Added ScanCastOptions class

Author: ankane

lib/polars.rb

@@ -67,6 +67,7 @@
 require_relative "polars/meta_expr"
 require_relative "polars/name_expr"
 require_relative "polars/rolling_group_by"
+require_relative "polars/scan_cast_options"
 require_relative "polars/schema"
 require_relative "polars/selectors"
 require_relative "polars/series"

lib/polars/scan_cast_options.rb

@@ -0,0 +1,64 @@
+module Polars
+  # Options for scanning files.
+  class ScanCastOptions
+    # Common configuration for scanning files.
+    #
+    # @note
+    #   This functionality is considered **unstable**. It may be changed
+    #   at any point without it being considered a breaking change.
+    #
+    # @param integer_cast ['upcast', 'forbid']
+    #   Configuration for casting from integer types:
+    #
+    #   * `upcast`: Allow lossless casting to wider integer types.
+    #   * `forbid`: Raises an error if dtypes do not match.
+    #
+    # @param float_cast ['upcast', 'downcast', 'forbid']
+    #   Configuration for casting from float types:
+    #
+    #   * `upcast`: Allow casting to higher precision float types.
+    #   * `downcast`: Allow casting to lower precision float types.
+    #   * `forbid`: Raises an error if dtypes do not match.
+    #
+    # @param datetime_cast ['nanosecond-downcast', 'convert-timezone', 'forbid']
+    #   Configuration for casting from datetime types:
+    #
+    #   * `nanosecond-downcast`: Allow nanosecond precision datetime to be
+    #     downcasted to any lower precision. This has a similar effect to
+    #     PyArrow's `coerce_int96_timestamp_unit`.
+    #   * `convert-timezone`: Allow casting to a different timezone.
+    #   * `forbid`: Raises an error if dtypes do not match.
+    #
+    # @param missing_struct_fields ['insert', 'raise']
+    #   Configuration for behavior when struct fields defined in the schema
+    #   are missing from the data:
+    #
+    #   * `insert`: Inserts the missing fields.
+    #   * `raise`: Raises an error.
+    #
+    # @param extra_struct_fields ['ignore', 'raise']
+    #   Configuration for behavior when extra struct fields outside of the
+    #   defined schema are encountered in the data:
+    #
+    #   * `ignore`: Silently ignores.
+    #   * `raise`: Raises an error.
+    def initialize(
+      integer_cast: "forbid",
+      float_cast: "forbid",
+      datetime_cast: "forbid",
+      missing_struct_fields: "raise",
+      extra_struct_fields: "raise",
+      _internal_call: false
+    )
+      @integer_cast = integer_cast
+      @float_cast = float_cast
+      @datetime_cast = datetime_cast
+      @missing_struct_fields = missing_struct_fields
+      @extra_struct_fields = extra_struct_fields
+    end
+
+    def self.default
+      new(_internal_call: true)
+    end
+  end
+end