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string.go
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string.go
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package index
import (
"fmt"
"reflect"
"sync"
)
var (
stringIndexes = make(map[cacheKey]map[string]int)
stringOrderedIndexes = make(map[cacheKey][]StringKey)
stringIndexesMutex sync.RWMutex
)
type StringKey struct {
Key string
Index int
}
// GetString returns struct indexes of map encoding.
func GetString(t reflect.Type, tagName string) (map[string]int, error) {
key := cacheKey{
t: t,
tag: tagName,
}
if indexes := lookupString(key, false); indexes != nil {
return indexes, nil
}
stringIndexesMutex.Lock()
defer stringIndexesMutex.Unlock()
if indexes := lookupString(key, true); indexes != nil {
return indexes, nil
}
ordered, unordered, err := buildString(t, tagName)
if err != nil {
return nil, err
}
setString(key, ordered, unordered)
return unordered, nil
}
// GetStringOrdered returns struct indexes of map encoding.
func GetStringOrdered(t reflect.Type, tagName string) ([]StringKey, error) {
key := cacheKey{
t: t,
tag: tagName,
}
if indexes := lookupOrderedString(key, false); indexes != nil {
return indexes, nil
}
stringIndexesMutex.Lock()
defer stringIndexesMutex.Unlock()
if indexes := lookupOrderedString(key, true); indexes != nil {
return indexes, nil
}
ordered, unordered, err := buildString(t, tagName)
if err != nil {
return nil, err
}
setString(key, ordered, unordered)
return ordered, nil
}
func lookupString(key cacheKey, locked bool) map[string]int {
if !locked {
stringIndexesMutex.RLock()
defer stringIndexesMutex.RUnlock()
}
indexes, ok := stringIndexes[key]
if !ok {
return nil
}
return indexes
}
func lookupOrderedString(key cacheKey, locked bool) []StringKey {
if !locked {
stringIndexesMutex.RLock()
defer stringIndexesMutex.RUnlock()
}
indexes, ok := stringOrderedIndexes[key]
if !ok {
return nil
}
return indexes
}
func buildString(t reflect.Type, tagName string) ([]StringKey, map[string]int, error) {
var (
ordered = make([]StringKey, 0)
unordered = make(map[string]int)
)
for i := 0; i < t.NumField(); i++ {
field := t.Field(i)
tag, ok := field.Tag.Lookup(tagName)
if ok && tag == "-" {
continue
}
if tag == "" {
tag = field.Name
}
if _, ok := unordered[tag]; ok {
return nil, nil, fmt.Errorf("encode key conflict: %s", tag)
}
ordered = append(ordered, StringKey{
Key: tag,
Index: i,
})
unordered[tag] = i
}
return ordered, unordered, nil
}
func setString(key cacheKey, ordered []StringKey, unordered map[string]int) {
stringIndexes[key] = unordered
stringOrderedIndexes[key] = ordered
}