> ## Documentation Index
> Fetch the complete documentation index at: https://differens.ossl.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Ruby

> Semantic diffing for Ruby

## Ruby extractor

The Ruby extractor maps tree-sitter Ruby CST nodes to canonical concepts. Class and module names come from the `name` field on constants; method names from the `name` field on identifiers.

### Detected concepts

| tree-sitter node type | Canonical concept |
| - | - |
| `class` | Class |
| `module` | Module |
| `method` | Method |
| `call` | CallExpression |
| `assignment` | Assignment |
| `instance_variable` | Variable |
| `constant` | Constant |
| `if` / `unless` / `if_modifier` | IfBlock |
| `while` / `until` | WhileLoop |
| `block` / `do_block` | Block |
| `array` | ArrayLiteral |
| `hash` | ObjectLiteral |
| `string` | string\_literal |

### Example

Renaming a method:

```ruby theme={null}
# old.rb
class Counter
  def total(n)
    n + 1
  end
end
```

```ruby theme={null}
# new.rb
class Counter
  def sum(n)
    n + 1
  end
end
```

Running `differens old.rb new.rb`:

```
~ renamed method `total` to `sum` in class `Counter`
```

### Known limitations

* Dynamic method definition (`define_method`) is a call, not a method: names built at runtime are invisible to the extractor.
* `true`, `false`, and `nil` are anonymous tokens in the grammar, so there are no named boolean or null literal nodes to report.