text-1.2.0.4: An efficient packed Unicode text type.

Copyright(c) Tom Harper 2008-2009, (c) Bryan O'Sullivan 2009-2010, (c) Duncan Coutts 2009
LicenseBSD-style
Maintainerbos@serpentine.com
Stabilityexperimental
PortabilityGHC
Safe HaskellNone
LanguageHaskell98

Data.Text.Internal.Fusion

Contents

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

Types

data Stream a Source

Constructors

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

Instances

Eq a => Eq (Stream a) 
Ord a => Ord (Stream a) 

data Step s a Source

Constructors

Done 
Skip !s 
Yield !a !s 

Creation and elimination

stream :: Text -> Stream Char Source

O(n) Convert a Text into a 'Stream Char'.

unstream :: Stream Char -> Text Source

O(n) Convert a 'Stream Char' into a Text.

reverseStream :: Text -> Stream Char Source

O(n) Convert a Text into a 'Stream Char', but iterate backwards.

length :: Stream Char -> Int Source

Transformations

reverse :: Stream Char -> Text Source

O(n) Reverse the characters of a string.

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.

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.

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.

Indexing

index :: Stream Char -> Int -> Char Source

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

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.

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

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