GH-50588: [Ruby] Add ArrowFormat::Array#[]

ruby/red-arrow-format/lib/arrow-format/array.rb

@@ -61,6 +61,14 @@ def null?(i)
       not valid?(i)
     end
 
+    def [](i)
+      if valid?(i)
+        unpack_value(i)
+      else
+        nil
+      end
+    end
+
     def n_nulls
       if @validity_buffer.nil?
         0
@@ -167,6 +175,14 @@ def initialize(size)
       super(NullType.singleton, size, nil)
     end
 
+    def valid?(i)
+      false
+    end
+
+    def null?(i)
+      true
+    end
+
     def each_buffer
       return to_enum(__method__) unless block_given?
     end
@@ -294,6 +310,11 @@ def pack_value(value, template, type)
       value = 0 if value.nil?
       [value].pack(template)
     end
+
+    def unpack_value(i)
+      offset = element_size * (@offset + i)
+      @values_buffer.get_value(@type.buffer_type, offset)
+    end
   end
 
   class BooleanArray < PrimitiveArray
@@ -362,6 +383,10 @@ def build_data(data, type)
       validity_buffer = validity_buffer_builder&.finish(n)
       return n, validity_buffer, values_buffer_builder.finish
     end
+
+    def unpack_value(i)
+      values_bitmap[i]
+    end
   end
 
   class IntArray < PrimitiveArray
@@ -600,6 +625,11 @@ def pack_value(value, template, type)
         value.pack(template)
       end
     end
+
+    def unpack_value(i)
+      offset = element_size * (@offset + i)
+      @values_buffer.get_values([@type.buffer_type] * 2, offset)
+    end
   end
 
   class MonthDayNanoIntervalArray < IntervalArray
@@ -661,6 +691,13 @@ def pack_value(value, template, type)
         value.pack(template)
       end
     end
+
+    def unpack_value(i)
+      buffer_types = @type.buffer_types
+      value_size = IO::Buffer.size_of(buffer_types)
+      offset = value_size * (@offset + i)
+      @values_buffer.get_values(buffer_types, offset)
+    end
   end
 
   class DurationArray < TemporalArray
@@ -768,6 +805,15 @@ def build_data(data)
     def offset_size
       IO::Buffer.size_of(@type.offset_buffer_type)
     end
+
+    def unpack_value(i)
+      offset_types = [@type.offset_buffer_type] * 2
+      offsets_offset = offset_size * (@offset + i)
+      offset, next_offset = @offsets_buffer.get_values(offset_types,
+                                                       offsets_offset)
+      length = next_offset - offset
+      @values_buffer.get_string(offset, length, @type.encoding)
+    end
   end
 
   class BinaryArray < VariableSizeBinaryArray

ruby/red-arrow-format/lib/arrow-format/error.rb

@@ -1,3 +1,4 @@
+# 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

ruby/red-arrow-format/lib/arrow-format/type.rb

@@ -1,3 +1,4 @@
+# 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

ruby/red-arrow-format/test/test-binary-array.rb

@@ -16,6 +16,11 @@
 # under the License.
 
 class TestBinaryArray < Test::Unit::TestCase
+  def setup
+    @values = ["\x00\x01".b, nil, "\xff\x10".b]
+    @array = ArrowFormat::BinaryArray.new(@values)
+  end
+
   sub_test_case("#initialize") do
     def test_no_null
       values = ["\x00\x01".b, "\xff\x10".b]
@@ -52,4 +57,14 @@ def test_sliced_different_content
       assert_not_equal(array1, array2.slice(1, 3))
     end
   end
+
+  sub_test_case("#[]") do
+    def test_valid
+      assert_equal(@values[3], @array[3])
+    end
+
+    def test_null
+      assert_nil(@array[1])
+    end
+  end
 end

ruby/red-arrow-format/test/test-boolean-array.rb

@@ -16,6 +16,11 @@
 # under the License.
 
 class TestBooleanArray < Test::Unit::TestCase
+  def setup
+    @values = [true, nil, false]
+    @array = ArrowFormat::BooleanArray.new(@values)
+  end
+
   sub_test_case("#initialize") do
     def test_no_null
       assert_equal([true, false],
@@ -53,4 +58,14 @@ def test_sliced_different_content
       assert_not_equal(array1, array2.slice(1, 3))
     end
   end
+
+  sub_test_case("#[]") do
+    def test_valid
+      assert_equal(@values[3], @array[3])
+    end
+
+    def test_null
+      assert_nil(@array[1])
+    end
+  end
 end

ruby/red-arrow-format/test/test-date32-array.rb

@@ -19,6 +19,8 @@ class TestDate32Array < Test::Unit::TestCase
   def setup
     @date_2017_08_28 = 17406
     @date_2025_12_09 = 20431
+    @values = [@date_2017_08_28, nil, @date_2025_12_09]
+    @array = ArrowFormat::Date32Array.new(@values)
   end
 
   sub_test_case("#initialize") do
@@ -57,4 +59,14 @@ def test_sliced_different_content
       assert_not_equal(array1, array2.slice(1, 3))
     end
   end
+
+  sub_test_case("#[]") do
+    def test_valid
+      assert_equal(@values[3], @array[3])
+    end
+
+    def test_null
+      assert_nil(@array[1])
+    end
+  end
 end

ruby/red-arrow-format/test/test-date64-array.rb

@@ -19,6 +19,8 @@ class TestDate64Array < Test::Unit::TestCase
   def setup
     @date_2017_08_28_00_00_00 = 1503878400000
     @date_2025_12_10_00_00_00 = 1765324800000
+    @values = [@date_2017_08_28_00_00_00, nil, @date_2025_12_10_00_00_00]
+    @array = ArrowFormat::Date64Array.new(@values)
   end
 
   sub_test_case("#initialize") do
@@ -57,4 +59,14 @@ def test_sliced_different_content
       assert_not_equal(array1, array2.slice(1, 3))
     end
   end
+
+  sub_test_case("#[]") do
+    def test_valid
+      assert_equal(@values[3], @array[3])
+    end
+
+    def test_null
+      assert_nil(@array[1])
+    end
+  end
 end

ruby/red-arrow-format/test/test-day-time-interval-array.rb

@@ -16,6 +16,15 @@
 # under the License.
 
 class TestDayTimeIntervalArray < Test::Unit::TestCase
+  def setup
+    @values = [
+      [1, 100],
+      nil,
+      [3, 300],
+    ]
+    @array = ArrowFormat::DayTimeIntervalArray.new(@values)
+  end
+
   sub_test_case("#initialize") do
     def test_no_null
       values = [
@@ -85,4 +94,14 @@ def test_sliced_different_content
       assert_not_equal(array1, array2.slice(1, 3))
     end
   end
+
+  sub_test_case("#[]") do
+    def test_valid
+      assert_equal(@values[3], @array[3])
+    end
+
+    def test_null
+      assert_nil(@array[1])
+    end
+  end
 end

ruby/red-arrow-format/test/test-duration-array.rb

@@ -16,6 +16,11 @@
 # under the License.
 
 class TestDurationArray < Test::Unit::TestCase
+  def setup
+    @values = [-(2 ** 63), nil, (2 ** 63) - 1]
+    @array = ArrowFormat::DurationArray.new(:second, @values)
+  end
+
   sub_test_case("#initialize") do
     def test_no_null
       values = [-(2 ** 63), (2 ** 63) - 1]
@@ -52,4 +57,14 @@ def test_sliced_different_content
       assert_not_equal(array1, array2.slice(1, 3))
     end
   end
+
+  sub_test_case("#[]") do
+    def test_valid
+      assert_equal(@values[3], @array[3])
+    end
+
+    def test_null
+      assert_nil(@array[1])
+    end
+  end
 end

ruby/red-arrow-format/test/test-float32-array.rb

@@ -16,6 +16,11 @@
 # under the License.
 
 class TestFloat32Array < Test::Unit::TestCase
+  def setup
+    @values = [-Float::INFINITY, nil, +Float::INFINITY]
+    @array = ArrowFormat::Float32Array.new(@values)
+  end
+
   sub_test_case("#initialize") do
     def test_no_null
       values = [-Float::INFINITY, -0.0, +0.0, +Float::INFINITY]
@@ -52,4 +57,14 @@ def test_sliced_different_content
       assert_not_equal(array1, array2.slice(1, 5))
     end
   end
+
+  sub_test_case("#[]") do
+    def test_valid
+      assert_equal(@values[3], @array[3])
+    end
+
+    def test_null
+      assert_nil(@array[1])
+    end
+  end
 end

ruby/red-arrow-format/test/test-float64-array.rb

@@ -16,6 +16,11 @@
 # under the License.
 
 class TestFloat64Array < Test::Unit::TestCase
+  def setup
+    @values = [-Float::INFINITY, nil, +Float::INFINITY]
+    @array = ArrowFormat::Float64Array.new(@values)
+  end
+
   sub_test_case("#initialize") do
     def test_no_null
       values = [-Float::INFINITY, -0.0, +0.0, +Float::INFINITY]
@@ -52,4 +57,14 @@ def test_sliced_different_content
       assert_not_equal(array1, array2.slice(1, 5))
     end
   end
+
+  sub_test_case("#[]") do
+    def test_valid
+      assert_equal(@values[3], @array[3])
+    end
+
+    def test_null
+      assert_nil(@array[1])
+    end
+  end
 end

ruby/red-arrow-format/test/test-int16-array.rb

@@ -16,6 +16,11 @@
 # under the License.
 
 class TestInt16Array < Test::Unit::TestCase
+  def setup
+    @values = [-(2 ** 15), nil, (2 ** 15) - 1]
+    @array = ArrowFormat::Int16Array.new(@values)
+  end
+
   sub_test_case("#initialize") do
     def test_no_null
       values = [-(2 ** 15), (2 ** 15) - 1]
@@ -52,4 +57,14 @@ def test_sliced_different_content
       assert_not_equal(array1, array2.slice(1, 3))
     end
   end
+
+  sub_test_case("#[]") do
+    def test_valid
+      assert_equal(@values[3], @array[3])
+    end
+
+    def test_null
+      assert_nil(@array[1])
+    end
+  end
 end

ruby/red-arrow-format/test/test-int32-array.rb

@@ -16,6 +16,11 @@
 # under the License.
 
 class TestInt32Array < Test::Unit::TestCase
+  def setup
+    @values = [-(2 ** 31), nil, (2 ** 31) - 1]
+    @array = ArrowFormat::Int32Array.new(@values)
+  end
+
   sub_test_case("#initialize") do
     def test_no_null
       values = [-(2 ** 31), (2 ** 31) - 1]
@@ -52,4 +57,14 @@ def test_sliced_different_content
       assert_not_equal(array1, array2.slice(1, 3))
     end
   end
+
+  sub_test_case("#[]") do
+    def test_valid
+      assert_equal(@values[3], @array[3])
+    end
+
+    def test_null
+      assert_nil(@array[1])
+    end
+  end
 end

ruby/red-arrow-format/test/test-int64-array.rb

@@ -16,6 +16,11 @@
 # under the License.
 
 class TestInt64Array < Test::Unit::TestCase
+  def setup
+    @values = [-(2 ** 63), nil, (2 ** 63) - 1]
+    @array = ArrowFormat::Int64Array.new(@values)
+  end
+
   sub_test_case("#initialize") do
     def test_no_null
       values = [-(2 ** 63), (2 ** 63) - 1]
@@ -52,4 +57,14 @@ def test_sliced_different_content
       assert_not_equal(array1, array2.slice(1, 3))
     end
   end
+
+  sub_test_case("#[]") do
+    def test_valid
+      assert_equal(@values[3], @array[3])
+    end
+
+    def test_null
+      assert_nil(@array[1])
+    end
+  end
 end