From 6fdd4041215f91f66f5868f521e80fe371de26aa Mon Sep 17 00:00:00 2001
From: Sutou Kouhei <kou@clear-code.com>
Date: Sun, 7 Dec 2025 14:44:15 +0900
Subject: [PATCH] GH-48380: [Ruby] Add support for reading float64 array

---
 .../lib/arrow-format/array.rb                 | 10 +++++--
 .../lib/arrow-format/file-reader.rb           |  5 ++--
 .../red-arrow-format/lib/arrow-format/type.rb | 27 ++++++++++++++++---
 3 files changed, 34 insertions(+), 8 deletions(-)

diff --git a/ruby/red-arrow-format/lib/arrow-format/array.rb b/ruby/red-arrow-format/lib/arrow-format/array.rb
index d4995cda3e68..41a553bcd9f5 100644
--- a/ruby/red-arrow-format/lib/arrow-format/array.rb
+++ b/ruby/red-arrow-format/lib/arrow-format/array.rb
@@ -91,19 +91,25 @@ def to_a
     end
   end
 
-  class FloatArray < Array
+  class FloatingPointArray < Array
     def initialize(type, size, validity_buffer, values_buffer)
       super(type, size, validity_buffer)
       @values_buffer = values_buffer
     end
   end
 
-  class Float32Array < FloatArray
+  class Float32Array < FloatingPointArray
     def to_a
       apply_validity(@values_buffer.values(:f32, 0, @size))
     end
   end
 
+  class Float64Array < FloatingPointArray
+    def to_a
+      apply_validity(@values_buffer.values(:f64, 0, @size))
+    end
+  end
+
   class VariableSizeBinaryLayoutArray < Array
     def initialize(type, size, validity_buffer, offsets_buffer, values_buffer)
       super(type, size, validity_buffer)
diff --git a/ruby/red-arrow-format/lib/arrow-format/file-reader.rb b/ruby/red-arrow-format/lib/arrow-format/file-reader.rb
index acd21b976481..72c5c9bca85b 100644
--- a/ruby/red-arrow-format/lib/arrow-format/file-reader.rb
+++ b/ruby/red-arrow-format/lib/arrow-format/file-reader.rb
@@ -154,6 +154,8 @@ def read_field(fb_field)
         case fb_type.precision
         when Org::Apache::Arrow::Flatbuf::Precision::SINGLE
           type = Float32Type.singleton
+        when Org::Apache::Arrow::Flatbuf::Precision::DOUBLE
+          type = Float64Type.singleton
         end
       when Org::Apache::Arrow::Flatbuf::List
         type = ListType.new(read_field(fb_field.children[0]))
@@ -189,8 +191,7 @@ def read_column(field, nodes, buffers, body)
 
       case field.type
       when BooleanType,
-           IntType,
-           FloatType
+           NumberType
         values_buffer = buffers.shift
         values = body.slice(values_buffer.offset, values_buffer.length)
         field.type.build_array(length, validity, values)
diff --git a/ruby/red-arrow-format/lib/arrow-format/type.rb b/ruby/red-arrow-format/lib/arrow-format/type.rb
index b6563956346b..c7cebcd745ea 100644
--- a/ruby/red-arrow-format/lib/arrow-format/type.rb
+++ b/ruby/red-arrow-format/lib/arrow-format/type.rb
@@ -54,7 +54,10 @@ def build_array(size, validity_buffer, values_buffer)
     end
   end
 
-  class IntType < Type
+  class NumberType < Type
+  end
+
+  class IntType < NumberType
     attr_reader :bit_width
     attr_reader :signed
     def initialize(name, bit_width, signed)
@@ -96,7 +99,7 @@ def build_array(size, validity_buffer, values_buffer)
     end
   end
 
-  class FloatType < Type
+  class FloatingPointType < NumberType
     attr_reader :precision
     def initialize(name, precision)
       super(name)
@@ -104,7 +107,7 @@ def initialize(name, precision)
     end
   end
 
-  class Float32Type < FloatType
+  class Float32Type < FloatingPointType
     class << self
       def singleton
         @singleton ||= new
@@ -112,7 +115,7 @@ def singleton
     end
 
     def initialize
-      super("Float32", 32)
+      super("Float32", :single)
     end
 
     def build_array(size, validity_buffer, values_buffer)
@@ -120,6 +123,22 @@ def build_array(size, validity_buffer, values_buffer)
     end
   end
 
+  class Float64Type < FloatingPointType
+    class << self
+      def singleton
+        @singleton ||= new
+      end
+    end
+
+    def initialize
+      super("Float64", :double)
+    end
+
+    def build_array(size, validity_buffer, values_buffer)
+      Float64Array.new(self, size, validity_buffer, values_buffer)
+    end
+  end
+
   class VariableSizeBinaryType < Type
   end