Add marshalling for 'h2o' [#5]

DESCRIPTION

@@ -1,13 +1,16 @@
 Package: marshal
 Version: 0.0.0-9033
 Title: Framework to Marshal Objects to be Used in Another R Process
+Depends:
+    R (>= 3.2.0)
 Suggests:
     bundle,
     caret,
     data.table,
     DBI,
       RSQLite,
     digest,
+    h2o,
     inline,
     keras,
       tensorflow,

NAMESPACE

@@ -3,6 +3,10 @@
 S3method(marshal,"magick-image")
 S3method(marshal,CFunc)
 S3method(marshal,DBIConnection)
+S3method(marshal,H2OAutoML)
+S3method(marshal,H2OBinomialModel)
+S3method(marshal,H2OMultinomialModel)
+S3method(marshal,H2ORegressionModel)
 S3method(marshal,RasterLayer)
 S3method(marshal,SOCK0node)
 S3method(marshal,SOCKcluster)
@@ -30,6 +34,10 @@ S3method(marshal,xml_nodeset)
 S3method(marshallable,"magick-image")
 S3method(marshallable,CFunc)
 S3method(marshallable,DBIConnection)
+S3method(marshallable,H2OAutoML)
+S3method(marshallable,H2OBinomialModel)
+S3method(marshallable,H2OMultinomialModel)
+S3method(marshallable,H2ORegressionModel)
 S3method(marshallable,RasterLayer)
 S3method(marshallable,SOCK0node)
 S3method(marshallable,SOCKcluster)

R/marshal.h2o.R

@@ -0,0 +1,118 @@
+#' Marshalling of 'h2o' objects
+#'
+#' @param x
+#' An "h2o" object.
+#'
+#' @param \dots Not used.
+#'
+#' @return
+#' A `marshalled` object as described in [marshal()].
+#'
+#' @details
+#' [h2o::h2o.save_mojo()] and [h2o::h2o.saveModel()] are used to produce
+#' a marshalled version of the original object.
+#' [h2o::h2o.import_mojo()] and [h2o::h2o.loadModel()] are used to
+#' reconstruct a version of the original object from the marshalled object.
+#'
+#' @rdname marshal.h2o
+#' @aliases marshal.H2OAutoML
+#' @export
+marshal.H2OAutoML <- function(x, ...) {
+  marshal_h2o(x, ...)
+}
+
+#' @rdname marshal.h2o
+#' @aliases marshal.H2OMultinomialModel
+#' @export
+marshal.H2OMultinomialModel <- function(x, ...) {
+  marshal_h2o(x, ...)
+}
+
+#' @rdname marshal.h2o
+#' @aliases marshal.H2OBinomialModel
+#' @export
+marshal.H2OBinomialModel <- function(x, ...) {
+  marshal_h2o(x, ...)
+}
+
+#' @rdname marshal.h2o
+#' @aliases marshal.H2ORegressionModel
+#' @export
+marshal.H2ORegressionModel <- function(x, ...) {
+  marshal_h2o(x, ...)
+}
+
+
+marshal_h2o <- function(x, ...) {
+  td <- tempdir()
+
+  have_mojo <- x@have_mojo
+  if (have_mojo) {
+    tf <- h2o::h2o.save_mojo(x, path = td)
+  } else {
+    tf <- h2o::h2o.saveModel(x, path = td)
+  }
+  on.exit(file.remove(tf))
+  raw <- readBin(tf, what = raw(), n = file.size(tf), endian = "little")
+
+  res <- list(
+    marshalled = raw,
+    have_mojo = have_mojo
+  )
+  class(res) <- marshal_class(x)
+
+  ## IMPORTANT: We don't want any of the input arguments
+  ## to be part of the unmarshal() environment
+  rm(list = c("x", names(list(...))))
+
+  res[["unmarshal"]] <- unmarshal_h2o
+  assert_no_references(res)
+  res
+}
+
+
+unmarshal_h2o <- function(x, ...) {
+  object <- x[["marshalled"]]
+
+  tf <- tempdir()
+  on.exit(file.remove(tf))
+  writeBin(object, con = tf, endian = "little")
+
+  if (x[["have_mojo"]]) {
+    res <- h2o::h2o.import_mojo(tf)
+  } else {
+    res <- h2o::h2o.loadModel(tf)
+  }
+
+  stopifnot(all.equal(class(res), marshal_unclass(x), check.attributes = FALSE))
+  res
+}
+
+
+#' @rdname marshal.h2o
+#' @aliases marshallable.H2OAutoML
+#' @export
+marshallable.H2OAutoML <- function(...) {
+  TRUE
+}
+
+#' @rdname marshal.h2o
+#' @aliases marshallable.H2OMultinomialModel
+#' @export
+marshallable.H2OMultinomialModel <- function(...) {
+  TRUE
+}
+
+#' @rdname marshal.h2o
+#' @aliases marshallable.H2OBinomialModel
+#' @export
+marshallable.H2OBinomialModel <- function(...) {
+  TRUE
+}
+
+#' @rdname marshal.h2o
+#' @aliases marshallable.H2ORegressionModel
+#' @export
+marshallable.H2ORegressionModel <- function(...) {
+  TRUE
+}