Tree-sitter-vhdl

A VHDL parser for syntax highlighting.

References

• VHDL-2000
• VHDL-2008
• VHDL-2019
• VHDL Library Files (search for "1076")
• VSCode Modern VHDL

Screenshots

Neovim, using nvim-treesitter and a Catppuccin colour scheme:

History

This version started off as a fork of alemuller/tree-sitter-vhdl, but ended up as a complete rewrite of the parser and highlighting scripts. It has very little in common with the original.

Limitations

This parser uses a simplified grammar, because the full formal grammar in the VHDL standard is highly ambiguous without compiling the entire code-base into a symbol table. In many cases, invalid syntax will parse into a valid tree.

For the same reason, there might be cases where valid syntax does not map to a valid tree. In this case, please log a bug report.

In addition, the following features are not implemented, and are considered outside the scope of this project.

• IEEE Property Specification Language
• VHDL Procedural Interface

Neovim Setup Process

This parser has not been merged into the official tree-sitter yet, so you need to perform a manual setup process. Configure your treesitter.lua (or equivalent) as follows:

local parser_config = require('nvim-treesitter.parsers').get_parser_configs()

parser_config.vhdl = {
  install_info = {
    url = "https://github.com/jpt13653903/tree-sitter-vhdl.git",
    files = { 'src/parser.c', 'src/scanner.c' },
    branch = 'master', -- or 'develop' if you want the latest features
    generate_requires_npm = false,
    requires_generate_from_grammar = false,
  },
  filetype = 'vhdl',
}

local treesitter = require('nvim-treesitter.configs')

treesitter.setup {
  ensure_installed = {
    -- Some list of languages...
    'vhdl',
    -- Some more languages...
  },

  -- Some other options and configuration...
}

Then copy the contents of the queries/Neovim folder to your after/queries/vhdl configuration folder, typically ~/.config/nvim/after/queries/vhdl on Linux and ~/AppData/Local/nvim/after/queries/vhdl on Windows.

Finally, run :TSUpdate.

Helix Setup Process

Helix still uses a fork of the old unmaintained alemuller/tree-sitter-vhdl. To manually use this tree-sitter instead, clone the Helix repo. In languages.toml replace the line:

source = { git = "https://github.com/teburd/tree-sitter-vhdl", rev = "c57313adee2231100db0a7880033f6865deeadb2" }

with:

source = { git = "https://github.com/jpt13653903/tree-sitter-vhdl", rev = "256ddae0ba5d1a36ef54d59a1bdb6f0360a9c818" }

Adjust the revision git hash if necessary (latest stable is recommended).

Now build Helix from source. You can check if you got the right tree-sitter source files in the helix/runtime/grammars/sources/vhdl/ directory.

Replace the helix/runtime/queries/vhdl/highlights.scm file with the queries/Helix/highlights.scm from this repo. You can also adjust the highlights.scm file to your liking or change the highlighting in your theme .toml file.

Building

• Follow the instructions here to setup your development environment.
• Run npm install --save-dev tree-sitter-cli
• Add node_modules/.bin to your environment path
• Run tree-sitter generate
• Run tree-sitter test

Contributing

Contributions are welcome. Read Contributing.md for more information.