juliusnehring / clean-core

A clean and lean reimagining of the C++ standard library

clean-core

clean-core (cc) is a clean and lean reimagining of the C++ standard library.

Goals

• significantly faster to compile than std
• forward declaration for all public types
• no slower than std
• safer than std
• more modular header design (each type can be separately included)
• convenient interfacing with code using std types
• removal of unintuitive behavior (e.g. vector<bool> or optional::operator bool)
• mostly keeping naming scheme and intent of std
• better debugging support and performance
• no dependency on exceptions

Requirements / Dependencies

• a C++17 compiler
• a few std features (that are hard to otherwise implement)

Allowed std includes

• <cstring> (1ms, for memcpy)
• <cstddef> (1ms, for some types)
• <type_traits> (5-8ms, many not implementable ourselves)
• <utility> (10-15ms, swap, declval, NOTE: cc has own move and forward)
• <atomic> (20ms, hard to implement ourselves)

Notable Changes

Changes that were rarely used features that increased implementation cost immensely:

• no allocators
• no custom deleters for unique_ptr

Error-prone and unintuitive or suprising features:

• no specialized vector<bool>
• no operator bool for optional<T>
• no operator< for optional<T>

Others:

• no strong exception support
• no iterator-pair library, only ranges
• no unreadable _UglyCase (leaking non-caps macros is a sin)
• traits types and values are not suffixed with _t or _v
• no volatile support
• no unique_ptr<T[]>
• some interfaces are stricter to prevent easy mistakes

New Features

• span (strided array view)
• flat_ containers
• inline_ types (no heap allocs)
• customizable low-impact assert
• internal assertions (optional)
  • bound-checked containers
  • null checks for smart pointer
  • contract checks

TODO

• big list of comparison between std and cc
  • name of feature/class (e.g. pair)
  • header name of std/cc
  • parse time std/cc
  • preprocessed, significant LOC of std/cc