Merge pull request #11 from absolutelightning/longest-prefix

Longest Prefix command

README.md

@@ -82,6 +82,7 @@ This graph shows the performance comparison between Treds - ZRangeScoreKeys and
 * `MSET key1 value1 [key2 value2 key3 value3 ....]`- Set values for multiple keys
 * `MGET key1 [key2 key3 ....]`- Get values for multiple keys
 * `DELPREFIX prefix` - Delete all keys having a common prefix. Returns number of keys deleted
+* `LNGPREFIX prefix` - Returns the key value pair in which key is the longest prefix in given prefix
 * `DBSIZE` - Get number of keys in the db
 * `SCANKEYS cursor prefix count` - Returns the count number of keys matching prefix starting from an index in lex order only present in Key/Value Store. Last element is the next cursor
 * `SCANKVS cursor prefix count` - Returns the count number of keys/value pair in which keys match prefix starting from an index in lex order only present in Key/Value Store. Last element is the next cursor

client/main.go

@@ -99,6 +99,7 @@ func completer(d prompt.Document) []prompt.Suggest {
 		{Text: "KVS", Description: "KVS regex - Returns all keys/values in which keys match a regex in lex order"},
 		{Text: "LINDEX", Description: "LINDEX key index - Returns the element at index of list with key"},
 		{Text: "LLEN", Description: "LLEN key - Returns the length of list with key"},
+		{Text: "LNGPREFIX", Description: "LNGPREFIX prefix - Returns the key value pair in which key is the longest prefix in given prefix"},
 		{Text: "LPOP", Description: "LPOP key count - Removes count elements from left of list with key and returns the popped elements"},
 		{Text: "LPUSH", Description: "LPUSH key element [element ...] - Adds elements to the left of list with key"},
 		{Text: "LRANGE", Description: "LRANGE key start stop - Returns the elements from start index to stop index in the list with key"},

commands/command.go

@@ -53,4 +53,5 @@ func RegisterCommands(r CommandRegistry) {
 	RegisterHValsCommand(r)
 	RegisterExpireCommand(r)
 	RegisterTtlCommand(r)
+	RegisterLongestPrefixCommand(r)
 }

commands/lng_prefix.go

@@ -0,0 +1,22 @@
+package commands
+
+import (
+	"treds/store"
+)
+
+const LongestPrefixCommand = "LNGPREFIX"
+
+func RegisterLongestPrefixCommand(r CommandRegistry) {
+	r.Add(&CommandRegistration{
+		Name:     LongestPrefixCommand,
+		Validate: validateDeletePrefix(),
+		Execute:  executeLongestPrefixCommand(),
+	})
+}
+
+func executeLongestPrefixCommand() ExecutionHook {
+	return func(args []string, store store.Store) (string, error) {
+		prefix := args[0]
+		return store.LongestPrefix(prefix)
+	}
+}

commands/mock_store.go

@@ -290,3 +290,7 @@ func (rs *MockStore) Expire(key string, expiration time.Time) error {
 func (rs *MockStore) Ttl(key string) int {
 	return 0
 }
+
+func (rs *MockStore) LongestPrefix(key string) (string, error) {
+	return "", nil
+}

store/store.go

@@ -55,4 +55,5 @@ type Store interface {
 	CleanUpExpiredKeys()
 	Expire(key string, at time.Time) error
 	Ttl(key string) int
+	LongestPrefix(string) (string, error)
 }

store/tred_store.go

@@ -1488,3 +1488,16 @@ func (rs *TredsStore) Ttl(key string) int {
 	}
 	return -2
 }
+
+func (rs *TredsStore) LongestPrefix(prefix string) (string, error) {
+	var res strings.Builder
+	key, val, found := rs.tree.Root().LongestPrefix([]byte(prefix))
+	if found {
+		res.WriteString(string(key))
+		res.WriteString("\n")
+		res.WriteString(val.(string))
+		res.WriteString("\n")
+		return res.String(), nil
+	}
+	return "", nil
+}