Details
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Task
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Status: Closed (View Workflow)
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Major
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Resolution: Fixed
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None
Description
In some cases the code in *.yy files related to expression parsed in their own LEX is hard to modify: reset_lex() and its correspoding restore_lex() reside in different grammar rules or different LEX methods.
In order to simplify this (and later join sql_yacc.yy and sql_yacc_ora.yy easier), let's add a class representing an expression (Item) pointer and its LEX (that was used to parse this expression).
Additionally, let's
- Move a few methods from LEX to sp_expr_lex
- Add a new sp_expr_lex method sp_repeat_loop_finalize()
- Add a new sp_expr_lex method sp_if_expr()
The tentative class structure is:
class sp_expr_lex: public sp_lex_local |
{
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Item *m_item; // The expression |
public: |
sp_expr_lex(THD *thd, LEX *oldlex)
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:sp_lex_local(thd, oldlex),
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m_item(NULL)
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{ }
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void set_item(Item *item) |
{
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m_item= item;
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}
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Item *get_item() const |
{
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return m_item; |
}
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// The following methods are to be moved from LEX |
bool sp_continue_when_statement(THD *thd); |
bool sp_continue_when_statement(THD *thd, const LEX_CSTRING *label_name); |
int case_stmt_action_expr(); |
int case_stmt_action_when(bool simple); |
bool sp_while_loop_expression(THD *thd) |
{
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return LEX::sp_while_loop_expression(thd, get_item()); |
}
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// The following methods are new, to simpify the code in *.yy: |
bool sp_repeat_loop_finalize(THD *thd); |
bool sp_if_expr(THD *thd); |
};
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The new rule that creates sp_expr_lex (i.e. LEX+Item) will look like this:
expr_lex:
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{
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DBUG_ASSERT(Lex->sphead);
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if (unlikely(!($<expr_lex>$= new (thd->mem_root) |
sp_expr_lex(thd, thd->lex))))
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MYSQL_YYABORT;
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Lex->sphead->reset_lex(thd, $<expr_lex>$);
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}
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expr
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{
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$$= $<expr_lex>1;
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$$->sp_lex_in_use= true; |
$$->set_item($2);
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if ($$->sphead->restore_lex(thd)) |
MYSQL_YYABORT;
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}
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;
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After these changes, it will be much easier to move grammar rules, because reset_lex() and its corresponding restore_lex() will reside inside the same rule expr_lex. A lot of restore_lex() calls will be gone.
Attachments
Issue Links
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- Closed
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