Struct StringInterner 

pub struct StringInterner { /* private fields */ }

Thread-safe string interner using Box<str> arena for single-allocation storage.

Strings are stored in an append-only Vec<Box<str>> (pointer-stable on heap). A hash-keyed map provides O(1) lookup with collision chaining.

Send and Sync are derived from RwLock — no manual unsafe impl needed.

Implementations

impl StringInterner

pub fn new() -> Self

Create a new string interner

pub fn with_capacity(capacity: usize) -> Self

Create a new string interner with the given capacity

pub fn intern(&self, s: &str) -> InternedString

Intern a string, returning its handle.

Fast path: read lock to check existence via hash. Slow path: write lock, double-check, allocate Box<str>.

pub fn resolve(&self, id: InternedString) -> Option<&str>

Resolve an interned string back to &str.

Safety argument

We return a &str whose lifetime is tied to &self (the interner), not to the read-lock guard. This is safe because:

1. Strings are never removed (append-only vec).
2. Box<str> is heap-allocated and pointer-stable — push to the vec does not move existing boxes.
3. The interner outlives all returned references (borrow checker enforces this).

pub fn len(&self) -> usize

Get current number of interned strings

pub fn is_empty(&self) -> bool

Check if the interner is empty

Trait Implementations

impl Default for StringInterner

fn default() -> Self

Returns the “default value” for a type.