Interner impl.

compiler/Cargo.toml

@@ -13,6 +13,7 @@ anyhow = { version = "1.0.81", features = ["backtrace"] }
 console_log = "1.0.0"
 log = "0.4.21"
 num_enum = "0.7.2"
+rustc-hash = "1.1.0"
 strum_macros = "0.26.2"
 wasm-bindgen = "0.2.92"
 

compiler/src/interner.rs

@@ -0,0 +1,64 @@
+use rustc_hash::FxHashMap as HashMap;
+use std::mem;
+
+#[derive(Debug, Clone, Copy, Eq, PartialEq, Hash)]
+struct StrId(u32);
+
+pub struct Interner {
+    map: HashMap<&'static str, StrId>,
+    vec: Vec<&'static str>,
+    buf: String,
+    full: Vec<String>,
+}
+
+impl Interner {
+    /// Create a new interner with the given buffer capacity (in bytes)
+    pub fn with_capacity(cap: usize) -> Interner {
+        let cap = cap.next_power_of_two();
+        Interner {
+            map: HashMap::default(),
+            vec: Vec::new(),
+            buf: String::with_capacity(cap),
+            full: Vec::new(),
+        }
+    }
+
+    /// Intern string, and get it's ID
+    pub fn intern(&mut self, name: &str) -> StrId {
+        if let Some(&id) = self.map.get(name) {
+            return id;
+        }
+        let name = unsafe { self.alloc(name) };
+        let id = StrId { 0: self.map.len() as u32 };
+        self.map.insert(name, id);
+        self.vec.push(name);
+
+        debug_assert!(self.lookup(id) == name);
+        debug_assert!(self.intern(name) == id);
+
+        id
+    }
+
+    /// Get a string, given it's ID
+    pub fn lookup(&self, id: StrId) -> &str {
+        self.vec[id.0 as usize]
+    }
+
+    unsafe fn alloc(&mut self, name: &str) -> &'static str {
+        let cap = self.buf.capacity();
+        if cap < self.buf.len() + name.len() {
+            let new_cap = (cap.max(name.len()) + 1).next_power_of_two();
+            let new_buf = String::with_capacity(new_cap);
+            let old_buf = mem::replace(&mut self.buf, new_buf);
+            self.full.push(old_buf);
+        }
+
+        let interned = {
+            let start = self.buf.len();
+            self.buf.push_str(name);
+            &self.buf[start..]
+        };
+
+        &*(interned as *const str)
+    }
+}

compiler/src/lib.rs

@@ -1,6 +1,7 @@
 pub mod chunk;
 pub mod common;
 pub mod compiler;
+pub mod interner;
 pub mod scanner;
 pub mod value;
 pub mod vm;

compiler/src/value.rs

@@ -25,7 +25,7 @@ pub fn print_value(value: &Value) {
 }
 
 #[cfg(not(feature = "tracing"))]
-pub fn print_value(&self, value: Value) {
+pub fn print_value(value: Value) {
     xprint!("Value {value}");
 }
 

native/Cargo.toml

@@ -7,3 +7,4 @@ edition = "2021"
 
 [dependencies]
 compiler = {path = "../compiler", features = ["tracing", "print_code"]}
+rustc-hash = "1.1.0"