From 9b29a00a9200a90a59373198f5c23b90875ac28d Mon Sep 17 00:00:00 2001
From: Jaremy Creechley <creechley@gmail.com>
Date: Mon, 28 Aug 2023 19:22:16 -0700
Subject: [PATCH] add memory (test) ds

---
 datastore/databuffer.nim |  5 +++++
 datastore/memoryds.nim   | 40 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+)

diff --git a/datastore/databuffer.nim b/datastore/databuffer.nim
index 7bd18d5..2bafb95 100644
--- a/datastore/databuffer.nim
+++ b/datastore/databuffer.nim
@@ -27,6 +27,8 @@ proc `=destroy`*(x: var DataBufferHolder) =
 
 proc len*(a: DataBuffer): int = a[].size
 
+proc isNil*(a: DataBuffer): bool = smartptrs.isNil(a)
+
 proc new*(tp: typedesc[DataBuffer], size: int = 0): DataBuffer =
   ## allocate new buffer with given size
   newSharedPtr(DataBufferHolder(
@@ -63,8 +65,11 @@ proc toBuffer*(err: ref Exception): CatchableErrorBuffer =
   )
 
 import ./key
+import stew/results
 
 proc new*(tp: typedesc[KeyBuffer], key: Key): KeyBuffer =
   KeyBuffer.new(key.id())
+proc toKey*(kb: KeyBuffer): Result[Key, ref CatchableError] =
+  Key.init(kb.toString())
 proc new*(tp: typedesc[ValueBuffer], data: seq[byte]): KeyBuffer =
   DataBuffer.new(data)
diff --git a/datastore/memoryds.nim b/datastore/memoryds.nim
index 56cfef8..437866d 100644
--- a/datastore/memoryds.nim
+++ b/datastore/memoryds.nim
@@ -1,4 +1,6 @@
 import std/tables
+import std/sequtils
+import std/strutils
 
 import pkg/chronos
 import pkg/questionable
@@ -80,6 +82,44 @@ method put*(
 
   return success()
 
+proc keyIterator(self: MemoryDatastore, queryKey: string): iterator: KeyBuffer =
+  return iterator(): KeyBuffer {.closure.} =
+    let keys = self.store.keys().toSeq()
+    for key in keys:
+      if key.toString().startsWith(queryKey):
+        yield key 
+
+method query*(
+  self: MemoryDatastore,
+  query: Query,
+): Future[?!QueryIter] {.async.} =
+
+  let
+    queryKey = query.key.id()
+    walker = keyIterator(self, queryKey)
+
+  var
+    iter = QueryIter.new()
+
+  proc next(): Future[?!QueryResponse] {.async.} =
+    let
+      kb = walker()
+
+    if finished(walker):
+      iter.finished = true
+      return success (Key.none, EmptyBytes)
+
+    let
+      key = kb.toKey().expect("should not fail")
+    var ds: ValueBuffer
+    if query.value:
+      ds = self.store[kb]
+    let data = if ds.isNil: EmptyBytes else: ds.toSeq(byte)
+
+    return success (key.some, data)
+
+  iter.next = next
+  return success iter
 method close*(self: MemoryDatastore): Future[?!void] {.async.} =
   self.store.clear()
   return success()