@@ -1,396 +1,156 @@
1−-- | `ArrayBuffer` serialization in the “builder monoid” style.
2−-- |
31-- | This module provides a `Builder` monoid and a `PutM` monad
4−-- | for building `ArrayBuffer`s. See the package README for usage examples.
2+-- | for serializing `Data.ArrayBuffer.Types.ArrayBuffer`s.
3+-- | See the package README for usage examples.
4+-- |
5+-- | Writing to an `ArrayBuffer` is an `Effect`ful activity, so most
6+-- | 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__.
512module Data.ArrayBuffer.Builder
6−( PutM
7−, Put
8−, execPutM
9−, execPut
10−, putArrayBuffer
11−, putUint8
12−, putInt8
13−, putUint16be
14−, putUint16le
15−, putInt16be
16−, putInt16le
17−, putUint32be
18−, putUint32le
19−, putInt32be
20−, putInt32le
21−, putFloat32be
22−, putFloat32le
23−, putFloat64be
24−, putFloat64le
25−, Builder
26−, (<>>)
27−, execBuilder
28−, singleton
29−, snoc
30−, encodeUint8
31−, encodeInt8
32−, encodeUint16be
33−, encodeUint16le
34−, encodeInt16be
35−, encodeInt16le
36−, encodeUint32be
37−, encodeUint32le
38−, encodeInt32be
39−, encodeInt32le
40−, encodeFloat32be
41−, encodeFloat32le
42−, encodeFloat64be
43−, encodeFloat64le
44−)
45−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
4637
4738import Prelude
4839
49−import Control.Monad.Writer.Trans (WriterT, execWriterT, tell)
50−import Data.ArrayBuffer.ArrayBuffer as AB
51−import Data.ArrayBuffer.DataView as DV
52−import Data.ArrayBuffer.Typed as AT
53−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)
5445import Data.Float32 (Float32)
55−import Data.Maybe (Maybe(..))
5646import Data.UInt (UInt)
5747import Effect (Effect)
58−import Effect.Class (class MonadEffect, liftEffect)
48+import Effect.Class (class MonadEffect)
5949
60−-- | The `PutM` monad is a Writer transformer monad which
61−-- | [gives us access to do-notation](https://wiki.haskell.org/Do_notation_considered_harmful#Library_design)
62−-- | 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.
6356type PutM = WriterT Builder
6457
65−-- | `Put` monad is the non-transformer version of `PutM`.
58+-- | The `PutM` type reified to `Effect`, in other words `WriterT Builder Effect`.
6659type Put = PutM Effect
6760
68−-- | Monoidal builder for `ArrayBuffer`s.
69−-- |
70−-- | ### 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.
7170-- |
72−-- | __TL;DR__ You probably don't want to use the `Builder` monoid directly
73−-- | 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.
7475-- |
75−-- | The `Builder` monoid in this library is efficient when we `snoc` single
76−-- | items onto the end of it, or when we only `cons` single items to the
77−-- | beginning, but it can be less efficient when we are mixing `cons` and
78−-- | `snoc`.
79−-- | This matters when we're appending three or more `Builder`s
80−-- | in one associative expression, because the
81−-- | `Semigroup` append operator `<>` is right-associative.
76+-- | In a `PutM` monad do-block, we can
8277-- |
83−-- | To solve this, we provide an operator `<>>` for appending `Builders`.
84−-- | `<>>` is exactly the same as `<>`, but left-associative.
85−-- | This only matters when we're chaining together three
86−-- | or more `Builder`s in a single associative expression.
87−-- | Instead of
88−-- | ```
89−-- | builder₁ <> builder₂ <> builder₃
90−-- | ```
91−-- | we should always prefer to
92−-- | write
9378-- | ```
94−-- | builder₁ <>> builder₂ <>> builder₃
95−-- | ```
96−-- | so that we get the efficient
97−-- | `snoc`ing of `Builder`s.
98−-- |
99−-- | If we build our `ArrayBuffer`s with the `PutM` monad instead of appending by
100−-- | using the `Semigroup` instance of `Builder`, then we always get the efficient
101−-- | `snoc` case.
79+-- | do
80+-- | messageBuilder <- subBuilder $ do
81+-- | putField1
82+-- | putField2
10283-- |
103−data Builder
104− = Node Builder ArrayBuffer Builder
105− | Null
106−
107−instance semigroupBuilder :: Semigroup Builder where
108− append Null Null = Null
109− append l Null = l
110− append Null r = r
111− append l (Node Null rx rr) = Node l rx rr -- this is the snoc case
112− append (Node ll lx Null) r = Node ll lx r -- found the rightmost Null
113− -- of the left tree
114− append (Node ll lx lr) r = Node ll lx $ append lr r -- search down the right
115− -- side of the left tree
116− -- to find the rightmost
117− -- Null
118−
119−infixl 5 append as <>>
120−
121−instance monoidBuilder :: Monoid Builder where
122− mempty = Null
123−
124−-- | `Builder` is not an instance of `Foldable` because `Builder` is monomorphic.
125−foldl :: forall b. (b -> ArrayBuffer -> b) -> b -> Builder -> b
126−foldl f a Null = a
127−foldl f a (Node l x r) = foldl f (f (foldl f a l) x) r
128−
129−-- | Monomorphic foldM copied from
130−-- | [`Data.Foldable.foldM`](https://pursuit.purescript.org/packages/purescript-foldable-traversable/4.1.1/docs/Data.Foldable#v:foldM)
131−foldM :: forall b m. (Monad m) => (b -> ArrayBuffer -> m b) -> b -> Builder -> m b
132−foldM f a0 = foldl (\ma b -> ma >>= flip f b) (pure a0)
133−
134−-- | Construct a `Builder` with a single `ArrayBuffer`. *O(1)*
135−singleton :: ArrayBuffer -> Builder
136−singleton buf = Node Null buf Null
137−
138−-- | Add an `ArrayBuffer` to the end of the `Builder`. *O(1)*
139−snoc :: Builder -> ArrayBuffer -> Builder
140−snoc bs x = Node bs x Null
141−
142−-- | Build a single `ArrayBuffer` from a `Builder`. *O(n)*
143−execBuilder :: forall m. (MonadEffect m) => Builder -> m ArrayBuffer
144−execBuilder bldr = do
145− let buflen = foldl (\b a -> b + AB.byteLength a) 0 bldr
146− -- Allocate the final ArrayBuffer
147− buf <- liftEffect $ AB.empty buflen
148− -- Then copy each ArrayBuffer into the final ArrayBuffer.
149− -- To memcpy from one ArrayBuffer to another, apparently we have to first view
150− -- both ArrayBuffers as ArrayView (Typed Array).
151− newview <- liftEffect (AT.whole buf :: Effect Uint8Array)
152− _ <- foldM
153− ( \offset a -> do
154− aview <- liftEffect (AT.whole a :: Effect Uint8Array)
155− _ <- liftEffect $ AT.setTyped newview (Just offset) aview
156− pure $ offset + AB.byteLength a
157− ) 0 bldr
158− pure buf
159−
160−-- | Build an `ArrayBuffer` with do-notation in any `MonadEffect`. *O(n)*
161−execPutM :: forall m. (MonadEffect m) => PutM m Unit -> m ArrayBuffer
162−execPutM = execBuilder <=< execWriterT
163−
164−-- | Build an `ArrayBuffer` with do-notation. *O(n)*
165−execPut :: Put Unit -> Effect ArrayBuffer
166−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
16789
16890-- | Append an `ArrayBuffer` to the builder.
169−putArrayBuffer :: forall m. (MonadEffect m) => ArrayBuffer -> PutM m Unit
170−putArrayBuffer = tell <<< singleton
91+putArrayBuffer :: forall m. Monad m => ArrayBuffer -> PutM m Unit
92+putArrayBuffer = tell <<< Internal.singleton <<< Internal.Buff
17193
172−-- | Serialize an 8-bit unsigned integer (byte) into a new `ArrayBuffer`.
173−encodeUint8 :: forall m. (MonadEffect m) => UInt -> m ArrayBuffer
174−encodeUint8 x = do
175− buf <- liftEffect $ AB.empty 1
176− _ <- liftEffect $ DV.setUint8 (DV.whole buf) 0 x
177− 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
17897
179−-- | Append an 8-bit unsigned integer (byte) to the builder.
180−putUint8 :: forall m. (MonadEffect m) => UInt -> PutM m Unit
181−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
182101
183−-- | Serialize an 8-bit two’s-complement signed integer (char) into a new `ArrayBuffer`.
184−encodeInt8 :: forall m. (MonadEffect m) => Int -> m ArrayBuffer
185−encodeInt8 x = do
186− buf <- liftEffect $ AB.empty 1
187− _ <- liftEffect $ DV.setInt8 (DV.whole buf) 0 x
188− 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
189105
190106-- | Append an 8-bit two’s-complement signed integer (char) to the builder.
191−putInt8 :: forall m. (MonadEffect m) => Int -> PutM m Unit
192−putInt8 = putArrayBuffer <=< encodeInt8
193−
194−-- | Serialize a 16-bit big-endian unsigned integer into a new `ArrayBuffer`.
195−encodeUint16be :: forall m. (MonadEffect m) => UInt -> m ArrayBuffer
196−encodeUint16be x = do
197− buf <- liftEffect $ AB.empty 2
198− _ <- liftEffect $ DV.setUint16be (DV.whole buf) 0 x
199− pure buf
107+putInt8 :: forall m. MonadEffect m => Int -> PutM m Unit
108+putInt8 = putArrayBuffer <=< Internal.encodeInt8
200109
201110-- | Append a 16-bit big-endian unsigned integer to the builder.
202−putUint16be :: forall m. (MonadEffect m) => UInt -> PutM m Unit
203−putUint16be = putArrayBuffer <=< encodeUint16be
204−
205−-- | Serialize a 16-bit little-endian unsigned integer into a new `ArrayBuffer`.
206−encodeUint16le :: forall m. (MonadEffect m) => UInt -> m ArrayBuffer
207−encodeUint16le x = do
208− buf <- liftEffect $ AB.empty 2
209− _ <- liftEffect $ DV.setUint16le (DV.whole buf) 0 x
210− pure buf
111+putUint16be :: forall m. MonadEffect m => UInt -> PutM m Unit
112+putUint16be = putArrayBuffer <=< Internal.encodeUint16be
211113
212114-- | Append a 16-bit little-endian unsigned integer to the builder.
213−putUint16le :: forall m. (MonadEffect m) => UInt -> PutM m Unit
214−putUint16le = putArrayBuffer <=< encodeUint16le
215−
216−-- | Serialize a 16-bit big-endian two’s-complement signed integer into a new `ArrayBuffer`.
217−encodeInt16be :: forall m. (MonadEffect m) => Int -> m ArrayBuffer
218−encodeInt16be x = do
219− buf <- liftEffect $ AB.empty 2
220− _ <- liftEffect $ DV.setInt16be (DV.whole buf) 0 x
221− pure buf
115+putUint16le :: forall m. MonadEffect m => UInt -> PutM m Unit
116+putUint16le = putArrayBuffer <=< Internal.encodeUint16le
222117
223118-- | Append a 16-bit big-endian two’s-complement signed integer to the builder.
224−putInt16be :: forall m. (MonadEffect m) => Int -> PutM m Unit
225−putInt16be = putArrayBuffer <=< encodeInt16be
226−
227−-- | Serialize a 16-bit little-endian two’s-complement signed integer into a new `ArrayBuffer`.
228−encodeInt16le :: forall m. (MonadEffect m) => Int -> m ArrayBuffer
229−encodeInt16le x = do
230− buf <- liftEffect $ AB.empty 2
231− _ <- liftEffect $ DV.setInt16le (DV.whole buf) 0 x
232− pure buf
119+putInt16be :: forall m. MonadEffect m => Int -> PutM m Unit
120+putInt16be = putArrayBuffer <=< Internal.encodeInt16be
233121
234122-- | Append a 16-bit little-endian two’s-complement signed integer to the builder.
235−putInt16le :: forall m. (MonadEffect m) => Int -> PutM m Unit
236−putInt16le = putArrayBuffer <=< encodeInt16le
237−
238−-- | Serialize a 32-bit big-endian unsigned integer into a new `ArrayBuffer`.
239−encodeUint32be :: forall m. (MonadEffect m) => UInt -> m ArrayBuffer
240−encodeUint32be x = do
241− buf <- liftEffect $ AB.empty 4
242− _ <- liftEffect $ DV.setUint32be (DV.whole buf) 0 x
243− pure buf
123+putInt16le :: forall m. MonadEffect m => Int -> PutM m Unit
124+putInt16le = putArrayBuffer <=< Internal.encodeInt16le
244125
245126-- | Append a 32-bit big-endian unsigned integer to the builder.
246−putUint32be :: forall m. (MonadEffect m) => UInt -> PutM m Unit
247−putUint32be = putArrayBuffer <=< encodeUint32be
248−
249−-- | Serialize a 32-bit little-endian unsigned integer into a new `ArrayBuffer`.
250−encodeUint32le :: forall m. (MonadEffect m) => UInt -> m ArrayBuffer
251−encodeUint32le x = do
252− buf <- liftEffect $ AB.empty 4
253− _ <- liftEffect $ DV.setUint32le (DV.whole buf) 0 x
254− pure buf
127+putUint32be :: forall m. MonadEffect m => UInt -> PutM m Unit
128+putUint32be = putArrayBuffer <=< Internal.encodeUint32be
255129
256130-- | Append a 32-bit little-endian unsigned integer to the builder.
257−putUint32le :: forall m. (MonadEffect m) => UInt -> PutM m Unit
258−putUint32le = putArrayBuffer <=< encodeUint32le
259−
260−-- | Serialize a 32-bit big-endian two’s-complement signed integer into a new `ArrayBuffer`.
261−encodeInt32be :: forall m. (MonadEffect m) => Int -> m ArrayBuffer
262−encodeInt32be x = do
263− buf <- liftEffect $ AB.empty 4
264− _ <- liftEffect $ DV.setInt32be (DV.whole buf) 0 x
265− pure buf
131+putUint32le :: forall m. MonadEffect m => UInt -> PutM m Unit
132+putUint32le = putArrayBuffer <=< Internal.encodeUint32le
266133
267134-- | Append a 32-bit big-endian two’s-complement signed integer to the builder.
268−putInt32be :: forall m. (MonadEffect m) => Int -> PutM m Unit
269−putInt32be = putArrayBuffer <=< encodeInt32be
270−
271−-- | Serialize a 32-bit little-endian two’s-complement signed integer into a new `ArrayBuffer`.
272−encodeInt32le :: forall m. (MonadEffect m) => Int -> m ArrayBuffer
273−encodeInt32le x = do
274− buf <- liftEffect $ AB.empty 4
275− _ <- liftEffect $ DV.setInt32le (DV.whole buf) 0 x
276− pure buf
135+putInt32be :: forall m. MonadEffect m => Int -> PutM m Unit
136+putInt32be = putArrayBuffer <=< Internal.encodeInt32be
277137
278138-- | Append a 32-bit little-endian two’s-complement signed integer to the builder.
279−putInt32le :: forall m. (MonadEffect m) => Int -> PutM m Unit
280−putInt32le = putArrayBuffer <=< encodeInt32le
281−
282−-- | Serialize a 32-bit big-endian IEEE single-precision float into a new `ArrayBuffer`.
283−encodeFloat32be :: forall m. (MonadEffect m) => Float32 -> m ArrayBuffer
284−encodeFloat32be x = do
285− buf <- liftEffect $ AB.empty 4
286− _ <- liftEffect $ DV.setFloat32be (DV.whole buf) 0 x
287− pure buf
139+putInt32le :: forall m. MonadEffect m => Int -> PutM m Unit
140+putInt32le = putArrayBuffer <=< Internal.encodeInt32le
288141
289142-- | Append a 32-bit big-endian IEEE single-precision float to the builder.
290−putFloat32be :: forall m. (MonadEffect m) => Float32 -> PutM m Unit
291−putFloat32be = putArrayBuffer <=< encodeFloat32be
292−
293−-- | Serialize a 32-bit little-endian IEEE single-precision float into a new `ArrayBuffer`.
294−encodeFloat32le :: forall m. (MonadEffect m) => Float32 -> m ArrayBuffer
295−encodeFloat32le x = do
296− buf <- liftEffect $ AB.empty 4
297− _ <- liftEffect $ DV.setFloat32le (DV.whole buf) 0 x
298− pure buf
143+putFloat32be :: forall m. MonadEffect m => Float32 -> PutM m Unit
144+putFloat32be = putArrayBuffer <=< Internal.encodeFloat32be
299145
300146-- | Append a 32-bit little-endian IEEE single-precision float to the builder.
301−putFloat32le :: forall m. (MonadEffect m) => Float32 -> PutM m Unit
302−putFloat32le = putArrayBuffer <=< encodeFloat32le
303−
304−-- | Serialize a 64-bit big-endian IEEE double-precision float into a new `ArrayBuffer`.
305−encodeFloat64be :: forall m. (MonadEffect m) => Number -> m ArrayBuffer
306−encodeFloat64be x = do
307− buf <- liftEffect $ AB.empty 8
308− _ <- liftEffect $ DV.setFloat64be (DV.whole buf) 0 x
309− pure buf
147+putFloat32le :: forall m. MonadEffect m => Float32 -> PutM m Unit
148+putFloat32le = putArrayBuffer <=< Internal.encodeFloat32le
310149
311150-- | Append a 64-bit big-endian IEEE double-precision float to the builder.
312−putFloat64be :: forall m. (MonadEffect m) => Number -> PutM m Unit
313−putFloat64be = putArrayBuffer <=< encodeFloat64be
314−
315−-- | Serialize a 64-bit little-endian IEEE double-precision float into a new `ArrayBuffer`.
316−encodeFloat64le :: forall m. (MonadEffect m) => Number -> m ArrayBuffer
317−encodeFloat64le x = do
318− buf <- liftEffect $ AB.empty 8
319− _ <- liftEffect $ DV.setFloat64le (DV.whole buf) 0 x
320− pure buf
151+putFloat64be :: forall m. MonadEffect m => Number -> PutM m Unit
152+putFloat64be = putArrayBuffer <=< Internal.encodeFloat64be
321153
322154-- | Append a 64-bit little-endian IEEE double-precision float to the builder.
323−putFloat64le :: forall m. (MonadEffect m) => Number -> PutM m Unit
324−putFloat64le = putArrayBuffer <=< encodeFloat64le
325−
326−
327−-- ## Implementation Details
328−--
329−-- We want our `Builder` to be a data structure with
330−-- * *O(1)* monoid append
331−-- * *O(n)* fold
332−--
333−-- Our `Builder` implementation is an unbalanced binary tree.
334−--
335−-- For monoid `append`, what we actually get is *O(1)* when either the
336−-- left or right tree is a singleton. If that's not true, then in the
337−-- unlikely worst case `append` might be *O(n)*.
338−--
339−-- `Builder` is optimized what we consider to be normal usage, that is,
340−-- `snoc`ing singleton elements to the end of the `Builder`.
341−--
342−-- If a Builder is built entirely by `snoc`ing, it will look like a
343−-- left-only binary tree, a.k.a. a linked list.
344−--
345−-- ```
346−-- ④
347−-- ╱
348−-- ③
349−-- ╱
350−-- ②
351−-- ╱
352−-- ①
353−-- ```
354−--
355−-- If two of these `snoc`-built trees are `append`ed, then the new tree
356−-- will look like
357−--
358−-- ```
359−-- ④
360−-- ╱ ╲
361−-- ③ ⑧
362−-- ╱ ╱
363−-- ② ⑦
364−-- ╱ ╱
365−-- ① ⑥
366−-- ╱
367−-- ⑤
368−-- ```
369−--
370−-- This is all similar to
371−-- [__bytestring-tree-builder__](https://hackage.haskell.org/package/bytestring-tree-builder)
372−-- , except that the
373−-- [`Tree`](https://hackage.haskell.org/package/bytestring-tree-builder-0.2.7.3/docs/src/ByteString.TreeBuilder.Tree.html#Tree)
374−-- structure in __bytestring-tree-builder__ only carries values in its
375−-- leaves, which is how it achieves *O(1)* appending, at the cost of
376−-- a higher coefficient time factor on the fold.
377−--
378−-- We hope that this implementation is fairly fast, but we
379−-- haven't chosen this implementation because it's fast, we've chosen
380−-- this implementation because it's simple.
381−-- If someone wants to create a fast Purescript ArrayBuffer serialization
382−-- library, then they can benchmark against this one to prove that the new
383−-- one is fast.
384−--
385−-- One relatively cheap and simple performance improvement for this library would be to
386−-- remove the Null constructor of `Builder` and instead use Javascript nulls.
387−--
388−-- In the longer term, it might make sense to try to change the Builder so
389−-- that it works like the
390−-- https://hackage.haskell.org/package/bytestring/docs/Data-ByteString-Builder.html
391−--
392−-- Here are some benchmarks of different Haskell ByteString builders
393−-- https://github.com/haskell-perf/strict-bytestring-builders
394−--
395−-- We've tried to design the API for this library with minimal assumptions,
396−-- 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