# Language Support
## Supported Languages
| Language | Extensions | Parser | Symbol Types | Decorators | Docstrings | Notes / Limitations |
| ---------- | ------------- | ---------------------- | -------------------------------------------------- | ------------- | -------------------------- | ---------------------------------------------------------------- |
| Python | `.py` | tree-sitter-python | function, class, method, constant, type | `@decorator` | Triple-quoted strings | Type aliases require Python 3.12+ syntax for full fidelity |
| JavaScript | `.js`, `.jsx` | tree-sitter-javascript | function, class, method, constant | — | `//` and `/** */` comments | Anonymous arrow functions without assigned names are not indexed |
| TypeScript | `.ts`, `.tsx` | tree-sitter-typescript | function, class, method, constant, type | `@decorator` | `//` and `/** */` comments | Decorator extraction depends on Stage-3 decorator syntax |
| Go | `.go` | tree-sitter-go | function, method, type, constant | — | `//` comments | No class hierarchy (language limitation) |
| Rust | `.rs` | tree-sitter-rust | function, type (struct/enum/trait), impl, constant | `#[attr]` | `///` and `//!` comments | Macro-generated symbols are not visible to the parser |
| Java | `.java` | tree-sitter-java | method, class, type (interface/enum), constant | `@Annotation` | `/** */` Javadoc | Deep inner-class nesting may be flattened |
---
## Parser Engine
All language parsing is powered by **tree-sitter** via the `tree-sitter-language-pack` Python package, providing:
* Incremental, error-tolerant parsing
* Uniform AST representation across languages
* Pre-compiled grammars for supported languages
**Dependency:** `tree-sitter-language-pack>=0.7.0` (pinned in `pyproject.toml`)
---
## Adding a New Language
1. **Define a `LanguageSpec`** in `src/jcodemunch_mcp/parser/languages.py`:
```python
NEW_LANG_SPEC = LanguageSpec(
ts_language="new_language",
symbol_node_types={
"function_definition": "function",
"class_definition": "class",
},
name_fields={
"function_definition": "name",
"class_definition": "name",
},
param_fields={
"function_definition": "parameters",
},
return_type_fields={},
docstring_strategy="preceding_comment",
decorator_node_type=None,
container_node_types=["class_definition"],
constant_patterns=[],
type_patterns=[],
)
```
2. **Register the language**:
```python
LANGUAGE_REGISTRY["new_language"] = NEW_LANG_SPEC
```
3. **Map file extensions**:
```python
LANGUAGE_EXTENSIONS[".ext"] = "new_language"
```
4. **Verify parser availability**:
```python
from tree_sitter_language_pack import get_parser
get_parser("new_language") # Must not raise
```
5. **Add parser tests**:
```python
def test_parse_new_language():
source = "..."
symbols = parse_file(source, "test.ext", "new_language")
assert len(symbols) >= 2
```
---
## Inspecting AST Node Types
To inspect the node types produced by tree-sitter for a source file:
```python
from tree_sitter_language_pack import get_parser
parser = get_parser("python")
tree = parser.parse(b"def foo(): pass")
def print_tree(node, indent=0):
print(" " * indent + f"{node.type} [{node.start_point}-{node.end_point}]")
for child in node.children:
print_tree(child, indent + 2)
print_tree(tree.root_node)
```
This inspection process helps identify the correct `symbol_node_types`, `name_fields`, and extraction rules when adding support for a new language.
