Merge pull request #6 from felixSchl/feature/read-size

Expose the `size` parameter to `Stream#read`

Author: hdgarrood

src/Node/Stream.js

@@ -4,6 +4,8 @@
 
 // module Node.Stream
 
+exports.undefined = undefined;
+
 exports.setEncodingImpl = function(s) {
     return function(enc) {
         return function() {
@@ -105,13 +107,15 @@ exports.readImpl = function(readChunk) {
     return function(Nothing) {
         return function(Just) {
             return function(r) {
-                return function() {
-                    const v = r.read();
-                    if (v === null) {
-                        return Nothing;
-                    } else {
-                        return Just(readChunk(v));
-                    }
+                return function(s) {
+                    return function() {
+                        const v = r.read(s);
+                        if (v === null) {
+                            return Nothing;
+                        } else {
+                            return Just(readChunk(v));
+                        }
+                    };
                 };
             };
         };

src/Node/Stream.purs

@@ -33,7 +33,7 @@ module Node.Stream
 import Prelude
 
 import Control.Bind ((<=<))
-import Data.Maybe (Maybe(..), maybe)
+import Data.Maybe (Maybe(..), maybe, fromMaybe)
 import Data.Either (Either(..))
 import Node.Encoding
 import Node.Buffer (Buffer())
@@ -66,6 +66,8 @@ type Writable r = Stream (write :: Write | r)
 -- | A duplex (readable _and_ writable stream)
 type Duplex = Stream (read :: Read, write :: Write)
 
+foreign import undefined :: forall a. a
+
 foreign import data Chunk :: *
 readChunk :: Chunk -> Either String Buffer
 readChunk = readChunkImpl Left Right
@@ -84,26 +86,26 @@ onData r cb =
       Right buf ->
         pure buf
 
-read :: forall w eff. Readable w (err :: EXCEPTION | eff) -> Eff (err :: EXCEPTION | eff) (Maybe Buffer)
-read r = do
-  v <- readEither r
+read :: forall w eff. Readable w (err :: EXCEPTION | eff) -> Maybe Int -> Eff (err :: EXCEPTION | eff) (Maybe Buffer)
+read r size = do
+  v <- readEither r size
   case v of
        Nothing        -> pure Nothing
        Just (Left _)  -> throw "Stream encoding should not be set"
        Just (Right b) -> pure (Just b)
 
-readString :: forall w eff. Readable w (err :: EXCEPTION | eff) -> Encoding -> Eff (err :: EXCEPTION | eff) (Maybe String)
-readString r enc = do
-  v <- readEither r
+readString :: forall w eff. Readable w (err :: EXCEPTION | eff) -> Maybe Int -> Encoding -> Eff (err :: EXCEPTION | eff) (Maybe String)
+readString r size enc = do
+  v <- readEither r size
   case v of
        Nothing          -> pure Nothing
        Just (Left _)    -> throw "Stream encoding should not be set"
        Just (Right buf) -> Just <$> (unsafeInterleaveEff $ Buffer.toString enc buf)
 
-readEither :: forall w eff. Readable w eff -> Eff eff (Maybe (Either String Buffer))
-readEither = readImpl readChunk Nothing Just
+readEither :: forall w eff. Readable w eff -> Maybe Int -> Eff eff (Maybe (Either String Buffer))
+readEither r size = readImpl readChunk Nothing Just r (fromMaybe undefined size)
 
-foreign import readImpl :: forall r eff. (Chunk -> Either String Buffer) -> (forall a. Maybe a) -> (forall a. a -> Maybe a) -> Readable r eff -> Eff eff (Maybe (Either String Buffer))
+foreign import readImpl :: forall r eff. (Chunk -> Either String Buffer) -> (forall a. Maybe a) -> (forall a. a -> Maybe a) -> Readable r eff -> Int -> Eff eff (Maybe (Either String Buffer))
 
 -- | Listen for `data` events, returning data in a String, which will be
 -- | decoded using the given encoding. Note that this will fail if `setEncoding`

test/Main.purs

@@ -54,11 +54,11 @@ testReads = do
   where
     testReadString = do
       sIn <- passThrough
-      v   <- readString sIn UTF8
+      v   <- readString sIn Nothing UTF8
       assert (isNothing v)
 
       onReadable sIn do
-        str <- readString sIn UTF8
+        str <- readString sIn Nothing UTF8
         assert (isJust str)
         assertEqual (fromJust str) testString
         return unit
@@ -68,11 +68,11 @@ testReads = do
 
     testReadBuf = do
       sIn <- passThrough
-      v   <- read sIn
+      v   <- read sIn Nothing
       assert (isNothing v)
 
       onReadable sIn do
-        buf <- read sIn
+        buf <- read sIn Nothing
         assert (isJust buf)
         assertEqual <$> (Buffer.toString UTF8 (fromJust buf))
                     <*> pure testString