tree-sitter-sysml

Tree-sitter grammar for SysML v2 and KerML textual notation per the OMG SysML v2.0 and KerML 1.0 specifications.

Features

• Near-complete language coverage — parses all 213 official OMG example and training files plus 92 of 94 standard library files from the SysML-v2-Release repository with zero errors, and 165 of the 169 code listings in the SysML v2 Book (Weilkiens, 2026-05) — the remaining 4 are deliberate fragments/errata in the book itself
• Definitions — unified rule covering 40+ definition keywords (part, action, state, port, connection, attribute, item, requirement, constraint, view, calc, class, struct, type, function, and more)
• Usages — unified rule covering 20+ usage keywords, plus specialized rules for action, state, connection, interface, constraint, requirement, event, allocation, flow, metadata, binding, succession, and KerML usages
• Behavioral constructs — actions, states, transitions, control flow (if/else-if/else, while/for with body and ref forms, typed for-loops with 1..n ranges), terminate (with occurrence argument), inline transitions, send/accept with when/at/after triggers, do action send ... via ... transition effects, entry/do/exit actions with names and types, while-until loops, fork/join/merge/decide nodes, action chaining with then (including then perform action and then include)
• Relationships — specialization (:> / specializes), redefinition (:>> / redefines), binding (::>), conjugation, chaining, crosses (=>), typed by / defined by, unions / intersects / differences, featuring by, disjoint from — all supporting comma-separated multiple targets
• Connections — named binding/succession usages with multiplicity on endpoints, multi-end connections with crosses, end features with occurrence/action/flow qualifiers, ::> bindings in parenthesized connect clauses
• Expressions — arithmetic, logical, comparison, invocation with named arguments (structured named_argument nodes) and qualified names, conditional, new expressions, function-literal body expressions ({ in x; expr }) as call arguments and values, -> collect/select/reduce arrows with bodies, invocations, and function references, .?{...} select, meta expressions, classification operators @ and @@, result expressions
• Requirements — assert/not satisfy, require constraint/requirement with bodies, subject/actor/objective/stakeholder/frame declarations with full type relationship and multiplicity support
• Metadata — # prefix annotations with qualified names (also before body statements like allocate), qualified metadata annotations with bodies (@Pkg::Def { ... }), structured metadata_body with redefines/:>> patterns, metadata ... about clause, member feature declarations
• Variability — variation/variant and all other modifiers are named modifier CST nodes, queryable for variant-aware tooling (Ch 35)
• Standard library patterns — standalone multiplicity definitions, feature qualifiers (nonunique, ordered), default with body values, bind statements, standalone :>> redefines in bodies, quoted operator names
• Views — render with rendering keyword and typing, expose, viewpoint frames
• Textual representation — rep/language blocks for embedding foreign code
• Multiplicity with ordered nonunique in any order, flexible positioning between name, type, and specialization
• Imports with recursive **, packages with short names, bare namespace (KerML), dependencies with comma-separated targets, comments with multi-target about and locale support

Test coverage

• 198 corpus tests covering definitions, usages, expressions, control flow, connections, requirements, states, imports, packages, comments, and KerML extensions
• 213 official OMG files (examples, training, KerML) — all parse with zero errors
• 92/94 standard library files — near-complete coverage of the SysML v2 and KerML standard libraries (Kernel Semantic, Kernel Function, Domain, Systems)

The 2 remaining standard library files (Actions.sysml, Occurrences.kerml) use inline action body chaining and complex end feature patterns that cannot be added without exceeding tree-sitter's generator memory limits.

Installation

GitHub Releases

Pre-built binaries (Linux, macOS, Windows) and WASM artifacts are published automatically on each tagged release. See Releases.

Emacs (29.1+)

Install the grammar:

(add-to-list 'treesit-language-source-alist
             '(sysml "https://github.com/jackhale98/tree-sitter-sysml" nil "src"))
(treesit-install-language-grammar 'sysml)

Then use sysml2-mode which automatically activates tree-sitter when the grammar is available.

Neovim

Add to your nvim-treesitter config:

local parser_config = require("nvim-treesitter.parsers").get_parser_configs()
parser_config.sysml = {
  install_info = {
    url = "https://github.com/jackhale98/tree-sitter-sysml",
    files = {"src/parser.c"},
    branch = "main",
  },
  filetype = "sysml",
}

Helix / Zed

Copy queries/ to your editor's runtime queries directory as sysml/.

Pairing with the language server

The grammar handles syntax; semantics (diagnostics, navigation, hover, completions) come from sysml-lsp, which embeds this grammar. Per-editor setup for both pieces together: Editor Setup.

Building from source

npm install
npx tree-sitter generate
npx tree-sitter test

Build WASM

npx tree-sitter build --wasm

Build shared library for Emacs

make emacs
cp tree-sitter-sysml.so ~/.emacs.d/tree-sitter/libtree-sitter-sysml.so

Queries

• queries/highlights.scm — Syntax highlighting
• queries/indents.scm — Indentation
• queries/folds.scm — Code folding

File types

• .sysml — SysML v2 files
• .kerml — KerML files

License

Licensed under either of

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

at your option (Apache-2.0 OR MIT).

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this work shall be dual licensed as above, without any additional terms or conditions.

Third-party content

The SysML v2 / KerML example models vendored under test/examples/ are taken or adapted from the OMG SysML-v2-Release repository and remain under their original licence, the Eclipse Public License 2.0 (EPL-2.0). They are test fixtures only: they are not part of the published grammar package (package.json and Cargo.toml do not include test/), and the dual licence above does not apply to them.