add deque style functions to ring buffer module, bug fixes

src/data/CCRingBuffer.ml

@@ -1,5 +1,5 @@
 (*
- * CCRingBufferIO - Polymorphic circular buffer with
+ * CCRingBuffer - Polymorphic circular buffer with
  * deque semantics for accessing both the head and tail.
  *
  * Copyright (C) 2014 Simon Cruanes
@@ -75,14 +75,15 @@ let resize b cap elem =
 let blit_from_bounded b from_buf o len =
   let cap = capacity b - len in
   (* resize if needed, with a constant to amortize *)
-   if cap < len then
+  if cap < len then begin
      let new_size =
        let desired = Array.length b.buf + len + 24 in
        min (b.size+1) desired in
-     resize b new_size from_buf.(0);
+     resize b new_size from_buf.(0)
+  end;
   let sub = Array.sub from_buf o len in
-  let capacity = capacity b in
   let iter x = 
+    let capacity = capacity b in
     Array.set b.buf b.stop x;
     if b.stop = capacity-1 then b.stop <- 0 else b.stop <- b.stop + 1;
     if b.start = b.stop then
@@ -165,7 +166,7 @@ let next b =
   if b.start = b.stop then raise Empty;
   b.buf.(b.start)
 
-let pop b =
+let take_front b =
   if b.start = b.stop then raise Empty;
   let c = b.buf.(b.start) in
   if b.start + 1 = Array.length b.buf
@@ -173,6 +174,13 @@ let pop b =
   else b.start <- b.start + 1;
   c
 
+let take_back b =
+  if b.start = b.stop then raise Empty;
+  if b.stop - 1 = 0
+  then b.stop <- Array.length b.buf - 1
+  else b.stop <- b.stop - 1;
+  b.buf.(b.stop)
+
 let junk b =
   if b.start = b.stop then raise Empty;
   if b.start + 1 = Array.length b.buf
@@ -232,4 +240,16 @@ let to_list b =
     (Array.to_list (Array.sub b.buf b.start (Array.length b.buf - b.start)))
     (Array.to_list (Array.sub b.buf 0 b.stop)) 
     
+let push_back b e = add b (Array.of_list [e])
+
+let peek_front b = if is_empty b then 
+  raise Empty else Array.get b.buf b.start
+
+let peek_back b = if is_empty b then
+  raise Empty else Array.get b.buf 
+    (if b.stop = 0 then capacity b - 1 else b.stop-1)
+
+
+
+
 

src/data/CCRingBuffer.mli

@@ -57,9 +57,6 @@ val blit_into : 'a t -> 'a array -> int -> int -> int
     @return the number of elements actually copied ([min len (length buf)]).
     @raise Invalid_argument if [o,len] is not a valid slice of [s] *)
 
-val add : 'a t -> 'a array -> unit
-(** [add buf t] adds elements [t] at the end of [buf]. *)
-
 val to_list : 'a t -> 'a list
 (** extract the current content into a list *)
 
@@ -76,10 +73,6 @@ val next : 'a t -> 'a
 (** obtain next element (the first one of the buffer)
     @raise Empty if the buffer is empty *)
 
-val pop : 'a t -> 'a
-(** obtain and remove next element (the first one)
-    @raise Empty if the buffer is empty *)
-
 val junk : 'a t -> unit
 (** Drop next element.
     @raise Empty if the buffer is already empty *)
@@ -96,3 +89,20 @@ val get : 'a t -> int -> 'a
 (** [get buf i] returns the [i]-th element of [buf], ie the one that
     is returned by [next buf] after [i-1] calls to [junk buf].
     @raise Invalid_argument if the index is invalid (> [length buf]) *)
+
+val push_back : 'a t -> 'a -> unit
+  (** Push value at the back *)
+
+val peek_front : 'a t -> 'a
+  (** First value, or Empty *)
+
+val peek_back : 'a t -> 'a
+  (** Last value, or Empty *)
+
+val take_back : 'a t -> 'a
+  (** Take last value, or raise Empty *)
+
+val take_front : 'a t -> 'a
+  (** Take first value, or raise Empty *)
+
+