From b92f8368c1c98cac62852d33f5f77df47a7c3306 Mon Sep 17 00:00:00 2001
From: Dmitriy Ryajov <dryajov@gmail.com>
Date: Sun, 12 Apr 2020 23:00:17 -0600
Subject: [PATCH] implement streaming length prefixed parser

---
 libp2p/stream/lenprefixed.nim |  1 -
 libp2p/stream/ringbuffer.nim  | 27 +++++++++++++++++++++++----
 2 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/libp2p/stream/lenprefixed.nim b/libp2p/stream/lenprefixed.nim
index 11d402874..fe777a4fa 100644
--- a/libp2p/stream/lenprefixed.nim
+++ b/libp2p/stream/lenprefixed.nim
@@ -72,7 +72,6 @@ proc read(lp: LenPrefixed,
         lp.mode = Mode.Reading
       else:
         result = lp.readBuff.read(lp.size)
-        echo result
         lp.size -= result.len
         if lp.size == 0:
           lp.mode = Mode.Decoding
diff --git a/libp2p/stream/ringbuffer.nim b/libp2p/stream/ringbuffer.nim
index 13c4d9309..0d54bf26d 100644
--- a/libp2p/stream/ringbuffer.nim
+++ b/libp2p/stream/ringbuffer.nim
@@ -110,7 +110,7 @@ proc read*[T](b: var RingBuffer[T], size: int = -1): seq[T] =
   ## assert(buff.read() == @[...])
   ##
   var isize = size
-  if size < 0:
+  if size < 0 or size > b.len:
     isize = b.len
 
   result = newSeq[T](isize)
@@ -131,7 +131,9 @@ proc clear*[T](b: var RingBuffer[T]) =
   b.buff.setLen(0)
 
 when isMainModule:
-  block Basic:
+
+  block:
+    ## Basic tests
     var buff = RingBuffer[char].init(10)
     var data = newSeq[char](10)
 
@@ -194,7 +196,23 @@ when isMainModule:
     assert(buff.head == 4, "head should be 9")
     assert(buff.tail == 4, "tail should be 9")
 
-  block Errors:
+  block:
+    ## Complex reading scenarios
+    var buff = RingBuffer[char].init(10)
+    var data = newSeq[char](10)
+
+    buff.append(@['a'])
+    assert(buff.len == 1, "len should be 1")
+    assert(buff.head == 0, "head should be 0")
+    assert(buff.tail == 1, "tail should be 1")
+
+    assert(buff.read(5) == @['a'])
+    assert(buff.len == 0, "len should be 0")
+    assert(buff.head == 1, "head should be 9")
+    assert(buff.tail == 1, "tail should be 9")
+
+  block:
+    ## Error checking
     var buff = RingBuffer[char].init(5)
 
     try:
@@ -219,7 +237,8 @@ when isMainModule:
     except CatchableError as exc:
       assert(true)
 
-  block Cleanup:
+  block:
+    ## Cleanup
     var buff = RingBuffer[char].init(5)
 
     buff.reset()