gorush/vendor/github.com/asdine/storm/extract.go

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package storm
import (
"fmt"
"reflect"
"strconv"
"strings"
"github.com/asdine/storm/index"
"github.com/boltdb/bolt"
)
// Storm tags
const (
tagID = "id"
tagIdx = "index"
tagUniqueIdx = "unique"
tagInline = "inline"
tagIncrement = "increment"
indexPrefix = "__storm_index_"
)
type fieldConfig struct {
Name string
Index string
IsZero bool
IsID bool
Increment bool
IncrementStart int64
IsInteger bool
Value *reflect.Value
}
// structConfig is a structure gathering all the relevant informations about a model
type structConfig struct {
Name string
Fields map[string]*fieldConfig
ID *fieldConfig
}
func extract(s *reflect.Value, mi ...*structConfig) (*structConfig, error) {
if s.Kind() == reflect.Ptr {
e := s.Elem()
s = &e
}
if s.Kind() != reflect.Struct {
return nil, ErrBadType
}
typ := s.Type()
var child bool
var m *structConfig
if len(mi) > 0 {
m = mi[0]
child = true
} else {
m = &structConfig{}
m.Fields = make(map[string]*fieldConfig)
}
if m.Name == "" {
m.Name = typ.Name()
}
numFields := s.NumField()
for i := 0; i < numFields; i++ {
field := typ.Field(i)
value := s.Field(i)
if field.PkgPath != "" {
continue
}
err := extractField(&value, &field, m, child)
if err != nil {
return nil, err
}
}
if child {
return m, nil
}
if m.ID == nil {
return nil, ErrNoID
}
if m.Name == "" {
return nil, ErrNoName
}
return m, nil
}
func extractField(value *reflect.Value, field *reflect.StructField, m *structConfig, isChild bool) error {
var f *fieldConfig
var err error
tag := field.Tag.Get("storm")
if tag != "" {
f = &fieldConfig{
Name: field.Name,
IsZero: isZero(value),
IsInteger: isInteger(value),
Value: value,
IncrementStart: 1,
}
tags := strings.Split(tag, ",")
for _, tag := range tags {
switch tag {
case "id":
f.IsID = true
case tagUniqueIdx, tagIdx:
f.Index = tag
case tagInline:
if value.Kind() == reflect.Ptr {
e := value.Elem()
value = &e
}
if value.Kind() == reflect.Struct {
a := value.Addr()
_, err := extract(&a, m)
if err != nil {
return err
}
}
// we don't need to save this field
return nil
default:
if strings.HasPrefix(tag, tagIncrement) {
f.Increment = true
parts := strings.Split(tag, "=")
if parts[0] != tagIncrement {
return ErrUnknownTag
}
if len(parts) > 1 {
f.IncrementStart, err = strconv.ParseInt(parts[1], 0, 64)
if err != nil {
return err
}
}
} else {
return ErrUnknownTag
}
}
}
if _, ok := m.Fields[f.Name]; !ok || !isChild {
m.Fields[f.Name] = f
}
}
if m.ID == nil && f != nil && f.IsID {
m.ID = f
}
// the field is named ID and no ID field has been detected before
if m.ID == nil && field.Name == "ID" {
if f == nil {
f = &fieldConfig{
Name: field.Name,
IsZero: isZero(value),
IsInteger: isInteger(value),
IsID: true,
Value: value,
IncrementStart: 1,
}
m.Fields[field.Name] = f
}
m.ID = f
}
return nil
}
func extractSingleField(ref *reflect.Value, fieldName string) (*structConfig, error) {
var cfg structConfig
cfg.Fields = make(map[string]*fieldConfig)
f, ok := ref.Type().FieldByName(fieldName)
if !ok || f.PkgPath != "" {
return nil, fmt.Errorf("field %s not found", fieldName)
}
v := ref.FieldByName(fieldName)
err := extractField(&v, &f, &cfg, false)
if err != nil {
return nil, err
}
return &cfg, nil
}
func getIndex(bucket *bolt.Bucket, idxKind string, fieldName string) (index.Index, error) {
var idx index.Index
var err error
switch idxKind {
case tagUniqueIdx:
idx, err = index.NewUniqueIndex(bucket, []byte(indexPrefix+fieldName))
case tagIdx:
idx, err = index.NewListIndex(bucket, []byte(indexPrefix+fieldName))
default:
err = ErrIdxNotFound
}
return idx, err
}
func isZero(v *reflect.Value) bool {
zero := reflect.Zero(v.Type()).Interface()
current := v.Interface()
return reflect.DeepEqual(current, zero)
}
func isInteger(v *reflect.Value) bool {
kind := v.Kind()
return v != nil && kind >= reflect.Int && kind <= reflect.Uint64
}