Skip to content

CLAUDE.md

Latest commit

 

History

History
50 lines (36 loc) · 2.49 KB

CLAUDE.md

File metadata and controls

50 lines (36 loc) · 2.49 KB

CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Project Overview

Linq.J is a zero-dependency Java library that brings LINQ (Language Integrated Query) capabilities to Java, enabling SQL-like querying of in-memory collections via a fluent, chainable API with lambda expressions.

  • Maven coordinates: xyz.erupt:linq.j:0.1.1
  • Requirements: JDK 8+, zero production dependencies
  • Test dependencies only: JUnit 4.13.2, Gson 2.9.1

Build & Test Commands

mvn clean compile                              # Compile
mvn clean test                                 # Run all tests
mvn clean test -Dtest=LinqTest                 # Run specific test class
mvn clean test -Dtest=LinqTest#selectId        # Run specific test method
mvn clean package                              # Build JAR
mvn clean install                              # Install locally

Architecture

Data flow: Linq (entry point) → builds a Dql schema → EruptEngine executes it → returns results.

Core layers

Package Role
grammar/ Six SQL-like interfaces: Select, Join, Where, GroupBy, OrderBy, Write
schema/ DQL data structures: Dql (full query), Row, Column, JoinSchema, WhereSchema, OrderBySchema
engine/ Engine (abstract) + EruptEngine (executes the Dql, handles joins, filtering, grouping, sorting)
lambda/ Lambda parsing: SFunction (serializable function), LambdaSee (extracts field names from lambdas), Th (identity helper)
util/ Columns (aggregation: sum/avg/min/max/count), RowUtil, ReflectField, CompareUtil
consts/ Enums: JoinMethod, OrderByDirection, CompareSymbol, JoinExchange

Key design decisions

  • Linq.java implements all six grammar interfaces; methods mutate a Dql instance, returning this for chaining.
  • Lambda expressions are serialized and parsed at runtime by LambdaSee using SerializedLambda reflection to extract field names — this is why the -parameters compiler flag is required (set in pom.xml).
  • EruptEngine uses hash-based join optimization; columns are represented as Map<Column, Object> internally (the Row type).
  • Results are materialized via write(Class<T>), writeMap(), or writeOne(Class<T>).
  • Objects must expose getter methods (Lombok @Getter recommended).

Planned features (not yet implemented)

  • UNION ALL / UNION / INTERSECT / EXCEPT
  • Window functions