migrate to tevo's structure

1 files changed, 0 insertions, 104 deletions

diff --git a/lib/VM.ml b/lib/VM.ml
deleted file mode 100644
index 1a5770e..0000000
--- a/lib/VM.ml
+++ /dev/null
@@ -1,104 +0,0 @@
-(** A plan is pure data ([Plan.t]) and execution state is never
-    reified: a compiled plan is a [Seq.t], whose forcing is the
-    Volcano eruption [Next]
-
-    The only effects sit at scan leaves, and those are idempotent page
-    reads against a pinned [Multigroup] snapshot. A stream node may be
-    forced twice and observe the same tuples. If a truly destructive
-    source ever appears, wrap its stream in [Seq.once]. *)
-
-module Tuple = struct
-  module AttributeMap = BatMap.String
-
-  (* TODO: The assumption here is that every value is stringified *)
-  (* TODO: The field [type'] currently is not enforced as all the
-     available types of RNT *)
-  type attribute = {value: string; type': string}
-  type t = attribute AttributeMap.t
-
-  let empty : t = AttributeMap.empty
-  let access (name : string) (t : t) : attribute option = AttributeMap.find_opt name t
-
-  let merge (left : t) (right : t) : t =
-    let merger _ (left : attribute option) (right : attribute option) : attribute option =
-      match left, right with
-      | Some a, Some b -> if a = b then Some a else None (* conflicting binding gets droped out *)
-      | (Some _ as a), None | None, (Some _ as a) -> a
-      | None, None -> None
-    in
-    AttributeMap.merge merger left right
-
-  let project (keep : BatSet.String.t) (t : t) : t =
-    AttributeMap.filter (fun name _ -> BatSet.String.mem name keep) t
-
-  let rename (mapping : string BatMap.String.t) (t : t) : t =
-    AttributeMap.fold
-      (fun name attr acc ->
-        let name = BatMap.String.find_default name name mapping in
-        AttributeMap.add name attr acc )
-      t AttributeMap.empty
-end
-
-(** Stub of the cursor layer (CursorManager + Merkle paging). [page]
-    yields the tuples of [relation] starting at [offset]; an empty
-    result marks exhaustion. [args] carries the bound values for
-    parameterized (ephemeral) relations and is ignored for stored
-    ones. *)
-module Source = struct
-  type t =
-    {page: relation:string -> args:string BatFingerTree.t -> offset:int -> Tuple.t BatFingerTree.t}
-
-  let unimplemented : t = {page= (fun ~relation:_ ~args:_ ~offset:_ -> failwith "NOT IMPLEMENTED")}
-end
-
-(** The stateless operator tree representing one constructor per
-    relational operator, carrying only its description without any
-    associated cursors, counters and buffers. *)
-module Plan = struct
-  (** One segment of a parameterized relation path in a SCAN. [Var]
-      segments are resolved from the enclosing JOIN's outer tuple at
-      execution time; [Const] segments are ground literals fixed at
-      the plan construction. *)
-  type path_arg = Var of string | Const of string
-
-  type t =
-    | Scan of {relation: string; args: path_arg BatFingerTree.t}
-    | Join of {left: t; right: t; attrs: BatSet.String.t}
-    | Take of {limit: int; from: t}
-    | Project of {attrs: BatSet.String.t; from: t}
-    | Materialize of t
-    | Rename of {attrs: string BatMap.String.t; from: t}
-    | Union of t BatFingerTree.t
-end
-
-(** Compiles a [Plan.t] into a demand driven tuple stream. *)
-module FOL = struct
-  type stream = Tuple.t BatSeq.t
-
-  (** Resolves a scan arguments template against the enclosing
-      bindings. *)
-  (* TODO: A [Var] missing from the bindings resolves to [""] to
-     mirror the C++ engine. This is a poor representation in the type
-     system. *)
-  let resolve (args : Plan.path_arg BatFingerTree.t) (bindings : Tuple.t) : string BatFingerTree.t =
-    BatFingerTree.map
-      (function
-        | Plan.Const value -> value
-        | Plan.Var name -> (match Tuple.access name bindings with Some a -> a.value | None -> "" ))
-      args
-
-  (** Pages through [relation] one fetch at a time. The offset lives
-      in the closure of each stream node, so re-forcing any node
-      re-reads the same page. This is the functional equivalent of the
-      cursor's [fetch_offset]. Only the current page should be
-      live. *)
-  let scan (src : Source.t) ~(relation : string) ~(args : string BatFingerTree.t) : stream =
-    let rec from offset () =
-      let page = src.page ~relation ~args ~offset in
-      if BatFingerTree.is_empty page then BatSeq.Nil
-      else
-        let rest = from (offset + BatFingerTree.size page) in
-        (BatFingerTree.fold_right (fun rest tuple () -> BatSeq.Cons (tuple, rest)) rest page) ()
-    in
-    from 0
-end