1 files changed, 170 insertions, 0 deletions
diff --git a/src/arrow/r/R/dataset-factory.R b/src/arrow/r/R/dataset-factory.R
new file mode 100644
index 000000000..c56a6b181
--- /dev/null
+++ b/src/arrow/r/R/dataset-factory.R
@@ -0,0 +1,170 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+#' @include dataset.R
+
+#' @usage NULL
+#' @format NULL
+#' @rdname Dataset
+#' @export
+DatasetFactory <- R6Class("DatasetFactory",
+  inherit = ArrowObject,
+  public = list(
+    Finish = function(schema = NULL, unify_schemas = FALSE) {
+      if (is.null(schema)) {
+        dataset___DatasetFactory__Finish1(self, unify_schemas)
+      } else {
+        assert_is(schema, "Schema")
+        dataset___DatasetFactory__Finish2(self, schema)
+      }
+    },
+    Inspect = function(unify_schemas = FALSE) {
+      dataset___DatasetFactory__Inspect(self, unify_schemas)
+    }
+  )
+)
+DatasetFactory$create <- function(x,
+                                  filesystem = NULL,
+                                  format = c("parquet", "arrow", "ipc", "feather", "csv", "tsv", "text"),
+                                  partitioning = NULL,
+                                  ...) {
+  if (is_list_of(x, "DatasetFactory")) {
+    return(dataset___UnionDatasetFactory__Make(x))
+  }
+
+  if (is.character(format)) {
+    format <- FileFormat$create(match.arg(format), ...)
+  } else {
+    assert_is(format, "FileFormat")
+  }
+
+  path_and_fs <- get_paths_and_filesystem(x, filesystem)
+  info <- path_and_fs$fs$GetFileInfo(path_and_fs$path)
+
+  if (length(info) > 1 || info[[1]]$type == FileType$File) {
+    # x looks like a vector of one or more file paths (not a directory path)
+    return(FileSystemDatasetFactory$create(path_and_fs$fs, NULL, path_and_fs$path, format))
+  }
+
+  if (!is.null(partitioning)) {
+    if (inherits(partitioning, "Schema")) {
+      partitioning <- DirectoryPartitioning$create(partitioning)
+    } else if (is.character(partitioning)) {
+      # These are the column/field names, and we should autodetect their types
+      partitioning <- DirectoryPartitioningFactory$create(partitioning)
+    }
+  }
+
+  selector <- FileSelector$create(path_and_fs$path, allow_not_found = FALSE, recursive = TRUE)
+
+  FileSystemDatasetFactory$create(path_and_fs$fs, selector, NULL, format, partitioning)
+}
+
+#' Create a DatasetFactory
+#'
+#' A [Dataset] can constructed using one or more [DatasetFactory]s.
+#' This function helps you construct a `DatasetFactory` that you can pass to
+#' [open_dataset()].
+#'
+#' If you would only have a single `DatasetFactory` (for example, you have a
+#' single directory containing Parquet files), you can call `open_dataset()`
+#' directly. Use `dataset_factory()` when you
+#' want to combine different directories, file systems, or file formats.
+#'
+#' @param x A string path to a directory containing data files, a vector of one
+#' one or more string paths to data files, or a list of `DatasetFactory` objects
+#' whose datasets should be combined. If this argument is specified it will be
+#' used to construct a `UnionDatasetFactory` and other arguments will be
+#' ignored.
+#' @param filesystem A [FileSystem] object; if omitted, the `FileSystem` will
+#' be detected from `x`
+#' @param format A [FileFormat] object, or a string identifier of the format of
+#' the files in `x`. Currently supported values:
+#' * "parquet"
+#' * "ipc"/"arrow"/"feather", all aliases for each other; for Feather, note that
+#'   only version 2 files are supported
+#' * "csv"/"text", aliases for the same thing (because comma is the default
+#'   delimiter for text files
+#' * "tsv", equivalent to passing `format = "text", delimiter = "\t"`
+#'
+#' Default is "parquet", unless a `delimiter` is also specified, in which case
+#' it is assumed to be "text".
+#' @param partitioning One of
+#'   * A `Schema`, in which case the file paths relative to `sources` will be
+#'    parsed, and path segments will be matched with the schema fields. For
+#'    example, `schema(year = int16(), month = int8())` would create partitions
+#'    for file paths like "2019/01/file.parquet", "2019/02/file.parquet", etc.
+#'   * A character vector that defines the field names corresponding to those
+#'    path segments (that is, you're providing the names that would correspond
+#'    to a `Schema` but the types will be autodetected)
+#'   * A `HivePartitioning` or `HivePartitioningFactory`, as returned
+#'    by [hive_partition()] which parses explicit or autodetected fields from
+#'    Hive-style path segments
+#'   * `NULL` for no partitioning
+#' @param ... Additional format-specific options, passed to
+#' `FileFormat$create()`. For CSV options, note that you can specify them either
+#' with the Arrow C++ library naming ("delimiter", "quoting", etc.) or the
+#' `readr`-style naming used in [read_csv_arrow()] ("delim", "quote", etc.).
+#' Not all `readr` options are currently supported; please file an issue if you
+#' encounter one that `arrow` should support.
+#' @return A `DatasetFactory` object. Pass this to [open_dataset()],
+#' in a list potentially with other `DatasetFactory` objects, to create
+#' a `Dataset`.
+#' @export
+dataset_factory <- DatasetFactory$create
+
+#' @usage NULL
+#' @format NULL
+#' @rdname Dataset
+#' @export
+FileSystemDatasetFactory <- R6Class("FileSystemDatasetFactory",
+  inherit = DatasetFactory
+)
+FileSystemDatasetFactory$create <- function(filesystem,
+                                            selector = NULL,
+                                            paths = NULL,
+                                            format,
+                                            partitioning = NULL) {
+  assert_is(filesystem, "FileSystem")
+  is.null(selector) || assert_is(selector, "FileSelector")
+  is.null(paths) || assert_is(paths, "character")
+  assert_that(
+    xor(is.null(selector), is.null(paths)),
+    msg = "Either selector or paths must be specified"
+  )
+  assert_is(format, "FileFormat")
+  if (!is.null(paths)) {
+    assert_that(is.null(partitioning), msg = "Partitioning not supported with paths")
+  }
+
+  if (!is.null(paths)) {
+    ptr <- dataset___FileSystemDatasetFactory__Make0(filesystem, paths, format)
+  } else if (is.null(partitioning)) {
+    ptr <- dataset___FileSystemDatasetFactory__Make1(filesystem, selector, format)
+  } else if (inherits(partitioning, "PartitioningFactory")) {
+    ptr <- dataset___FileSystemDatasetFactory__Make3(filesystem, selector, format, partitioning)
+  } else if (inherits(partitioning, "Partitioning")) {
+    ptr <- dataset___FileSystemDatasetFactory__Make2(filesystem, selector, format, partitioning)
+  } else {
+    stop(
+      "Expected 'partitioning' to be NULL, PartitioningFactory or Partitioning",
+      call. = FALSE
+    )
+  }
+
+  ptr
+}