
      SerializedTypeID
      getSType () const override
      {
          return STI_PATHSET;
      }
  
      bool
      assembleAdd(STPath const& base, STPathElement const& tail);
  
      bool
      isEquivalent (const STBase& t) const override;
  
      bool
      isDefault () const override
      {
          return value.empty ();
      }
  
      // std::vector like interface:
      std::vector<STPath>::const_reference
      operator[] (std::vector<STPath>::size_type n) const
      {
          return value[n];
      }
  
      std::vector<STPath>::reference
      operator[] (std::vector<STPath>::size_type n)
      {
          return value[n];
      }
  
      std::vector<STPath>::const_iterator
      begin () const
      {
          return value.begin ();
      }
  
      std::vector<STPath>::const_iterator
      end () const
      {
          return value.end ();
      }
  
      std::vector<STPath>::size_type
      size () const
      {
          return value.size ();
      }
  
      bool
      empty () const
      {
          return value.empty ();
      }
  
      void
      push_back (STPath const& e)
      {
          value.push_back (e);
      }
  
      template <typename... Args>
      void emplace_back (Args&&... args)
      {
          value.emplace_back (std::forward<Args> (args)...);
      }
  
  private:
      std::vector<STPath> value;
  };
  
  } // ripple
  
  #endif
  