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:

Summary: +85,507 / -12,731

Top 5 Removed Lines	Top 5 Added Lines
`- )` × 219`- r#"` × 140`- },` × 108`- check(` × 90`- );` × 87	`+ },` × 131`+"#)` × 104`+ check(r#"` × 79`+}` × 75`+ }` × 68

Top 20 Most Impacted Files

Rank	Size Rank	Diff Rank	Impact	+	-	File
1	1	24	1.4%	161	11,163	`ide/src_hover_tests`
2	2	14	3.1%	199	6,520	`hir/src_lib`
3	3	11	3.5%	217	6,119	`ide_assists/src_handlers_extract_function`
4	7	5	8.7%	335	3,870	`ide/src_goto_definition`
5	15	3	12.1%	368	3,029	`rust_analyzer/src_lsp_to_proto`
6	56	1	46.3%	715	1,544	`hir_expand/src_builtin_derive_macro`
7	29	4	14.8%	348	2,357	`hir_ty/src_next_solver_interner`
8	5	33	3.4%	141	4,156	`rust_analyzer/src_config`
9	96	2	40.9%	460	1,125	`ide/src_navigation_target`
10	8	42	3.4%	129	3,799	`ide/src_rename`
11	26	15	7.6%	188	2,459	`ide/src_highlight_related`
12	10	40	3.7%	130	3,516	`hir_def/src_expr_store_lower`
13	32	19	8.0%	178	2,223	`ide_assists/src_handlers_add_missing_match_arms`
14	13	50	3.6%	113	3,116	`ide_assists/src_handlers_generate_function`
15	11	61	3.1%	101	3,269	`ide_completion/src_render`
16	114	6	25.6%	259	1,010	`hir_def/src_expr_store`
17	61	12	14.6%	217	1,486	`hir_def/src_lib`
18	4	200	0.8%	42	5,039	`hir_ty/src_tests_traits`
19	14	58	3.4%	103	3,054	`ide/src_references`
20	37	22	8.3%	171	2,053	`ide_assists/src_handlers_destructure_tuple_binding`

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 0.7.2