Update vendor github.com/lib/pq (#2752)

vendor/github.com/lib/pq/rows.go

@@ -0,0 +1,93 @@
+package pq
+
+import (
+	"math"
+	"reflect"
+	"time"
+
+	"github.com/lib/pq/oid"
+)
+
+const headerSize = 4
+
+type fieldDesc struct {
+	// The object ID of the data type.
+	OID oid.Oid
+	// The data type size (see pg_type.typlen).
+	// Note that negative values denote variable-width types.
+	Len int
+	// The type modifier (see pg_attribute.atttypmod).
+	// The meaning of the modifier is type-specific.
+	Mod int
+}
+
+func (fd fieldDesc) Type() reflect.Type {
+	switch fd.OID {
+	case oid.T_int8:
+		return reflect.TypeOf(int64(0))
+	case oid.T_int4:
+		return reflect.TypeOf(int32(0))
+	case oid.T_int2:
+		return reflect.TypeOf(int16(0))
+	case oid.T_varchar, oid.T_text:
+		return reflect.TypeOf("")
+	case oid.T_bool:
+		return reflect.TypeOf(false)
+	case oid.T_date, oid.T_time, oid.T_timetz, oid.T_timestamp, oid.T_timestamptz:
+		return reflect.TypeOf(time.Time{})
+	case oid.T_bytea:
+		return reflect.TypeOf([]byte(nil))
+	default:
+		return reflect.TypeOf(new(interface{})).Elem()
+	}
+}
+
+func (fd fieldDesc) Name() string {
+	return oid.TypeName[fd.OID]
+}
+
+func (fd fieldDesc) Length() (length int64, ok bool) {
+	switch fd.OID {
+	case oid.T_text, oid.T_bytea:
+		return math.MaxInt64, true
+	case oid.T_varchar, oid.T_bpchar:
+		return int64(fd.Mod - headerSize), true
+	default:
+		return 0, false
+	}
+}
+
+func (fd fieldDesc) PrecisionScale() (precision, scale int64, ok bool) {
+	switch fd.OID {
+	case oid.T_numeric, oid.T__numeric:
+		mod := fd.Mod - headerSize
+		precision = int64((mod >> 16) & 0xffff)
+		scale = int64(mod & 0xffff)
+		return precision, scale, true
+	default:
+		return 0, 0, false
+	}
+}
+
+// ColumnTypeScanType returns the value type that can be used to scan types into.
+func (rs *rows) ColumnTypeScanType(index int) reflect.Type {
+	return rs.colTyps[index].Type()
+}
+
+// ColumnTypeDatabaseTypeName return the database system type name.
+func (rs *rows) ColumnTypeDatabaseTypeName(index int) string {
+	return rs.colTyps[index].Name()
+}
+
+// ColumnTypeLength returns the length of the column type if the column is a
+// variable length type. If the column is not a variable length type ok
+// should return false.
+func (rs *rows) ColumnTypeLength(index int) (length int64, ok bool) {
+	return rs.colTyps[index].Length()
+}
+
+// ColumnTypePrecisionScale should return the precision and scale for decimal
+// types. If not applicable, ok should be false.
+func (rs *rows) ColumnTypePrecisionScale(index int) (precision, scale int64, ok bool) {
+	return rs.colTyps[index].PrecisionScale()
+}