Fix typos, add doc (#78)

* Update lru.go

fix typo

* Update lfu.go

Fix typo

* Update arc.go

Fix typo

* fix typos. Add doc in the interface

arc.go

@@ -172,7 +172,7 @@ func (c *ARC) Get(key interface{}) (interface{}, error) {
 }
 
 // GetIFPresent gets a value from cache pool using key if it exists.
-// If it dose not exists key, returns KeyNotFoundError.
+// If it does not exists key, returns KeyNotFoundError.
 // And send a request which refresh value for specified key if cache object has LoaderFunc.
 func (c *ARC) GetIFPresent(key interface{}) (interface{}, error) {
 	v, err := c.get(key, false)

cache.go

@@ -17,16 +17,32 @@ const (
 var KeyNotFoundError = errors.New("Key not found.")
 
 type Cache interface {
+	// Set inserts or updates the specified key-value pair.
 	Set(key, value interface{}) error
+	// SetWithExpire inserts or updates the specified key-value pair with an expiration time.
 	SetWithExpire(key, value interface{}, expiration time.Duration) error
+	// Get returns the value for the specified key if it is present in the cache.
+	// If the key is not present in the cache and the cache has LoaderFunc,
+	// invoke the `LoaderFunc` function and inserts the key-value pair in the cache.
+	// If the key is not present in the cache and the cache does not have a LoaderFunc,
+	// return KeyNotFoundError.
 	Get(key interface{}) (interface{}, error)
+	// GetIFPresent returns the value for the specified key if it is present in the cache.
+	// Return KeyNotFoundError if the key is not present.
 	GetIFPresent(key interface{}) (interface{}, error)
+	// GetAll returns a map containing all key-value pairs in the cache.
 	GetALL(checkExpired bool) map[interface{}]interface{}
 	get(key interface{}, onLoad bool) (interface{}, error)
+	// Remove removes the specified key from the cache if the key is present.
+	// Returns true if the key was present and the key has been deleted.
 	Remove(key interface{}) bool
+	// Purge removes all key-value pairs from the cache.
 	Purge()
+	// Keys returns a slice containing all keys in the cache.
 	Keys(checkExpired bool) []interface{}
+	// Len returns the number of items in the cache.
 	Len(checkExpired bool) int
+	// Has returns true if the key exists in the cache.
 	Has(key interface{}) bool
 
 	statsAccessor

lfu.go

@@ -112,7 +112,7 @@ func (c *LFUCache) set(key, value interface{}) (interface{}, error) {
 }
 
 // Get a value from cache pool using key if it exists.
-// If it dose not exists key and has LoaderFunc,
+// If it does not exists key and has LoaderFunc,
 // generate a value using `LoaderFunc` method returns value.
 func (c *LFUCache) Get(key interface{}) (interface{}, error) {
 	v, err := c.get(key, false)
@@ -123,7 +123,7 @@ func (c *LFUCache) Get(key interface{}) (interface{}, error) {
 }
 
 // GetIFPresent gets a value from cache pool using key if it exists.
-// If it dose not exists key, returns KeyNotFoundError.
+// If it does not exists key, returns KeyNotFoundError.
 // And send a request which refresh value for specified key if cache object has LoaderFunc.
 func (c *LFUCache) GetIFPresent(key interface{}) (interface{}, error) {
 	v, err := c.get(key, false)

lru.go

@@ -89,7 +89,7 @@ func (c *LRUCache) SetWithExpire(key, value interface{}, expiration time.Duratio
 }
 
 // Get a value from cache pool using key if it exists.
-// If it dose not exists key and has LoaderFunc,
+// If it does not exists key and has LoaderFunc,
 // generate a value using `LoaderFunc` method returns value.
 func (c *LRUCache) Get(key interface{}) (interface{}, error) {
 	v, err := c.get(key, false)
@@ -100,7 +100,7 @@ func (c *LRUCache) Get(key interface{}) (interface{}, error) {
 }
 
 // GetIFPresent gets a value from cache pool using key if it exists.
-// If it dose not exists key, returns KeyNotFoundError.
+// If it does not exists key, returns KeyNotFoundError.
 // And send a request which refresh value for specified key if cache object has LoaderFunc.
 func (c *LRUCache) GetIFPresent(key interface{}) (interface{}, error) {
 	v, err := c.get(key, false)

simple.go

@@ -87,7 +87,7 @@ func (c *SimpleCache) set(key, value interface{}) (interface{}, error) {
 }
 
 // Get a value from cache pool using key if it exists.
-// If it dose not exists key and has LoaderFunc,
+// If it does not exists key and has LoaderFunc,
 // generate a value using `LoaderFunc` method returns value.
 func (c *SimpleCache) Get(key interface{}) (interface{}, error) {
 	v, err := c.get(key, false)
@@ -98,7 +98,7 @@ func (c *SimpleCache) Get(key interface{}) (interface{}, error) {
 }
 
 // GetIFPresent gets a value from cache pool using key if it exists.
-// If it dose not exists key, returns KeyNotFoundError.
+// If it does not exists key, returns KeyNotFoundError.
 // And send a request which refresh value for specified key if cache object has LoaderFunc.
 func (c *SimpleCache) GetIFPresent(key interface{}) (interface{}, error) {
 	v, err := c.get(key, false)