diff options
Diffstat (limited to 'sql/item.h')
| -rw-r--r-- | sql/item.h | 114 |
1 files changed, 114 insertions, 0 deletions
diff --git a/sql/item.h b/sql/item.h index 97913e40916..a2bf33398cc 100644 --- a/sql/item.h +++ b/sql/item.h @@ -106,6 +106,120 @@ public: } }; + +/*************************************************************************/ +/* + A framework to easily handle different return types for hybrid items + (hybrid item is an item whose operand can be of any type, e.g. integer, + real, decimal). +*/ + +struct Hybrid_type_traits; + +struct Hybrid_type +{ + longlong integer; + + double real; + /* + Use two decimal buffers interchangeably to speed up += operation + which has no native support in decimal library. + Hybrid_type+= arg is implemented as dec_buf[1]= dec_buf[0] + arg. + The third decimal is used as a handy temporary storage. + */ + my_decimal dec_buf[3]; + int used_dec_buf_no; + + /* + Traits moved to a separate class to + a) be able to easily change object traits in runtime + b) they work as a differentiator for the union above + */ + const Hybrid_type_traits *traits; + + Hybrid_type() {} + /* XXX: add traits->copy() when needed */ + Hybrid_type(const Hybrid_type &rhs) :traits(rhs.traits) {} +}; + + +/* Hybryd_type_traits interface + default implementation for REAL_RESULT */ + +struct Hybrid_type_traits +{ + virtual Item_result type() const { return REAL_RESULT; } + + virtual void + fix_length_and_dec(Item *item, Item *arg) const; + + /* Hybrid_type operations. */ + virtual void set_zero(Hybrid_type *val) const { val->real= 0.0; } + virtual void add(Hybrid_type *val, Field *f) const + { val->real+= f->val_real(); } + virtual void div(Hybrid_type *val, ulonglong u) const + { val->real/= ulonglong2double(u); } + + virtual longlong val_int(Hybrid_type *val, bool unsigned_flag) const + { return (longlong) val->real; } + virtual double val_real(Hybrid_type *val) const { return val->real; } + virtual my_decimal *val_decimal(Hybrid_type *val, my_decimal *buf) const; + virtual String *val_str(Hybrid_type *val, String *buf, uint8 decimals) const; + static const Hybrid_type_traits *instance(); +}; + + +struct Hybrid_type_traits_decimal: public Hybrid_type_traits +{ + virtual Item_result type() const { return DECIMAL_RESULT; } + + virtual void + fix_length_and_dec(Item *arg, Item *item) const; + + /* Hybrid_type operations. */ + virtual void set_zero(Hybrid_type *val) const; + virtual void add(Hybrid_type *val, Field *f) const; + virtual void div(Hybrid_type *val, ulonglong u) const; + + virtual longlong val_int(Hybrid_type *val, bool unsigned_flag) const; + virtual double val_real(Hybrid_type *val) const; + virtual my_decimal *val_decimal(Hybrid_type *val, my_decimal *buf) const + { return &val->dec_buf[val->used_dec_buf_no]; } + virtual String *val_str(Hybrid_type *val, String *buf, uint8 decimals) const; + static const Hybrid_type_traits_decimal *instance(); +}; + + +struct Hybrid_type_traits_integer: public Hybrid_type_traits +{ + virtual Item_result type() const { return INT_RESULT; } + + virtual void + fix_length_and_dec(Item *arg, Item *item) const; + + /* Hybrid_type operations. */ + virtual void set_zero(Hybrid_type *val) const + { val->integer= 0; } + virtual void add(Hybrid_type *val, Field *f) const + { val->integer+= f->val_int(); } + virtual void div(Hybrid_type *val, ulonglong u) const + { val->integer/= (longlong) u; } + + virtual longlong val_int(Hybrid_type *val, bool unsigned_flag) const + { return val->integer; } + virtual double val_real(Hybrid_type *val) const + { return (double) val->integer; } + virtual my_decimal *val_decimal(Hybrid_type *val, my_decimal *buf) const + { + int2my_decimal(E_DEC_FATAL_ERROR, val->integer, 0, &val->dec_buf[2]); + return &val->dec_buf[2]; + } + virtual String *val_str(Hybrid_type *val, String *buf, uint8 decimals) const + { buf->set(val->integer, &my_charset_bin); return buf;} + static const Hybrid_type_traits_integer *instance(); +}; + +/*************************************************************************/ + typedef bool (Item::*Item_processor)(byte *arg); typedef Item* (Item::*Item_transformer) (byte *arg); |