codemod_core/
language.rs

1//! Language adapter trait for tree-sitter integration.
2//!
3//! Each programming language supported by codemod-pilot must implement the
4//! [`LanguageAdapter`] trait. This provides tree-sitter grammar access and
5//! language-specific metadata such as file extensions, statement types, and
6//! identifier node types.
7//!
8//! ## Implementing a new language
9//!
10//! ```rust,ignore
11//! use codemod_core::LanguageAdapter;
12//! use tree_sitter::Language;
13//!
14//! pub struct RustAdapter;
15//!
16//! impl LanguageAdapter for RustAdapter {
17//!     fn name(&self) -> &str { "rust" }
18//!     fn language(&self) -> Language { tree_sitter_rust::LANGUAGE.into() }
19//!     fn file_extensions(&self) -> &[&str] { &["rs"] }
20//!     fn statement_node_types(&self) -> &[&str] { &["let_declaration", "expression_statement"] }
21//!     fn expression_node_types(&self) -> &[&str] { &["call_expression", "binary_expression"] }
22//!     fn identifier_node_types(&self) -> &[&str] { &["identifier", "type_identifier"] }
23//! }
24//! ```
25
26use tree_sitter::Language;
27
28/// Trait for language-specific adapters.
29///
30/// Each supported language implements this trait to provide
31/// tree-sitter grammar and language-specific utilities that the
32/// pattern engine uses for parsing, matching, and transformation.
33pub trait LanguageAdapter: Send + Sync {
34    /// Returns the human-readable language name (e.g., `"rust"`, `"javascript"`).
35    fn name(&self) -> &str;
36
37    /// Returns the [`tree_sitter::Language`] grammar used for parsing.
38    fn language(&self) -> Language;
39
40    /// Returns common file extensions for this language (without the leading dot).
41    ///
42    /// # Examples
43    ///
44    /// Rust: `&["rs"]`
45    /// JavaScript: `&["js", "jsx", "mjs"]`
46    fn file_extensions(&self) -> &[&str];
47
48    /// Returns tree-sitter node types that represent "statements".
49    ///
50    /// These are used during pattern inference to decide structural
51    /// boundaries for extraction.
52    fn statement_node_types(&self) -> &[&str];
53
54    /// Returns tree-sitter node types that represent "expressions".
55    fn expression_node_types(&self) -> &[&str];
56
57    /// Returns tree-sitter node types that represent identifiers
58    /// (variable names, type names, etc.).
59    fn identifier_node_types(&self) -> &[&str];
60
61    /// Checks if a file path is supported by this language adapter.
62    ///
63    /// The default implementation matches the file extension against
64    /// [`Self::file_extensions`].
65    fn supports_file(&self, path: &std::path::Path) -> bool {
66        path.extension()
67            .and_then(|ext| ext.to_str())
68            .map(|ext| self.file_extensions().contains(&ext))
69            .unwrap_or(false)
70    }
71
72    /// Returns true if the given tree-sitter node kind represents a leaf
73    /// token (identifier or literal) that could become a pattern variable.
74    fn is_leaf_variable_candidate(&self, node_kind: &str) -> bool {
75        self.identifier_node_types().contains(&node_kind)
76    }
77
78    /// Returns true if the given tree-sitter node kind is a structural
79    /// container (statement or expression) that should be compared recursively.
80    fn is_structural_node(&self, node_kind: &str) -> bool {
81        self.statement_node_types().contains(&node_kind)
82            || self.expression_node_types().contains(&node_kind)
83    }
84
85    /// Parse source code into a tree-sitter [`Tree`](tree_sitter::Tree).
86    ///
87    /// This is a convenience method that creates a parser, sets the language,
88    /// and parses the given source.
89    fn parse(&self, source: &str) -> std::result::Result<tree_sitter::Tree, String> {
90        let mut parser = tree_sitter::Parser::new();
91        parser
92            .set_language(&self.language())
93            .map_err(|e| format!("Failed to set language: {e}"))?;
94        parser
95            .parse(source, None)
96            .ok_or_else(|| "tree-sitter returned no tree".to_string())
97    }
98}
codemod_core/language.rs

codemod_core/
language.rs
