@@ -4,395 +4,153 @@
44-- |
55-- | Writing to an `ArrayBuffer` is an `Effect`ful activity, so most
66-- | functions in this module must be run in a `MonadEffect` context.
7+-- |
8+-- | For other operations for working with `ArrayBuffer`, see
9+-- | module
10+-- | [`Data.ArrayBuffer.ArrayBuffer`](https://pursuit.purescript.org/packages/purescript-arraybuffer/docs/Data.ArrayBuffer.ArrayBuffer)
11+-- | in package __arraybuffer__.
712module Data.ArrayBuffer.Builder
8−( PutM
9−, Put
10−, execPutM
11−, execPut
12−, putArrayBuffer
13−, putUint8
14−, putInt8
15−, putUint16be
16−, putUint16le
17−, putInt16be
18−, putInt16le
19−, putUint32be
20−, putUint32le
21−, putInt32be
22−, putInt32le
23−, putFloat32be
24−, putFloat32le
25−, putFloat64be
26−, putFloat64le
27−, Builder
28−, (<>>)
29−, execBuilder
30−, singleton
31−, snoc
32−, encodeUint8
33−, encodeInt8
34−, encodeUint16be
35−, encodeUint16le
36−, encodeInt16be
37−, encodeInt16le
38−, encodeUint32be
39−, encodeUint32le
40−, encodeInt32be
41−, encodeInt32le
42−, encodeFloat32be
43−, encodeFloat32le
44−, encodeFloat64be
45−, encodeFloat64le
46−)
47−where
13+ ( PutM
14+ , Put
15+ , execPutM
16+ , execPut
17+ , subBuilder
18+ , putArrayBuffer
19+ , putDataView
20+ , putDataBuff
21+ , putUint8
22+ , putInt8
23+ , putUint16be
24+ , putUint16le
25+ , putInt16be
26+ , putInt16le
27+ , putUint32be
28+ , putUint32le
29+ , putInt32be
30+ , putInt32le
31+ , putFloat32be
32+ , putFloat32le
33+ , putFloat64be
34+ , putFloat64le
35+ , module Data.ArrayBuffer.Builder.Internal
36+ ) where
4837
4938import Prelude
5039
51−import Control.Monad.Writer.Trans (WriterT, execWriterT, tell)
52−import Data.ArrayBuffer.ArrayBuffer as AB
53−import Data.ArrayBuffer.DataView as DV
54−import Data.ArrayBuffer.Typed as AT
55−import Data.ArrayBuffer.Types (ArrayBuffer, Uint8Array)
40+import Control.Monad.Rec.Class (class MonadRec)
41+import Control.Monad.Writer.Trans (WriterT, execWriterT, tell, lift)
42+import Data.ArrayBuffer.Builder.Internal (Builder, DataBuff(..), length, toView, (<>>))
43+import Data.ArrayBuffer.Builder.Internal as Internal
44+import Data.ArrayBuffer.Types (ArrayBuffer, DataView)
5645import Data.Float32 (Float32)
57−import Data.Maybe (Maybe(..))
5846import Data.UInt (UInt)
5947import Effect (Effect)
60−import Effect.Class (class MonadEffect, liftEffect)
48+import Effect.Class (class MonadEffect)
6149
62−-- | The `PutM` monad is a Writer transformer monad which
63−-- | [gives us access to do-notation](https://wiki.haskell.org/Do_notation_considered_harmful#Library_design)
64−-- | for building `ArrayBuffer`s.
50+-- | The `PutM` monad is a `WriterT Builder` transformer monad which
51+-- | gives us do-notation for the `Builder` monoid. The base monad must be
52+-- | a `MonadEffect`.
53+-- |
54+-- | To append `Builder`s in this monad call `tell`, or any of the `put*`
55+-- | functions in this module.
6556type PutM = WriterT Builder
6657
67−-- | `Put` monad is the non-transformer version of `PutM`.
58+-- | The `PutM` type reified to `Effect`, in other words `WriterT Builder Effect`.
6859type Put = PutM Effect
6960
70−-- | Monoidal builder for `ArrayBuffer`s.
71−-- |
72−-- | ### Left-associative `<>>` append operator
61+-- | Build an `ArrayBuffer` with do-notation in any `MonadEffect`. *O(n)* Stack-safe.
62+execPutM :: forall m. MonadEffect m => MonadRec m => PutM m Unit -> m ArrayBuffer
63+execPutM = Internal.execBuilder <=< execWriterT
64+
65+-- | Build an `ArrayBuffer` with do-notation in `Effect`. *O(n)* Stack-safe.
66+execPut :: Put Unit -> Effect ArrayBuffer
67+execPut = execPutM
68+
69+-- | Build up a sub-`Builder` without `tell`ing it to the `Writer` yet.
7370-- |
74−-- | __TL;DR__ You probably don't want to use the `Builder` monoid directly
75−-- | in your code, it’s better to use the `PutM` monad with do-notation instead.
71+-- | One case where we might want to call a `subBuilder` is when
72+-- | serializing length-prefixed messages in some protocol. In that case,
73+-- | we must serialize the message first, calculate the message length,
74+-- | append the message length, and then append the message.
7675-- |
77−-- | The `Builder` monoid in this library is efficient when we `snoc` single
78−-- | items onto the end of it, or when we only `cons` single items to the
79−-- | beginning, but it can be less efficient when we are mixing `cons` and
80−-- | `snoc`.
81−-- | This matters when we're appending three or more `Builder`s
82−-- | in one associative expression, because the
83−-- | `Semigroup` append operator `<>` is right-associative.
76+-- | In a `PutM` monad do-block, we can
8477-- |
85−-- | To solve this, we provide an operator `<>>` for appending `Builders`.
86−-- | `<>>` is exactly the same as `<>`, but left-associative.
87−-- | This only matters when we're chaining together three
88−-- | or more `Builder`s in a single associative expression.
89−-- | Instead of
90−-- | ```
91−-- | builder₁ <> builder₂ <> builder₃
92−-- | ```
93−-- | we should always prefer to
94−-- | write
95−-- | ```
96−-- | builder₁ <>> builder₂ <>> builder₃
9778-- | ```
98−-- | so that we get the efficient
99−-- | `snoc`ing of `Builder`s.
79+-- | do
80+-- | messageBuilder <- subBuilder $ do
81+-- | putField1
82+-- | putField2
10083-- |
101−-- | If we build our `ArrayBuffer`s with the `PutM` monad instead of appending by
102−-- | using the `Semigroup` instance of `Builder`, then we always get the efficient
103−-- | `snoc` case.
104−-- |
105−data Builder
106− = Node Builder ArrayBuffer Builder
107− | Null
108−
109−instance semigroupBuilder :: Semigroup Builder where
110− append Null Null = Null
111− append l Null = l
112− append Null r = r
113− append l (Node Null rx rr) = Node l rx rr -- this is the snoc case
114− append (Node ll lx Null) r = Node ll lx r -- found the rightmost Null
115− -- of the left tree
116− append (Node ll lx lr) r = Node ll lx $ append lr r -- search down the right
117− -- side of the left tree
118− -- to find the rightmost
119− -- Null
120−
121−infixl 5 append as <>>
122−
123−instance monoidBuilder :: Monoid Builder where
124− mempty = Null
125−
126−-- | `Builder` is not an instance of `Foldable` because `Builder` is monomorphic.
127−foldl :: forall b. (b -> ArrayBuffer -> b) -> b -> Builder -> b
128−foldl f a Null = a
129−foldl f a (Node l x r) = foldl f (f (foldl f a l) x) r
130−
131−-- | Monomorphic foldM copied from
132−-- | [`Data.Foldable.foldM`](https://pursuit.purescript.org/packages/purescript-foldable-traversable/4.1.1/docs/Data.Foldable#v:foldM)
133−foldM :: forall b m. (Monad m) => (b -> ArrayBuffer -> m b) -> b -> Builder -> m b
134−foldM f a0 = foldl (\ma b -> ma >>= flip f b) (pure a0)
135−
136−-- | Construct a `Builder` with a single `ArrayBuffer`. *O(1)*
137−singleton :: ArrayBuffer -> Builder
138−singleton buf = Node Null buf Null
139−
140−-- | Add an `ArrayBuffer` to the end of the `Builder`. *O(1)*
141−snoc :: Builder -> ArrayBuffer -> Builder
142−snoc bs x = Node bs x Null
143−
144−-- | Build a single `ArrayBuffer` from a `Builder`. *O(n)*
145−execBuilder :: forall m. (MonadEffect m) => Builder -> m ArrayBuffer
146−execBuilder bldr = do
147− let buflen = foldl (\b a -> b + AB.byteLength a) 0 bldr
148− -- Allocate the final ArrayBuffer
149− buf <- liftEffect $ AB.empty buflen
150− -- Then copy each ArrayBuffer into the final ArrayBuffer.
151− -- To memcpy from one ArrayBuffer to another, apparently we have to first view
152− -- both ArrayBuffers as ArrayView (Typed Array).
153− newview <- liftEffect (AT.whole buf :: Effect Uint8Array)
154− _ <- foldM
155− ( \offset a -> do
156− aview <- liftEffect (AT.whole a :: Effect Uint8Array)
157− _ <- liftEffect $ AT.setTyped newview (Just offset) aview
158− pure $ offset + AB.byteLength a
159− ) 0 bldr
160− pure buf
161−
162−-- | Build an `ArrayBuffer` with do-notation in any `MonadEffect`. *O(n)*
163−execPutM :: forall m. (MonadEffect m) => PutM m Unit -> m ArrayBuffer
164−execPutM = execBuilder <=< execWriterT
165−
166−-- | Build an `ArrayBuffer` with do-notation. *O(n)*
167−execPut :: Put Unit -> Effect ArrayBuffer
168−execPut = execPutM
84+-- | putInt32be $ length messageBuilder
85+-- | tell messageBuilder
86+-- | ```
87+subBuilder :: forall m. Monad m => PutM m Unit -> PutM m Builder
88+subBuilder = lift <<< execWriterT
16989
17090-- | Append an `ArrayBuffer` to the builder.
171−putArrayBuffer :: forall m. (MonadEffect m) => ArrayBuffer -> PutM m Unit
172−putArrayBuffer = tell <<< singleton
91+putArrayBuffer :: forall m. Monad m => ArrayBuffer -> PutM m Unit
92+putArrayBuffer = tell <<< Internal.singleton <<< Internal.Buff
17393
174−-- | Serialize an 8-bit unsigned integer (byte) into a new `ArrayBuffer`.
175−encodeUint8 :: forall m. (MonadEffect m) => UInt -> m ArrayBuffer
176−encodeUint8 x = do
177− buf <- liftEffect $ AB.empty 1
178− _ <- liftEffect $ DV.setUint8 (DV.whole buf) 0 x
179− pure buf
94+-- | Append a `DataView` to the builder.
95+putDataView :: forall m. Monad m => DataView -> PutM m Unit
96+putDataView = tell <<< Internal.singleton <<< Internal.View
18097
181−-- | Append an 8-bit unsigned integer (byte) to the builder.
182−putUint8 :: forall m. (MonadEffect m) => UInt -> PutM m Unit
183−putUint8 = putArrayBuffer <=< encodeUint8
98+-- | Append either an `ArrayBuffer` or a `DataView` to the builder.
99+putDataBuff :: forall m. Monad m => DataBuff -> PutM m Unit
100+putDataBuff = tell <<< Internal.singleton
184101
185−-- | Serialize an 8-bit two’s-complement signed integer (char) into a new `ArrayBuffer`.
186−encodeInt8 :: forall m. (MonadEffect m) => Int -> m ArrayBuffer
187−encodeInt8 x = do
188− buf <- liftEffect $ AB.empty 1
189− _ <- liftEffect $ DV.setInt8 (DV.whole buf) 0 x
190− pure buf
102+-- | Append an 8-bit unsigned integer (byte) to the builder.
103+putUint8 :: forall m. MonadEffect m => UInt -> PutM m Unit
104+putUint8 = putArrayBuffer <=< Internal.encodeUint8
191105
192106-- | Append an 8-bit two’s-complement signed integer (char) to the builder.
193−putInt8 :: forall m. (MonadEffect m) => Int -> PutM m Unit
194−putInt8 = putArrayBuffer <=< encodeInt8
195−
196−-- | Serialize a 16-bit big-endian unsigned integer into a new `ArrayBuffer`.
197−encodeUint16be :: forall m. (MonadEffect m) => UInt -> m ArrayBuffer
198−encodeUint16be x = do
199− buf <- liftEffect $ AB.empty 2
200− _ <- liftEffect $ DV.setUint16be (DV.whole buf) 0 x
201− pure buf
107+putInt8 :: forall m. MonadEffect m => Int -> PutM m Unit
108+putInt8 = putArrayBuffer <=< Internal.encodeInt8
202109
203110-- | Append a 16-bit big-endian unsigned integer to the builder.
204−putUint16be :: forall m. (MonadEffect m) => UInt -> PutM m Unit
205−putUint16be = putArrayBuffer <=< encodeUint16be
206−
207−-- | Serialize a 16-bit little-endian unsigned integer into a new `ArrayBuffer`.
208−encodeUint16le :: forall m. (MonadEffect m) => UInt -> m ArrayBuffer
209−encodeUint16le x = do
210− buf <- liftEffect $ AB.empty 2
211− _ <- liftEffect $ DV.setUint16le (DV.whole buf) 0 x
212− pure buf
111+putUint16be :: forall m. MonadEffect m => UInt -> PutM m Unit
112+putUint16be = putArrayBuffer <=< Internal.encodeUint16be
213113
214114-- | Append a 16-bit little-endian unsigned integer to the builder.
215−putUint16le :: forall m. (MonadEffect m) => UInt -> PutM m Unit
216−putUint16le = putArrayBuffer <=< encodeUint16le
217−
218−-- | Serialize a 16-bit big-endian two’s-complement signed integer into a new `ArrayBuffer`.
219−encodeInt16be :: forall m. (MonadEffect m) => Int -> m ArrayBuffer
220−encodeInt16be x = do
221− buf <- liftEffect $ AB.empty 2
222− _ <- liftEffect $ DV.setInt16be (DV.whole buf) 0 x
223− pure buf
115+putUint16le :: forall m. MonadEffect m => UInt -> PutM m Unit
116+putUint16le = putArrayBuffer <=< Internal.encodeUint16le
224117
225118-- | Append a 16-bit big-endian two’s-complement signed integer to the builder.
226−putInt16be :: forall m. (MonadEffect m) => Int -> PutM m Unit
227−putInt16be = putArrayBuffer <=< encodeInt16be
228−
229−-- | Serialize a 16-bit little-endian two’s-complement signed integer into a new `ArrayBuffer`.
230−encodeInt16le :: forall m. (MonadEffect m) => Int -> m ArrayBuffer
231−encodeInt16le x = do
232− buf <- liftEffect $ AB.empty 2
233− _ <- liftEffect $ DV.setInt16le (DV.whole buf) 0 x
234− pure buf
119+putInt16be :: forall m. MonadEffect m => Int -> PutM m Unit
120+putInt16be = putArrayBuffer <=< Internal.encodeInt16be
235121
236122-- | Append a 16-bit little-endian two’s-complement signed integer to the builder.
237−putInt16le :: forall m. (MonadEffect m) => Int -> PutM m Unit
238−putInt16le = putArrayBuffer <=< encodeInt16le
239−
240−-- | Serialize a 32-bit big-endian unsigned integer into a new `ArrayBuffer`.
241−encodeUint32be :: forall m. (MonadEffect m) => UInt -> m ArrayBuffer
242−encodeUint32be x = do
243− buf <- liftEffect $ AB.empty 4
244− _ <- liftEffect $ DV.setUint32be (DV.whole buf) 0 x
245− pure buf
123+putInt16le :: forall m. MonadEffect m => Int -> PutM m Unit
124+putInt16le = putArrayBuffer <=< Internal.encodeInt16le
246125
247126-- | Append a 32-bit big-endian unsigned integer to the builder.
248−putUint32be :: forall m. (MonadEffect m) => UInt -> PutM m Unit
249−putUint32be = putArrayBuffer <=< encodeUint32be
250−
251−-- | Serialize a 32-bit little-endian unsigned integer into a new `ArrayBuffer`.
252−encodeUint32le :: forall m. (MonadEffect m) => UInt -> m ArrayBuffer
253−encodeUint32le x = do
254− buf <- liftEffect $ AB.empty 4
255− _ <- liftEffect $ DV.setUint32le (DV.whole buf) 0 x
256− pure buf
127+putUint32be :: forall m. MonadEffect m => UInt -> PutM m Unit
128+putUint32be = putArrayBuffer <=< Internal.encodeUint32be
257129
258130-- | Append a 32-bit little-endian unsigned integer to the builder.
259−putUint32le :: forall m. (MonadEffect m) => UInt -> PutM m Unit
260−putUint32le = putArrayBuffer <=< encodeUint32le
261−
262−-- | Serialize a 32-bit big-endian two’s-complement signed integer into a new `ArrayBuffer`.
263−encodeInt32be :: forall m. (MonadEffect m) => Int -> m ArrayBuffer
264−encodeInt32be x = do
265− buf <- liftEffect $ AB.empty 4
266− _ <- liftEffect $ DV.setInt32be (DV.whole buf) 0 x
267− pure buf
131+putUint32le :: forall m. MonadEffect m => UInt -> PutM m Unit
132+putUint32le = putArrayBuffer <=< Internal.encodeUint32le
268133
269134-- | Append a 32-bit big-endian two’s-complement signed integer to the builder.
270−putInt32be :: forall m. (MonadEffect m) => Int -> PutM m Unit
271−putInt32be = putArrayBuffer <=< encodeInt32be
272−
273−-- | Serialize a 32-bit little-endian two’s-complement signed integer into a new `ArrayBuffer`.
274−encodeInt32le :: forall m. (MonadEffect m) => Int -> m ArrayBuffer
275−encodeInt32le x = do
276− buf <- liftEffect $ AB.empty 4
277− _ <- liftEffect $ DV.setInt32le (DV.whole buf) 0 x
278− pure buf
135+putInt32be :: forall m. MonadEffect m => Int -> PutM m Unit
136+putInt32be = putArrayBuffer <=< Internal.encodeInt32be
279137
280138-- | Append a 32-bit little-endian two’s-complement signed integer to the builder.
281−putInt32le :: forall m. (MonadEffect m) => Int -> PutM m Unit
282−putInt32le = putArrayBuffer <=< encodeInt32le
283−
284−-- | Serialize a 32-bit big-endian IEEE single-precision float into a new `ArrayBuffer`.
285−encodeFloat32be :: forall m. (MonadEffect m) => Float32 -> m ArrayBuffer
286−encodeFloat32be x = do
287− buf <- liftEffect $ AB.empty 4
288− _ <- liftEffect $ DV.setFloat32be (DV.whole buf) 0 x
289− pure buf
139+putInt32le :: forall m. MonadEffect m => Int -> PutM m Unit
140+putInt32le = putArrayBuffer <=< Internal.encodeInt32le
290141
291142-- | Append a 32-bit big-endian IEEE single-precision float to the builder.
292−putFloat32be :: forall m. (MonadEffect m) => Float32 -> PutM m Unit
293−putFloat32be = putArrayBuffer <=< encodeFloat32be
294−
295−-- | Serialize a 32-bit little-endian IEEE single-precision float into a new `ArrayBuffer`.
296−encodeFloat32le :: forall m. (MonadEffect m) => Float32 -> m ArrayBuffer
297−encodeFloat32le x = do
298− buf <- liftEffect $ AB.empty 4
299− _ <- liftEffect $ DV.setFloat32le (DV.whole buf) 0 x
300− pure buf
143+putFloat32be :: forall m. MonadEffect m => Float32 -> PutM m Unit
144+putFloat32be = putArrayBuffer <=< Internal.encodeFloat32be
301145
302146-- | Append a 32-bit little-endian IEEE single-precision float to the builder.
303−putFloat32le :: forall m. (MonadEffect m) => Float32 -> PutM m Unit
304−putFloat32le = putArrayBuffer <=< encodeFloat32le
305−
306−-- | Serialize a 64-bit big-endian IEEE double-precision float into a new `ArrayBuffer`.
307−encodeFloat64be :: forall m. (MonadEffect m) => Number -> m ArrayBuffer
308−encodeFloat64be x = do
309− buf <- liftEffect $ AB.empty 8
310− _ <- liftEffect $ DV.setFloat64be (DV.whole buf) 0 x
311− pure buf
147+putFloat32le :: forall m. MonadEffect m => Float32 -> PutM m Unit
148+putFloat32le = putArrayBuffer <=< Internal.encodeFloat32le
312149
313150-- | Append a 64-bit big-endian IEEE double-precision float to the builder.
314−putFloat64be :: forall m. (MonadEffect m) => Number -> PutM m Unit
315−putFloat64be = putArrayBuffer <=< encodeFloat64be
316−
317−-- | Serialize a 64-bit little-endian IEEE double-precision float into a new `ArrayBuffer`.
318−encodeFloat64le :: forall m. (MonadEffect m) => Number -> m ArrayBuffer
319−encodeFloat64le x = do
320− buf <- liftEffect $ AB.empty 8
321− _ <- liftEffect $ DV.setFloat64le (DV.whole buf) 0 x
322− pure buf
151+putFloat64be :: forall m. MonadEffect m => Number -> PutM m Unit
152+putFloat64be = putArrayBuffer <=< Internal.encodeFloat64be
323153
324154-- | Append a 64-bit little-endian IEEE double-precision float to the builder.
325−putFloat64le :: forall m. (MonadEffect m) => Number -> PutM m Unit
326−putFloat64le = putArrayBuffer <=< encodeFloat64le
327−
328−
329−-- ## Implementation Details
330−--
331−-- We want our `Builder` to be a data structure with
332−-- * *O(1)* monoid append
333−-- * *O(n)* fold
334−--
335−-- Our `Builder` implementation is an unbalanced binary tree.
336−--
337−-- For monoid `append`, what we actually get is *O(1)* when either the
338−-- left or right tree is a singleton. If that's not true, then in the
339−-- unlikely worst case `append` might be *O(n)*.
340−--
341−-- `Builder` is optimized what we consider to be normal usage, that is,
342−-- `snoc`ing singleton elements to the end of the `Builder`.
343−--
344−-- If a Builder is built entirely by `snoc`ing, it will look like a
345−-- left-only binary tree, a.k.a. a linked list.
346−--
347−-- ```
348−-- ④
349−-- ╱
350−-- ③
351−-- ╱
352−-- ②
353−-- ╱
354−-- ①
355−-- ```
356−--
357−-- If two of these `snoc`-built trees are `append`ed, then the new tree
358−-- will look like
359−--
360−-- ```
361−-- ④
362−-- ╱ ╲
363−-- ③ ⑧
364−-- ╱ ╱
365−-- ② ⑦
366−-- ╱ ╱
367−-- ① ⑥
368−-- ╱
369−-- ⑤
370−-- ```
371−--
372−-- This is all similar to
373−-- [__bytestring-tree-builder__](https://hackage.haskell.org/package/bytestring-tree-builder)
374−-- , except that the
375−-- [`Tree`](https://hackage.haskell.org/package/bytestring-tree-builder-0.2.7.3/docs/src/ByteString.TreeBuilder.Tree.html#Tree)
376−-- structure in __bytestring-tree-builder__ only carries values in its
377−-- leaves, which is how it achieves *O(1)* appending, at the cost of
378−-- a higher coefficient time factor on the fold.
379−--
380−-- We hope that this implementation is fairly fast, but we
381−-- haven't chosen this implementation because it's fast, we've chosen
382−-- this implementation because it's simple.
383−-- If someone wants to create a fast Purescript ArrayBuffer serialization
384−-- library, then they can benchmark against this one to prove that the new
385−-- one is fast.
386−--
387−-- One relatively cheap and simple performance improvement for this library would be to
388−-- remove the Null constructor of `Builder` and instead use Javascript nulls.
389−--
390−-- In the longer term, it might make sense to try to change the Builder so
391−-- that it works like the
392−-- https://hackage.haskell.org/package/bytestring/docs/Data-ByteString-Builder.html
393−--
394−-- Here are some benchmarks of different Haskell ByteString builders
395−-- https://github.com/haskell-perf/strict-bytestring-builders
396−--
397−-- We've tried to design the API for this library with minimal assumptions,
398−-- so that if we want to change the Builder implementation later then we can.
155+putFloat64le :: forall m. MonadEffect m => Number -> PutM m Unit
156+putFloat64le = putArrayBuffer <=< Internal.encodeFloat64le