Stack 0.2.0 → 0.3.0

raw patch · 4 files changed

+162/−10 lines, 4 filesdep +natsdep +stmPVP ok

version bump matches the API change (PVP)

Dependencies added: nats, stm

API changes (from Hackage documentation)

Files

• Stack.cabal +9/−6
• src/Control/Concurrent/STM/Stack.hs +84/−0
• src/Control/Concurrent/Stack.hs +57/−0
• src/Data/Stack.hs +12/−4

@@ -1,22 +1,25 @@ name:                Stack-version:             0.2.0-synopsis:            Stack data structure type-description:         Please see README.md+version:             0.3.0+synopsis:            Stack data structure+description:         A stack is a basic data structure that can be logically thought as linear structure represented by a real physical stack or pile, a structure where insertion and deletion of items takes place at one end called top of the stack.+                     .+                     <<https://upload.wikimedia.org/wikipedia/commons/b/b4/Lifo_stack.png>> homepage:            https://en.wikipedia.org/wiki/Stack_(abstract_data_type) license:             BSD3 license-file:        LICENSE author:              Robert Walker maintainer:          rwlock404@yahoo.com copyright:           2016 Robert Walker-category:            Web+category:            Data Structures build-type:          Simple cabal-version:       >=1.10  library   hs-source-dirs:      src-  exposed-modules:     Data.Stack-  build-depends:       base >= 4.7 && < 5+  exposed-modules:     Data.Stack, Control.Concurrent.STM.Stack, Control.Concurrent.Stack+  build-depends:       base >= 4.7 && < 5, nats, stm   default-language:    Haskell2010+  ghc-options: -Wall  source-repository head   type:     git

@@ -0,0 +1,84 @@+-- | Provides a synchronized stack for use in the STM monad+--+-- See also "Control.Concurrent.Stack"+module Control.Concurrent.STM.Stack (+    Stack,+    stackNew,+    stackPush,+    stackPeek,+    stackTryPeek,+    stackPop,+    stackTryPop,+    stackIsEmpty,+    stackSize,+  )+  where++import Control.Concurrent.STM.TVar+import Control.Monad.STM+import Numeric.Natural++-- | Synchronized stack data type+data Stack a = Stack (TVar [a])++-- | Create new Stack+stackNew :: STM (Stack a)+stackNew = do+    items <- newTVar []+    return (Stack items)++-- | Push item onto Stack+stackPush :: Stack a -> a -> STM ()+stackPush (Stack itemsVar) item = do+    items <- readTVar itemsVar+    writeTVar itemsVar (item:items)++-- | Pop most recently added item without removing from the Stack+stackTryPeek :: Stack a -> STM (Maybe a)+stackTryPeek (Stack itemsVar) = do+    items <- readTVar itemsVar+    if null items+        then return Nothing+        else return (Just (head items))++-- | Pop most recently added item without removing from the Stack+--+-- Automatically retries if stack is empty+stackPeek :: Stack a -> STM a+stackPeek (Stack itemsVar) = do+    items <- readTVar itemsVar+    if null items+        then retry+        else return (head items)++-- | Pop most recently added item from Stack+stackTryPop :: Stack a -> STM (Maybe a)+stackTryPop (Stack itemsVar) = do+    items <- readTVar itemsVar+    if null items+        then return Nothing+        else do writeTVar itemsVar (tail items)+                return (Just (head items))++-- | Pop most recently added item from Stack+--+-- Automatically retries if stack is empty+stackPop :: Stack a -> STM a+stackPop (Stack itemsVar) = do+    items <- readTVar itemsVar+    if null items+        then retry+        else do writeTVar itemsVar (tail items)+                return (head items)++-- | Test if stack is empty+stackIsEmpty :: Stack a -> STM Bool+stackIsEmpty (Stack itemsVar) = do+    items <- readTVar itemsVar+    if null items then return True else return False++-- | Compute number of elements contained in the Stack+stackSize :: Stack a -> STM Natural+stackSize (Stack itemsVar) = do+    items <- readTVar itemsVar+    return (fromIntegral (length items))

@@ -0,0 +1,57 @@+-- | Provides a synchronized stack for use in the IO monad+--+-- See also "Control.Concurrent.STM.Stack"+module Control.Concurrent.Stack (+    Stack,+    stackNew,+    stackPush,+    stackPeek,+    stackTryPeek,+    stackPop,+    stackTryPop,+    stackIsEmpty,+    stackSize,+  )+  where++import Control.Monad.STM+import Numeric.Natural++import qualified Control.Concurrent.STM.Stack as STM+import Control.Concurrent.STM.Stack (Stack)++-- | Create new Stack+stackNew :: IO (Stack a)+stackNew = atomically STM.stackNew++-- | Push item onto Stack+stackPush :: Stack a -> a -> IO ()+stackPush stack item = atomically (STM.stackPush stack item)++-- | Pop most recently added item without removing from the Stack+stackTryPeek :: Stack a -> IO (Maybe a)+stackTryPeek stack = atomically (STM.stackTryPeek stack)++-- | Pop most recently added item without removing from the Stack+--+-- Blocks if stack is empty+stackPeek :: Stack a -> IO a+stackPeek stack = atomically (STM.stackPeek stack)++-- | Pop most recently added item from Stack+stackTryPop :: Stack a -> IO (Maybe a)+stackTryPop stack = atomically (STM.stackTryPop stack)++-- | Pop most recently added item from Stack+--+-- Blocks if stack is empty+stackPop :: Stack a -> IO a+stackPop stack = atomically (STM.stackPop stack)++-- | Test if stack is empty+stackIsEmpty :: Stack a -> IO Bool+stackIsEmpty stack = atomically (STM.stackIsEmpty stack)++-- | Compute number of elements contained in the Stack+stackSize :: Stack a -> IO Natural+stackSize stack = atomically (STM.stackSize stack)

@@ -1,6 +1,12 @@--- | Abstract Stack data type+-- | Stack data structure and associated operations ----- <https://en.wikipedia.org/wiki/Stack_(abstract_data_type)>+-- A stack is a basic data structure that can be logically thought as linear structure represented by a real physical stack or pile, a structure where insertion and deletion of items takes place at one end called top of the stack.+--+-- In other words, a 'Stack' is an abstract data type that serves as a collection of elements, with two principal operations: 'stackPush', which adds an element to the collection, and 'stackPop', which removes the most recently added element that was not yet removed.+--+-- <<https://upload.wikimedia.org/wikipedia/commons/b/b4/Lifo_stack.png>>+--+-- See also <https://en.wikipedia.org/wiki/Stack_(abstract_data_type)> module Data.Stack (     Stack,     stackNew,@@ -12,6 +18,8 @@   )   where +import Numeric.Natural+ -- | Abstract Stack data type data Stack a = Stack [a] deriving (Read,Show) @@ -55,5 +63,5 @@ -- -- > stackSize stackNew == 0 -- > (∀x)(∀s)((stackSize s == n) ⇒ (stackSize (stackPush s x) == n+1))-stackSize :: Stack a -> Int-stackSize (Stack items) = length items+stackSize :: Stack a -> Natural+stackSize (Stack items) = fromIntegral (length items)