qb-linq-development

name	qb-linq-development
description	Develop or debug the qb-linq header-only C++17 LINQ library (qb::linq): locate declarations and definitions, extend iterators and views, run qb_linq_tests and optional benchmarks. Use when editing include/qb/linq, adding terminals or lazy views, or writing tests for this repo.

qb-linq development

When this applies

Use this skill for work inside the qb-linq repository: changing pipelines, iterators, materializers, tests, or benchmarks—not for application code that only consumes qb::linq::from(...).

Required context (read first)

1. docs/BUILDING.md — CMake target qb::linq, options, presets, qb_linq_tests / qb_linq_benchmark / qb_linq_docs.
2. docs/LLM_CONTEXT.md — include graph, handle types, out-of-line split (query.h vs extra_views.h), materialized_range pitfall.
3. AGENTS.md — checklist and file map.
4. include/qb/linq.h — Doxygen linq group: public caveats.
5. CONTRIBUTING.md — tests, PR checklist, CHANGELOG for user-visible changes.

Workflow

1. Locate the API — Methods on enumerable trace to query_range_algorithms in query_range.h.
2. Declaration vs definition — Declarations in query_range.h; definitions in query.h or extra_views.h per LLM_CONTEXT.md.
3. New iterators — Extend patterns in iterators.h or extra_views.h; respect iterator category rules (clamp_iterator_category_t where appropriate).
4. Verify — Build qb_linq_tests, run ctest. For perf-sensitive code, enable QB_BUILD_BENCHMARKS and keep qb_linq_benchmark building.
5. Portability — Validate on multiple compilers when possible (GCC, Clang, MSVC).

Pitfalls

• Do not break materialized_range safe construction documented in query.h.
• select_many yields a tuple of projections per element, not a flattened sequence (not C# SelectMany).
• scan_iterator must not outlive scan_view (F* into the view).
• reverse() + take / take_while: use the dedicated reversed_view specializations in query.h; new logical-end iterators must not break reverse_iterator equality or bounds.

Output expectations

• Minimal diffs, consistent style and Doxygen.
• Tests for behaviour changes.
• English commit messages; state what and why.