Struct TreeCache 

pub struct TreeCache { /* private fields */ }

LRU cache for parsed trees to enable incremental parsing.

Stores recently parsed trees so that when a file changes, we can:

1. Retrieve the old tree from cache
2. Calculate the InputEdit describing the change
3. Call tree.edit(InputEdit) to inform tree-sitter
4. Re-parse with the edited tree (tree-sitter reuses unchanged subtrees)

Capacity

Default capacity is 100 trees. Assuming ~10-50KB per tree, this uses ~1-5MB memory. Oldest trees are evicted when capacity is exceeded (LRU policy).

Thread Safety

The cache is wrapped in a Mutex for thread-safe access. Lock contention should be minimal as operations are fast (hash lookups, no disk I/O).

Example

let cache = TreeCache::with_default_capacity();
cache.insert(&path, tree, hash);
if let Some((old_tree, old_hash)) = cache.get(&path) {
    // Use old_tree for incremental parsing
}

Implementations

impl TreeCache

pub const DEFAULT_CAPACITY: usize = 100

Default cache capacity (number of trees).

pub fn new(capacity: usize) -> Self

Create a new tree cache with the specified capacity.

Arguments

• capacity - Maximum number of trees to cache (must be > 0)

Panics

Panics if capacity is 0.

pub fn with_default_capacity() -> Self

Create a new tree cache with default capacity (100 trees).

pub fn insert(&self, path: &Path, tree: Tree, hash: u64)

Insert a tree into the cache.

Arguments

• path - Absolute path to the file
• tree - The parsed tree
• hash - Hash of the content the tree was parsed from

If the cache is at capacity, the least recently used tree is evicted.

pub fn get(&self, path: &Path) -> Option<(Tree, u64)>

Retrieve a tree from the cache.

Arguments

• path - Absolute path to the file

Returns

Some((tree, hash)) if the tree is cached, None otherwise. The returned tree is cloned (tree-sitter trees are cheap to clone).

Note

Accessing a tree marks it as recently used (LRU update).

pub fn remove(&self, path: &Path) -> bool

Remove a tree from the cache.

Arguments

• path - Absolute path to the file

Returns

true if the tree was present and removed, false if not found.

pub fn clear(&self)

Clear all trees from the cache.

pub fn len(&self) -> usize

Get the current number of cached trees.

pub fn is_empty(&self) -> bool

Check if the cache is empty.