/
order_by.go
164 lines (126 loc) · 3.27 KB
/
order_by.go
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package exql
import (
"fmt"
"strings"
)
// Order represents the order in which SQL results are sorted.
type Order uint8
// Possible values for Order
const (
DefaultOrder = Order(iota)
Ascendent
Descendent
)
// SortColumn represents the column-order relation in an ORDER BY clause.
type SortColumn struct {
Column Fragment
Order
hash hash
}
var _ = Fragment(&SortColumn{})
type sortColumnT struct {
Column string
Order string
}
var _ = Fragment(&SortColumn{})
// SortColumns represents the columns in an ORDER BY clause.
type SortColumns struct {
Columns []Fragment
hash hash
}
var _ = Fragment(&SortColumns{})
// OrderBy represents an ORDER BY clause.
type OrderBy struct {
SortColumns Fragment
hash hash
}
var _ = Fragment(&OrderBy{})
type orderByT struct {
SortColumns string
}
// JoinSortColumns creates and returns an array of column-order relations.
func JoinSortColumns(values ...Fragment) *SortColumns {
return &SortColumns{Columns: values}
}
// JoinWithOrderBy creates an returns an OrderBy using the given SortColumns.
func JoinWithOrderBy(sc *SortColumns) *OrderBy {
return &OrderBy{SortColumns: sc}
}
// Hash returns a unique identifier for the struct.
func (s *SortColumn) Hash() string {
return s.hash.Hash(s)
}
// Compile transforms the SortColumn into an equivalent SQL representation.
func (s *SortColumn) Compile(layout *Template) (compiled string, err error) {
if c, ok := layout.Read(s); ok {
return c, nil
}
column, err := s.Column.Compile(layout)
if err != nil {
return "", err
}
orderBy, err := s.Order.Compile(layout)
if err != nil {
return "", err
}
data := sortColumnT{Column: column, Order: orderBy}
compiled = layout.MustCompile(layout.SortByColumnLayout, data)
layout.Write(s, compiled)
return
}
// Hash returns a unique identifier for the struct.
func (s *SortColumns) Hash() string {
return s.hash.Hash(s)
}
// Compile transforms the SortColumns into an equivalent SQL representation.
func (s *SortColumns) Compile(layout *Template) (compiled string, err error) {
if z, ok := layout.Read(s); ok {
return z, nil
}
z := make([]string, len(s.Columns))
for i := range s.Columns {
z[i], err = s.Columns[i].Compile(layout)
if err != nil {
return "", err
}
}
compiled = strings.Join(z, layout.IdentifierSeparator)
layout.Write(s, compiled)
return
}
// Hash returns a unique identifier for the struct.
func (s *OrderBy) Hash() string {
return s.hash.Hash(s)
}
// Compile transforms the SortColumn into an equivalent SQL representation.
func (s *OrderBy) Compile(layout *Template) (compiled string, err error) {
if z, ok := layout.Read(s); ok {
return z, nil
}
if s.SortColumns != nil {
sortColumns, err := s.SortColumns.Compile(layout)
if err != nil {
return "", err
}
data := orderByT{
SortColumns: sortColumns,
}
compiled = layout.MustCompile(layout.OrderByLayout, data)
}
layout.Write(s, compiled)
return
}
// Hash returns a unique identifier.
func (s *Order) Hash() string {
return fmt.Sprintf("%T.%d", s, uint8(*s))
}
// Compile transforms the SortColumn into an equivalent SQL representation.
func (s Order) Compile(layout *Template) (string, error) {
switch s {
case Ascendent:
return layout.AscKeyword, nil
case Descendent:
return layout.DescKeyword, nil
}
return "", nil
}