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package hstore
import (
"database/sql"
"database/sql/driver"
"strings"
)
// Hstore is a wrapper for transferring Hstore values back and forth easily.
type Hstore struct {
Map map[string]sql.NullString
}
// escapes and quotes hstore keys/values
// s should be a sql.NullString or string
func hQuote(s interface{}) string {
var str string
switch v := s.(type) {
case sql.NullString:
if !v.Valid {
return "NULL"
}
str = v.String
case string:
str = v
default:
panic("not a string or sql.NullString")
}
str = strings.Replace(str, "\\", "\\\\", -1)
return `"` + strings.Replace(str, "\"", "\\\"", -1) + `"`
}
// Scan implements the Scanner interface.
//
// Note h.Map is reallocated before the scan to clear existing values. If the
// hstore column's database value is NULL, then h.Map is set to nil instead.
func (h *Hstore) Scan(value interface{}) error {
if value == nil {
h.Map = nil
return nil
}
h.Map = make(map[string]sql.NullString)
var b byte
pair := [][]byte{{}, {}}
pi := 0
inQuote := false
didQuote := false
sawSlash := false
bindex := 0
for bindex, b = range value.([]byte) {
if sawSlash {
pair[pi] = append(pair[pi], b)
sawSlash = false
continue
}
switch b {
case '\\':
sawSlash = true
continue
case '"':
inQuote = !inQuote
if !didQuote {
didQuote = true
}
continue
default:
if !inQuote {
switch b {
case ' ', '\t', '\n', '\r':
continue
case '=':
continue
case '>':
pi = 1
didQuote = false
continue
case ',':
s := string(pair[1])
if !didQuote && len(s) == 4 && strings.ToLower(s) == "null" {
h.Map[string(pair[0])] = sql.NullString{String: "", Valid: false}
} else {
h.Map[string(pair[0])] = sql.NullString{String: string(pair[1]), Valid: true}
}
pair[0] = []byte{}
pair[1] = []byte{}
pi = 0
continue
}
}
}
pair[pi] = append(pair[pi], b)
}
if bindex > 0 {
s := string(pair[1])
if !didQuote && len(s) == 4 && strings.ToLower(s) == "null" {
h.Map[string(pair[0])] = sql.NullString{String: "", Valid: false}
} else {
h.Map[string(pair[0])] = sql.NullString{String: string(pair[1]), Valid: true}
}
}
return nil
}
// Value implements the driver Valuer interface. Note if h.Map is nil, the
// database column value will be set to NULL.
func (h Hstore) Value() (driver.Value, error) {
if h.Map == nil {
return nil, nil
}
parts := []string{}
for key, val := range h.Map {
thispart := hQuote(key) + "=>" + hQuote(val)
parts = append(parts, thispart)
}
return []byte(strings.Join(parts, ",")), nil
}
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