arith-encode-1.0.1: src/Data/ArithEncode/Util.hs
--- Copyright (c) 2014 Eric McCorkle. All rights reserved.
--
-- Redistribution and use in source and binary forms, with or without
-- modification, are permitted provided that the following conditions
-- are met:
--
-- 1. Redistributions of source code must retain the above copyright
-- notice, this list of conditions and the following disclaimer.
--
-- 2. Redistributions in binary form must reproduce the above copyright
-- notice, this list of conditions and the following disclaimer in the
-- documentation and/or other materials provided with the distribution.
--
-- 3. Neither the name of the author nor the names of any contributors
-- may be used to endorse or promote products derived from this software
-- without specific prior written permission.
--
-- THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS''
-- AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
-- TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
-- PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS
-- OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-- SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-- LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
-- USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
-- ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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-- OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
-- SUCH DAMAGE.
{-# OPTIONS_GHC -Wall #-}
{-# LANGUAGE DeriveDataTypeable, ScopedTypeVariables #-}
-- | Derived encodings for standard datatypes.
--
-- This module contains a number of useful constructions which can be
-- defined using the constructions from "Basic".
module Data.ArithEncode.Util(
-- * Simple Encodings
unit,
void,
-- * Non-Empty Containers
nonEmptySeq,
nonEmptyOptionSeq,
nonEmptySet,
nonEmptyHashSet,
-- * Functions and Relations
function,
functionHashable,
relation,
relationHashable,
{-
hashMap,
hashFunc,
-}
-- * Trees
tree
) where
import Control.Exception
import Data.ArithEncode.Basic
import Data.Hashable
import Data.List
import Data.Maybe
import Data.Set(Set)
import Data.HashMap.Lazy(HashMap)
import Data.HashSet(HashSet)
import Data.Tree
import Prelude hiding (seq)
--import Debug.Trace
import qualified Data.HashMap.Lazy as HashMap
import qualified Data.Map as Map
import qualified Data.Set as Set
-- | An encoding that produces @()@.
unit :: Encoding ()
unit = singleton ()
-- | An empty encoding, which contains no mappings.
void :: Encoding b
void = mkEncoding (\_ -> throw (IllegalArgument "void encoding"))
(\_ -> throw (IllegalArgument "void encoding"))
(Just 0) (const False)
-- | Build an encoding that produces non-empty sequences from an
-- encoding for the elements of the sequence.
nonEmptySeq :: Encoding ty
-- ^ The encoding for the element type
-> Encoding [ty]
nonEmptySeq = nonzero . seq
-- | Build an encoding that produces non-empty sets from an encoding
-- for the elements of the set.
nonEmptySet :: Ord ty =>
Encoding ty
-- ^ The encoding for the element type
-> Encoding (Set ty)
nonEmptySet = nonzero . set
-- | Build an encoding that produces non-empty hash sets from an encoding
-- for the elements of the set.
nonEmptyHashSet :: (Hashable ty, Ord ty) =>
Encoding ty
-- ^ The encoding for the element type
-> Encoding (HashSet ty)
nonEmptyHashSet = nonzero . hashSet
-- | Build an encoding for lists of @Maybe@s, where the last element
-- of the list is always guaranteed not to be @Nothing@. This is
-- useful for building function encodings.
nonEmptyOptionSeq :: Encoding ty
-- ^ The encoding for the element type
-> Encoding [Maybe ty]
nonEmptyOptionSeq enc =
let
fwdfunc Nothing = Just []
fwdfunc (Just (first, rest)) = Just (reverse (Just first : rest))
revfunc' [] = Just Nothing
revfunc' (Just first : rest) = Just (Just (first, rest))
revfunc' _ = Nothing
revfunc = revfunc' . reverse
in
wrap revfunc fwdfunc (optional (pair enc (seq (optional enc))))
-- | Build an encoding for bounded-length lists of @Maybe@s, where the
-- last element of the list is always guaranteed not to be @Nothing@.
-- This is useful for building function encodings.
nonEmptyBoundedOptionSeq :: Integer
-- ^ The maximum length of the sequence
-> Encoding ty
-- ^ The encoding for the element type
-> Encoding [Maybe ty]
nonEmptyBoundedOptionSeq len enc =
let
fwdfunc Nothing = Just []
fwdfunc (Just (first, rest)) = Just (reverse (Just first : rest))
revfunc' [] = Just Nothing
revfunc' (Just first : rest) = Just (Just (first, rest))
revfunc' _ = Nothing
revfunc = revfunc' . reverse
in
wrap revfunc fwdfunc (optional (pair enc (boundedSeq (len - 1) (optional enc))))
-- | Build an encoding that produces a (finite partial) function from
-- one type to another. This function is represented using a @Map@.
function :: Ord keyty =>
Encoding keyty
-- ^ The encoding for the domain type (ie. key type)
-> Encoding valty
-- ^ The encoding for the range type (ie. value type)
-> Encoding (Map.Map keyty valty)
function keyenc valenc =
let
seqToMap val =
let
convertEnt (_, Nothing) = Nothing
convertEnt (key', Just val') = Just (decode keyenc key', val')
contents = catMaybes (map convertEnt (zip (iterate (+ 1) 0) val))
in
Just (Map.fromList contents)
mapToSeq val
| all (inDomain keyenc) (Map.keys val) =
let
foldfun (count, accum) (idx, val') =
(idx + 1,
Just val' : replicate (fromInteger (idx - count)) Nothing ++ accum)
sorted = sortBy (\(a, _) (b, _) -> compare a b)
(map (\(key, val') -> (encode keyenc key, val'))
(Map.assocs val))
(_, out) = foldl foldfun (0, []) sorted
reversed = reverse out
in
Just reversed
| otherwise = Nothing
innerenc =
case size keyenc of
Just finitesize -> nonEmptyBoundedOptionSeq finitesize valenc
Nothing -> nonEmptyOptionSeq valenc
in
wrap mapToSeq seqToMap innerenc
-- | Build an encoding that produces a (finite partial) function from
-- one type to another. This function is represented using a @HashMap@.
functionHashable :: (Ord keyty, Hashable keyty) =>
Encoding keyty
-- ^ The encoding for the domain type (ie. key type)
-> Encoding valty
-- ^ The encoding for the range type (ie. value type)
-> Encoding (HashMap keyty valty)
functionHashable keyenc valenc =
let
seqToMap val =
let
convertEnt (_, Nothing) = Nothing
convertEnt (key', Just val') = Just (decode keyenc key', val')
contents = catMaybes (map convertEnt (zip (iterate (+ 1) 0) val))
in
Just (HashMap.fromList contents)
mapToSeq val
| all (inDomain keyenc) (HashMap.keys val) =
let
foldfun (count, accum) (idx, val') =
(idx + 1,
Just val' : replicate (fromInteger (idx - count)) Nothing ++ accum)
sorted = sortBy (\(a, _) (b, _) -> compare a b)
(map (\(key, val') -> (encode keyenc key, val'))
(HashMap.toList val))
(_, out) = foldl foldfun (0, []) sorted
reversed = reverse out
in
Just reversed
| otherwise = Nothing
innerenc =
case size keyenc of
Just finitesize -> nonEmptyBoundedOptionSeq finitesize valenc
Nothing -> nonEmptyOptionSeq valenc
in
wrap mapToSeq seqToMap innerenc
-- | Build an encoding that produces relations between two types.
-- These relations are represented as @Map@s from the first type to
-- @Set@s of the second.
relation :: (Ord keyty, Ord valty) =>
Encoding keyty
-- ^ The encoding for the left-hand type (ie. key type)
-> Encoding valty
-- ^ The encoding for the right-hand type (ie. value type)
-> Encoding (Map.Map keyty (Set.Set valty))
relation keyenc = function keyenc . nonEmptySet
-- | Build an encoding that produces relations between two types.
-- These relations are represented as @HashMap@s from the first type to
-- @HashSet@s of the second.
relationHashable :: (Hashable keyty, Ord keyty, Hashable valty, Ord valty) =>
Encoding keyty
-- ^ The encoding for the left-hand type (ie. key type)
-> Encoding valty
-- ^ The encoding for the right-hand type (ie. value type)
-> Encoding (HashMap keyty (HashSet valty))
relationHashable keyenc = functionHashable keyenc . nonEmptyHashSet
-- | Build an encoding that produces trees from an encoding for the
-- node labels.
tree :: Encoding ty
-- ^ The encoding for the node data type
-> Encoding (Tree ty)
tree enc =
let
makeNode (label, children) =
Just Node { rootLabel = label, subForest = children }
unmakeNode Node { rootLabel = label, subForest = children } =
Just (label, children)
nodeEncoding nodeenc =
wrap unmakeNode makeNode (pair enc (seq nodeenc))
in
recursive nodeEncoding