Refactor shared array-backed tree API helpers

Extract common collection and serialization-related instance methods into Tree::Utils::ArrayTreeApiMethods and use it in FenwickTree and SegmentTree while preserving public behavior.

Author: evolve75

CHANGELOG.md

@@ -17,6 +17,9 @@ Changes section to scan for breaking or behavioral changes.
 * Refactor shared binary heap internals into
   `Tree::Utils::HeapSharedMethods` to reduce duplication between min-heap and
   max-heap implementations without changing public behavior.
+* Refactor shared array-backed tree API helpers into
+  `Tree::Utils::ArrayTreeApiMethods` and use it in `Tree::FenwickTree` and
+  `Tree::SegmentTree` without changing public behavior.
 * Make `Tree::TrieNode#<<` use trie word-insert semantics (`insert(word)`)
   instead of generic child-node attachment semantics.
 * Add `<<` insertion shorthand to `Tree::AATree` and `Tree::BTree` for

lib/tree/fenwicktree.rb

@@ -38,6 +38,7 @@
 # frozen_string_literal: true
 
 require 'json'
+require_relative 'utils/array_tree_api_methods'
 
 module Tree
   # Provides a Fenwick (binary indexed) tree implementation.
@@ -63,6 +64,7 @@ module Tree
   class FenwickTree
     include Enumerable
     include Comparable
+    include Tree::Utils::ArrayTreeApiMethods
 
     # @!attribute [r] size
     # Size of the tree (number of elements).
@@ -92,26 +94,6 @@ def initialize(size, values = nil)
       end
     end
 
-    # Convenience synonym for {#size}.
-    #
-    # @return [Integer] The number of elements tracked by the tree.
-    def length
-      size
-    end
-
-    # Iterate over values in index order.
-    #
-    # @yieldparam value [Numeric] Value at each index.
-    #
-    # @return [Tree::FenwickTree] The receiver, if a block is given.
-    # @return [Enumerator] An enumerator, if no block is given.
-    def each(&)
-      return to_enum(:each) unless block_given?
-
-      0.upto(@size - 1) { |index| yield self[index] }
-      self
-    end
-
     # Add a delta to the value at the specified index.
     #
     # @param [Integer] index Zero-based index to update.
@@ -200,37 +182,6 @@ def []=(index, delta)
       self[index]
     end
 
-    # Returns all values in index order.
-    #
-    # @return [Array<Numeric>] Values in index order.
-    def values
-      to_a
-    end
-
-    # Returns all indices in order.
-    #
-    # @return [Array<Integer>] Indices in order.
-    def keys
-      (0...@size).to_a
-    end
-
-    # Returns all values as an Array.
-    #
-    # @return [Array<Numeric>] Values in index order.
-    def to_a
-      map { |value| value }
-    end
-
-    # Returns a Hash representation of the tree.
-    #
-    # @return [Hash] Hash representation of the Fenwick tree.
-    def to_h
-      {
-        size: size,
-        values: to_a
-      }
-    end
-
     # Build a Fenwick tree from a Hash representation.
     #
     # @param [Hash] hash Hash representation of a Fenwick tree.
@@ -251,22 +202,6 @@ def self.from_hash(hash)
       new(size, values)
     end
 
-    # JSON serialization for the Fenwick tree.
-    #
-    # @param [Hash] _options JSON serialization options.
-    # @return [Hash] Hash representation for JSON serialization.
-    def as_json(_options = {})
-      to_h
-    end
-
-    # Serialize the Fenwick tree to JSON.
-    #
-    # @param [Array] args JSON.generate arguments.
-    # @return [String] JSON representation of the tree.
-    def to_json(*args)
-      JSON.generate(as_json, *args)
-    end
-
     # Create a Fenwick tree from a JSON hash.
     #
     # @param [Hash] json_hash JSON hash representation.
@@ -275,16 +210,6 @@ def self.json_create(json_hash)
       from_hash(json_hash)
     end
 
-    # Compare Fenwick trees by their ordered values.
-    #
-    # @param [Tree::FenwickTree] other The Fenwick tree to compare.
-    # @return [Integer, nil] -1, 0, 1, or +nil+ if not comparable.
-    def <=>(other)
-      return nil unless other.is_a?(Tree::FenwickTree)
-
-      to_a <=> other.to_a
-    end
-
     private
 
     # Validate the size for the tree.

lib/tree/segmenttree.rb

@@ -37,6 +37,7 @@
 # frozen_string_literal: true
 
 require 'json'
+require_relative 'utils/array_tree_api_methods'
 
 module Tree
   # Provides a Segment Tree implementation for range sum queries.
@@ -61,6 +62,7 @@ module Tree
   class SegmentTree
     include Enumerable
     include Comparable
+    include Tree::Utils::ArrayTreeApiMethods
 
     # @!attribute [r] size
     # Size of the tree (number of elements).
@@ -90,26 +92,6 @@ def initialize(size, values = nil)
       end
     end
 
-    # Convenience synonym for {#size}.
-    #
-    # @return [Integer] The number of elements tracked by the tree.
-    def length
-      size
-    end
-
-    # Iterate over values in index order.
-    #
-    # @yieldparam value [Numeric] Value at each index.
-    #
-    # @return [Tree::SegmentTree] The receiver, if a block is given.
-    # @return [Enumerator] An enumerator, if no block is given.
-    def each(&)
-      return to_enum(:each) unless block_given?
-
-      0.upto(@size - 1) { |index| yield self[index] }
-      self
-    end
-
     # Set the value at the specified index.
     #
     # @param [Integer] index Zero-based index to update.
@@ -173,37 +155,6 @@ def []=(index, value)
       self[index]
     end
 
-    # Returns all values in index order.
-    #
-    # @return [Array<Numeric>] Values in index order.
-    def values
-      to_a
-    end
-
-    # Returns all indices in order.
-    #
-    # @return [Array<Integer>] Indices in order.
-    def keys
-      (0...@size).to_a
-    end
-
-    # Returns all values as an Array.
-    #
-    # @return [Array<Numeric>] Values in index order.
-    def to_a
-      map { |value| value }
-    end
-
-    # Returns a Hash representation of the tree.
-    #
-    # @return [Hash] Hash representation of the segment tree.
-    def to_h
-      {
-        size: size,
-        values: to_a
-      }
-    end
-
     # Build a segment tree from a Hash representation.
     #
     # @param [Hash] hash Hash representation of a segment tree.
@@ -224,22 +175,6 @@ def self.from_hash(hash)
       new(size, values)
     end
 
-    # JSON serialization for the segment tree.
-    #
-    # @param [Hash] _options JSON serialization options.
-    # @return [Hash] Hash representation for JSON serialization.
-    def as_json(_options = {})
-      to_h
-    end
-
-    # Serialize the segment tree to JSON.
-    #
-    # @param [Array] args JSON.generate arguments.
-    # @return [String] JSON representation of the tree.
-    def to_json(*args)
-      JSON.generate(as_json, *args)
-    end
-
     # Create a segment tree from a JSON hash.
     #
     # @param [Hash] json_hash JSON hash representation.
@@ -248,16 +183,6 @@ def self.json_create(json_hash)
       from_hash(json_hash)
     end
 
-    # Compare segment trees by their ordered values.
-    #
-    # @param [Tree::SegmentTree] other The segment tree to compare.
-    # @return [Integer, nil] -1, 0, 1, or +nil+ if not comparable.
-    def <=>(other)
-      return nil unless other.is_a?(Tree::SegmentTree)
-
-      to_a <=> other.to_a
-    end
-
     private
 
     # Validate the size for the tree.

lib/tree/utils/array_tree_api_methods.rb

@@ -0,0 +1,122 @@
+# array_tree_api_methods.rb - This file is part of the RubyTree package.
+#
+# = array_tree_api_methods.rb - Shared API helpers for array-backed trees.
+#
+# Provides shared instance-level API methods for non-TreeNode, array-backed
+# tree implementations.
+#
+# Author:: Anupam Sengupta (anupamsg@gmail.com)
+#
+
+# Copyright (c) 2026 Anupam Sengupta. All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are met:
+#
+# - Redistributions of source code must retain the above copyright notice, this
+#   list of conditions and the following disclaimer.
+#
+# - Redistributions in binary form must reproduce the above copyright notice,
+#   this list of conditions and the following disclaimer in the documentation
+#   and/or other materials provided with the distribution.
+#
+# - Neither the name of the organization nor the names of its contributors may
+#   be used to endorse or promote products derived from this software without
+#   specific prior written permission.
+#
+#   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
+# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#
+# frozen_string_literal: true
+
+module Tree
+  module Utils
+    # Shared instance-level API methods for array-backed tree types.
+    module ArrayTreeApiMethods
+      # Convenience synonym for +size+.
+      #
+      # @return [Integer] The number of elements tracked by the tree.
+      def length
+        size
+      end
+
+      # Iterate over values in index order.
+      #
+      # @yieldparam value [Numeric] Value at each index.
+      #
+      # @return [Object] The receiver, if a block is given.
+      # @return [Enumerator] An enumerator, if no block is given.
+      def each(&)
+        return to_enum(:each) unless block_given?
+
+        0.upto(@size - 1) { |index| yield self[index] }
+        self
+      end
+
+      # Returns all values in index order.
+      #
+      # @return [Array<Numeric>] Values in index order.
+      def values
+        to_a
+      end
+
+      # Returns all indices in order.
+      #
+      # @return [Array<Integer>] Indices in order.
+      def keys
+        (0...@size).to_a
+      end
+
+      # Returns all values as an Array.
+      #
+      # @return [Array<Numeric>] Values in index order.
+      def to_a
+        map { |value| value }
+      end
+
+      # Returns a Hash representation of the tree.
+      #
+      # @return [Hash] Hash representation of the tree.
+      def to_h
+        {
+          size: size,
+          values: to_a
+        }
+      end
+
+      # JSON serialization for the tree.
+      #
+      # @param [Hash] _options JSON serialization options.
+      # @return [Hash] Hash representation for JSON serialization.
+      def as_json(_options = {})
+        to_h
+      end
+
+      # Serialize the tree to JSON.
+      #
+      # @param [Array] args JSON.generate arguments.
+      # @return [String] JSON representation of the tree.
+      def to_json(*args)
+        JSON.generate(as_json, *args)
+      end
+
+      # Compare trees by their ordered values.
+      #
+      # @param [Object] other The tree to compare.
+      # @return [Integer, nil] -1, 0, 1, or +nil+ if not comparable.
+      def <=>(other)
+        return nil unless other.is_a?(self.class)
+
+        to_a <=> other.to_a
+      end
+    end
+  end
+end