git-svn-id: http://mc-server.googlecode.com/svn/trunk@484 0a769ca7-a7f5-676a-18bf-c427514a06d6
275 lines
7.8 KiB
C++
275 lines
7.8 KiB
C++
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// FastNBT.h
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// Interfaces to the fast NBT parser and writer
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/*
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The fast parser parses the data into a vector of cFastNBTTag structures. These structures describe the NBT tree,
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but themselves are allocated in a vector, thus minimizing reallocation.
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The structures have a minimal constructor, setting all member "pointers" to "invalid".
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The fast writer doesn't need a NBT tree structure built beforehand, it is commanded to open, append and close tags
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(just like XML); it keeps the internal tag stack and reports errors in usage.
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It directly outputs a string containing the serialized NBT data.
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*/
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#pragma once
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#include "Endianness.h"
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enum eTagType
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{
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TAG_Min = 0, // The minimum value for a tag type
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TAG_End = 0,
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TAG_Byte = 1,
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TAG_Short = 2,
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TAG_Int = 3,
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TAG_Long = 4,
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TAG_Float = 5,
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TAG_Double = 6,
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TAG_ByteArray = 7,
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TAG_String = 8,
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TAG_List = 9,
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TAG_Compound = 10,
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TAG_IntArray = 11,
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TAG_Max = 11, // The maximum value for a tag type
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} ;
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/** This structure is used for all NBT tags.
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It contains indices to the parent array of tags, building the NBT tree this way.
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Also contains indices into the data stream being parsed, used for values;
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NO dynamically allocated memory is used!
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Structure (all with the tree structure it describes) supports moving in memory (std::vector reallocation)
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*/
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struct cFastNBTTag
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{
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public:
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eTagType m_Type;
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// The following members are indices into the data stream. m_DataLength == 0 if no data available
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// They must not be pointers, because the datastream may be copied into another AString object in the meantime.
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int m_NameStart;
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int m_NameLength;
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int m_DataStart;
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int m_DataLength;
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// The following members are indices into the array returned; -1 if not valid
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// They must not be pointers, because pointers would not survive std::vector reallocation
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int m_Parent;
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int m_PrevSibling;
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int m_NextSibling;
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int m_FirstChild;
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int m_LastChild;
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cFastNBTTag(eTagType a_Type, int a_Parent) :
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m_Type(a_Type),
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m_NameLength(0),
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m_DataLength(0),
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m_Parent(a_Parent),
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m_PrevSibling(-1),
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m_NextSibling(-1),
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m_FirstChild(-1),
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m_LastChild(-1)
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{
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}
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cFastNBTTag(eTagType a_Type, int a_Parent, int a_PrevSibling) :
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m_Type(a_Type),
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m_NameLength(0),
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m_DataLength(0),
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m_Parent(a_Parent),
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m_PrevSibling(a_PrevSibling),
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m_NextSibling(-1),
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m_FirstChild(-1),
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m_LastChild(-1)
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{
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}
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} ;
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/** Parses and contains the parsed data
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Also implements data accessor functions for tree traversal and value getters
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The data pointer passed in the constructor is assumed to be valid throughout the object's life. Care must be taken not to initialize from a temporary.
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*/
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class cParsedNBT
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{
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public:
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cParsedNBT(const char * a_Data, int a_Length);
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bool IsValid(void) const {return m_IsValid; }
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int GetRoot(void) const {return 0; }
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int GetFirstChild (int a_Tag) const { return m_Tags[a_Tag].m_FirstChild; }
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int GetLastChild (int a_Tag) const { return m_Tags[a_Tag].m_LastChild; }
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int GetNextSibling(int a_Tag) const { return m_Tags[a_Tag].m_NextSibling; }
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int GetPrevSibling(int a_Tag) const { return m_Tags[a_Tag].m_PrevSibling; }
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int GetDataLength (int a_Tag) const { return m_Tags[a_Tag].m_DataLength; }
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const char * GetData(int a_Tag) const
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{
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ASSERT(m_Tags[a_Tag].m_Type != TAG_List);
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ASSERT(m_Tags[a_Tag].m_Type != TAG_Compound);
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return m_Data + m_Tags[a_Tag].m_DataStart;
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}
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int FindChildByName(int a_Tag, const AString & a_Name) const
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{
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return FindChildByName(a_Tag, a_Name.c_str(), a_Name.length());
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}
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int FindChildByName(int a_Tag, const char * a_Name, size_t a_NameLength = 0) const;
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int FindTagByPath (int a_Tag, const AString & a_Path) const;
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eTagType GetType(int a_Tag) const { return m_Tags[a_Tag].m_Type; }
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/// Returns the children type for a list tag; undefined on other tags. If list empty, returns TAG_End
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eTagType GetChildrenType(int a_Tag) const
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{
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ASSERT(m_Tags[a_Tag].m_Type == TAG_List);
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return (m_Tags[a_Tag].m_FirstChild < 0) ? TAG_End : m_Tags[m_Tags[a_Tag].m_FirstChild].m_Type;
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}
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inline unsigned char GetByte(int a_Tag) const
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{
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ASSERT(m_Tags[a_Tag].m_Type == TAG_Byte);
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return (unsigned char)(m_Data[m_Tags[a_Tag].m_DataStart]);
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}
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inline Int16 GetShort(int a_Tag) const
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{
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ASSERT(m_Tags[a_Tag].m_Type == TAG_Short);
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return ntohs(*((Int16 *)(m_Data + m_Tags[a_Tag].m_DataStart)));
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}
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inline Int32 GetInt(int a_Tag) const
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{
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ASSERT(m_Tags[a_Tag].m_Type == TAG_Int);
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return ntohl(*((Int32 *)(m_Data + m_Tags[a_Tag].m_DataStart)));
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}
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inline Int64 GetLong(int a_Tag) const
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{
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ASSERT(m_Tags[a_Tag].m_Type == TAG_Long);
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return NetworkToHostLong8(m_Data + m_Tags[a_Tag].m_DataStart);
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}
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inline float GetFloat(int a_Tag) const
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{
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ASSERT(m_Tags[a_Tag].m_Type == TAG_Float);
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Int32 tmp = ntohl(*((Int32 *)(m_Data + m_Tags[a_Tag].m_DataStart)));
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return *((float *)&tmp);
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}
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inline double GetDouble(int a_Tag) const
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{
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ASSERT(m_Tags[a_Tag].m_Type == TAG_Double);
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return NetworkToHostDouble8(m_Data + m_Tags[a_Tag].m_DataStart);
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}
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protected:
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const char * m_Data;
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int m_Length;
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std::vector<cFastNBTTag> m_Tags;
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bool m_IsValid; // True if parsing succeeded
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// Used while parsing:
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int m_Pos;
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bool Parse(void);
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bool ReadString(int & a_StringStart, int & a_StringLen); // Reads a simple string (2 bytes length + data), sets the string descriptors
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bool ReadCompound(void); // Reads the latest tag as a compound
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bool ReadList(eTagType a_ChildrenType); // Reads the latest tag as a list of items of type a_ChildrenType
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bool ReadTag(void); // Reads the latest tag, depending on its m_Type setting
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} ;
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class cFastNBTWriter
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{
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public:
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cFastNBTWriter(void);
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void BeginCompound(const AString & a_Name);
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void EndCompound(void);
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void BeginList(const AString & a_Name, eTagType a_ChildrenType);
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void EndList(void);
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void AddByte (const AString & a_Name, unsigned char a_Value);
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void AddShort (const AString & a_Name, Int16 a_Value);
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void AddInt (const AString & a_Name, Int32 a_Value);
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void AddLong (const AString & a_Name, Int64 a_Value);
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void AddFloat (const AString & a_Name, float a_Value);
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void AddDouble (const AString & a_Name, double a_Value);
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void AddString (const AString & a_Name, const AString & a_Value);
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void AddByteArray(const AString & a_Name, const char * a_Value, size_t a_NumElements);
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void AddIntArray (const AString & a_Name, const int * a_Value, size_t a_NumElements);
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void AddByteArray(const AString & a_Name, const AString & a_Value)
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{
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AddByteArray(a_Name, a_Value.data(), a_Value.size());
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}
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const AString & GetResult(void) const {return m_Result; }
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void Finish(void);
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protected:
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struct sParent
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{
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int m_Type; // TAG_Compound or TAG_List
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int m_Pos; // for TAG_List, the position of the list count
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int m_Count; // for TAG_List, the element count
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} ;
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static const int MAX_STACK = 50; // Highliy doubtful that an NBT would be constructed this many levels deep
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// These two fields emulate a stack. A raw array is used due to speed issues - no reallocations are allowed.
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sParent m_Stack[MAX_STACK];
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int m_CurrentStack;
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AString m_Result;
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bool IsStackTopCompound(void) const { return (m_Stack[m_CurrentStack].m_Type == TAG_Compound); }
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void WriteString(const char * a_Data, short a_Length);
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inline void TagCommon(const AString & a_Name, eTagType a_Type)
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{
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if (IsStackTopCompound())
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{
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// Compound: add the type and name:
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m_Result.push_back((char)a_Type);
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WriteString(a_Name.c_str(), a_Name.length());
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}
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else
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{
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// List: add to the counter
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m_Stack[m_CurrentStack].m_Count++;
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}
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}
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} ;
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