Region.milone

module rec Std.Region

open Std.Ptr

/// Allocates a block of memory in the current region.
/// (Similar to `calloc`.)
///
/// Contents are zeroed.
let rawRegionAlloc (count: int) (size: int) : voidptr =
  if count >= 0 && size >= 0 && not (count = 0 && size = 0) then
    __nativeExpr ("milone_region_alloc({0}, {1})", count, size)
  else
    Ptr.nullPtr

module Region =
  /// Runs a function in new region.
  let run (action: unit -> int) : int =
    __nativeStmt "milone_region_enter();"
    let code = action ()
    __nativeStmt "milone_region_leave();"
    code

  /// Allocates a block of memory in current region.
  let alloc (count: int) : OutPtr<'T> =
    __nativeCast (rawRegionAlloc count sizeof<'T>)

  /// Registers a function to be executed when to leave of current region.
  let defer (action: unit -> unit) : unit =
    __nativeStmt ("milone_region_defer({0}.fun, {0}.env);", action)