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nested_map.go
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nested_map.go
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/*
* @Author: jinde.zgm
* @Date: 2020-11-22 13:02:09
* @Descripttion:
*/
package concurrent
import (
"errors"
"reflect"
"sync"
)
// Define error code for NestedMap.
var (
ErrNotBranch = errors.New("keys are not branch") // A node in the path specified by keys is not branch.
ErrNotLeaf = errors.New("keys are not leaf") // A node in the path specified by keys is not leaf.
ErrNotExist = errors.New("value is not exist") // No value is present
)
// NestedMap is is a map that can be nested infinitely, as shown below:
// /->key1:value1
// /->branch_map1 -->key2:value2
// root_map \->key3:value3
// \->branch_map2 -->branch_map3 -->key4:value4
// \->key5:value5
// NestedMap key type is ...interface{}, it can only be in the following formats:
// 1. "a", 2, "c" or,
// 2. [1, "b", 3]
// But it cannot be in the following format:
// 1. "a", ["b", "c"] or,
// 2. 1, [2, 3] or,
// 3. "a", [2, 3] or,
// 4. 1, ["b", "c"]
type NestedMap sync.Map
// Load returns the value stored in the map for a key, or nil if no value is present.
func (nm *NestedMap) Load(keys ...interface{}) (interface{}, error) {
keys = nm.convertKeys(keys...)
m, err := nm.search(keys[:len(keys)-1]...)
if nil != err {
return nil, err
}
value, exist := m.Load(keys[len(keys)-1])
if !exist {
return nil, ErrNotExist
} else if _, ok := value.(*NestedMap); ok {
return nil, ErrNotLeaf
}
return value, nil
}
// Store sets the value for keys.
func (nm *NestedMap) Store(value interface{}, keys ...interface{}) error {
keys = nm.convertKeys(keys...)
m, err := nm.searchOrCreate(keys[:len(keys)-1]...)
if nil != err {
return err
}
m.Store(keys[len(keys)-1], value)
return nil
}
// LoadOrStore returns the existing value for the keys if present.
// Otherwise, it stores and returns the given value.
// The loaded result is true if the value was loaded, false if stored.
func (nm *NestedMap) LoadOrStore(value interface{}, keys ...interface{}) (actual interface{}, loaded bool, err error) {
keys = nm.convertKeys(keys...)
m, err := nm.searchOrCreate(keys[:len(keys)-1]...)
if nil != err {
return nil, false, err
}
actual, loaded = m.LoadOrStore(keys[len(keys)-1], value)
return actual, loaded, nil
}
// Delete deletes the value for keys.
func (nm *NestedMap) Delete(keys ...interface{}) error {
keys = nm.convertKeys(keys...)
m, err := nm.search(keys[:len(keys)-1]...)
if nil != err {
return err
}
m.Delete(keys[len(keys)-1])
return nil
}
// Range calls f sequentially for each key and value present in the map. If f returns false, range stops the iteration.
func (nm *NestedMap) Range(f func(keys []interface{}, value interface{}) bool, keys ...interface{}) error {
keys = nm.convertKeys(keys...)
m, err := nm.search(keys...)
if nil != err {
return err
}
nm.nestRange(m, f, keys)
return nil
}
// nestRange recursive range the map.
func (nm *NestedMap) nestRange(m *sync.Map, f func(keys []interface{}, value interface{}) bool, keys []interface{}) bool {
// Extend keys.
keys = append(keys, nil)
depth := len(keys)
// Iterate branch.
m.Range(func(key, value interface{}) bool {
// Set key.
keys[depth-1] = key
// Check branch.
b, ok := value.(*NestedMap)
if !ok {
return f(keys, value)
}
// Recursive range.
ok = nm.nestRange((*sync.Map)(b), f, keys)
keys = keys[:depth]
return ok
})
keys = keys[:depth-1]
return true
}
// nest nested search path specified by keys.
func (nm *NestedMap) search(keys ...interface{}) (*sync.Map, error) {
b, m := nm, (*sync.Map)(nm)
for i := 0; i < len(keys); i++ {
// Search path.
value, exist := m.Load(keys[i])
if !exist {
return nil, ErrNotExist
}
// Check branch type.
var ok bool
if b, ok = value.(*NestedMap); !ok {
return nil, ErrNotBranch
}
// Continue search.
m = (*sync.Map)(b)
}
return m, nil
}
// searchOrCreate nested search path specified by keys, create if the branch does not exist.
func (nm *NestedMap) searchOrCreate(keys ...interface{}) (*sync.Map, error) {
b, m := nm, (*sync.Map)(nm)
for i := 0; i < len(keys); i++ {
// Load before store to avoid useless memory applyment.
value, exist := m.Load(keys[i])
if !exist {
value, _ = m.LoadOrStore(keys[i], new(NestedMap))
}
// Check branch type.
var ok bool
if b, ok = value.(*NestedMap); !ok {
return nil, ErrNotBranch
}
// Continue search.
m = (*sync.Map)(b)
}
return m, nil
}
// convertKeys unify keys' type []interface{}
func (*NestedMap) convertKeys(keys ...interface{}) []interface{} {
// Convert when there is only one key and it is a slice type
if len(keys) != 1 {
return keys
} else if t := reflect.TypeOf(keys[0]); t.Kind() != reflect.Slice {
return keys
} else if t.Elem().Kind() == reflect.Interface {
return keys[0].([]interface{})
}
// Convert one by one.
s := reflect.ValueOf(keys[0])
r := make([]interface{}, s.Len())
for i := 0; i < s.Len(); i++ {
r[i] = s.Index(i).Interface()
}
return r
}