greenplumn CWStringBase 源码
greenplumn CWStringBase 代码
文件路径：/src/backend/gporca/libgpos/include/gpos/string/CWStringBase.h
//---------------------------------------------------------------------------
// Greenplum Database
// Copyright (C) 2010 Greenplum, Inc.
//
// @filename:
// CWStringBase.h
//
// @doc:
// Abstract wide character string class
//---------------------------------------------------------------------------
#ifndef GPOS_CWStringBase_H
#define GPOS_CWStringBase_H
#include "gpos/common/clibwrapper.h"
#include "gpos/types.h"
#define GPOS_WSZ_LENGTH(x) gpos::clib::Wcslen(x)
#define GPOS_WSZ_STR_LENGTH(x) GPOS_WSZ_LIT(x), GPOS_WSZ_LENGTH(GPOS_WSZ_LIT(x))
#define WCHAR_EOS GPOS_WSZ_LIT('\0')
namespace gpos
{
class CWStringConst;
class CMemoryPool;
//---------------------------------------------------------------------------
// @class:
// CWStringBase
//
// @doc:
// Abstract wide character string class.
// Currently, the class has two derived classes: CWStringConst and CWString.
// CWString is used to represent constant strings that once initialized are never
// modified. This class is not responsible for any memory management, rather
// its users are in charge for allocating and releasing the necessary memory.
// In contrast, CWString can be used to store strings that are modified after
// they are created. CWString is in charge of dynamically allocating and deallocating
// memory for storing the characters of the string.
//
//---------------------------------------------------------------------------
class CWStringBase
{
private:
protected:
// represents end-of-wide-string character
static const WCHAR m_empty_wcstr;
// size of the string in number of WCHAR units (not counting the terminating '\0')
ULONG m_length;
// whether string owns its memory and should take care of deallocating it at destruction time
BOOL m_owns_memory;
// checks whether the string is byte-wise equal to a given string literal
virtual BOOL Equals(const WCHAR *w_str_buffer) const;
public:
CWStringBase(const CWStringBase &) = delete;
// ctor
CWStringBase(ULONG length, BOOL owns_memory)
: m_length(length), m_owns_memory(owns_memory)
{
}
// dtor
virtual ~CWStringBase() = default;
// deep copy of the string
virtual CWStringConst *Copy(CMemoryPool *mp) const;
// accessors
virtual ULONG Length() const;
// checks whether the string is byte-wise equal to another string
virtual BOOL Equals(const CWStringBase *str) const;
// checks whether the string contains any characters
virtual BOOL IsEmpty() const;
// checks whether a string is properly null-terminated
bool IsValid() const;
// equality operator
BOOL operator==(const CWStringBase &str) const;
// returns the wide character buffer storing the string
virtual const WCHAR *GetBuffer() const = 0;
// returns the index of the first occurrence of a character, -1 if not found
INT Find(WCHAR wc) const;
// checks if a character is escaped
BOOL HasEscapedCharAt(ULONG offset) const;
// count how many times the character appears in string
ULONG CountOccurrencesOf(const WCHAR wc) const;
};
} // namespace gpos
#endif // !GPOS_CWStringBase_H
// EOF
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