flat_map: ordered-container design, learned from Chromium

This directory takes apart Chromium's flat_map / flat_tree and works through the industrial-strength design of implementing an associative container on a sorted vector: why an array beats a tree at small N, the read-heavy write-light home turf, the zero-cost sorted_unique construction, transparent comparators, and EBO. It sits alongside OnceCallback and WeakPtr, rounding out the container-and-performance piece of vol9/chrome.

Full tutorial (full/)

Prerequisites (6 chapters):

• ordered associative containers, introduced
• vector internals and growth
• complexity and amortization
• comparators and transparent lookup
• tag dispatch and sorted_unique
• no_unique_address, EBO, and pair storage

Hands-on (6 chapters):

• motivation and API design
• the flat_tree skeleton
• lookup and insert
• sorted_unique construction
• iterator invalidation and bulk build
• testing and performance

Hands-on design guide (hands_on/)

For readers comfortable with templates and performance:

• design
• implementation
• testing and performance