@@ -1,472 +1,185 @@
1−{-# LANGUAGE BangPatterns, CPP, MagicHash, Rank2Types, UnboxedTuples #-}
1+{-# LANGUAGE BangPatterns #-}
22{-# OPTIONS_GHC -fno-warn-orphans #-}
3−#if __GLASGOW_HASKELL__ >= 702
4−{-# LANGUAGE Trustworthy #-}
5−#endif
6−#if __GLASGOW_HASKELL__ >= 708
7−{-# LANGUAGE TypeFamilies #-}
8−#endif
9−
10−-- |
11−-- Module : Data.Text
12−-- Copyright : (c) 2009, 2010, 2011, 2012 Bryan O'Sullivan,
13−-- (c) 2009 Duncan Coutts,
14−-- (c) 2008, 2009 Tom Harper
15−--
16−-- License : BSD-style
17−-- Maintainer : bos@serpentine.com
18−-- Stability : experimental
19−-- Portability : GHC
20−--
21−-- A time and space-efficient implementation of Unicode text.
22−-- Suitable for performance critical use, both in terms of large data
23−-- quantities and high speed.
24−--
25−-- /Note/: Read below the synopsis for important notes on the use of
26−-- this module.
27−--
28−-- This module is intended to be imported @qualified@, to avoid name
29−-- clashes with "Prelude" functions, e.g.
30−--
31−-- > import qualified Data.Text as T
32−--
33−-- To use an extended and very rich family of functions for working
34−-- with Unicode text (including normalization, regular expressions,
35−-- non-standard encodings, text breaking, and locales), see
36−-- <http://hackage.haskell.org/package/text-icu the text-icu package >.
373
384module Data.Text
395 (
40− -- * Strict vs lazy types
41− -- $strict
42−
43− -- * Acceptable data
44− -- $replacement
45−
46− -- * Fusion
47− -- $fusion
48−
49− -- * Types
506 Text
51−
52− -- * Creation and elimination
7+ , Encoding(..)
538 , pack
549 , unpack
5510 , singleton
56− , empty
57−
58− -- * Basic interface
11+ , encode
12+ , decode
5913 , cons
6014 , snoc
6115 , append
62− , uncons
6316 , head
6417 , last
6518 , tail
6619 , init
6720 , null
6821 , length
69− , compareLength
70−
71− -- * Transformations
7222 , map
73− , intercalate
7423 , intersperse
7524 , transpose
76− , reverse
77− , replace
78−
79− -- ** Case conversion
80− -- $case
81− , toCaseFold
82− , toLower
83− , toUpper
84− , toTitle
85−
86− -- ** Justification
87− , justifyLeft
88− , justifyRight
89− , center
90−
91− -- * Folds
9225 , foldl
9326 , foldl'
9427 , foldl1
9528 , foldl1'
9629 , foldr
9730 , foldr1
98−
99− -- ** Special folds
10031 , concat
10132 , concatMap
10233 , any
10334 , all
10435 , maximum
10536 , minimum
106−
107− -- * Construction
108−
109− -- ** Scans
110− , scanl
111− , scanl1
112− , scanr
113− , scanr1
114−
115− -- ** Accumulating maps
116− , mapAccumL
117− , mapAccumR
118−
119− -- ** Generation and unfolding
120− , replicate
12137 , unfoldr
12238 , unfoldrN
123−
124− -- * Substrings
125−
126− -- ** Breaking strings
12739 , take
128− , takeEnd
12940 , drop
130− , dropEnd
13141 , takeWhile
132− , takeWhileEnd
13342 , dropWhile
134− , dropWhileEnd
135− , dropAround
136− , strip
137− , stripStart
138− , stripEnd
139− , splitAt
140− , breakOn
141− , breakOnEnd
142− , break
143− , span
144− , group
145− , groupBy
146− , inits
147− , tails
148−
149− -- ** Breaking into many substrings
150− -- $split
151− , splitOn
152− , split
153− , chunksOf
154−
155− -- ** Breaking into lines and words
156− , lines
157− --, lines'
158− , words
159− , unlines
160− , unwords
161−
162− -- * Predicates
163− , isPrefixOf
164− , isSuffixOf
165− , isInfixOf
166−
167− -- ** View patterns
168− , stripPrefix
169− , stripSuffix
170− , commonPrefixes
171−
172− -- * Searching
173− , filter
174− , breakOnAll
43+ , elem
17544 , find
176− , partition
177−
178− -- , findSubstring
179−
180− -- * Indexing
181− -- $index
45+ , filter
18246 , index
18347 , findIndex
184− , count
185−
186− -- * Zipping
187− , zip
48+ , elemIndex
18849 , zipWith
189−
190− -- -* Ordered text
191− -- , sort
192−
193− -- * Low level operations
194− , copy
195− , unpackCString#
50+ , words
51+ , readFile
19652 ) where
19753
198−import Prelude (Char, Bool(..), Int, Maybe(..), String,
199− Eq(..), Ord(..), Ordering(..), (++),
200− Read(..),
201− (&&), (||), (+), (-), (.), ($), ($!), (>>),
202− not, return, otherwise, quot)
203−#if defined(HAVE_DEEPSEQ)
204−import Control.DeepSeq (NFData(rnf))
205−#endif
206−#if defined(ASSERTS)
207−import Control.Exception (assert)
208−#endif
54+import Prelude (Char,Bool,Int,Maybe,String,
55+ Eq,(==),
56+ Show,showsPrec,
57+ Read,readsPrec,
58+ (&&),(||),(+),(-),($),(<),(>),(<=),(>=),(.),(>>=),
59+ return,otherwise,seq,
60+ IO, FilePath)
61+
20962import Data.Char (isSpace)
210−import Data.Data (Data(gfoldl, toConstr, gunfold, dataTypeOf), constrIndex,
211− Constr, mkConstr, DataType, mkDataType, Fixity(Prefix))
212−import Control.Monad (foldM)
213−import Control.Monad.ST (ST)
214−import qualified Data.Text.Array as A
63+import Control.Monad.ST(ST)
64+import Data.Array.Base(unsafeNewArray_,unsafeWrite,unsafeAt)
65+import Data.Array.ST(STUArray, runSTUArray)
66+import qualified Data.ByteString as B
67+import Data.ByteString(ByteString)
21568import qualified Data.List as L
216−import Data.Binary (Binary(get, put))
217−import Data.Monoid (Monoid(..))
218−#if MIN_VERSION_base(4,9,0)
219−import Data.Semigroup (Semigroup(..))
220−#endif
69+import Data.Monoid(Monoid(..))
70+import Data.Word(Word16)
22171import Data.String (IsString(..))
222−import qualified Data.Text.Internal.Fusion as S
223−import qualified Data.Text.Internal.Fusion.Common as S
224−import Data.Text.Encoding (decodeUtf8', encodeUtf8)
225−import Data.Text.Internal.Fusion (stream, reverseStream, unstream)
226−import Data.Text.Internal.Private (span_)
227−import Data.Text.Internal (Text(..), empty, firstf, mul, safe, text)
228−import Data.Text.Show (singleton, unpack, unpackCString#)
229−import qualified Prelude as P
230−import Data.Text.Unsafe (Iter(..), iter, iter_, lengthWord16, reverseIter,
231− reverseIter_, unsafeHead, unsafeTail)
232−import Data.Text.Internal.Unsafe.Char (unsafeChr)
233−import qualified Data.Text.Internal.Functions as F
234−import qualified Data.Text.Internal.Encoding.Utf16 as U16
235−import Data.Text.Internal.Search (indices)
236−#if defined(__HADDOCK__)
237−import Data.ByteString (ByteString)
238−import qualified Data.Text.Lazy as L
239−import Data.Int (Int64)
240−#endif
241−import GHC.Base (eqInt, neInt, gtInt, geInt, ltInt, leInt)
242−#if __GLASGOW_HASKELL__ >= 708
243−import qualified GHC.Exts as Exts
244−#endif
245−#if MIN_VERSION_base(4,7,0)
246−import Text.Printf (PrintfArg, formatArg, formatString)
247−#endif
248−
249−-- $strict
250−--
251−-- This package provides both strict and lazy 'Text' types. The
252−-- strict type is provided by the "Data.Text" module, while the lazy
253−-- type is provided by the "Data.Text.Lazy" module. Internally, the
254−-- lazy @Text@ type consists of a list of strict chunks.
255−--
256−-- The strict 'Text' type requires that an entire string fit into
257−-- memory at once. The lazy 'Data.Text.Lazy.Text' type is capable of
258−-- streaming strings that are larger than memory using a small memory
259−-- footprint. In many cases, the overhead of chunked streaming makes
260−-- the lazy 'Data.Text.Lazy.Text' type slower than its strict
261−-- counterpart, but this is not always the case. Sometimes, the time
262−-- complexity of a function in one module may be different from the
263−-- other, due to their differing internal structures.
264−--
265−-- Each module provides an almost identical API, with the main
266−-- difference being that the strict module uses 'Int' values for
267−-- lengths and counts, while the lazy module uses 'Data.Int.Int64'
268−-- lengths.
26972
270−-- $replacement
271−--
272−-- A 'Text' value is a sequence of Unicode scalar values, as defined
273−-- in
274−-- <http://www.unicode.org/versions/Unicode5.2.0/ch03.pdf#page=35 §3.9, definition D76 of the Unicode 5.2 standard >.
275−-- As such, a 'Text' cannot contain values in the range U+D800 to
276−-- U+DFFF inclusive. Haskell implementations admit all Unicode code
277−-- points
278−-- (<http://www.unicode.org/versions/Unicode5.2.0/ch03.pdf#page=13 §3.4, definition D10 >)
279−-- as 'Char' values, including code points from this invalid range.
280−-- This means that there are some 'Char' values that are not valid
281−-- Unicode scalar values, and the functions in this module must handle
282−-- those cases.
283−--
284−-- Within this module, many functions construct a 'Text' from one or
285−-- more 'Char' values. Those functions will substitute 'Char' values
286−-- that are not valid Unicode scalar values with the replacement
287−-- character \"�\" (U+FFFD). Functions that perform this
288−-- inspection and replacement are documented with the phrase
289−-- \"Performs replacement on invalid scalar values\".
290−--
291−-- (One reason for this policy of replacement is that internally, a
292−-- 'Text' value is represented as packed UTF-16 data. Values in the
293−-- range U+D800 through U+DFFF are used by UTF-16 to denote surrogate
294−-- code points, and so cannot be represented. The functions replace
295−-- invalid scalar values, instead of dropping them, as a security
296−-- measure. For details, see
297−-- <http://unicode.org/reports/tr36/#Deletion_of_Noncharacters Unicode Technical Report 36, §3.5 >.)
298−
299−-- $fusion
300−--
301−-- Most of the functions in this module are subject to /fusion/,
302−-- meaning that a pipeline of such functions will usually allocate at
303−-- most one 'Text' value.
304−--
305−-- As an example, consider the following pipeline:
306−--
307−-- > import Data.Text as T
308−-- > import Data.Text.Encoding as E
309−-- > import Data.ByteString (ByteString)
310−-- >
311−-- > countChars :: ByteString -> Int
312−-- > countChars = T.length . T.toUpper . E.decodeUtf8
313−--
314−-- From the type signatures involved, this looks like it should
315−-- allocate one 'Data.ByteString.ByteString' value, and two 'Text'
316−-- values. However, when a module is compiled with optimisation
317−-- enabled under GHC, the two intermediate 'Text' values will be
318−-- optimised away, and the function will be compiled down to a single
319−-- loop over the source 'Data.ByteString.ByteString'.
320−--
321−-- Functions that can be fused by the compiler are documented with the
322−-- phrase \"Subject to fusion\".
73+import qualified Data.Text.Fusion as S
74+import Data.Text.Fusion (Stream(..),Step(..),Encoding(..),
75+ stream,unstream,stream_bs,unstream_bs,restream,
76+ errorEmptyList)
77+import Data.Text.Internal(Text(..),empty)
78+import qualified Prelude as P
79+import Data.Text.UnsafeChar(unsafeChr)
80+import qualified Data.Text.Utf16 as U16
32381
32482instance Eq Text where
325− Text arrA offA lenA == Text arrB offB lenB
326− | lenA == lenB = A.equal arrA offA arrB offB lenA
327− | otherwise = False
328− {-# INLINE (==) #-}
83+ t1 == t2 = (stream t1) `S.eq` (stream t2)
32984
330−instance Ord Text where
331− compare = compareText
85+instance Show Text where
86+ showsPrec p ps r = showsPrec p (unpack ps) r
33287
33388instance Read Text where
33489 readsPrec p str = [(pack x,y) | (x,y) <- readsPrec p str]
33590
336−#if MIN_VERSION_base(4,9,0)
337−-- Semigroup orphan instances for older GHCs are provided by
338−-- 'semigroups` package
339−
340−instance Semigroup Text where
341− (<>) = append
342−#endif
343−
34491instance Monoid Text where
34592 mempty = empty
346−#if MIN_VERSION_base(4,9,0)
347− mappend = (<>) -- future-proof definition
348−#else
34993 mappend = append
350−#endif
35194 mconcat = concat
35295
35396instance IsString Text where
35497 fromString = pack
35598
356−#if __GLASGOW_HASKELL__ >= 708
357−instance Exts.IsList Text where
358− type Item Text = Char
359− fromList = pack
360− toList = unpack
361−#endif
362−
363−#if defined(HAVE_DEEPSEQ)
364−instance NFData Text where rnf !_ = ()
365−#endif
366−
367−instance Binary Text where
368− put t = put (encodeUtf8 t)
369− get = do
370− bs <- get
371− case decodeUtf8' bs of
372− P.Left exn -> P.fail (P.show exn)
373− P.Right a -> P.return a
374−
375−-- | This instance preserves data abstraction at the cost of inefficiency.
376−-- We omit reflection services for the sake of data abstraction.
377−--
378−-- This instance was created by copying the updated behavior of
379−-- @"Data.Set".@'Data.Set.Set' and @"Data.Map".@'Data.Map.Map'. If you
380−-- feel a mistake has been made, please feel free to submit
381−-- improvements.
382−--
383−-- The original discussion is archived here:
384−-- <http://groups.google.com/group/haskell-cafe/browse_thread/thread/b5bbb1b28a7e525d/0639d46852575b93 could we get a Data instance for Data.Text.Text? >
385−--
386−-- The followup discussion that changed the behavior of 'Data.Set.Set'
387−-- and 'Data.Map.Map' is archived here:
388−-- <http://markmail.org/message/trovdc6zkphyi3cr#query:+page:1+mid:a46der3iacwjcf6n+state:results Proposal: Allow gunfold for Data.Map, ... >
389−
390−instance Data Text where
391− gfoldl f z txt = z pack `f` (unpack txt)
392− toConstr _ = packConstr
393− gunfold k z c = case constrIndex c of
394− 1 -> k (z pack)
395− _ -> P.error "gunfold"
396− dataTypeOf _ = textDataType
397−
398−#if MIN_VERSION_base(4,7,0)
399−-- | Only defined for @base-4.7.0.0@ and later
400−instance PrintfArg Text where
401− formatArg txt = formatString $ unpack txt
402−#endif
403−
404−packConstr :: Constr
405−packConstr = mkConstr textDataType "pack" [] Prefix
406−
407−textDataType :: DataType
408−textDataType = mkDataType "Data.Text.Text" [packConstr]
409−
410−-- | /O(n)/ Compare two 'Text' values lexicographically.
411−compareText :: Text -> Text -> Ordering
412−compareText ta@(Text _arrA _offA lenA) tb@(Text _arrB _offB lenB)
413− | lenA == 0 && lenB == 0 = EQ
414− | otherwise = go 0 0
415− where
416− go !i !j
417− | i >= lenA || j >= lenB = compare lenA lenB
418− | a < b = LT
419− | a > b = GT
420− | otherwise = go (i+di) (j+dj)
421− where Iter a di = iter ta i
422− Iter b dj = iter tb j
423−
42499-- -----------------------------------------------------------------------------
425100-- * Conversion to/from 'Text'
426101
427−-- | /O(n)/ Convert a 'String' into a 'Text'. Subject to
428−-- fusion. Performs replacement on invalid scalar values.
102+-- | /O(n)/ Convert a String into a Text.
103+--
104+-- This function is subject to array fusion, so calling other fusible
105+-- function(s) on a packed string will only cause one 'Text' to be written
106+-- out at the end of the pipeline, instead of one before and one after.
429107pack :: String -> Text
430−pack = unstream . S.map safe . S.streamList
108+pack str = (unstream (stream_list str))
109+ where
110+ stream_list s0 = S.Stream next s0 (P.length s0) -- total guess
111+ where
112+ next [] = S.Done
113+ next (x:xs) = S.Yield x xs
431114{-# INLINE [1] pack #-}
115+-- TODO: Has to do validation! -- No, it doesn't, the
116+
117+-- | /O(n)/ Convert a Text into a String.
118+-- Subject to array fusion.
119+unpack :: Text -> String
120+unpack txt = (unstream_list (stream txt))
121+ where
122+ unstream_list (S.Stream next s0 _len) = unfold s0
123+ where
124+ unfold !s = case next s of
125+ S.Done -> []
126+ S.Skip s' -> seq s' $ unfold s'
127+ S.Yield x s' -> seq s' $ x : unfold s'
128+{-# INLINE [1] unpack #-}
129+
130+-- | Convert a character into a Text.
131+-- Subject to array fusion.
132+singleton :: Char -> Text
133+singleton c = unstream (Stream next (c:[]) 1)
134+ where
135+ {-# INLINE next #-}
136+ next (c:cs) = Yield c cs
137+ next [] = Done
138+{-# INLINE [1] singleton #-}
139+
140+decode :: Encoding -> ByteString -> Text
141+decode enc bs = unstream (stream_bs enc bs)
142+{-# INLINE decode #-}
143+
144+encode :: Encoding -> Text -> ByteString
145+encode enc txt = unstream_bs (restream enc (stream txt))
146+{-# INLINE encode #-}
432147
433148-- -----------------------------------------------------------------------------
434149-- * Basic functions
435150
436−-- | /O(n)/ Adds a character to the front of a 'Text'. This function
437−-- is more costly than its 'List' counterpart because it requires
438−-- copying a new array. Subject to fusion. Performs replacement on
439−-- invalid scalar values.
151+-- | /O(n)/ Adds a character to the front of a 'Text'. This function is more
152+-- costly than its 'List' counterpart because it requires copying a new array.
153+-- Subject to array fusion.
440154cons :: Char -> Text -> Text
441−cons c t = unstream (S.cons (safe c) (stream t))
155+cons c t = unstream (S.cons c (stream t))
442156{-# INLINE cons #-}
443157
444−infixr 5 `cons`
445−
446−-- | /O(n)/ Adds a character to the end of a 'Text'. This copies the
447−-- entire array in the process, unless fused. Subject to fusion.
448−-- Performs replacement on invalid scalar values.
158+-- | /O(n)/ Adds a character to the end of a 'Text'. This copies the entire
159+-- array in the process.
160+-- Subject to array fusion.
449161snoc :: Text -> Char -> Text
450−snoc t c = unstream (S.snoc (stream t) (safe c))
162+snoc t c = unstream (S.snoc (stream t) c)
451163{-# INLINE snoc #-}
452164
453−-- | /O(n)/ Appends one 'Text' to the other by copying both of them
454−-- into a new 'Text'. Subject to fusion.
165+-- | /O(n)/ Appends one Text to the other by copying both of them into a new
166+-- Text.
167+-- Subject to array fusion
455168append :: Text -> Text -> Text
456−append a@(Text arr1 off1 len1) b@(Text arr2 off2 len2)
457− | len1 == 0 = b
458− | len2 == 0 = a
459− | len > 0 = Text (A.run x) 0 len
460− | otherwise = overflowError "append"
169+append (Text arr1 off1 len1) (Text arr2 off2 len2) = Text (runSTUArray x) 0 len
461170 where
462171 len = len1+len2
463− x :: ST s (A.MArray s)
464172 x = do
465− arr <- A.new len
466− A.copyI arr 0 arr1 off1 len1
467− A.copyI arr len1 arr2 off2 len
173+ arr <- unsafeNewArray_ (0,len-1) :: ST s (STUArray s Int Word16)
174+ copy arr1 off1 (len1+off1) arr 0
175+ copy arr2 off2 (len2+off2) arr len1
468176 return arr
469−{-# NOINLINE append #-}
177+ where
178+ copy arr i max arr' j
179+ | i >= max = return ()
180+ | otherwise = do unsafeWrite arr' j (arr `unsafeAt` i)
181+ copy arr (i+1) max arr' (j+1)
182+{-# INLINE append #-}
470183
471184{-# RULES
472185"TEXT append -> fused" [~1] forall t1 t2.
@@ -475,34 +188,22 @@ append a@(Text arr1 off1 len1) b@(Text arr2 off2 len2)
475188 unstream (S.append (stream t1) (stream t2)) = append t1 t2
476189 #-}
477190
478−-- | /O(1)/ Returns the first character of a 'Text', which must be
479−-- non-empty. Subject to fusion.
191+-- | /O(1)/ Returns the first character of a Text, which must be non-empty.
192+-- Subject to array fusion.
480193head :: Text -> Char
481194head t = S.head (stream t)
482195{-# INLINE head #-}
483196
484−-- | /O(1)/ Returns the first character and rest of a 'Text', or
485−-- 'Nothing' if empty. Subject to fusion.
486−uncons :: Text -> Maybe (Char, Text)
487−uncons t@(Text arr off len)
488− | len <= 0 = Nothing
489− | otherwise = Just $ let !(Iter c d) = iter t 0
490− in (c, text arr (off+d) (len-d))
491−{-# INLINE [1] uncons #-}
492−
493−-- | Lifted from Control.Arrow and specialized.
494−second :: (b -> c) -> (a,b) -> (a,c)
495−second f (a, b) = (a, f b)
496−
497−-- | /O(1)/ Returns the last character of a 'Text', which must be
498−-- non-empty. Subject to fusion.
197+-- | /O(n)/ Returns the last character of a Text, which must be non-empty.
198+-- Subject to array fusion.
499199last :: Text -> Char
500200last (Text arr off len)
501− | len <= 0 = emptyError "last"
201+ | len <= 0 = errorEmptyList "last"
502202 | n < 0xDC00 || n > 0xDFFF = unsafeChr n
503− | otherwise = U16.chr2 n0 n
504− where n = A.unsafeIndex arr (off+len-1)
505− n0 = A.unsafeIndex arr (off+len-2)
203+ | otherwise = U16.chr2 n0 n
204+ where
205+ n = unsafeAt arr (off+len-1)
206+ n0 = unsafeAt arr (off+len-2)
506207{-# INLINE [1] last #-}
507208
508209{-# RULES
@@ -512,30 +213,30 @@ last (Text arr off len)
512213 S.last (stream t) = last t
513214 #-}
514215
515−-- | /O(1)/ Returns all characters after the head of a 'Text', which
516−-- must be non-empty. Subject to fusion.
216+
217+-- | /O(1)/ Returns all characters after the head of a Text, which must
218+-- be non-empty.
219+-- Subject to array fusion.
517220tail :: Text -> Text
518−tail t@(Text arr off len)
519− | len <= 0 = emptyError "tail"
520− | otherwise = text arr (off+d) (len-d)
521− where d = iter_ t 0
221+tail (Text arr off len)
222+ | len <= 0 = errorEmptyList "tail"
223+ | n >= 0xD800 && n <= 0xDBFF = Text arr (off+2) (len-2)
224+ | otherwise = Text arr (off+1) (len-1)
225+ where
226+ n = unsafeAt arr off
522227{-# INLINE [1] tail #-}
523228
524−{-# RULES
525−"TEXT tail -> fused" [~1] forall t.
526− tail t = unstream (S.tail (stream t))
527−"TEXT tail -> unfused" [1] forall t.
528− unstream (S.tail (stream t)) = tail t
529− #-}
530229
531−-- | /O(1)/ Returns all but the last character of a 'Text', which must
532−-- be non-empty. Subject to fusion.
230+
231+-- | /O(1)/ Returns all but the last character of a Text, which
232+-- must be non-empty.
233+-- Subject to array fusion.
533234init :: Text -> Text
534−init (Text arr off len) | len <= 0 = emptyError "init"
535− | n >= 0xDC00 && n <= 0xDFFF = text arr off (len-2)
536− | otherwise = text arr off (len-1)
235+init (Text arr off len) | len <= 0 = errorEmptyList "init"
236+ | n >= 0xDC00 && n <= 0xDFFF = Text arr off (len-2)
237+ | otherwise = Text arr off (len-1)
537238 where
538− n = A.unsafeIndex arr (off+len-1)
239+ n = unsafeAt arr (off+len-1)
539240{-# INLINE [1] init #-}
540241
541242{-# RULES
@@ -545,346 +246,81 @@ init (Text arr off len) | len <= 0 = emptyError "init"
545246 unstream (S.init (stream t)) = init t
546247 #-}
547248
548−-- | /O(1)/ Tests whether a 'Text' is empty or not. Subject to
549−-- fusion.
249+-- | /O(1)/ Tests whether a Text is empty or not.
250+-- Subject to array fusion.
550251null :: Text -> Bool
551−null (Text _arr _off len) =
552−#if defined(ASSERTS)
553− assert (len >= 0) $
554−#endif
555− len <= 0
556−{-# INLINE [1] null #-}
557−
558−{-# RULES
559−"TEXT null -> fused" [~1] forall t.
560− null t = S.null (stream t)
561−"TEXT null -> unfused" [1] forall t.
562− S.null (stream t) = null t
563− #-}
252+null t = S.null (stream t)
253+{-# INLINE null #-}
564254
565−-- | /O(1)/ Tests whether a 'Text' contains exactly one character.
566−-- Subject to fusion.
567−isSingleton :: Text -> Bool
568−isSingleton = S.isSingleton . stream
569−{-# INLINE isSingleton #-}
570−
571−-- | /O(n)/ Returns the number of characters in a 'Text'.
572−-- Subject to fusion.
255+-- | /O(n)/ Returns the number of characters in a text.
256+-- Subject to array fusion.
573257length :: Text -> Int
574258length t = S.length (stream t)
575−{-# INLINE [0] length #-}
576−-- length needs to be phased after the compareN/length rules otherwise
577−-- it may inline before the rules have an opportunity to fire.
578−
579−-- | /O(n)/ Compare the count of characters in a 'Text' to a number.
580−-- Subject to fusion.
581−--
582−-- This function gives the same answer as comparing against the result
583−-- of 'length', but can short circuit if the count of characters is
584−-- greater than the number, and hence be more efficient.
585−compareLength :: Text -> Int -> Ordering
586−compareLength t n = S.compareLengthI (stream t) n
587−{-# INLINE [1] compareLength #-}
588−
589−{-# RULES
590−"TEXT compareN/length -> compareLength" [~1] forall t n.
591− compare (length t) n = compareLength t n
592− #-}
593−
594−{-# RULES
595−"TEXT ==N/length -> compareLength/==EQ" [~1] forall t n.
596− eqInt (length t) n = compareLength t n == EQ
597− #-}
598−
599−{-# RULES
600−"TEXT /=N/length -> compareLength//=EQ" [~1] forall t n.
601− neInt (length t) n = compareLength t n /= EQ
602− #-}
603−
604−{-# RULES
605−"TEXT <N/length -> compareLength/==LT" [~1] forall t n.
606− ltInt (length t) n = compareLength t n == LT
607− #-}
608−
609−{-# RULES
610−"TEXT <=N/length -> compareLength//=GT" [~1] forall t n.
611− leInt (length t) n = compareLength t n /= GT
612− #-}
613−
614−{-# RULES
615−"TEXT >N/length -> compareLength/==GT" [~1] forall t n.
616− gtInt (length t) n = compareLength t n == GT
617− #-}
618−
619−{-# RULES
620−"TEXT >=N/length -> compareLength//=LT" [~1] forall t n.
621− geInt (length t) n = compareLength t n /= LT
622− #-}
259+{-# INLINE length #-}
623260
624261-- -----------------------------------------------------------------------------
625262-- * Transformations
626−-- | /O(n)/ 'map' @f@ @t@ is the 'Text' obtained by applying @f@ to
627−-- each element of @t@. Subject to fusion. Performs replacement on
628−-- invalid scalar values.
263+-- | /O(n)/ 'map' @f @xs is the Text obtained by applying @f@ to each
264+-- element of @xs@.
265+-- Subject to array fusion.
629266map :: (Char -> Char) -> Text -> Text
630−map f t = unstream (S.map (safe . f) (stream t))
267+map f t = unstream (S.map f (stream t))
631268{-# INLINE [1] map #-}
632269
633−-- | /O(n)/ The 'intercalate' function takes a 'Text' and a list of
634−-- 'Text's and concatenates the list after interspersing the first
635−-- argument between each element of the list.
636−intercalate :: Text -> [Text] -> Text
637−intercalate t = concat . (F.intersperse t)
638−{-# INLINE intercalate #-}
639−
640−-- | /O(n)/ The 'intersperse' function takes a character and places it
641−-- between the characters of a 'Text'. Subject to fusion. Performs
642−-- replacement on invalid scalar values.
270+-- | /O(n)/ The 'intersperse' function takes a character and places it between
271+-- the characters of a Text.
272+-- Subject to array fusion.
643273intersperse :: Char -> Text -> Text
644−intersperse c t = unstream (S.intersperse (safe c) (stream t))
274+intersperse c t = unstream (S.intersperse c (stream t))
645275{-# INLINE intersperse #-}
646276
647−-- | /O(n)/ Reverse the characters of a string. Subject to fusion.
648−reverse :: Text -> Text
649−reverse t = S.reverse (stream t)
650−{-# INLINE reverse #-}
651−
652−-- | /O(m+n)/ Replace every non-overlapping occurrence of @needle@ in
653−-- @haystack@ with @replacement@.
654−--
655−-- This function behaves as though it was defined as follows:
656−--
657−-- @
658−-- replace needle replacement haystack =
659−-- 'intercalate' replacement ('splitOn' needle haystack)
660−-- @
661−--
662−-- As this suggests, each occurrence is replaced exactly once. So if
663−-- @needle@ occurs in @replacement@, that occurrence will /not/ itself
664−-- be replaced recursively:
665−--
666−-- > replace "oo" "foo" "oo" == "foo"
667−--
668−-- In cases where several instances of @needle@ overlap, only the
669−-- first one will be replaced:
670−--
671−-- > replace "ofo" "bar" "ofofo" == "barfo"
672−--
673−-- In (unlikely) bad cases, this function's time complexity degrades
674−-- towards /O(n*m)/.
675−replace :: Text
676− -- ^ @needle@ to search for. If this string is empty, an
677− -- error will occur.
678− -> Text
679− -- ^ @replacement@ to replace @needle@ with.
680− -> Text
681− -- ^ @haystack@ in which to search.
682− -> Text
683−replace needle@(Text _ _ neeLen)
684− (Text repArr repOff repLen)
685− haystack@(Text hayArr hayOff hayLen)
686− | neeLen == 0 = emptyError "replace"
687− | L.null ixs = haystack
688− | len > 0 = Text (A.run x) 0 len
689− | otherwise = empty
690− where
691− ixs = indices needle haystack
692− len = hayLen - (neeLen - repLen) `mul` L.length ixs
693− x :: ST s (A.MArray s)
694− x = do
695− marr <- A.new len
696− let loop (i:is) o d = do
697− let d0 = d + i - o
698− d1 = d0 + repLen
699− A.copyI marr d hayArr (hayOff+o) d0
700− A.copyI marr d0 repArr repOff d1
701− loop is (i + neeLen) d1
702− loop [] o d = A.copyI marr d hayArr (hayOff+o) len
703− loop ixs 0 0
704− return marr
705−
706−-- ----------------------------------------------------------------------------
707−-- ** Case conversions (folds)
708−
709−-- $case
710−--
711−-- When case converting 'Text' values, do not use combinators like
712−-- @map toUpper@ to case convert each character of a string
713−-- individually, as this gives incorrect results according to the
714−-- rules of some writing systems. The whole-string case conversion
715−-- functions from this module, such as @toUpper@, obey the correct
716−-- case conversion rules. As a result, these functions may map one
717−-- input character to two or three output characters. For examples,
718−-- see the documentation of each function.
719−--
720−-- /Note/: In some languages, case conversion is a locale- and
721−-- context-dependent operation. The case conversion functions in this
722−-- module are /not/ locale sensitive. Programs that require locale
723−-- sensitivity should use appropriate versions of the
724−-- <http://hackage.haskell.org/package/text-icu-0.6.3.7/docs/Data-Text-ICU.html#g:4 case mapping functions from the text-icu package >.
725−
726−-- | /O(n)/ Convert a string to folded case. Subject to fusion.
727−--
728−-- This function is mainly useful for performing caseless (also known
729−-- as case insensitive) string comparisons.
730−--
731−-- A string @x@ is a caseless match for a string @y@ if and only if:
732−--
733−-- @toCaseFold x == toCaseFold y@
734−--
735−-- The result string may be longer than the input string, and may
736−-- differ from applying 'toLower' to the input string. For instance,
737−-- the Armenian small ligature \"ﬓ\" (men now, U+FB13) is case
738−-- folded to the sequence \"մ\" (men, U+0574) followed by
739−-- \"ն\" (now, U+0576), while the Greek \"µ\" (micro sign,
740−-- U+00B5) is case folded to \"μ\" (small letter mu, U+03BC)
741−-- instead of itself.
742−toCaseFold :: Text -> Text
743−toCaseFold t = unstream (S.toCaseFold (stream t))
744−{-# INLINE toCaseFold #-}
745−
746−-- | /O(n)/ Convert a string to lower case, using simple case
747−-- conversion. Subject to fusion.
748−--
749−-- The result string may be longer than the input string. For
750−-- instance, \"İ\" (Latin capital letter I with dot above,
751−-- U+0130) maps to the sequence \"i\" (Latin small letter i, U+0069)
752−-- followed by \" ̇\" (combining dot above, U+0307).
753−toLower :: Text -> Text
754−toLower t = unstream (S.toLower (stream t))
755−{-# INLINE toLower #-}
756−
757−-- | /O(n)/ Convert a string to upper case, using simple case
758−-- conversion. Subject to fusion.
759−--
760−-- The result string may be longer than the input string. For
761−-- instance, the German \"ß\" (eszett, U+00DF) maps to the
762−-- two-letter sequence \"SS\".
763−toUpper :: Text -> Text
764−toUpper t = unstream (S.toUpper (stream t))
765−{-# INLINE toUpper #-}
766−
767−-- | /O(n)/ Convert a string to title case, using simple case
768−-- conversion. Subject to fusion.
769−--
770−-- The first letter of the input is converted to title case, as is
771−-- every subsequent letter that immediately follows a non-letter.
772−-- Every letter that immediately follows another letter is converted
773−-- to lower case.
774−--
775−-- The result string may be longer than the input string. For example,
776−-- the Latin small ligature fl (U+FB02) is converted to the
777−-- sequence Latin capital letter F (U+0046) followed by Latin small
778−-- letter l (U+006C).
779−--
780−-- /Note/: this function does not take language or culture specific
781−-- rules into account. For instance, in English, different style
782−-- guides disagree on whether the book name \"The Hill of the Red
783−-- Fox\" is correctly title cased—but this function will
784−-- capitalize /every/ word.
785−toTitle :: Text -> Text
786−toTitle t = unstream (S.toTitle (stream t))
787−{-# INLINE toTitle #-}
788−
789−-- | /O(n)/ Left-justify a string to the given length, using the
790−-- specified fill character on the right. Subject to fusion.
791−-- Performs replacement on invalid scalar values.
792−--
793−-- Examples:
794−--
795−-- > justifyLeft 7 'x' "foo" == "fooxxxx"
796−-- > justifyLeft 3 'x' "foobar" == "foobar"
797−justifyLeft :: Int -> Char -> Text -> Text
798−justifyLeft k c t
799− | len >= k = t
800− | otherwise = t `append` replicateChar (k-len) c
801− where len = length t
802−{-# INLINE [1] justifyLeft #-}
803−
804−{-# RULES
805−"TEXT justifyLeft -> fused" [~1] forall k c t.
806− justifyLeft k c t = unstream (S.justifyLeftI k c (stream t))
807−"TEXT justifyLeft -> unfused" [1] forall k c t.
808− unstream (S.justifyLeftI k c (stream t)) = justifyLeft k c t
809− #-}
810−
811−-- | /O(n)/ Right-justify a string to the given length, using the
812−-- specified fill character on the left. Performs replacement on
813−-- invalid scalar values.
814−--
815−-- Examples:
816−--
817−-- > justifyRight 7 'x' "bar" == "xxxxbar"
818−-- > justifyRight 3 'x' "foobar" == "foobar"
819−justifyRight :: Int -> Char -> Text -> Text
820−justifyRight k c t
821− | len >= k = t
822− | otherwise = replicateChar (k-len) c `append` t
823− where len = length t
824−{-# INLINE justifyRight #-}
825−
826−-- | /O(n)/ Center a string to the given length, using the specified
827−-- fill character on either side. Performs replacement on invalid
828−-- scalar values.
829−--
830−-- Examples:
831−--
832−-- > center 8 'x' "HS" = "xxxHSxxx"
833−center :: Int -> Char -> Text -> Text
834−center k c t
835− | len >= k = t
836− | otherwise = replicateChar l c `append` t `append` replicateChar r c
837− where len = length t
838− d = k - len
839− r = d `quot` 2
840− l = d - r
841−{-# INLINE center #-}
842−
843−-- | /O(n)/ The 'transpose' function transposes the rows and columns
844−-- of its 'Text' argument. Note that this function uses 'pack',
845−-- 'unpack', and the list version of transpose, and is thus not very
846−-- efficient.
277+-- | /O(n)/ The 'transpose' function transposes the rows and columns of its
278+-- Text argument. Note that this function uses pack, unpack, and the 'List'
279+-- version of transpose and is thus not very efficient.
847280transpose :: [Text] -> [Text]
848281transpose ts = P.map pack (L.transpose (P.map unpack ts))
849282
850283-- -----------------------------------------------------------------------------
851284-- * Reducing 'Text's (folds)
852285
853−-- | /O(n)/ 'foldl', applied to a binary operator, a starting value
854−-- (typically the left-identity of the operator), and a 'Text',
855−-- reduces the 'Text' using the binary operator, from left to right.
856−-- Subject to fusion.
857−foldl :: (a -> Char -> a) -> a -> Text -> a
286+-- | 'foldl', applied to a binary operator, a starting value (typically the
287+-- left-identity of the operator), and a Text, reduces the Text using the
288+-- binary operator, from left to right.
289+-- Subject to array fusion.
290+foldl :: (b -> Char -> b) -> b -> Text -> b
858291foldl f z t = S.foldl f z (stream t)
859292{-# INLINE foldl #-}
860293
861−-- | /O(n)/ A strict version of 'foldl'. Subject to fusion.
862−foldl' :: (a -> Char -> a) -> a -> Text -> a
294+-- | A strict version of 'foldl'.
295+-- Subject to array fusion.
296+foldl' :: (b -> Char -> b) -> b -> Text -> b
863297foldl' f z t = S.foldl' f z (stream t)
864298{-# INLINE foldl' #-}
865299
866−-- | /O(n)/ A variant of 'foldl' that has no starting value argument,
867−-- and thus must be applied to a non-empty 'Text'. Subject to fusion.
300+-- | 'foldl1' is a variant of 'foldl' that has no starting value argument,
301+-- and thus must be applied to non-empty 'Text's.
302+-- Subject to array fusion.
868303foldl1 :: (Char -> Char -> Char) -> Text -> Char
869304foldl1 f t = S.foldl1 f (stream t)
870305{-# INLINE foldl1 #-}
871306
872−-- | /O(n)/ A strict version of 'foldl1'. Subject to fusion.
307+-- | A strict version of 'foldl1'.
308+-- Subject to array fusion.
873309foldl1' :: (Char -> Char -> Char) -> Text -> Char
874310foldl1' f t = S.foldl1' f (stream t)
875311{-# INLINE foldl1' #-}
876312
877−-- | /O(n)/ 'foldr', applied to a binary operator, a starting value
878−-- (typically the right-identity of the operator), and a 'Text',
879−-- reduces the 'Text' using the binary operator, from right to left.
880−-- Subject to fusion.
881−foldr :: (Char -> a -> a) -> a -> Text -> a
313+-- | 'foldr', applied to a binary operator, a starting value (typically the
314+-- right-identity of the operator), and a Text, reduces the Text using the
315+-- binary operator, from right to left.
316+-- Subject to array fusion.
317+foldr :: (Char -> b -> b) -> b -> Text -> b
882318foldr f z t = S.foldr f z (stream t)
883319{-# INLINE foldr #-}
884320
885−-- | /O(n)/ A variant of 'foldr' that has no starting value argument,
886−-- and thus must be applied to a non-empty 'Text'. Subject to
887−-- fusion.
321+-- | 'foldr1' is a variant of 'foldr' that has no starting value argument,
322+-- and thust must be applied to non-empty 'Text's.
323+-- Subject to array fusion.
888324foldr1 :: (Char -> Char -> Char) -> Text -> Char
889325foldr1 f t = S.foldr1 f (stream t)
890326{-# INLINE foldr1 #-}
@@ -892,48 +328,39 @@ foldr1 f t = S.foldr1 f (stream t)
892328-- -----------------------------------------------------------------------------
893329-- ** Special folds
894330
895−-- | /O(n)/ Concatenate a list of 'Text's.
331+-- | /O(n)/ Concatenate a list of 'Text's. Subject to array fusion.
896332concat :: [Text] -> Text
897−concat ts = case ts' of
898− [] -> empty
899− [t] -> t
900− _ -> Text (A.run go) 0 len
901− where
902− ts' = L.filter (not . null) ts
903− len = sumP "concat" $ L.map lengthWord16 ts'
904− go :: ST s (A.MArray s)
905− go = do
906− arr <- A.new len
907− let step i (Text a o l) =
908− let !j = i + l in A.copyI arr i a o j >> return j
909− foldM step 0 ts' >> return arr
910−
911−-- | /O(n)/ Map a function over a 'Text' that results in a 'Text', and
912−-- concatenate the results.
333+concat ts = unstream (S.concat (L.map stream ts))
334+{-# INLINE concat #-}
335+
336+-- | Map a function over a Text that results in a Text and concatenate the
337+-- results. This function is subject to array fusion, and note that if in
338+-- 'concatMap' @f @xs, @f@ is defined in terms of fusible functions it will
339+-- also be fusible.
913340concatMap :: (Char -> Text) -> Text -> Text
914−concatMap f = concat . foldr ((:) . f) []
341+concatMap f t = unstream (S.concatMap (stream . f) (stream t))
915342{-# INLINE concatMap #-}
916343
917−-- | /O(n)/ 'any' @p@ @t@ determines whether any character in the
918−-- 'Text' @t@ satisfies the predicate @p@. Subject to fusion.
344+-- | 'any' @p @xs determines if any character in the 'Text' @xs@ satisifes the
345+-- predicate @p@. Subject to array fusion.
919346any :: (Char -> Bool) -> Text -> Bool
920347any p t = S.any p (stream t)
921348{-# INLINE any #-}
922349
923−-- | /O(n)/ 'all' @p@ @t@ determines whether all characters in the
924−-- 'Text' @t@ satisfy the predicate @p@. Subject to fusion.
350+-- | 'all' @p @xs determines if all characters in the 'Text' @xs@ satisify the
351+-- predicate @p@. Subject to array fusion.
925352all :: (Char -> Bool) -> Text -> Bool
926353all p t = S.all p (stream t)
927354{-# INLINE all #-}
928355
929−-- | /O(n)/ 'maximum' returns the maximum value from a 'Text', which
930−-- must be non-empty. Subject to fusion.
356+-- | /O(n)/ 'maximum' returns the maximum value from a 'Text', which must be
357+-- non-empty. Subject to array fusion.
931358maximum :: Text -> Char
932359maximum t = S.maximum (stream t)
933360{-# INLINE maximum #-}
934361
935−-- | /O(n)/ 'minimum' returns the minimum value from a 'Text', which
936−-- must be non-empty. Subject to fusion.
362+-- | /O(n)/ 'minimum' returns the minimum value from a 'Text', which must be
363+-- non-empty. Subject to array fusion.
937364minimum :: Text -> Char
938365minimum t = S.minimum (stream t)
939366{-# INLINE minimum #-}
@@ -941,141 +368,46 @@ minimum t = S.minimum (stream t)
941368-- -----------------------------------------------------------------------------
942369-- * Building 'Text's
943370
944−-- | /O(n)/ 'scanl' is similar to 'foldl', but returns a list of
945−-- successive reduced values from the left. Subject to fusion.
946−-- Performs replacement on invalid scalar values.
947−--
948−-- > scanl f z [x1, x2, ...] == [z, z `f` x1, (z `f` x1) `f` x2, ...]
949−--
950−-- Note that
951−--
952−-- > last (scanl f z xs) == foldl f z xs.
953−scanl :: (Char -> Char -> Char) -> Char -> Text -> Text
954−scanl f z t = unstream (S.scanl g z (stream t))
955− where g a b = safe (f a b)
956−{-# INLINE scanl #-}
957−
958−-- | /O(n)/ 'scanl1' is a variant of 'scanl' that has no starting
959−-- value argument. Subject to fusion. Performs replacement on
960−-- invalid scalar values.
961−--
962−-- > scanl1 f [x1, x2, ...] == [x1, x1 `f` x2, ...]
963−scanl1 :: (Char -> Char -> Char) -> Text -> Text
964−scanl1 f t | null t = empty
965− | otherwise = scanl f (unsafeHead t) (unsafeTail t)
966−{-# INLINE scanl1 #-}
967−
968−-- | /O(n)/ 'scanr' is the right-to-left dual of 'scanl'. Performs
969−-- replacement on invalid scalar values.
970−--
971−-- > scanr f v == reverse . scanl (flip f) v . reverse
972−scanr :: (Char -> Char -> Char) -> Char -> Text -> Text
973−scanr f z = S.reverse . S.reverseScanr g z . reverseStream
974− where g a b = safe (f a b)
975−{-# INLINE scanr #-}
976−
977−-- | /O(n)/ 'scanr1' is a variant of 'scanr' that has no starting
978−-- value argument. Subject to fusion. Performs replacement on
979−-- invalid scalar values.
980−scanr1 :: (Char -> Char -> Char) -> Text -> Text
981−scanr1 f t | null t = empty
982− | otherwise = scanr f (last t) (init t)
983−{-# INLINE scanr1 #-}
984−
985−-- | /O(n)/ Like a combination of 'map' and 'foldl''. Applies a
986−-- function to each element of a 'Text', passing an accumulating
987−-- parameter from left to right, and returns a final 'Text'. Performs
988−-- replacement on invalid scalar values.
989−mapAccumL :: (a -> Char -> (a,Char)) -> a -> Text -> (a, Text)
990−mapAccumL f z0 = S.mapAccumL g z0 . stream
991− where g a b = second safe (f a b)
992−{-# INLINE mapAccumL #-}
993−
994−-- | The 'mapAccumR' function behaves like a combination of 'map' and
995−-- a strict 'foldr'; it applies a function to each element of a
996−-- 'Text', passing an accumulating parameter from right to left, and
997−-- returning a final value of this accumulator together with the new
998−-- 'Text'.
999−-- Performs replacement on invalid scalar values.
1000−mapAccumR :: (a -> Char -> (a,Char)) -> a -> Text -> (a, Text)
1001−mapAccumR f z0 = second reverse . S.mapAccumL g z0 . reverseStream
1002− where g a b = second safe (f a b)
1003−{-# INLINE mapAccumR #-}
1004−
1005371-- -----------------------------------------------------------------------------
1006372-- ** Generating and unfolding 'Text's
1007373
1008−-- | /O(n*m)/ 'replicate' @n@ @t@ is a 'Text' consisting of the input
1009−-- @t@ repeated @n@ times.
1010−replicate :: Int -> Text -> Text
1011−replicate n t@(Text a o l)
1012− | n <= 0 || l <= 0 = empty
1013− | n == 1 = t
1014− | isSingleton t = replicateChar n (unsafeHead t)
1015− | otherwise = Text (A.run x) 0 len
1016− where
1017− len = l `mul` n
1018− x :: ST s (A.MArray s)
1019− x = do
1020− arr <- A.new len
1021− let loop !d !i | i >= n = return arr
1022− | otherwise = let m = d + l
1023− in A.copyI arr d a o m >> loop m (i+1)
1024− loop 0 0
1025−{-# INLINE [1] replicate #-}
1026−
1027−{-# RULES
1028−"TEXT replicate/singleton -> replicateChar" [~1] forall n c.
1029− replicate n (singleton c) = replicateChar n c
1030− #-}
1031−
1032−-- | /O(n)/ 'replicateChar' @n@ @c@ is a 'Text' of length @n@ with @c@ the
1033−-- value of every element. Subject to fusion.
1034−replicateChar :: Int -> Char -> Text
1035−replicateChar n c = unstream (S.replicateCharI n (safe c))
1036−{-# INLINE replicateChar #-}
1037−
1038−-- | /O(n)/, where @n@ is the length of the result. The 'unfoldr'
1039−-- function is analogous to the List 'L.unfoldr'. 'unfoldr' builds a
1040−-- 'Text' from a seed value. The function takes the element and
1041−-- returns 'Nothing' if it is done producing the 'Text', otherwise
1042−-- 'Just' @(a,b)@. In this case, @a@ is the next 'Char' in the
1043−-- string, and @b@ is the seed value for further production. Subject
1044−-- to fusion. Performs replacement on invalid scalar values.
374+-- /O(n)/, where @n@ is the length of the result. The unfoldr function
375+-- is analogous to the List 'unfoldr'. unfoldr builds a Text
376+-- from a seed value. The function takes the element and returns
377+-- Nothing if it is done producing the Text or returns Just
378+-- (a,b), in which case, a is the next Char in the string, and b is
379+-- the seed value for further production.
1045380unfoldr :: (a -> Maybe (Char,a)) -> a -> Text
1046−unfoldr f s = unstream (S.unfoldr (firstf safe . f) s)
381+unfoldr f s = unstream (S.unfoldr f s)
1047382{-# INLINE unfoldr #-}
1048383
1049−-- | /O(n)/ Like 'unfoldr', 'unfoldrN' builds a 'Text' from a seed
384+-- O(n) Like unfoldr, unfoldrN builds a Text from a seed
1050385-- value. However, the length of the result should be limited by the
1051−-- first argument to 'unfoldrN'. This function is more efficient than
1052−-- 'unfoldr' when the maximum length of the result is known and
1053−-- correct, otherwise its performance is similar to 'unfoldr'. Subject
1054−-- to fusion. Performs replacement on invalid scalar values.
386+-- first argument to unfoldrN. This function is more efficient than
387+-- unfoldr when the maximum length of the result and correct,
388+-- otherwise its complexity performance is similar to 'unfoldr'
1055389unfoldrN :: Int -> (a -> Maybe (Char,a)) -> a -> Text
1056−unfoldrN n f s = unstream (S.unfoldrN n (firstf safe . f) s)
390+unfoldrN n f s = unstream (S.unfoldrN n f s)
1057391{-# INLINE unfoldrN #-}
1058392
1059393-- -----------------------------------------------------------------------------
1060394-- * Substrings
1061395
1062−-- | /O(n)/ 'take' @n@, applied to a 'Text', returns the prefix of the
1063−-- 'Text' of length @n@, or the 'Text' itself if @n@ is greater than
1064−-- the length of the Text. Subject to fusion.
396+-- O(n) 'take' @n, applied to a Text, returns the prefix of the
397+-- Text of length n, or the Text itself if n is greater than the
398+-- length of the Text.
1065399take :: Int -> Text -> Text
1066−take n t@(Text arr off len)
1067− | n <= 0 = empty
1068− | n >= len = t
1069− | otherwise = text arr off (iterN n t)
400+take n (Text arr off len) = Text arr off (loop off 0)
401+ where
402+ end = off+len
403+ loop !i !count
404+ | i >= end || count >= n = i - off
405+ | c < 0xD800 || c > 0xDBFF = loop (i+1) (count+1)
406+ | otherwise = loop (i+2) (count+1)
407+ where
408+ c = arr `unsafeAt` i
1070409{-# INLINE [1] take #-}
1071410
1072−iterN :: Int -> Text -> Int
1073−iterN n t@(Text _arr _off len) = loop 0 0
1074− where loop !i !cnt
1075− | i >= len || cnt >= n = i
1076− | otherwise = loop (i+d) (cnt+1)
1077− where d = iter_ t i
1078−
1079411{-# RULES
1080412"TEXT take -> fused" [~1] forall n t.
1081413 take n t = unstream (S.take n (stream t))
@@ -1083,36 +415,20 @@ iterN n t@(Text _arr _off len) = loop 0 0
1083415 unstream (S.take n (stream t)) = take n t
1084416 #-}
1085417
1086−-- | /O(n)/ 'takeEnd' @n@ @t@ returns the suffix remaining after
1087−-- taking @n@ characters from the end of @t@.
1088−--
1089−-- Examples:
1090−--
1091−-- > takeEnd 3 "foobar" == "bar"
1092−takeEnd :: Int -> Text -> Text
1093−takeEnd n t@(Text arr off len)
1094− | n <= 0 = empty
1095− | n >= len = t
1096− | otherwise = text arr (off+i) (len-i)
1097− where i = iterNEnd n t
1098−
1099−iterNEnd :: Int -> Text -> Int
1100−iterNEnd n t@(Text _arr _off len) = loop (len-1) n
1101− where loop i !m
1102− | i <= 0 = 0
1103− | m <= 1 = i
1104− | otherwise = loop (i+d) (m-1)
1105− where d = reverseIter_ t i
1106−
1107−-- | /O(n)/ 'drop' @n@, applied to a 'Text', returns the suffix of the
1108−-- 'Text' after the first @n@ characters, or the empty 'Text' if @n@
1109−-- is greater than the length of the 'Text'. Subject to fusion.
418+-- /O(n)/ 'drop' @n, applied to a Text, returns the suffix of the
419+-- Text of length @n, or the empty Text if @n is greater than the
420+-- length of the Text.
1110421drop :: Int -> Text -> Text
1111−drop n t@(Text arr off len)
1112− | n <= 0 = t
1113− | n >= len = empty
1114− | otherwise = text arr (off+i) (len-i)
1115− where i = iterN n t
422+drop n (Text arr off len) = (Text arr newOff newLen)
423+ where
424+ (newOff, newLen) = loop off 0 len
425+ end = off + len
426+ loop !i !count !l
427+ | i >= end || count >= n = (i,l)
428+ | c < 0xD800 || c > 0xDBFF = loop (i+1) (count+1) (l-1)
429+ | otherwise = loop (i+2) (count+1) (l-2)
430+ where
431+ c = arr `unsafeAt` i
1116432{-# INLINE [1] drop #-}
1117433
1118434{-# RULES
@@ -1122,282 +438,36 @@ drop n t@(Text arr off len)
1122438 unstream (S.drop n (stream t)) = drop n t
1123439 #-}
1124440
1125−-- | /O(n)/ 'dropEnd' @n@ @t@ returns the prefix remaining after
1126−-- dropping @n@ characters from the end of @t@.
1127−--
1128−-- Examples:
1129−--
1130−-- > dropEnd 3 "foobar" == "foo"
1131−dropEnd :: Int -> Text -> Text
1132−dropEnd n t@(Text arr off len)
1133− | n <= 0 = t
1134− | n >= len = empty
1135− | otherwise = text arr off (iterNEnd n t)
1136−
1137−-- | /O(n)/ 'takeWhile', applied to a predicate @p@ and a 'Text',
1138−-- returns the longest prefix (possibly empty) of elements that
1139−-- satisfy @p@. Subject to fusion.
441+-- | 'takeWhile', applied to a predicate @p@ and a stream, returns the
442+-- longest prefix (possibly empty) of elements that satisfy p.
1140443takeWhile :: (Char -> Bool) -> Text -> Text
1141−takeWhile p t@(Text arr off len) = loop 0
1142− where loop !i | i >= len = t
1143− | p c = loop (i+d)
1144− | otherwise = text arr off i
1145− where Iter c d = iter t i
1146−{-# INLINE [1] takeWhile #-}
1147−
1148−{-# RULES
1149−"TEXT takeWhile -> fused" [~1] forall p t.
1150− takeWhile p t = unstream (S.takeWhile p (stream t))
1151−"TEXT takeWhile -> unfused" [1] forall p t.
1152− unstream (S.takeWhile p (stream t)) = takeWhile p t
1153− #-}
1154−
1155−-- | /O(n)/ 'takeWhileEnd', applied to a predicate @p@ and a 'Text',
1156−-- returns the longest suffix (possibly empty) of elements that
1157−-- satisfy @p@. Subject to fusion.
1158−-- Examples:
1159−--
1160−-- > takeWhileEnd (=='o') "foo" == "oo"
1161−takeWhileEnd :: (Char -> Bool) -> Text -> Text
1162−takeWhileEnd p t@(Text arr off len) = loop (len-1) len
1163− where loop !i !l | l <= 0 = t
1164− | p c = loop (i+d) (l+d)
1165− | otherwise = text arr (off+l) (len-l)
1166− where (c,d) = reverseIter t i
1167−{-# INLINE [1] takeWhileEnd #-}
1168−
1169−{-# RULES
1170−"TEXT takeWhileEnd -> fused" [~1] forall p t.
1171− takeWhileEnd p t = S.reverse (S.takeWhile p (S.reverseStream t))
1172−"TEXT takeWhileEnd -> unfused" [1] forall p t.
1173− S.reverse (S.takeWhile p (S.reverseStream t)) = takeWhileEnd p t
1174− #-}
444+takeWhile p t = unstream (S.takeWhile p (stream t))
1175445
1176−-- | /O(n)/ 'dropWhile' @p@ @t@ returns the suffix remaining after
1177−-- 'takeWhile' @p@ @t@. Subject to fusion.
446+-- | 'dropWhile' @p @xs returns the suffix remaining after 'takeWhile' @p @xs.
1178447dropWhile :: (Char -> Bool) -> Text -> Text
1179−dropWhile p t@(Text arr off len) = loop 0 0
1180− where loop !i !l | l >= len = empty
1181− | p c = loop (i+d) (l+d)
1182− | otherwise = Text arr (off+i) (len-l)
1183− where Iter c d = iter t i
1184−{-# INLINE [1] dropWhile #-}
1185−
1186−{-# RULES
1187−"TEXT dropWhile -> fused" [~1] forall p t.
1188− dropWhile p t = unstream (S.dropWhile p (stream t))
1189−"TEXT dropWhile -> unfused" [1] forall p t.
1190− unstream (S.dropWhile p (stream t)) = dropWhile p t
1191− #-}
1192−
1193−-- | /O(n)/ 'dropWhileEnd' @p@ @t@ returns the prefix remaining after
1194−-- dropping characters that satisfy the predicate @p@ from the end of
1195−-- @t@. Subject to fusion.
1196−--
1197−-- Examples:
1198−--
1199−-- > dropWhileEnd (=='.') "foo..." == "foo"
1200−dropWhileEnd :: (Char -> Bool) -> Text -> Text
1201−dropWhileEnd p t@(Text arr off len) = loop (len-1) len
1202− where loop !i !l | l <= 0 = empty
1203− | p c = loop (i+d) (l+d)
1204− | otherwise = Text arr off l
1205− where (c,d) = reverseIter t i
1206−{-# INLINE [1] dropWhileEnd #-}
1207−
1208−{-# RULES
1209−"TEXT dropWhileEnd -> fused" [~1] forall p t.
1210− dropWhileEnd p t = S.reverse (S.dropWhile p (S.reverseStream t))
1211−"TEXT dropWhileEnd -> unfused" [1] forall p t.
1212− S.reverse (S.dropWhile p (S.reverseStream t)) = dropWhileEnd p t
1213− #-}
1214−
1215−-- | /O(n)/ 'dropAround' @p@ @t@ returns the substring remaining after
1216−-- dropping characters that satisfy the predicate @p@ from both the
1217−-- beginning and end of @t@. Subject to fusion.
1218−dropAround :: (Char -> Bool) -> Text -> Text
1219−dropAround p = dropWhile p . dropWhileEnd p
1220−{-# INLINE [1] dropAround #-}
1221−
1222−-- | /O(n)/ Remove leading white space from a string. Equivalent to:
1223−--
1224−-- > dropWhile isSpace
1225−stripStart :: Text -> Text
1226−stripStart = dropWhile isSpace
1227−{-# INLINE [1] stripStart #-}
1228−
1229−-- | /O(n)/ Remove trailing white space from a string. Equivalent to:
1230−--
1231−-- > dropWhileEnd isSpace
1232−stripEnd :: Text -> Text
1233−stripEnd = dropWhileEnd isSpace
1234−{-# INLINE [1] stripEnd #-}
1235−
1236−-- | /O(n)/ Remove leading and trailing white space from a string.
1237−-- Equivalent to:
1238−--
1239−-- > dropAround isSpace
1240−strip :: Text -> Text
1241−strip = dropAround isSpace
1242−{-# INLINE [1] strip #-}
1243−
1244−-- | /O(n)/ 'splitAt' @n t@ returns a pair whose first element is a
1245−-- prefix of @t@ of length @n@, and whose second is the remainder of
1246−-- the string. It is equivalent to @('take' n t, 'drop' n t)@.
1247−splitAt :: Int -> Text -> (Text, Text)
1248−splitAt n t@(Text arr off len)
1249− | n <= 0 = (empty, t)
1250− | n >= len = (t, empty)
1251− | otherwise = let k = iterN n t
1252− in (text arr off k, text arr (off+k) (len-k))
1253−
1254−-- | /O(n)/ 'span', applied to a predicate @p@ and text @t@, returns
1255−-- a pair whose first element is the longest prefix (possibly empty)
1256−-- of @t@ of elements that satisfy @p@, and whose second is the
1257−-- remainder of the list.
1258−span :: (Char -> Bool) -> Text -> (Text, Text)
1259−span p t = case span_ p t of
1260− (# hd,tl #) -> (hd,tl)
1261−{-# INLINE span #-}
1262−
1263−-- | /O(n)/ 'break' is like 'span', but the prefix returned is
1264−-- over elements that fail the predicate @p@.
1265−break :: (Char -> Bool) -> Text -> (Text, Text)
1266−break p = span (not . p)
1267−{-# INLINE break #-}
1268−
1269−-- | /O(n)/ Group characters in a string according to a predicate.
1270−groupBy :: (Char -> Char -> Bool) -> Text -> [Text]
1271−groupBy p = loop
1272− where
1273− loop t@(Text arr off len)
1274− | null t = []
1275− | otherwise = text arr off n : loop (text arr (off+n) (len-n))
1276− where Iter c d = iter t 0
1277− n = d + findAIndexOrEnd (not . p c) (Text arr (off+d) (len-d))
1278−
1279−-- | Returns the /array/ index (in units of 'Word16') at which a
1280−-- character may be found. This is /not/ the same as the logical
1281−-- index returned by e.g. 'findIndex'.
1282−findAIndexOrEnd :: (Char -> Bool) -> Text -> Int
1283−findAIndexOrEnd q t@(Text _arr _off len) = go 0
1284− where go !i | i >= len || q c = i
1285− | otherwise = go (i+d)
1286− where Iter c d = iter t i
1287−
1288−-- | /O(n)/ Group characters in a string by equality.
1289−group :: Text -> [Text]
1290−group = groupBy (==)
1291−
1292−-- | /O(n)/ Return all initial segments of the given 'Text', shortest
1293−-- first.
1294−inits :: Text -> [Text]
1295−inits t@(Text arr off len) = loop 0
1296− where loop i | i >= len = [t]
1297− | otherwise = Text arr off i : loop (i + iter_ t i)
1298−
1299−-- | /O(n)/ Return all final segments of the given 'Text', longest
1300−-- first.
1301−tails :: Text -> [Text]
1302−tails t | null t = [empty]
1303− | otherwise = t : tails (unsafeTail t)
1304−
1305−-- $split
1306−--
1307−-- Splitting functions in this library do not perform character-wise
1308−-- copies to create substrings; they just construct new 'Text's that
1309−-- are slices of the original.
1310−
1311−-- | /O(m+n)/ Break a 'Text' into pieces separated by the first 'Text'
1312−-- argument (which cannot be empty), consuming the delimiter. An empty
1313−-- delimiter is invalid, and will cause an error to be raised.
1314−--
1315−-- Examples:
1316−--
1317−-- > splitOn "\r\n" "a\r\nb\r\nd\r\ne" == ["a","b","d","e"]
1318−-- > splitOn "aaa" "aaaXaaaXaaaXaaa" == ["","X","X","X",""]
1319−-- > splitOn "x" "x" == ["",""]
1320−--
1321−-- and
1322−--
1323−-- > intercalate s . splitOn s == id
1324−-- > splitOn (singleton c) == split (==c)
1325−--
1326−-- (Note: the string @s@ to split on above cannot be empty.)
1327−--
1328−-- In (unlikely) bad cases, this function's time complexity degrades
1329−-- towards /O(n*m)/.
1330−splitOn :: Text
1331− -- ^ String to split on. If this string is empty, an error
1332− -- will occur.
1333− -> Text
1334− -- ^ Input text.
1335− -> [Text]
1336−splitOn pat@(Text _ _ l) src@(Text arr off len)
1337− | l <= 0 = emptyError "splitOn"
1338− | isSingleton pat = split (== unsafeHead pat) src
1339− | otherwise = go 0 (indices pat src)
1340− where
1341− go !s (x:xs) = text arr (s+off) (x-s) : go (x+l) xs
1342− go s _ = [text arr (s+off) (len-s)]
1343−{-# INLINE [1] splitOn #-}
1344−
1345−{-# RULES
1346−"TEXT splitOn/singleton -> split/==" [~1] forall c t.
1347− splitOn (singleton c) t = split (==c) t
1348− #-}
1349−
1350−-- | /O(n)/ Splits a 'Text' into components delimited by separators,
1351−-- where the predicate returns True for a separator element. The
1352−-- resulting components do not contain the separators. Two adjacent
1353−-- separators result in an empty component in the output. eg.
1354−--
1355−-- > split (=='a') "aabbaca" == ["","","bb","c",""]
1356−-- > split (=='a') "" == [""]
1357−split :: (Char -> Bool) -> Text -> [Text]
1358−split _ t@(Text _off _arr 0) = [t]
1359−split p t = loop t
1360− where loop s | null s' = [l]
1361− | otherwise = l : loop (unsafeTail s')
1362− where (# l, s' #) = span_ (not . p) s
1363−{-# INLINE split #-}
1364−
1365−-- | /O(n)/ Splits a 'Text' into components of length @k@. The last
1366−-- element may be shorter than the other chunks, depending on the
1367−-- length of the input. Examples:
1368−--
1369−-- > chunksOf 3 "foobarbaz" == ["foo","bar","baz"]
1370−-- > chunksOf 4 "haskell.org" == ["hask","ell.","org"]
1371−chunksOf :: Int -> Text -> [Text]
1372−chunksOf k = go
1373− where
1374− go t = case splitAt k t of
1375− (a,b) | null a -> []
1376− | otherwise -> a : go b
1377−{-# INLINE chunksOf #-}
448+dropWhile p t = unstream (S.dropWhile p (stream t))
1378449
1379450-- ----------------------------------------------------------------------------
1380451-- * Searching
1381452
453+-------------------------------------------------------------------------------
454+-- ** Searching by equality
455+
456+-- | /O(n)/ 'elem' is the 'Text' membership predicate.
457+elem :: Char -> Text -> Bool
458+elem c t = S.elem c (stream t)
459+{-# INLINE elem #-}
460+
1382461-------------------------------------------------------------------------------
1383462-- ** Searching with a predicate
1384463
1385−-- | /O(n)/ The 'find' function takes a predicate and a 'Text', and
1386−-- returns the first element matching the predicate, or 'Nothing' if
1387−-- there is no such element.
464+-- | /O(n)/ The 'find' function takes a predicate and a 'Text',
465+-- and returns the first element in matching the predicate, or 'Nothing'
466+-- if there is no such element.
1388467find :: (Char -> Bool) -> Text -> Maybe Char
1389−find p t = S.findBy p (stream t)
468+find p t = S.find p (stream t)
1390469{-# INLINE find #-}
1391470
1392−-- | /O(n)/ The 'partition' function takes a predicate and a 'Text',
1393−-- and returns the pair of 'Text's with elements which do and do not
1394−-- satisfy the predicate, respectively; i.e.
1395−--
1396−-- > partition p t == (filter p t, filter (not . p) t)
1397−partition :: (Char -> Bool) -> Text -> (Text, Text)
1398−partition p t = (filter p t, filter (not . p) t)
1399−{-# INLINE partition #-}
1400−
1401471-- | /O(n)/ 'filter', applied to a predicate and a 'Text',
1402472-- returns a 'Text' containing those characters that satisfy the
1403473-- predicate.
@@ -1405,351 +475,53 @@ filter :: (Char -> Bool) -> Text -> Text
1405475filter p t = unstream (S.filter p (stream t))
1406476{-# INLINE filter #-}
1407477
1408−-- | /O(n+m)/ Find the first instance of @needle@ (which must be
1409−-- non-'null') in @haystack@. The first element of the returned tuple
1410−-- is the prefix of @haystack@ before @needle@ is matched. The second
1411−-- is the remainder of @haystack@, starting with the match.
1412−--
1413−-- Examples:
1414−--
1415−-- > breakOn "::" "a::b::c" ==> ("a", "::b::c")
1416−-- > breakOn "/" "foobar" ==> ("foobar", "")
1417−--
1418−-- Laws:
1419−--
1420−-- > append prefix match == haystack
1421−-- > where (prefix, match) = breakOn needle haystack
1422−--
1423−-- If you need to break a string by a substring repeatedly (e.g. you
1424−-- want to break on every instance of a substring), use 'breakOnAll'
1425−-- instead, as it has lower startup overhead.
1426−--
1427−-- In (unlikely) bad cases, this function's time complexity degrades
1428−-- towards /O(n*m)/.
1429−breakOn :: Text -> Text -> (Text, Text)
1430−breakOn pat src@(Text arr off len)
1431− | null pat = emptyError "breakOn"
1432− | otherwise = case indices pat src of
1433− [] -> (src, empty)
1434− (x:_) -> (text arr off x, text arr (off+x) (len-x))
1435−{-# INLINE breakOn #-}
1436−
1437−-- | /O(n+m)/ Similar to 'breakOn', but searches from the end of the
1438−-- string.
1439−--
1440−-- The first element of the returned tuple is the prefix of @haystack@
1441−-- up to and including the last match of @needle@. The second is the
1442−-- remainder of @haystack@, following the match.
1443−--
1444−-- > breakOnEnd "::" "a::b::c" ==> ("a::b::", "c")
1445−breakOnEnd :: Text -> Text -> (Text, Text)
1446−breakOnEnd pat src = (reverse b, reverse a)
1447− where (a,b) = breakOn (reverse pat) (reverse src)
1448−{-# INLINE breakOnEnd #-}
1449−
1450−-- | /O(n+m)/ Find all non-overlapping instances of @needle@ in
1451−-- @haystack@. Each element of the returned list consists of a pair:
1452−--
1453−-- * The entire string prior to the /k/th match (i.e. the prefix)
1454−--
1455−-- * The /k/th match, followed by the remainder of the string
1456−--
1457−-- Examples:
1458−--
1459−-- > breakOnAll "::" ""
1460−-- > ==> []
1461−-- > breakOnAll "/" "a/b/c/"
1462−-- > ==> [("a", "/b/c/"), ("a/b", "/c/"), ("a/b/c", "/")]
1463−--
1464−-- In (unlikely) bad cases, this function's time complexity degrades
1465−-- towards /O(n*m)/.
1466−--
1467−-- The @needle@ parameter may not be empty.
1468−breakOnAll :: Text -- ^ @needle@ to search for
1469− -> Text -- ^ @haystack@ in which to search
1470− -> [(Text, Text)]
1471−breakOnAll pat src@(Text arr off slen)
1472− | null pat = emptyError "breakOnAll"
1473− | otherwise = L.map step (indices pat src)
1474− where
1475− step x = (chunk 0 x, chunk x (slen-x))
1476− chunk !n !l = text arr (n+off) l
1477−{-# INLINE breakOnAll #-}
1478478
1479479-------------------------------------------------------------------------------
1480480-- ** Indexing 'Text's
1481481
1482−-- $index
1483−--
1484−-- If you think of a 'Text' value as an array of 'Char' values (which
1485−-- it is not), you run the risk of writing inefficient code.
1486−--
1487−-- An idiom that is common in some languages is to find the numeric
1488−-- offset of a character or substring, then use that number to split
1489−-- or trim the searched string. With a 'Text' value, this approach
1490−-- would require two /O(n)/ operations: one to perform the search, and
1491−-- one to operate from wherever the search ended.
1492−--
1493−-- For example, suppose you have a string that you want to split on
1494−-- the substring @\"::\"@, such as @\"foo::bar::quux\"@. Instead of
1495−-- searching for the index of @\"::\"@ and taking the substrings
1496−-- before and after that index, you would instead use @breakOnAll \"::\"@.
1497−
1498−-- | /O(n)/ 'Text' index (subscript) operator, starting from 0.
482+-- | /O(1)/ 'Text' index (subscript) operator, starting from 0.
1499483index :: Text -> Int -> Char
1500484index t n = S.index (stream t) n
1501485{-# INLINE index #-}
1502486
1503−-- | /O(n)/ The 'findIndex' function takes a predicate and a 'Text'
1504−-- and returns the index of the first element in the 'Text' satisfying
1505−-- the predicate. Subject to fusion.
487+-- | The 'findIndex' function takes a predicate and a 'Text' and
488+-- returns the index of the first element in the 'Text'
489+-- satisfying the predicate.
1506490findIndex :: (Char -> Bool) -> Text -> Maybe Int
1507491findIndex p t = S.findIndex p (stream t)
1508492{-# INLINE findIndex #-}
1509493
1510−-- | /O(n+m)/ The 'count' function returns the number of times the
1511−-- query string appears in the given 'Text'. An empty query string is
1512−-- invalid, and will cause an error to be raised.
1513−--
1514−-- In (unlikely) bad cases, this function's time complexity degrades
1515−-- towards /O(n*m)/.
1516−count :: Text -> Text -> Int
1517−count pat src
1518− | null pat = emptyError "count"
1519− | isSingleton pat = countChar (unsafeHead pat) src
1520− | otherwise = L.length (indices pat src)
1521−{-# INLINE [1] count #-}
1522−
1523−{-# RULES
1524−"TEXT count/singleton -> countChar" [~1] forall c t.
1525− count (singleton c) t = countChar c t
1526− #-}
1527−
1528−-- | /O(n)/ The 'countChar' function returns the number of times the
1529−-- query element appears in the given 'Text'. Subject to fusion.
1530−countChar :: Char -> Text -> Int
1531−countChar c t = S.countChar c (stream t)
1532−{-# INLINE countChar #-}
494+-- | /O(n)/ The 'elemIndex' function returns the index of the first
495+-- element in the given 'Text' which is equal to the query element, or
496+-- 'Nothing' if there is no such element.
497+elemIndex :: Char -> Text -> Maybe Int
498+elemIndex c t = S.elemIndex c (stream t)
1533499
1534500-------------------------------------------------------------------------------
1535501-- * Zipping
1536502
1537−-- | /O(n)/ 'zip' takes two 'Text's and returns a list of
1538−-- corresponding pairs of bytes. If one input 'Text' is short,
1539−-- excess elements of the longer 'Text' are discarded. This is
1540−-- equivalent to a pair of 'unpack' operations.
1541−zip :: Text -> Text -> [(Char,Char)]
1542−zip a b = S.unstreamList $ S.zipWith (,) (stream a) (stream b)
1543−{-# INLINE zip #-}
1544−
1545503-- | /O(n)/ 'zipWith' generalises 'zip' by zipping with the function
1546504-- given as the first argument, instead of a tupling function.
1547−-- Performs replacement on invalid scalar values.
1548505zipWith :: (Char -> Char -> Char) -> Text -> Text -> Text
1549−zipWith f t1 t2 = unstream (S.zipWith g (stream t1) (stream t2))
1550− where g a b = safe (f a b)
1551−{-# INLINE zipWith #-}
1552−
1553−-- | /O(n)/ Breaks a 'Text' up into a list of words, delimited by 'Char's
1554−-- representing white space.
1555−words :: Text -> [Text]
1556−words t@(Text arr off len) = loop 0 0
1557− where
1558− loop !start !n
1559− | n >= len = if start == n
1560− then []
1561− else [Text arr (start+off) (n-start)]
1562− | isSpace c =
1563− if start == n
1564− then loop (start+1) (start+1)
1565− else Text arr (start+off) (n-start) : loop (n+d) (n+d)
1566− | otherwise = loop start (n+d)
1567− where Iter c d = iter t n
1568−{-# INLINE words #-}
506+zipWith f t1 t2 = unstream (S.zipWith f (stream t1) (stream t2))
1569507
1570−-- | /O(n)/ Breaks a 'Text' up into a list of 'Text's at
1571−-- newline 'Char's. The resulting strings do not contain newlines.
1572−lines :: Text -> [Text]
1573−lines ps | null ps = []
1574− | otherwise = h : if null t
1575− then []
1576− else lines (unsafeTail t)
1577− where (# h,t #) = span_ (/= '\n') ps
1578−{-# INLINE lines #-}
1579−
1580−{-
1581−-- | /O(n)/ Portably breaks a 'Text' up into a list of 'Text's at line
1582−-- boundaries.
1583−--
1584−-- A line boundary is considered to be either a line feed, a carriage
1585−-- return immediately followed by a line feed, or a carriage return.
1586−-- This accounts for both Unix and Windows line ending conventions,
1587−-- and for the old convention used on Mac OS 9 and earlier.
1588−lines' :: Text -> [Text]
1589−lines' ps | null ps = []
1590− | otherwise = h : case uncons t of
1591− Nothing -> []
1592− Just (c,t')
1593− | c == '\n' -> lines t'
1594− | c == '\r' -> case uncons t' of
1595− Just ('\n',t'') -> lines t''
1596− _ -> lines t'
1597− where (h,t) = span notEOL ps
1598− notEOL c = c /= '\n' && c /= '\r'
1599−{-# INLINE lines' #-}
1600−-}
1601−
1602−-- | /O(n)/ Joins lines, after appending a terminating newline to
1603−-- each.
1604−unlines :: [Text] -> Text
1605−unlines = concat . L.map (`snoc` '\n')
1606−{-# INLINE unlines #-}
1607−
1608−-- | /O(n)/ Joins words using single space characters.
1609−unwords :: [Text] -> Text
1610−unwords = intercalate (singleton ' ')
1611−{-# INLINE unwords #-}
1612−
1613−-- | /O(n)/ The 'isPrefixOf' function takes two 'Text's and returns
1614−-- 'True' iff the first is a prefix of the second. Subject to fusion.
1615−isPrefixOf :: Text -> Text -> Bool
1616−isPrefixOf a@(Text _ _ alen) b@(Text _ _ blen) =
1617− alen <= blen && S.isPrefixOf (stream a) (stream b)
1618−{-# INLINE [1] isPrefixOf #-}
508+-- File I/O
1619509
1620−{-# RULES
1621−"TEXT isPrefixOf -> fused" [~1] forall s t.
1622− isPrefixOf s t = S.isPrefixOf (stream s) (stream t)
1623− #-}
510+readFile :: Encoding -> FilePath -> IO Text
511+readFile enc f = B.readFile f >>= return . unstream . stream_bs enc
512+{-# INLINE [1] readFile #-}
1624513
1625−-- | /O(n)/ The 'isSuffixOf' function takes two 'Text's and returns
1626−-- 'True' iff the first is a suffix of the second.
1627−isSuffixOf :: Text -> Text -> Bool
1628−isSuffixOf a@(Text _aarr _aoff alen) b@(Text barr boff blen) =
1629− d >= 0 && a == b'
1630− where d = blen - alen
1631− b' | d == 0 = b
1632− | otherwise = Text barr (boff+d) alen
1633−{-# INLINE isSuffixOf #-}
1634−
1635−-- | /O(n+m)/ The 'isInfixOf' function takes two 'Text's and returns
1636−-- 'True' iff the first is contained, wholly and intact, anywhere
1637−-- within the second.
1638−--
1639−-- In (unlikely) bad cases, this function's time complexity degrades
1640−-- towards /O(n*m)/.
1641−isInfixOf :: Text -> Text -> Bool
1642−isInfixOf needle haystack
1643− | null needle = True
1644− | isSingleton needle = S.elem (unsafeHead needle) . S.stream $ haystack
1645− | otherwise = not . L.null . indices needle $ haystack
1646−{-# INLINE [1] isInfixOf #-}
1647−
1648−{-# RULES
1649−"TEXT isInfixOf/singleton -> S.elem/S.stream" [~1] forall n h.
1650− isInfixOf (singleton n) h = S.elem n (S.stream h)
1651− #-}
1652−
1653−-------------------------------------------------------------------------------
1654−-- * View patterns
1655−
1656−-- | /O(n)/ Return the suffix of the second string if its prefix
1657−-- matches the entire first string.
1658−--
1659−-- Examples:
1660−--
1661−-- > stripPrefix "foo" "foobar" == Just "bar"
1662−-- > stripPrefix "" "baz" == Just "baz"
1663−-- > stripPrefix "foo" "quux" == Nothing
1664−--
1665−-- This is particularly useful with the @ViewPatterns@ extension to
1666−-- GHC, as follows:
1667−--
1668−-- > {-# LANGUAGE ViewPatterns #-}
1669−-- > import Data.Text as T
1670−-- >
1671−-- > fnordLength :: Text -> Int
1672−-- > fnordLength (stripPrefix "fnord" -> Just suf) = T.length suf
1673−-- > fnordLength _ = -1
1674−stripPrefix :: Text -> Text -> Maybe Text
1675−stripPrefix p@(Text _arr _off plen) t@(Text arr off len)
1676− | p `isPrefixOf` t = Just $! text arr (off+plen) (len-plen)
1677− | otherwise = Nothing
1678−
1679−-- | /O(n)/ Find the longest non-empty common prefix of two strings
1680−-- and return it, along with the suffixes of each string at which they
1681−-- no longer match.
1682−--
1683−-- If the strings do not have a common prefix or either one is empty,
1684−-- this function returns 'Nothing'.
1685−--
1686−-- Examples:
1687−--
1688−-- > commonPrefixes "foobar" "fooquux" == Just ("foo","bar","quux")
1689−-- > commonPrefixes "veeble" "fetzer" == Nothing
1690−-- > commonPrefixes "" "baz" == Nothing
1691−commonPrefixes :: Text -> Text -> Maybe (Text,Text,Text)
1692−commonPrefixes t0@(Text arr0 off0 len0) t1@(Text arr1 off1 len1) = go 0 0
1693− where
1694− go !i !j | i < len0 && j < len1 && a == b = go (i+d0) (j+d1)
1695− | i > 0 = Just (Text arr0 off0 i,
1696− text arr0 (off0+i) (len0-i),
1697− text arr1 (off1+j) (len1-j))
1698− | otherwise = Nothing
1699− where Iter a d0 = iter t0 i
1700− Iter b d1 = iter t1 j
1701−
1702−-- | /O(n)/ Return the prefix of the second string if its suffix
1703−-- matches the entire first string.
1704−--
1705−-- Examples:
1706−--
1707−-- > stripSuffix "bar" "foobar" == Just "foo"
1708−-- > stripSuffix "" "baz" == Just "baz"
1709−-- > stripSuffix "foo" "quux" == Nothing
1710−--
1711−-- This is particularly useful with the @ViewPatterns@ extension to
1712−-- GHC, as follows:
1713−--
1714−-- > {-# LANGUAGE ViewPatterns #-}
1715−-- > import Data.Text as T
1716−-- >
1717−-- > quuxLength :: Text -> Int
1718−-- > quuxLength (stripSuffix "quux" -> Just pre) = T.length pre
1719−-- > quuxLength _ = -1
1720−stripSuffix :: Text -> Text -> Maybe Text
1721−stripSuffix p@(Text _arr _off plen) t@(Text arr off len)
1722− | p `isSuffixOf` t = Just $! text arr off (len-plen)
1723− | otherwise = Nothing
1724−
1725−-- | Add a list of non-negative numbers. Errors out on overflow.
1726−sumP :: String -> [Int] -> Int
1727−sumP fun = go 0
1728− where go !a (x:xs)
1729− | ax >= 0 = go ax xs
1730− | otherwise = overflowError fun
1731− where ax = a + x
1732− go a _ = a
1733−
1734−emptyError :: String -> a
1735−emptyError fun = P.error $ "Data.Text." ++ fun ++ ": empty input"
1736−
1737−overflowError :: String -> a
1738−overflowError fun = P.error $ "Data.Text." ++ fun ++ ": size overflow"
1739−
1740−-- | /O(n)/ Make a distinct copy of the given string, sharing no
1741−-- storage with the original string.
1742−--
1743−-- As an example, suppose you read a large string, of which you need
1744−-- only a small portion. If you do not use 'copy', the entire original
1745−-- array will be kept alive in memory by the smaller string. Making a
1746−-- copy \"breaks the link\" to the original array, allowing it to be
1747−-- garbage collected if there are no other live references to it.
1748−copy :: Text -> Text
1749−copy (Text arr off len) = Text (A.run go) 0 len
1750− where
1751− go :: ST s (A.MArray s)
1752− go = do
1753− marr <- A.new len
1754− A.copyI marr 0 arr off len
1755− return marr
514+words :: Text -> [Text]
515+words (Text arr off len) = loop0 off off
516+ where
517+ loop0 start n
518+ | isSpace (unsafeChr c) = if start == n
519+ then loop0 (start+1) (start+1)
520+ else (Text arr start (n-start)):loop0 (n+1) (n+1)
521+ | n < (off+len) = loop0 start (n+1)
522+ | otherwise = if start == n
523+ then []
524+ else [(Text arr start (n-start))]
525+ where
526+ c = arr `unsafeAt` n
527+{-# INLINE words #-}