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94 lines
2.4 KiB
Go
94 lines
2.4 KiB
Go
5 months ago
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package gokb
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import (
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"math"
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"reflect"
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"time"
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"kingbase.com/gokb/oid"
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)
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const headerSize = 4
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type fieldDesc struct {
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// The object ID of the data type.
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OID oid.Oid
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// The data type size (see pg_type.typlen).
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// Note that negative values denote variable-width types.
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Len int
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// The type modifier (see pg_attribute.atttypmod).
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// The meaning of the modifier is type-specific.
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Mod int
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}
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func (fd fieldDesc) Type() reflect.Type {
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switch fd.OID {
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case oid.T_int8:
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return reflect.TypeOf(int64(0))
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case oid.T_int4:
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return reflect.TypeOf(int32(0))
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case oid.T_int2:
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return reflect.TypeOf(int16(0))
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case oid.T_varchar, oid.T_text:
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return reflect.TypeOf("")
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case oid.T_bool:
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return reflect.TypeOf(false)
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case oid.T_date, oid.T_time, oid.T_timetz, oid.T_timestamp, oid.T_timestamptz:
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return reflect.TypeOf(time.Time{})
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case oid.T_bytea:
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return reflect.TypeOf([]byte(nil))
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default:
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return reflect.TypeOf(new(interface{})).Elem()
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}
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}
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func (fd fieldDesc) Name() string {
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return oid.TypeName[fd.OID]
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}
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func (fd fieldDesc) Length() (length int64, ok bool) {
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switch fd.OID {
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case oid.T_text, oid.T_bytea:
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return math.MaxInt64, true
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case oid.T_varchar, oid.T_bpchar:
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return int64(fd.Mod - headerSize), true
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default:
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return 0, false
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}
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}
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func (fd fieldDesc) PrecisionScale() (precision, scale int64, ok bool) {
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switch fd.OID {
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case oid.T_numeric, oid.T__numeric:
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mod := fd.Mod - headerSize
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precision = int64((mod >> 16) & 0xffff)
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scale = int64(mod & 0xffff)
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return precision, scale, true
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default:
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return 0, 0, false
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}
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}
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// ColumnTypeScanType returns the value type that can be used to scan types into.
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func (rs *rows) ColumnTypeScanType(index int) reflect.Type {
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return rs.colTyps[index].Type()
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}
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// ColumnTypeDatabaseTypeName return the database system type name.
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func (rs *rows) ColumnTypeDatabaseTypeName(index int) string {
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return rs.colTyps[index].Name()
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}
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// ColumnTypeLength returns the length of the column type if the column is a
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// variable length type. If the column is not a variable length type ok
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// should return false.
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func (rs *rows) ColumnTypeLength(index int) (length int64, ok bool) {
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return rs.colTyps[index].Length()
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}
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// ColumnTypePrecisionScale should return the precision and scale for decimal
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// types. If not applicable, ok should be false.
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func (rs *rows) ColumnTypePrecisionScale(index int) (precision, scale int64, ok bool) {
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return rs.colTyps[index].PrecisionScale()
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}
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