Copyright	(c) Tom Harper 2008-2009 (c) Bryan O'Sullivan 2009-2010 (c) Duncan Coutts 2009
License	BSD-style
Maintainer	bos@serpentine.com
Stability	experimental
Portability	GHC
Safe Haskell	Safe-Inferred
Language	Haskell2010

Data.Text.Internal.Fusion

Contents

Types
Creation and elimination
Transformations
Construction
Indexing

Description

Warning: this is an internal module, and does not have a stable API or name. Functions in this module may not check or enforce preconditions expected by public modules. Use at your own risk!

Text manipulation functions represented as fusible operations over streams.

Synopsis

data Stream a = forall s. Stream (s -> Step s a) !s !Size
data Step s a
- = Done
- | Skip !s
- | Yield !a !s
stream :: Text -> Stream Char
unstream :: Stream Char -> Text
reverseStream :: Text -> Stream Char
length :: Stream Char -> Int
reverse :: Stream Char -> Text
reverseScanr :: (Char -> Char -> Char) -> Char -> Stream Char -> Stream Char
mapAccumL :: (a -> Char -> (a, Char)) -> a -> Stream Char -> (a, Text)
unfoldrN :: Int -> (a -> Maybe (Char, a)) -> a -> Stream Char
index :: HasCallStack => Stream Char -> Int -> Char
findIndex :: (Char -> Bool) -> Stream Char -> Maybe Int
countChar :: Char -> Stream Char -> Int

Types

data Stream a Source #

A co-recursive type yielding a single element at a time depending on the internal state it carries.

Constructors

forall s. Stream (s -> Step s a) !s !Size

Instances

Instances details

Eq a => Eq (Stream a) Source #
Instance details Defined in Data.Text.Internal.Fusion.Types Methods (==) :: Stream a -> Stream a -> Bool Source # (/=) :: Stream a -> Stream a -> Bool Source #
Ord a => Ord (Stream a) Source #
Instance details Defined in Data.Text.Internal.Fusion.Types Methods compare :: Stream a -> Stream a -> Ordering Source # (<) :: Stream a -> Stream a -> Bool Source # (<=) :: Stream a -> Stream a -> Bool Source # (>) :: Stream a -> Stream a -> Bool Source # (>=) :: Stream a -> Stream a -> Bool Source # max :: Stream a -> Stream a -> Stream a Source # min :: Stream a -> Stream a -> Stream a Source #

data Step s a Source #

Intermediate result in a processing pipeline.

Constructors

Done
Skip !s
Yield !a !s

Creation and elimination

stream :: Text -> Stream Char Source #

O(n) Convert Text into a Stream Char.

Properties

unstream . stream = id

stream . unstream = id

unstream :: Stream Char -> Text Source #

O(n) Convert Stream Char into a Text.

Properties

unstream . stream = id

stream . unstream = id

reverseStream :: Text -> Stream Char Source #

O(n) Converts Text into a Stream Char, but iterates backwards through the text.

Properties

unstream . reverseStream = reverse

length :: Stream Char -> Int Source #

O(n) Returns the number of characters in a Stream.

Properties

length . stream = length

Transformations

reverse :: Stream Char -> Text Source #

O(n) Reverse the characters of a Stream returning Text.

Properties

reverse . stream = reverse

Construction

Scans

reverseScanr :: (Char -> Char -> Char) -> Char -> Stream Char -> Stream Char Source #

O(n) Perform the equivalent of scanr over a list, only with the input and result reversed.

Properties

reverse . reverseScanr f c . reverseStream = scanr f c

Accumulating maps

mapAccumL :: (a -> Char -> (a, Char)) -> a -> Stream Char -> (a, Text) Source #

O(n) Like a combination of map and foldl'. Applies a function to each element of a Text, passing an accumulating parameter from left to right, and returns a final Text.

Properties

mapAccumL g z0 . stream = mapAccumL g z0

Generation and unfolding

unfoldrN :: Int -> (a -> Maybe (Char, a)) -> a -> Stream Char Source #

O(n) Like unfoldr, unfoldrN builds a stream from a seed value. However, the length of the result is limited by the first argument to unfoldrN. This function is more efficient than unfoldr when the length of the result is known.

Properties

unstream (unfoldrN n f a) = unfoldrN n f a

Indexing

index :: HasCallStack => Stream Char -> Int -> Char Source #

O(n) stream index (subscript) operator, starting from 0.

Properties

index (stream t) n  = index t n

findIndex :: (Char -> Bool) -> Stream Char -> Maybe Int Source #

The findIndex function takes a predicate and a stream and returns the index of the first element in the stream satisfying the predicate.

Properties

findIndex p . stream  = findIndex p

countChar :: Char -> Stream Char -> Int Source #

O(n) The count function returns the number of times the query element appears in the given stream.

Properties

countChar c . stream  = countChar c