Symbol.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "uLang/Common/Containers/Array.h"
#include "uLang/Common/Containers/HashTraits.h"
#include "uLang/Common/Containers/SharedPointer.h" // For CSharedMix
#include "uLang/Common/Memory/ArenaAllocator.h"
#include "uLang/Common/Misc/Optional.h"
#include "uLang/Common/Text/UTF8String.h"
 
#define UE_API ULANGCORE_API
 
namespace uLang
{
 
using SymbolId = uint32_t;
 
enum { SymbolId_Null = 0 };
 
class CSymbol;
 
class CSymbolTable : public CSharedMix
{
public:
    UE_API CSymbolTable(uint32_t NumHashBuckets = 1024, uint32_t IdChunkShift = 10);
 
    UE_API ~CSymbolTable();
 
    CSymbol Get(SymbolId Id) const;
 
    UE_API TOptional<CSymbol> Find(const CUTF8StringView& Text, bool bIsGenerated = false) const;
 
    UE_API TOptional<CSymbol> Add(const CUTF8StringView& Text, bool bIsGenerated = false);
 
    UE_API CSymbol AddChecked(const CUTF8StringView& Text, bool bIsGenerated = false);
 
    UE_API void ReAdd(CSymbol& Symbol);
 
    static constexpr uint32_t MaxSymbolLength = 1024; // A symbol can be accepted here, but fail later in the compiler due to name transformations.   
 
private:
    friend class CSymbol;
 
    struct SEntry
    {
        SEntry*     _HashNext;         
        SymbolId    _Id;               
        uint32_t    _ByteLength : 31;  
        uint32_t    _bIsGenerated : 1; 
        UTF8Char    _Data[1];
 
        ULANG_FORCEINLINE CUTF8StringView AsStringView() const
        {
            return { _Data, _Data + _ByteLength };
        }
 
        ULANG_FORCEINLINE const char* AsCString() const
        {
            return (const char *)_Data;
        }
    };
 
    UE_API uint32_t       GetBucketIndex(const CUTF8StringView& Text) const;
    UE_API const SEntry * AddInternal(const CUTF8StringView& Text, uint32_t BucketIndex, bool bIsGenerated);
    UE_API const SEntry * FindOrAddInternal(const CUTF8StringView& Text, bool bIsGenerated);
 
    // No copying allowed
    CSymbolTable(const CSymbolTable&) = delete;
    void operator = (const CSymbolTable&) = delete;
    void operator = (CSymbolTable&&) = delete;
 
    TArray<SEntry*>  _HashBuckets;    
    CArenaAllocator  _Allocator;      
    TArray<SEntry**> _IdLookupTable;  
    uint32_t         _IdChunkShift;   
    SymbolId         _HighestUsedId;  
 
    static UE_API const SEntry _EntryNull; 
};
 
class CSymbol
{
public:
    ULANG_FORCEINLINE CSymbol() : _Entry(&CSymbolTable::_EntryNull) {}
 
    ULANG_FORCEINLINE SymbolId GetId() const   { return _Entry->_Id; }
    ULANG_FORCEINLINE bool IsNull() const      { return _Entry->_Id == SymbolId_Null; }
    ULANG_FORCEINLINE bool IsGenerated() const { return _Entry->_bIsGenerated; }
 
    ULANG_FORCEINLINE CUTF8String AsString() const          { return _Entry->AsStringView(); }
    ULANG_FORCEINLINE CUTF8StringView AsStringView() const  { return _Entry->AsStringView(); }
    ULANG_FORCEINLINE const char* AsCString() const         { return _Entry->AsCString(); }
    ULANG_FORCEINLINE UTF8Char FirstByte() const            { return _Entry->_Data[0]; }
 
    ULANG_FORCEINLINE EEquate Compare(const CSymbol& Other) const   { return (_Entry == Other._Entry) ? EEquate::Equal : ((_Entry < Other._Entry) ? EEquate::Less : EEquate::Greater); }
    ULANG_FORCEINLINE bool operator == (const CSymbol& Other) const { return _Entry == Other._Entry; }
    ULANG_FORCEINLINE bool operator != (const CSymbol& Other) const { return _Entry != Other._Entry; }
    ULANG_FORCEINLINE bool operator <= (const CSymbol& Other) const { return _Entry <= Other._Entry; }
    ULANG_FORCEINLINE bool operator >= (const CSymbol& Other) const { return _Entry >= Other._Entry; }
    ULANG_FORCEINLINE bool operator <  (const CSymbol& Other) const { return _Entry <  Other._Entry; }
    ULANG_FORCEINLINE bool operator >  (const CSymbol& Other) const { return _Entry >  Other._Entry; }
    
    ULANG_FORCEINLINE friend uint32_t GetTypeHash(CSymbol Symbol)
    {
        return GetTypeHash(Symbol._Entry->_Id);
    }
 
private:
    friend class CSymbolTable;
 
    ULANG_FORCEINLINE CSymbol(const CSymbolTable::SEntry* Entry) : _Entry(Entry) {}
 
    const CSymbolTable::SEntry * _Entry;
};
 
//=======================================================================================
// CSymbolTable Inline Methods
//=======================================================================================
 
ULANG_FORCEINLINE CSymbol CSymbolTable::Get(SymbolId Id) const
{
    ULANG_ASSERTF(Id <= _HighestUsedId, "Id out of range!");
 
    if (Id == SymbolId_Null) return CSymbol();
 
    uint32_t Index = Id - 1;
    uint32_t ChunkIndex = Index >> _IdChunkShift;
    uint32_t WithinChunkIndex = Index & ((1 << _IdChunkShift) - 1);
    return CSymbol(_IdLookupTable[ChunkIndex][WithinChunkIndex]);
}
 
}
 
#undef UE_API