$ show kaminari/kaminari
Kaminari is a pagination library for Ruby on Rails and other web frameworks. It provides scope-based pagination for ActiveRecord models and generic arrays, with view helpers to render pagination controls. The architecture consists of three main components: kaminari-core (pagination logic), kaminari-activerecord (ActiveRecord adapter), and kaminari-actionview (view helpers). Key features include customizable pagination windows, optional count queries for performance, and support for multiple ORMs and template engines. The implementation demonstrates strong craftsmanship in its windowing algorithms, parameter handling, and the innovative 'without_count' optimization that avoids expensive COUNT queries by fetching one extra record.
The LLM identified 4 files worth highlighting for reuse:
Implements the core pagination logic for determining which page links to display based on current page, total pages, and windowing configurations. Contains sophisticated relevance algorithms for inner/outer windows and gap detection. The PageProxy class provides smart page state methods (current?, first?, last?, etc.) that are essential for pagination UI. This component is highly reusable as it contains no framework-specific dependencies and could be extracted for any pagination UI implementation.
Defines the tag-based system for rendering pagination elements (links, gaps, etc.) with intelligent URL generation and parameter handling. Supports multiple template engines (ERB, Haml, Slim) through an abstract Tag base class. The Link module and specialized tag classes (Page, PrevPage, NextPage, etc.) demonstrate excellent abstraction for generating pagination controls. This system could be reused for any navigation or link generation context with minimal adaptation.
Provides PaginatableArray, a drop-in replacement for Ruby arrays that adds pagination capabilities. Implements the same pagination interface (page, per, total_count, etc.) as ActiveRecord relations, enabling consistent pagination API across in-memory arrays and database queries. Shows excellent application of the adapter pattern to extend pagination beyond ORM-backed collections. This component is completely self-contained and could be used in any Ruby project needing array pagination.
Implements the core page state methods used across all paginated collections (current_page, total_pages, next_page, prev_page, etc.). Contains the mathematical logic for calculating pagination state from offset, limit, and total count values. This module is completely decoupled from persistence mechanisms and represents the pure logic of pagination state management. It could be extracted for use with any paginated dataset regardless of storage mechanism.