Output of case_tree example:

var is 5
((! var != 5) && var >= 5)
├── (! var != 5)
|   └── var != 5
└── var >= 5

An extension trait is added to make a Displayable struct that will print out the above tree.

• This is built off of find_case which will find the Case that prove whether the Predicate succeeds or fails.
• To reduce overhead, Case only owns by-Products of the Predicate evaluation, parameters are made available as references on the PredicateReflection trait
  • This had the benefit of simplifying the Case API because Parameter and Product have different ownership requirements.
• PredicateReflection is also use to homogenize the predicate tree
  • Because of predicate adapters, you could have a tree that includes Predicate<[u8]>, Predicate<str>, etc.

Once this is in, to reduce API breaks from impacting the assert-ecosystem, #30 will be implemented and this repo will be turned into a workspace for

• predicate-core: core.rs, reflection.rs
• predicate-tree: tree.rs
• predicates
  • All existing predicates
  • Re-export predicate-core

aka the only change to most end-users will be predicate-tree being removed from the API while the assert-ecosystem will use predicate_core::Predicate in its public API.

This supersedes #39 due to having an API that we are more comfortable moving to 1.0

• Unlike WIP: Pretty error printer for predicates. #39, we do not include item in the Display, allowing us to avoid requiring Item: Debug. Instead we just rely on every Predicate implementing Display, usually doing so by having an Item: Debug requirement but clients are free to bypass that by creating their own Predicate.

BREAKING CHANGES

• Predicates must also implement PredicateReflection. Provided methods make this a impl PredicateReflection for X {}