An immutable map implementation with snapshot/checkpoint and merge semantics, used extensively in Spoon's pattern matching engine to manage variable bindings without mutation. It is self-contained (no dependencies on internal Spoon modules) and can be extracted for any project needing an immutable map with cheap snapshot and merge from multiple sources.

A list implementation that automatically maintains parent references and fires change events via a listener system. It is the foundation for all Spoon AST child collections. Despite being specific to Spoon's model, the pattern of an observable list with parent updates is generic and reusable for any tree-like data structure that needs automatic parent synchronization.

Part of Spoon's 'sniper' pretty printer that preserves original source formatting during modifications. This class manages the printing context for single-valued AST children, tracking which source fragments have been consumed. The pattern of decomposing source code into tokens and fragments is applicable to any tool that needs to output modified code while keeping non-modified parts unchanged.

A generic control flow graph implementation that models program execution paths with nodes and edges, supporting exception handling, branch kinds, and path enumeration. It is self-contained within the spoon-control-flow submodule and can be reused for any Java-like control flow analysis (e.g., in other static analyzers or compilers).