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Removing some duplicate code in THD::convert_string() & friends
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1. Adding THD::convert_string(LEX_CSTRING *to,...) as a wrapper
   for convert_string(LEX_STRING *to,...), as LEX_CSTRING
   is now frequently used for conversion purpose.
   This reduced duplicate code in TEXT_STRING_sys,
   TEXT_STRING_literal, TEXT_STRING_filesystem grammar rules in *.yy

2. Adding yet another THD::convert_string() with an extra parameter
   "bool simple_copy_is_possible". This even more reduced
   repeatable code in the mentioned grammar rules in *.yy

3. Deriving Lex_ident_cli_st from Lex_string_with_metadata_st,
   as they have very similar functionality. Moving m_quote
   from Lex_ident_cli_st to Lex_string_with_metadata_st,
   as m_quote will be used later to optimize string literals anyway
   (e.g. avoid redundant copying on the tokenizer stage).
   Adjusting Lex_input_stream::get_text() accordingly.

4. Moving the reminders of the code in TEXT_STRING_sys, TEXT_STRING_literal,
   TEXT_STRING_filesystem grammar rules as new methods in THD:
   - make_text_string_sys()
   - make_text_string_connection()
   - make_text_string_filesystem()
   and changing *.yy to use these new methods.
   This reduced the amount of similar code in
   sql_yacc.yy and sql_yacc_ora.yy.

5. Removing duplicate code in Lex_input_stream::body_utf8_append_ident():
   by reusing THD::make_text_string_sys(). Thanks to #3 and #4.

6. Making THD members charset_is_system_charset,
   charset_is_collation_connection, charset_is_character_set_filesystem
   private, as they are not needed externally any more.
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@abarkov
abarkov committed May 11, 2018
1 parent af68252 commit 4a126bf
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Showing 5 changed files with 101 additions and 130 deletions.
41 changes: 40 additions & 1 deletion sql/sql_class.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -3130,8 +3130,10 @@ class THD :public Statement,
is set if a statement accesses a temporary table created through
CREATE TEMPORARY TABLE.
*/
bool charset_is_system_charset, charset_is_collation_connection;
private:
bool charset_is_system_charset, charset_is_collation_connection;
bool charset_is_character_set_filesystem;
public:
bool enable_slow_log; /* Enable slow log for current statement */
bool abort_on_warning;
bool got_warning; /* Set on call to push_warning() */
Expand Down Expand Up @@ -3706,6 +3708,25 @@ class THD :public Statement,
bool convert_string(LEX_STRING *to, CHARSET_INFO *to_cs,
const char *from, size_t from_length,
CHARSET_INFO *from_cs);
bool convert_string(LEX_CSTRING *to, CHARSET_INFO *to_cs,
const char *from, size_t from_length,
CHARSET_INFO *from_cs)
{
LEX_STRING tmp;
bool rc= convert_string(&tmp, to_cs, from, from_length, from_cs);
to->str= tmp.str;
to->length= tmp.length;
return rc;
}
bool convert_string(LEX_CSTRING *to, CHARSET_INFO *tocs,
const LEX_CSTRING *from, CHARSET_INFO *fromcs,
bool simple_copy_is_possible)
{
if (!simple_copy_is_possible)
return unlikely(convert_string(to, tocs, from->str, from->length, fromcs));
*to= *from;
return false;
}
/*
Convert a strings between character sets.
Uses my_convert_fix(), which uses an mb_wc .. mc_mb loop internally.
Expand Down Expand Up @@ -3767,6 +3788,24 @@ class THD :public Statement,
Item_basic_constant *make_string_literal_nchar(const Lex_string_with_metadata_st &str);
Item_basic_constant *make_string_literal_charset(const Lex_string_with_metadata_st &str,
CHARSET_INFO *cs);
bool make_text_string_sys(LEX_CSTRING *to,
const Lex_string_with_metadata_st *from)
{
return convert_string(to, system_charset_info,
from, charset(), charset_is_system_charset);
}
bool make_text_string_connection(LEX_CSTRING *to,
const Lex_string_with_metadata_st *from)
{
return convert_string(to, variables.collation_connection,
from, charset(), charset_is_collation_connection);
}
bool make_text_string_filesystem(LEX_CSTRING *to,
const Lex_string_with_metadata_st *from)
{
return convert_string(to, variables.character_set_filesystem,
from, charset(), charset_is_character_set_filesystem);
}
void add_changed_table(TABLE *table);
void add_changed_table(const char *key, size_t key_length);
CHANGED_TABLE_LIST * changed_table_dup(const char *key, size_t key_length);
Expand Down
43 changes: 15 additions & 28 deletions sql/sql_lex.cc
View file
Original file line number Diff line number Diff line change
Expand Up @@ -416,32 +416,18 @@ void Lex_input_stream::body_utf8_append(const char *ptr)
operation.
*/

void Lex_input_stream::body_utf8_append_ident(THD *thd,
const LEX_CSTRING *txt,
const char *end_ptr)
void
Lex_input_stream::body_utf8_append_ident(THD *thd,
const Lex_string_with_metadata_st *txt,
const char *end_ptr)
{
if (!m_cpp_utf8_processed_ptr)
return;

LEX_CSTRING utf_txt;
CHARSET_INFO *txt_cs= thd->charset();

if (!my_charset_same(txt_cs, &my_charset_utf8_general_ci))
{
LEX_STRING to;
thd->convert_string(&to,
&my_charset_utf8_general_ci,
txt->str, (uint) txt->length,
txt_cs);
utf_txt.str= to.str;
utf_txt.length= to.length;

}
else
utf_txt= *txt;
thd->make_text_string_sys(&utf_txt, txt); // QQ: check return value?

/* NOTE: utf_txt.length is in bytes, not in symbols. */

memcpy(m_body_utf8_ptr, utf_txt.str, utf_txt.length);
m_body_utf8_ptr += utf_txt.length;
*m_body_utf8_ptr= 0;
Expand Down Expand Up @@ -1043,13 +1029,13 @@ bool Lex_input_stream::get_text(Lex_string_with_metadata_st *dst, uint sep,
uchar c;
uint found_escape=0;
CHARSET_INFO *cs= m_thd->charset();
bool is_8bit= false;

dst->set_8bit(false);
while (! eof())
{
c= yyGet();
if (c & 0x80)
dst->set_8bit(true);
is_8bit= true;
#ifdef USE_MB
{
int l;
Expand Down Expand Up @@ -1093,23 +1079,24 @@ bool Lex_input_stream::get_text(Lex_string_with_metadata_st *dst, uint sep,

if (!(to= (char*) m_thd->alloc((uint) (end - str) + 1)))
{
dst->str= ""; // Sql_alloc has set error flag
dst->length= 0;
return true;
dst->set(&empty_clex_str, 0, '\0');
return true; // Sql_alloc has set error flag
}
dst->str= to;

m_cpp_text_start= m_cpp_tok_start + pre_skip;
m_cpp_text_end= get_cpp_ptr() - post_skip;

if (!found_escape)
{
memcpy(to, str, dst->length= (end - str));
to[dst->length]= 0;
size_t len= (end - str);
memcpy(to, str, len);
to[len]= '\0';
dst->set(to, len, is_8bit, '\0');
}
else
{
dst->length= unescape(cs, to, str, end, sep);
size_t len= unescape(cs, to, str, end, sep);
dst->set(to, len, is_8bit, '\0');
}
return false;
}
Expand Down
58 changes: 33 additions & 25 deletions sql/sql_lex.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -37,22 +37,47 @@


/**
A string with metadata.
A string with metadata. Usually points to a string in the client
character set, but unlike Lex_ident_cli_st (see below) it does not
necessarily point to a query fragment. It can also point to memory
of other kinds (e.g. an additional THD allocated memory buffer
not overlapping with the current query text).
We'll add more flags here eventually, to know if the string has, e.g.:
- multi-byte characters
- bad byte sequences
- backslash escapes: 'a\nb'
- separator escapes: 'a''b'
and reuse the original query fragments instead of making the string
copy too early, in Lex_input_stream::get_text().
This will allow to avoid unnecessary copying, as well as
create more optimal Item types in sql_yacc.yy
*/
struct Lex_string_with_metadata_st: public LEX_CSTRING
{
private:
bool m_is_8bit; // True if the string has 8bit characters
char m_quote; // Quote character, or 0 if not quoted
public:
void set_8bit(bool is_8bit) { m_is_8bit= is_8bit; }
void set_metadata(bool is_8bit, char quote)
{
m_is_8bit= is_8bit;
m_quote= quote;
}
void set(const char *s, size_t len, bool is_8bit, char quote)
{
str= s;
length= len;
set_metadata(is_8bit, quote);
}
void set(const LEX_CSTRING *s, bool is_8bit, char quote)
{
((LEX_CSTRING &)*this)= *s;
set_metadata(is_8bit, quote);
}
bool is_8bit() const { return m_is_8bit; }
bool is_quoted() const { return m_quote != '\0'; }
char quote() const { return m_quote; }
// Get string repertoire by the 8-bit flag and the character set
uint repertoire(CHARSET_INFO *cs) const
{
Expand All @@ -71,44 +96,27 @@ struct Lex_string_with_metadata_st: public LEX_CSTRING
Used to store identifiers in the client character set.
Points to a query fragment.
*/
struct Lex_ident_cli_st: public LEX_CSTRING
struct Lex_ident_cli_st: public Lex_string_with_metadata_st
{
private:
bool m_is_8bit;
char m_quote;
public:
void set_keyword(const char *s, size_t len)
{
str= s;
length= len;
m_is_8bit= false;
m_quote= '\0';
set(s, len, false, '\0');
}
void set_ident(const char *s, size_t len, bool is_8bit)
{
str= s;
length= len;
m_is_8bit= is_8bit;
m_quote= '\0';
set(s, len, is_8bit, '\0');
}
void set_ident_quoted(const char *s, size_t len, bool is_8bit, char quote)
{
str= s;
length= len;
m_is_8bit= is_8bit;
m_quote= quote;
set(s, len, is_8bit, quote);
}
void set_unquoted(const LEX_CSTRING *s, bool is_8bit)
{
((LEX_CSTRING &)*this)= *s;
m_is_8bit= is_8bit;
m_quote= '\0';
set(s, is_8bit, '\0');
}
const char *pos() const { return str - is_quoted(); }
const char *end() const { return str + length + is_quoted(); }
bool is_quoted() const { return m_quote != '\0'; }
bool is_8bit() const { return m_is_8bit; }
char quote() const { return m_quote; }
};


Expand Down Expand Up @@ -2453,7 +2461,7 @@ class Lex_input_stream
void body_utf8_append(const char *ptr);
void body_utf8_append(const char *ptr, const char *end_ptr);
void body_utf8_append_ident(THD *thd,
const LEX_CSTRING *txt,
const Lex_string_with_metadata_st *txt,
const char *end_ptr);
void body_utf8_append_escape(THD *thd,
const LEX_CSTRING *txt,
Expand Down
45 changes: 7 additions & 38 deletions sql/sql_yacc.yy
View file
Original file line number Diff line number Diff line change
Expand Up @@ -15170,57 +15170,26 @@ IDENT_sys:
TEXT_STRING_sys:
TEXT_STRING
{
if (thd->charset_is_system_charset)
$$= $1;
else
{
LEX_STRING to;
if (unlikely(thd->convert_string(&to, system_charset_info,
$1.str, $1.length,
thd->charset())))
MYSQL_YYABORT;
$$.str= to.str;
$$.length= to.length;
}
if (thd->make_text_string_sys(&$$, &$1))
MYSQL_YYABORT;
}
;

TEXT_STRING_literal:
TEXT_STRING
{
if (thd->charset_is_collation_connection)
$$= $1;
else
{
LEX_STRING to;
if (unlikely(thd->convert_string(&to,
thd->variables.collation_connection,
$1.str, $1.length,
thd->charset())))
MYSQL_YYABORT;
$$.str= to.str;
$$.length= to.length;
}
if (thd->make_text_string_connection(&$$, &$1))
MYSQL_YYABORT;
}
;

TEXT_STRING_filesystem:
TEXT_STRING
{
if (thd->charset_is_character_set_filesystem)
$$= $1;
else
{
LEX_STRING to;
if (unlikely(thd->convert_string(&to,
thd->variables.character_set_filesystem,
$1.str, $1.length,
thd->charset())))
MYSQL_YYABORT;
$$.str= to.str;
$$.length= to.length;
}
if (thd->make_text_string_filesystem(&$$, &$1))
MYSQL_YYABORT;
}
;

ident_table_alias:
IDENT_sys
Expand Down
44 changes: 6 additions & 38 deletions sql/sql_yacc_ora.yy
View file
Original file line number Diff line number Diff line change
Expand Up @@ -14919,56 +14919,24 @@ IDENT_sys:
TEXT_STRING_sys:
TEXT_STRING
{
if (thd->charset_is_system_charset)
$$= $1;
else
{
LEX_STRING to;
if (unlikely(thd->convert_string(&to, system_charset_info,
$1.str, $1.length,
thd->charset())))
MYSQL_YYABORT;
$$.str= to.str;
$$.length= to.length;
}
if (thd->make_text_string_sys(&$$, &$1))
MYSQL_YYABORT;
}
;

TEXT_STRING_literal:
TEXT_STRING
{
if (thd->charset_is_collation_connection)
$$= $1;
else
{
LEX_STRING to;
if (unlikely(thd->convert_string(&to,
thd->variables.collation_connection,
$1.str, $1.length,
thd->charset())))
MYSQL_YYABORT;
$$.str= to.str;
$$.length= to.length;
}
if (thd->make_text_string_connection(&$$, &$1))
MYSQL_YYABORT;
}
;

TEXT_STRING_filesystem:
TEXT_STRING
{
if (thd->charset_is_character_set_filesystem)
$$= $1;
else
{
LEX_STRING to;
if (unlikely(thd->convert_string(&to,
thd->variables.character_set_filesystem,
$1.str, $1.length,
thd->charset())))
MYSQL_YYABORT;
$$.str= to.str;
$$.length= to.length;
}
if (thd->make_text_string_filesystem(&$$, &$1))
MYSQL_YYABORT;
}
;

Expand Down

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