chloro

chloro is a minimal Rust code formatter.

Motivation

For when you want to format two source files in a consistent way, as fast as possible.

How it works

Using rowan from the rust-analyzer project, which can give both green and red trees. The latter are notoriously expensive, but a formatter should only need the former.

Proof of concept library/CLI to explore a fast and low memory code formatter [WIP], with use cases of code diffing in mind.

Rustfmt Conformance

Diff 'leaderboard' for how well formatting with chloro matches rustfmt, as tested on rust-analyzer's crates:

Top 5 Removed Lines	Top 5 Added Lines
`- }` × 154`- {` × 135`- },` × 93`- );` × 87`- ///` × 72	`+}` × 75`+///` × 75`+ },` × 65`+ }` × 65`+};` × 44

Top 20 Most Impacted Files

Rank	Size Rank	Diff Rank	Impact	+	-	File
1	9	1	43.1%	1,617	3,748	`rust_analyzer/src_config`
2	2	17	2.2%	241	11,083	`ide/src_hover_tests`
3	4	9	4.7%	281	6,011	`ide_assists/src_handlers_extract_function`
4	3	19	3.7%	235	6,366	`hir/src_lib`
5	16	4	15.0%	444	2,951	`rust_analyzer/src_lsp_to_proto`
6	7	12	6.6%	256	3,859	`ide/src_goto_definition`
7	62	2	55.0%	808	1,469	`hir_expand/src_builtin_derive_macro`
8	31	5	17.7%	400	2,259	`hir_ty/src_next_solver_interner`
9	8	34	4.8%	180	3,758	`ide/src_rename`
10	95	3	42.2%	473	1,120	`ide/src_navigation_target`
11	76	6	28.1%	357	1,272	`hir_def/src_lib`
12	1	516	0.1%	12	19,633	`ide_db/src_generated_lints`
13	47	11	15.0%	260	1,739	`ide_assists/src_handlers_auto_import`
14	14	44	5.4%	163	3,036	`ide_assists/src_handlers_generate_function`
15	34	20	10.2%	221	2,174	`ide_assists/src_handlers_add_missing_match_arms`
16	15	50	4.9%	149	3,018	`ide/src_references`
17	20	42	6.6%	167	2,534	`ide_assists/src_handlers_extract_variable`
18	23	39	6.9%	172	2,506	`rust_analyzer/src_handlers_request`
19	45	22	12.0%	217	1,804	`ide_assists/src_handlers_generate_delegate_trait`
20	12	84	3.5%	114	3,238	`ide_completion/src_render`

Installation

Add chloro to your Cargo.toml:

[dependencies]
chloro = "0.5"

CLI Installation

pre-built binary: cargo binstall chloro (requires cargo-binstall),
build from source: cargo install chloro --features cli

License

This project is licensed under either of:

Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

chloro 0.6.2