1 files changed, 51 insertions, 0 deletions
diff --git a/buffer.sml b/buffer.sml
new file mode 100644
index 0000000..03292bb
--- /dev/null
+++ b/buffer.sml
@@ -0,0 +1,51 @@
+structure Buffer =
+struct
+  fun append (a : Word8ArraySlice.slice) (b : Word8VectorSlice.slice) : Word8ArraySlice.slice =
+    let
+      val bLen = Word8VectorSlice.length b
+      val (base, i, aLen) = Word8ArraySlice.base a
+      val baseLen = Word8Array.length base
+    in
+      if i + aLen + bLen <= baseLen
+      then
+        (Word8ArraySlice.copyVec { src = b, dst = base, di = i + aLen } ;
+         Word8ArraySlice.slice (base, i, SOME (aLen + bLen)))
+      else
+        let val newBuf = Word8Array.array (baseLen * 2 + bLen, Word8.fromInt 0)
+        in
+          Word8ArraySlice.copy { src = a, dst = newBuf, di = 0 } ;
+          Word8ArraySlice.copyVec { src = b, dst = newBuf, di = aLen } ;
+          Word8ArraySlice.slice (newBuf, 0, SOME (aLen + bLen))
+        end
+    end
+
+  fun buf () : BinIO.outstream * Word8ArraySlice.slice ref =
+    let val buffer = ref (Word8ArraySlice.full (Word8Array.array (0, Word8.fromInt 0)))
+    in
+      (BinIO.mkOutstream
+        (BinIO.StreamIO.mkOutstream
+          (BinPrimIO.augmentWriter
+            (BinPrimIO.WR
+              { name = "buffer"
+              , chunkSize = 1
+              , writeVec =
+                  SOME
+                    (fn a =>
+                      (buffer := append (!buffer) a ;
+                       Word8VectorSlice.length a))
+              , writeArr = NONE
+              , writeVecNB = NONE
+              , writeArrNB = NONE
+              , block = SOME (fn () => ())
+              , canOutput = SOME (fn () => true)
+              , getPos = NONE
+              , setPos = NONE
+              , endPos = NONE
+              , verifyPos = NONE
+              , close = fn () => ()
+              , ioDesc = NONE
+              }),
+           IO.NO_BUF)),
+       buffer)
+    end
+end