no_std support

[richardanaya]

Having no_std support would lend this library into web assembly projects better. Some of the standard libraries end up being quite huge in wasm.

[chinedufn]

Sounds good to me.

Here's a list of everything that would be needed for no_std support. Should be fairly quick since rectangle-pack is fairly small.

I'm not sure when I will get to this - but in the meantime, if you need this quickly, feel free to PR some or all of these steps and I can get them merged.

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• Remove all HashMap usage in favor of BTreeMap

  • This adds some additional runtime cost, but until someone has a use case where they need to pack rectangles at top speed this is fine for now. In the future, if necessary, we could expose a feature flag to pull in a no_std compatible hash map implementation.

• Add feature flag

  [features]
  default = ["std"]
  std = []
  

• Use Rust's core crate instead of std

• Use Rust's alloc crate instead of std

  #[macro_use]
  extern crate alloc;
  

• Replace PathBuf with &'static str in the deterministic_packing test case

• Enable #![no_std] when the std feature is disabled

• Test both std and no_std in CI

• Release a new patch version

[chinedufn]

Closed by #4