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#ifndef CHAR_BUFFER_INCLUDED
#define CHAR_BUFFER_INCLUDED
/*
Copyright (c) 2023, MariaDB
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; version 2 of
the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1335 USA
*/
/*
A string buffer with length.
This template class is useful to store things like database, table names,
whose maximum length a small fixed known value. Mainly to be used as
stack variables to store temporary values.
Can store exact string copies or casefolded string copies.
The stored value is returned as a LEX_CSTRING.
*/
template<size_t buff_sz>
class CharBuffer
{
char m_buff[buff_sz + 1 /* one extra byte for '\0' */];
size_t m_length;
bool is_sane() const
{
return m_length <= buff_sz; // One byte is still left for '\0'
}
bool buffer_overlaps(const LEX_CSTRING &str) const
{
return str.str + str.length >= m_buff && str.str <= m_buff + sizeof(m_buff);
}
public:
constexpr size_t max_data_size() const
{
return buff_sz; // The maximum data size, without the trailing '\0' byte.
}
size_t available_size() const
{
DBUG_ASSERT(is_sane());
return buff_sz - m_length;
}
CharBuffer()
:m_length(0)
{
m_buff[0]= '\0';
}
CharBuffer<buff_sz> & copy(const LEX_CSTRING &str)
{
DBUG_ASSERT(!buffer_overlaps(str));
m_length= MY_MIN(buff_sz, str.length);
memcpy(m_buff, str.str, m_length);
m_buff[m_length]= '\0';
return *this;
}
CharBuffer<buff_sz> & copy_casedn(CHARSET_INFO *cs, const LEX_CSTRING &str)
{
DBUG_ASSERT(!buffer_overlaps(str));
m_length= cs->cset->casedn(cs, str.str, str.length, m_buff, buff_sz);
/*
casedn() never writes outsize of buff_sz (unless a bug in casedn()),
so it's safe to write '\0' at the position m_length:
*/
DBUG_ASSERT(is_sane());
m_buff[m_length]= '\0';
return *this;
}
CharBuffer<buff_sz> & copy_caseup(CHARSET_INFO *cs, const LEX_CSTRING &str)
{
DBUG_ASSERT(!buffer_overlaps(str));
m_length= cs->cset->caseup(cs, str.str, str.length, m_buff, buff_sz);
DBUG_ASSERT(is_sane());
m_buff[m_length]= '\0'; // See comments in copy_casedn()
return *this;
}
CharBuffer<buff_sz> & copy_casedn(CHARSET_INFO *cs, const LEX_CSTRING &str,
bool casedn)
{
casedn ? copy_casedn(cs, str) : copy(str);
return *this;
}
// Append one character
CharBuffer<buff_sz> & append_char(char ch)
{
DBUG_ASSERT(is_sane());
if (available_size())
{
m_buff[m_length++]= ch;
m_buff[m_length]= '\0';
}
DBUG_ASSERT(is_sane());
return *this;
}
// Append a string
CharBuffer<buff_sz> & append(const LEX_CSTRING &str)
{
DBUG_ASSERT(is_sane());
DBUG_ASSERT(!buffer_overlaps(str));
size_t len= MY_MIN(available_size(), str.length);
memcpy(m_buff + m_length, str.str, len);
m_length+= len;
DBUG_ASSERT(is_sane());
m_buff[m_length]= '\0';
return *this;
}
// Append a string with casedn conversion
CharBuffer<buff_sz> & append_casedn(CHARSET_INFO *cs, const LEX_CSTRING &str)
{
DBUG_ASSERT(is_sane());
DBUG_ASSERT(!buffer_overlaps(str));
size_t casedn_length= cs->casedn(str.str, str.length,
m_buff + m_length, available_size());
m_length+= casedn_length;
DBUG_ASSERT(is_sane());
m_buff[m_length]= '\0';
return *this;
}
CharBuffer<buff_sz> & append_opt_casedn(CHARSET_INFO *cs,
const LEX_CSTRING &str,
bool casedn)
{
return casedn ? append_casedn(cs, str) : append(str);
}
// Append a string with caseup conversion
CharBuffer<buff_sz> & append_caseup(CHARSET_INFO *cs, const LEX_CSTRING &str)
{
DBUG_ASSERT(is_sane());
DBUG_ASSERT(!buffer_overlaps(str));
size_t casedn_length= cs->caseup(str.str, str.length,
m_buff + m_length, available_size());
m_length+= casedn_length;
DBUG_ASSERT(is_sane());
m_buff[m_length]= '\0';
return *this;
}
CharBuffer<buff_sz> & truncate(size_t length)
{
DBUG_ASSERT(is_sane());
if (m_length > length)
{
m_length= length;
m_buff[m_length]= '\0';
DBUG_ASSERT(is_sane());
}
return *this;
}
LEX_CSTRING to_lex_cstring() const
{
return LEX_CSTRING{m_buff, m_length};
}
const char *ptr() const { return m_buff; }
size_t length() const { return m_length; }
const char *end() const { return m_buff + m_length; }
};
#endif // CHAR_BUFFER_INCLUDED
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