晋太元中,武陵人捕鱼为业。缘溪行,忘路之远近。忽逢桃花林,夹岸数百步,中无杂树,芳草鲜美,落英缤纷。渔人甚异之,复前行,欲穷其林。 林尽水源,便得一山,山有小口,仿佛若有光。便舍船,从口入。初极狭,才通人。复行数十步,豁然开朗。土地平旷,屋舍俨然,有良田、美池、桑竹之属。阡陌交通,鸡犬相闻。其中往来种作,男女衣着,悉如外人。黄发垂髫,并怡然自乐。 见渔人,乃大惊,问所从来。具答之。便要还家,设酒杀鸡作食。村中闻有此人,咸来问讯。自云先世避秦时乱,率妻子邑人来此绝境,不复出焉,遂与外人间隔。问今是何世,乃不知有汉,无论魏晋。此人一一为具言所闻,皆叹惋。余人各复延至其家,皆出酒食。停数日,辞去。此中人语云:“不足为外人道也。”(间隔 一作:隔绝) 既出,得其船,便扶向路,处处志之。及郡下,诣太守,说如此。太守即遣人随其往,寻向所志,遂迷,不复得路。 南阳刘子骥,高尚士也,闻之,欣然规往。未果,寻病终。后遂无问津者。
| DIR:/usr/include/mysql/server/private/ |
| Current File : //usr/include/mysql/server/private/lex_ident.h |
#ifndef LEX_IDENT_INCLUDED
#define LEX_IDENT_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
*/
#include "char_buffer.h"
extern MYSQL_PLUGIN_IMPORT CHARSET_INFO *table_alias_charset;
/*
Identifiers for the database objects stored on disk,
e.g. databases, tables, triggers.
*/
class Lex_ident_fs: public LEX_CSTRING
{
public:
Lex_ident_fs()
:LEX_CSTRING({0,0})
{ }
Lex_ident_fs(const char *str, size_t length)
:LEX_CSTRING({str, length})
{ }
explicit Lex_ident_fs(const LEX_CSTRING &str)
:LEX_CSTRING(str)
{ }
static bool check_body(const char *name, size_t length,
bool disallow_path_chars);
bool check_db_name() const;
bool check_db_name_with_error() const;
#ifndef DBUG_OFF
bool is_in_lower_case() const;
bool ok_for_lower_case_names() const;
#endif
#if MYSQL_VERSION_ID<=110501
private:
static bool is_valid_ident(const LEX_CSTRING &str)
{
// NULL identifier, or 0-terminated identifier
return (str.str == NULL && str.length == 0) || str.str[str.length] == 0;
}
public:
static CHARSET_INFO *charset_info()
{
return table_alias_charset;
}
bool streq(const LEX_CSTRING &rhs) const
{
DBUG_ASSERT(is_valid_ident(*this));
DBUG_ASSERT(is_valid_ident(rhs));
return length == rhs.length &&
my_strcasecmp(charset_info(), str, rhs.str) == 0;
}
#else
/*
Starting from 11.5.1 streq() is inherited from the base.
The above implementations of
charset_info(), streq() and is_valid_ident() should be removed.
*/
#error Remove streq() above.
#endif // MYSQL_VERSION_ID<=110501
};
/**
A valid database name identifier,
checked with check_db_name().
It's not known if it was lower-cased or is
in the user typed way.
*/
class Lex_ident_db: public Lex_ident_fs
{
bool is_null() const
{
return length == 0 && str == NULL;
}
// {empty_c_string,0} is used by derived tables
bool is_empty() const
{
return length == 0 && str != NULL;
}
public:
Lex_ident_db()
:Lex_ident_fs(NULL, 0)
{ }
explicit Lex_ident_db(const LEX_CSTRING &str)
:Lex_ident_fs(str)
{
DBUG_SLOW_ASSERT(is_null() || is_empty() || !check_db_name());
}
Lex_ident_db(const char *str, size_t length)
:Lex_ident_fs(str, length)
{
DBUG_SLOW_ASSERT(is_null() || is_empty() || !check_db_name());
}
};
/**
A normalized database name:
- checked with check_db_name()
- lower-cased if lower_case_table_names>0
*/
class Lex_ident_db_normalized: public Lex_ident_db
{
public:
Lex_ident_db_normalized(const char *str, size_t length)
:Lex_ident_db(str, length)
{
DBUG_SLOW_ASSERT(ok_for_lower_case_names());
}
explicit Lex_ident_db_normalized(const LEX_CSTRING &str)
:Lex_ident_db(str.str, str.length)
{
DBUG_SLOW_ASSERT(ok_for_lower_case_names());
}
};
class Lex_ident_table: public Lex_ident_fs
{
public:
using Lex_ident_fs::Lex_ident_fs;
};
template<size_t buff_sz>
class IdentBuffer: public CharBuffer<buff_sz>
{
constexpr static CHARSET_INFO *charset()
{
return &my_charset_utf8mb3_general_ci;
}
public:
IdentBuffer()
{ }
IdentBuffer<buff_sz> & copy_casedn(const LEX_CSTRING &str)
{
CharBuffer<buff_sz>::copy_casedn(charset(), str);
return *this;
}
};
template<size_t buff_sz>
class IdentBufferCasedn: public IdentBuffer<buff_sz>
{
public:
IdentBufferCasedn(const LEX_CSTRING &str)
{
IdentBuffer<buff_sz>::copy_casedn(str);
}
};
/*
A helper class to store temporary database names in a buffer.
After constructing it's typically should be checked using
Lex_ident_fs::check_db_name().
Note, the database name passed to the constructor can originally
come from the parser and can be of an atribtrary long length.
Let's reserve additional buffer space for one extra character
(SYSTEM_CHARSET_MBMAXLEN bytes), so check_db_name() can still
detect too long names even if the constructor cuts the data.
*/
class DBNameBuffer: public CharBuffer<SAFE_NAME_LEN + MY_CS_MBMAXLEN>
{
public:
DBNameBuffer()
{ }
DBNameBuffer(const LEX_CSTRING &db, bool casedn)
{
copy_casedn(&my_charset_utf8mb3_general_ci, db, casedn);
}
Lex_ident_db to_lex_ident_db() const
{
const LEX_CSTRING tmp= to_lex_cstring();
if (Lex_ident_fs(tmp).check_db_name())
return Lex_ident_db();
return Lex_ident_db(tmp.str, tmp.length);
}
Lex_ident_db to_lex_ident_db_with_error() const
{
const LEX_CSTRING tmp= to_lex_cstring();
if (Lex_ident_fs(tmp).check_db_name_with_error())
return Lex_ident_db();
return Lex_ident_db(tmp.str, tmp.length);
}
};
#endif // LEX_IDENT_INCLUDED
|