facet-rs / facet / 20074615249

58%

Build Type

push

github

Committed by fasterthanlime

Commit Message

feat(facet-core): add #[facet(metadata = kind)] field attribute

Adds a new `metadata` field attribute for marking fields that contain
auxiliary information (like source spans) that should be excluded from
structural equality and hashing.

Changes:
- Add `metadata: Option<&'static str>` field to `Field` struct
- Add `is_metadata()` and `metadata_kind()` helper methods
- Add `.metadata(kind)` builder method to `FieldBuilder`
- Handle `#[facet(metadata = kind)]` in derive macro
- Update `structural_hash` to skip metadata fields
- Update `Spanned<T>` to use `#[facet(metadata = span)]` on span field
- Update `is_spanned_shape()` to detect via metadata field
- Add `find_span_metadata_field()` helper function
- Update facet-json deserializer to use new metadata detection

This allows any struct to have span tracking by adding the metadata
attribute, not just the built-in `Spanned<T>` wrapper. Deserializers
can check `field.metadata_kind() == Some("span")` to know which field
to populate with source location information.

Also includes preparatory work for GumTree-style tree diffing:
- Add tree.rs module with tree building and diff algorithm
- Update showcase to demonstrate new tree diff output

Run Details

359 of 495 new or added lines in 7 files covered. (72.53%)

1 existing line in 1 file now uncovered.

26860 of 45919 relevant lines covered (58.49%)

619.28 hits per line