Dolos

Supported programming languages

Dolos uses Tree-sitteropen in new window parsers to process source files. As a result, Dolos supports all programming languages for which a Tree-sitter parser is available. The list of available parsersopen in new window is sheer endless

Tree-sitter logo

Each of these parsers has its own package which needs to be installed if you want to use it. By default, Dolos ships out-of-the box with parsers installed for the most common programming languages:

  • JavaScript
  • Java
  • Python
  • C
  • C#
  • Bash

However, adding a new language is very easy.

Adding a new language

Dolos discovers tree-sitter parsers at runtime. This means that in order to add support for a new language, you only need that parser to be available on your system in your NODE_PATH.

We will demonstrate this by adding language support for the programming language Rust.

Check availability

To make sure Dolos doesn't already support the desired language, you can simply start an anlysis:

dolos -l rust *.rs

If the parser is not installed, you will get an error message:

[error] Error: No tokenizer found for rust

Find a parser

If the parser is not installed, you can search for it on the Tree-sitter websiteopen in new window or on the Tree-sitter GitHub pageopen in new window.

A Rust parser existsopen in new window and the package is named, unsurprisingly, tree-sitter-rust.

TIP

If the language you are looking for is not listed on either the website or GitHub, it might be that there is no parser available. If that is the case, you can contact us and we will see if we can help.

It is possible to create a new parseropen in new window, but this quickly becomes complicated.

Install the parser

First, you need to check which version of Tree-sitter Dolos is currently using, by running the command dolos --version. The output will look like this:

Dolos v1.0.1
Node v14.17.3
Tree-sitter v0.19.0

Tree-sitter parsers need to have the same (major) version of the core library, so you will need to specify the version explicitly by suffixing the parser name with @<version>. In the example above, Dolos is using Tree-sitter v0.19.0, so you would need to install tree-sitter-rust@0.19. You may safely omit the minor version (the numbers after the last dot).

Install a Tree-sitter parser for a specific programming language using npm or yarn:

npm install -g tree-sitter-rust@0.19

Start Dolos with the new parser

Once the parser is installed, Dolos will be able to detect the new parser, and you can run the analysis on your files.