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spicy-format

This provides an opinionated source code formatter for the Spicy language.

Installation

Prebuilt binaries

Navigate to the latest release and run the mentioned installation script, e.g.,

curl --proto '=https' --tlsv1.2 -LsSf https://github.com/bbannier/spicy-format/releases/download/v0.10.0/spicy-format-installer.sh | sh

Follow the printed instructions. This will install both the formatter spicy-format itself as well as an updater script spicy-format-update which can be used to update to newer releases.

Alternatively you can also download prebuilt binaries and updaters on the release page.

Building from source

If no binaries are available for you platform you need to install from source. This requires a Rust installation, use e.g., rustup for setting one up.

You can then install the project with

cargo install --locked --git https://github.com/bbannier/spicy-format

It is strongly suggested to use --locked to use dependency versions locked in the project.

Development

This formatter is implemented in Rust with Topiary. It uses tree-sitter-spicy for parsing input source code into a tree-sitter CST. Formatting of that CST is done through Topiary queries. The actual queries are defined in src/query.scm. Most of the time changing the formatter should not require any changes to the Rust code, but only to the query file.

Working with the Spicy tree-sitter grammar

General process

To change formatting of certain nodes it might often be sufficient to inspect the Spicy tree-sitter grammar and change formatting of the nodes in src/query.scm.

To instead inspect the full parse trees of code samples check out tree-sitter-spicy and use it to parse the code, e.g.,

# Get Spicy tree-sitter grammar.
git clone https://github.com/bbannier/tree-sitter-spicy
$ cd tree-sitter-spicy

# If needed install the tree-sitter CLI.
$ npm install tree-sitter

# Use tree-sitter to parse a source file.
$ tree-sitter parse hello.spicy
(module [0, 0] - [3, 0]
  entities: (module_decl [0, 0] - [0, 13]
    name: (ident [0, 7] - [0, 12]
      (name [0, 7] - [0, 12])))
  entities: (statement [2, 0] - [2, 18]
    (print [2, 0] - [2, 18]
      (expression [2, 6] - [2, 17]
        (string [2, 6] - [2, 17])))))

Use this information to write dedicated formatter queries.

Making adjustments to the grammar

If the grammar does not have support for constructs or incorrectly parses them the grammar needs to be updated and bumped. The used version of the grammar is specified in Cargo.toml,

[dependencies]
tree-sitter-spicy = { git = "https://github.com/bbannier/tree-sitter-spicy" }
...

You can specify a different repository here, or enforce a specific revision, e.g.,

tree-sitter-spicy = { git = "https://github.com/MY_FORK/tree-sitter-spicy", rev = "b9958baeda3dc77fa94af2ca2cd84723bd532d08" }

In order to use a unpublished local version you can replace the dependency with a path dependency, e.g.,

tree-sitter-spicy = { path = "path/to/local/version" }

Tests

Test cases are collected and automatically discovered by the test harness in the corpus/ directory. To execute the test harness run

cargo t

For each corpus/<INPUT>.spicy the repository contains a matching expected result baseline corpus/<INPUT>.spicy.expected. To update the baselines execute the test harness with the environment variable UPDATE_BASELINE set.

UPDATE_BASELINE=1 cargo t

This will update or if needed create the outdated baselines. When adding new tests to the corpus, commit the baseline as well.

To run formatting against an external corpus run the test suite with SPICY_FORMAT_EXTERNAL_CORPUS set.

SPICY_FORMAT_EXTERNAL_CORPUS=<PATH TO SPICY CORPUS> cargo t corpus_external

The suite automatically filters out of some files in the Spicy test suite with known unsupported constructs.