text / Data / Text.hs

The default branch has multiple heads

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
{-# LANGUAGE BangPatterns #-}
{-# OPTIONS_GHC -fno-warn-orphans #-}

-- |
-- Module      : Data.Text
-- Copyright   : (c) Tom Harper 2008-2009,
--               (c) Bryan O'Sullivan 2009,
--               (c) Duncan Coutts 2009
--
-- License     : BSD-style
-- Maintainer  : rtharper@aftereternity.co.uk, bos@serpentine.com,
--               duncan@haskell.org
-- Stability   : experimental
-- Portability : GHC
--
-- A time and space-efficient implementation of Unicode text using
-- packed Word16 arrays.  Suitable for performance critical use, both
-- in terms of large data quantities and high speed.
--
-- This module is intended to be imported @qualified@, to avoid name
-- clashes with "Prelude" functions, e.g.
--
-- > import qualified Data.Text as T

module Data.Text
    (
    -- * Fusion
    -- $fusion

    -- * Types
      Text

    -- * Creation and elimination
    , pack
    , unpack
    , singleton
    , empty

    -- * Basic interface
    , cons
    , snoc
    , append
    , uncons
    , head
    , last
    , tail
    , init
    , null
    , length

    -- * Transformations
    , map
    , intercalate
    , intersperse
    , transpose
    , reverse

    -- * Folds
    , foldl
    , foldl'
    , foldl1
    , foldl1'
    , foldr
    , foldr1

    -- ** Special folds
    , concat
    , concatMap
    , any
    , all
    , maximum
    , minimum

    -- * Construction
    , unfoldr
    , unfoldrN

    -- * Substrings

    -- ** Breaking strings
    , take
    , drop
    , takeWhile
    , dropWhile

    -- ** Breaking into lines and words
    , words

    -- * Searching
    , elem
    , filter

    -- * Indexing
    , find
    , index
    , findIndex
    , elemIndex

    -- * Zipping and unzipping
    , zipWith
    ) where

import Prelude (Char, Bool, Int, Maybe(..), String,
                Eq, (==), (++), error,
                Show, showsPrec,
                Read, readsPrec,
                (&&), (||), (+), (-), (<), (>), (<=), (>=), (.),
                return, otherwise)
import Data.Char (isSpace)
import Control.Monad.ST (ST)
import qualified Data.Text.Array as A
import qualified Data.List as L
import Data.Monoid (Monoid(..))
import Data.Word (Word16)
import Data.String (IsString(..))

import qualified Data.Text.Fusion as S
import Data.Text.Fusion (Stream(..), Step(..), stream, unstream)
import Data.Text.Internal (Text(..), empty)
import qualified Prelude as P
import Data.Text.UnsafeChar (unsafeChr)
import qualified Data.Text.Utf16 as U16

-- $fusion
--
-- Most of the functions in this module are subject to /array fusion/,
-- meaning that a pipeline of functions will usually allocate at most
-- one 'Text' value.

instance Eq Text where
    t1 == t2 = (stream t1) `S.eq` (stream t2)

instance Show Text where
    showsPrec p ps r = showsPrec p (unpack ps) r

instance Read Text where
    readsPrec p str = [(pack x,y) | (x,y) <- readsPrec p str]

instance Monoid Text where
    mempty  = empty
    mappend = append
    mconcat = concat

instance IsString Text where
    fromString = pack

-- -----------------------------------------------------------------------------
-- * Conversion to/from 'Text'

-- | /O(n)/ Convert a 'String' into a 'Text'.
--
-- This function is subject to array fusion.
pack :: String -> Text
pack str = (unstream (stream_list str))
    where
      stream_list s0 = S.Stream next s0 (P.length s0) -- total guess
          where
            next []     = S.Done
            next (x:xs) = S.Yield x xs
{-# INLINE [1] pack #-}
-- TODO: Has to do validation! -- No, it doesn't, the

-- | /O(n)/ Convert a Text into a String.
-- Subject to array fusion.
unpack :: Text -> String
unpack txt = (unstream_list (stream txt))
    where
      unstream_list (S.Stream next s0 _len) = unfold s0
          where
            unfold !s = case next s of
                          S.Done       -> []
                          S.Skip s'    -> unfold s'
                          S.Yield x s' -> x : unfold s'
{-# INLINE [1] unpack #-}

-- | /O(1)/ Convert a character into a Text.
-- Subject to array fusion.
singleton :: Char -> Text
singleton c = unstream (Stream next (c:[]) 1)
    where
      {-# INLINE next #-}
      next (k:ks) = Yield k ks
      next []     = Done
{-# INLINE [1] singleton #-}

-- -----------------------------------------------------------------------------
-- * Basic functions

-- | /O(n)/ Adds a character to the front of a 'Text'.  This function
-- is more costly than its 'List' counterpart because it requires
-- copying a new array.  Subject to array fusion.
cons :: Char -> Text -> Text
cons c t = unstream (S.cons c (stream t))
{-# INLINE cons #-}

-- | /O(n)/ Adds a character to the end of a 'Text'.  This copies the
-- entire array in the process.  Subject to array fusion.
snoc :: Text -> Char -> Text
snoc t c = unstream (S.snoc (stream t) c)
{-# INLINE snoc #-}

-- | /O(n)/ Appends one 'Text' to the other by copying both of them
-- into a new 'Text'.  Subject to array fusion.
append :: Text -> Text -> Text
append (Text arr1 off1 len1) (Text arr2 off2 len2) = Text (A.run x) 0 len
    where
      len = len1+len2
      x = do
        arr <- A.unsafeNew len :: ST s (A.MArray s Word16)
        copy arr1 off1 (len1+off1) arr 0
        copy arr2 off2 (len2+off2) arr len1
        return arr
            where
              copy arr i max arr' j
                  | i >= max  = return ()
                  | otherwise = do A.unsafeWrite arr' j (arr `A.unsafeIndex` i)
                                   copy arr (i+1) max arr' (j+1)
{-# INLINE append #-}

{-# RULES
"TEXT append -> fused" [~1] forall t1 t2.
    append t1 t2 = unstream (S.append (stream t1) (stream t2))
"TEXT append -> unfused" [1] forall t1 t2.
    unstream (S.append (stream t1) (stream t2)) = append t1 t2
 #-}

-- | /O(1)/ Returns the first character of a 'Text', which must be
-- non-empty.  Subject to array fusion.
head :: Text -> Char
head t = S.head (stream t)
{-# INLINE head #-}

-- | /O(1)/ Returns the first character and rest of a 'Text', or
-- 'Nothing' if empty. Subject to array fusion.
uncons :: Text -> Maybe (Char, Text)
uncons t = case S.uncons (stream t) of
             Just (c, s) -> Just (c, unstream s)
             Nothing     -> Nothing
{-# INLINE uncons #-}

-- | /O(n)/ Returns the last character of a 'Text', which must be
-- non-empty.  Subject to array fusion.
last :: Text -> Char
last (Text arr off len)
    | len <= 0                   = errorEmptyList "last"
    | n < 0xDC00 || n > 0xDFFF = unsafeChr n
    | otherwise                  = U16.chr2 n0 n
    where
      n  = A.unsafeIndex arr (off+len-1)
      n0 = A.unsafeIndex arr (off+len-2)
{-# INLINE [1] last #-}

{-# RULES
"TEXT last -> fused" [~1] forall t.
    last t = S.last (stream t)
"TEXT last -> unfused" [1] forall t.
    S.last (stream t) = last t
  #-}


-- | /O(1)/ Returns all characters after the head of a 'Text', which
-- must be non-empty.  Subject to array fusion.
tail :: Text -> Text
tail (Text arr off len)
    | len <= 0                   = errorEmptyList "tail"
    | n >= 0xD800 && n <= 0xDBFF = Text arr (off+2) (len-2)
    | otherwise                  = Text arr (off+1) (len-1)
    where
      n = A.unsafeIndex arr off
{-# INLINE [1] tail #-}



-- | /O(1)/ Returns all but the last character of a 'Text', which must
-- be non-empty.  Subject to array fusion.
init :: Text -> Text
init (Text arr off len) | len <= 0                   = errorEmptyList "init"
                        | n >= 0xDC00 && n <= 0xDFFF = Text arr off (len-2)
                        | otherwise                  = Text arr off (len-1)
    where
      n = A.unsafeIndex arr (off+len-1)
{-# INLINE [1] init #-}

{-# RULES
"TEXT init -> fused" [~1] forall t.
    init t = unstream (S.init (stream t))
"TEXT init -> unfused" [1] forall t.
    unstream (S.init (stream t)) = init t
 #-}

-- | /O(1)/ Tests whether a 'Text' is empty or not.  Subject to array
-- fusion.
null :: Text -> Bool
null t = S.null (stream t)
{-# INLINE null #-}

-- | /O(n)/ Returns the number of characters in a 'Text'.
-- Subject to array fusion.
length :: Text -> Int
length t = S.length (stream t)
{-# INLINE length #-}

-- -----------------------------------------------------------------------------
-- * Transformations
-- | /O(n)/ 'map' @f @xs is the 'Text' obtained by applying @f@ to
-- each element of @xs@.  Subject to array fusion.
map :: (Char -> Char) -> Text -> Text
map f t = unstream (S.map f (stream t))
{-# INLINE [1] map #-}

-- | /O(n)/ The 'intercalate' function takes a 'Text' and a list of
-- 'Text's and concatenates the list after interspersing the first
-- argument between each element of the list.
intercalate :: Text -> [Text] -> Text
intercalate t ts = unstream (S.intercalate (stream t) (L.map stream ts))
{-# INLINE intercalate #-}

-- | /O(n)/ The 'intersperse' function takes a character and places it
-- between the characters of a 'Text'.  Subject to array fusion.
intersperse     :: Char -> Text -> Text
intersperse c t = unstream (S.intersperse c (stream t))
{-# INLINE intersperse #-}

-- | /O(n)/ Reverse the characters of a string. Subject to array fusion.
reverse :: Text -> Text
reverse t = S.reverse (stream t)
{-# INLINE reverse #-}

-- | /O(n)/ The 'transpose' function transposes the rows and columns
-- of its 'Text' argument.  Note that this function uses 'pack',
-- 'unpack', and the 'List' version of transpose and is thus not very
-- efficient.
transpose :: [Text] -> [Text]
transpose ts = P.map pack (L.transpose (P.map unpack ts))

-- -----------------------------------------------------------------------------
-- * Reducing 'Text's (folds)

-- | 'foldl', applied to a binary operator, a starting value
-- (typically the left-identity of the operator), and a 'Text',
-- reduces the 'Text' using the binary operator, from left to right.
-- Subject to array fusion.
foldl :: (b -> Char -> b) -> b -> Text -> b
foldl f z t = S.foldl f z (stream t)
{-# INLINE foldl #-}

-- | A strict version of 'foldl'.
-- Subject to array fusion.
foldl' :: (b -> Char -> b) -> b -> Text -> b
foldl' f z t = S.foldl' f z (stream t)
{-# INLINE foldl' #-}

-- | A variant of 'foldl' that has no starting value argument, and
-- thus must be applied to a non-empty 'Text'.  Subject to array
-- fusion.
foldl1 :: (Char -> Char -> Char) -> Text -> Char
foldl1 f t = S.foldl1 f (stream t)
{-# INLINE foldl1 #-}

-- | A strict version of 'foldl1'.
-- Subject to array fusion.
foldl1' :: (Char -> Char -> Char) -> Text -> Char
foldl1' f t = S.foldl1' f (stream t)
{-# INLINE foldl1' #-}

-- | 'foldr', applied to a binary operator, a starting value
-- (typically the right-identity of the operator), and a 'Text',
-- reduces the 'Text' using the binary operator, from right to left.
-- Subject to array fusion.
foldr :: (Char -> b -> b) -> b -> Text -> b
foldr f z t = S.foldr f z (stream t)
{-# INLINE foldr #-}

-- | A variant of 'foldr' that has no starting value argument, and
-- thust must be applied to a non-empty 'Text'.  Subject to array
-- fusion.
foldr1 :: (Char -> Char -> Char) -> Text -> Char
foldr1 f t = S.foldr1 f (stream t)
{-# INLINE foldr1 #-}

-- -----------------------------------------------------------------------------
-- ** Special folds

-- | /O(n)/ Concatenate a list of 'Text's. Subject to array fusion.
concat :: [Text] -> Text
concat ts = unstream (S.concat (L.map stream ts))
{-# INLINE concat #-}

-- | Map a function over a 'Text' that results in a 'Text', and concatenate the
-- results.  This function is subject to array fusion.
--
-- Note: if in 'concatMap' @f @xs, @f@ is defined in terms of fusible
-- functions, it will also be fusible.
concatMap :: (Char -> Text) -> Text -> Text
concatMap f t = unstream (S.concatMap (stream . f) (stream t))
{-# INLINE concatMap #-}

-- | 'any' @p @xs determines whether any character in the 'Text' @xs@
-- satisifes the predicate @p@. Subject to array fusion.
any :: (Char -> Bool) -> Text -> Bool
any p t = S.any p (stream t)
{-# INLINE any #-}

-- | 'all' @p @xs determines whether all characters in the 'Text' @xs@
-- satisify the predicate @p@. Subject to array fusion.
all :: (Char -> Bool) -> Text -> Bool
all p t = S.all p (stream t)
{-# INLINE all #-}

-- | /O(n)/ 'maximum' returns the maximum value from a 'Text', which
-- must be non-empty. Subject to array fusion.
maximum :: Text -> Char
maximum t = S.maximum (stream t)
{-# INLINE maximum #-}

-- | /O(n)/ 'minimum' returns the minimum value from a 'Text', which
-- must be non-empty. Subject to array fusion.
minimum :: Text -> Char
minimum t = S.minimum (stream t)
{-# INLINE minimum #-}

-- -----------------------------------------------------------------------------
-- * Building 'Text's

-- -----------------------------------------------------------------------------
-- ** Generating and unfolding 'Text's

-- | /O(n)/, where @n@ is the length of the result. The 'unfoldr'
-- function is analogous to the List 'L.unfoldr'. 'unfoldr' builds a
-- 'Text' from a seed value. The function takes the element and
-- returns 'Nothing' if it is done producing the 'Text', otherwise
-- 'Just' @(a,b)@.  In this case, @a@ is the next 'Char' in the
-- string, and @b@ is the seed value for further production.
unfoldr     :: (a -> Maybe (Char,a)) -> a -> Text
unfoldr f s = unstream (S.unfoldr f s)
{-# INLINE unfoldr #-}

-- | /O(n)/ Like 'unfoldr', 'unfoldrN' builds a 'Text' from a seed
-- value. However, the length of the result should be limited by the
-- first argument to 'unfoldrN'. This function is more efficient than
-- 'unfoldr' when the maximum length of the result is known and
-- correct, otherwise its performance is similar to 'unfoldr'.
unfoldrN     :: Int -> (a -> Maybe (Char,a)) -> a -> Text
unfoldrN n f s = unstream (S.unfoldrN n f s)
{-# INLINE unfoldrN #-}

-- -----------------------------------------------------------------------------
-- * Substrings

-- /O(n) 'take' @n@, applied to a 'Text', returns the prefix of the
-- 'Text' of length @n@, or the 'Text' itself if @n@ is greater than
-- the length of the Text.
take :: Int -> Text -> Text
take n t@(Text arr off len)
    | n <= 0    = empty
    | n >= len  = t
    | otherwise = Text arr off (loop off 0)
  where
      end = off+len
      loop !i !count
           | i >= end || count >= n   = i - off
           | c < 0xD800 || c > 0xDBFF = loop (i+1) (count+1)
           | otherwise                = loop (i+2) (count+1)
           where
             c = arr `A.unsafeIndex` i
{-# INLINE [1] take #-}

{-# RULES
"TEXT take -> fused" [~1] forall n t.
    take n t = unstream (S.take n (stream t))
"TEXT take -> unfused" [1] forall n t.
    unstream (S.take n (stream t)) = take n t
  #-}

-- | /O(n)/ 'drop' @n@, applied to a 'Text', returns the suffix of the
-- 'Text' of length @n@, or the empty 'Text' if @n@ is greater than the
-- length of the 'Text'.
drop :: Int -> Text -> Text
drop n t@(Text arr off len)
    | n <= 0    = t
    | n >= len  = empty
    | otherwise = Text arr newOff newLen
  where
      (newOff, newLen) = loop off 0 len
      end = off + len
      loop !i !count !l
          | i >= end || count >= n   = (i,l)
          | c < 0xD800 || c > 0xDBFF = loop (i+1) (count+1) (l-1)
          | otherwise                = loop (i+2) (count+1) (l-2)
          where
            c = arr `A.unsafeIndex` i
{-# INLINE [1] drop #-}

{-# RULES
"TEXT drop -> fused" [~1] forall n t.
    drop n t = unstream (S.drop n (stream t))
"TEXT drop -> unfused" [1] forall n t.
    unstream (S.drop n (stream t)) = drop n t
  #-}

-- | 'takeWhile', applied to a predicate @p@ and a 'Text', returns the
-- longest prefix (possibly empty) of elements that satisfy @p@.
takeWhile :: (Char -> Bool) -> Text -> Text
takeWhile p t = unstream (S.takeWhile p (stream t))

-- | 'dropWhile' @p@ @xs@ returns the suffix remaining after
-- 'takeWhile' @p@ @xs@.
dropWhile :: (Char -> Bool) -> Text -> Text
dropWhile p t = unstream (S.dropWhile p (stream t))

-- ----------------------------------------------------------------------------
-- * Searching

-------------------------------------------------------------------------------
-- ** Searching by equality

-- | /O(n)/ 'elem' is the 'Text' membership predicate.
elem :: Char -> Text -> Bool
elem c t = S.elem c (stream t)
{-# INLINE elem #-}

-------------------------------------------------------------------------------
-- ** Searching with a predicate

-- | /O(n)/ The 'find' function takes a predicate and a 'Text',
-- and returns the first element in matching the predicate, or 'Nothing'
-- if there is no such element.
find :: (Char -> Bool) -> Text -> Maybe Char
find p t = S.find p (stream t)
{-# INLINE find #-}

-- | /O(n)/ 'filter', applied to a predicate and a 'Text',
-- returns a 'Text' containing those characters that satisfy the
-- predicate.
filter :: (Char -> Bool) -> Text -> Text
filter p t = unstream (S.filter p (stream t))
{-# INLINE filter #-}


-------------------------------------------------------------------------------
-- ** Indexing 'Text's

-- | /O(1)/ 'Text' index (subscript) operator, starting from 0.
index :: Text -> Int -> Char
index t n = S.index (stream t) n
{-# INLINE index #-}

-- | The 'findIndex' function takes a predicate and a 'Text' and
-- returns the index of the first element in the 'Text'
-- satisfying the predicate.
findIndex :: (Char -> Bool) -> Text -> Maybe Int
findIndex p t = S.findIndex p (stream t)
{-# INLINE findIndex #-}

-- | /O(n)/ The 'elemIndex' function returns the index of the first
-- element in the given 'Text' which is equal to the query element, or
-- 'Nothing' if there is no such element.
elemIndex :: Char -> Text -> Maybe Int
elemIndex c t = S.elemIndex c (stream t)

-------------------------------------------------------------------------------
-- * Zipping

-- | /O(n)/ 'zipWith' generalises 'zip' by zipping with the function
-- given as the first argument, instead of a tupling function.
zipWith :: (Char -> Char -> Char) -> Text -> Text -> Text
zipWith f t1 t2 = unstream (S.zipWith f (stream t1) (stream t2))

words :: Text -> [Text]
words (Text arr off len) = loop0 off off
    where
      loop0 start n
            | isSpace (unsafeChr c) = if start == n
                                      then loop0 (start+1) (start+1)
                                      else (Text arr start (n-start)):loop0 (n+1) (n+1)
            | n < (off+len) = loop0 start (n+1)
            | otherwise = if start == n
                          then []
                          else [(Text arr start (n-start))]
            where
              c = arr `A.unsafeIndex` n
{-# INLINE words #-}

errorEmptyList :: String -> a
errorEmptyList fun = error ("Data.Text." ++ fun ++ ": empty list")
Tip: Filter by directory path e.g. /media app.js to search for public/media/app.js.
Tip: Use camelCasing e.g. ProjME to search for ProjectModifiedEvent.java.
Tip: Filter by extension type e.g. /repo .js to search for all .js files in the /repo directory.
Tip: Separate your search with spaces e.g. /ssh pom.xml to search for src/ssh/pom.xml.
Tip: Use ↑ and ↓ arrow keys to navigate and return to view the file.
Tip: You can also navigate files with Ctrl+j (next) and Ctrl+k (previous) and view the file with Ctrl+o.
Tip: You can also navigate files with Alt+j (next) and Alt+k (previous) and view the file with Alt+o.