Adding in unintern function (#1828)

* Adding in unintern function

* Adding in some basic unit tests for interning and uninterning

Author: Pauan

src/cache/intern.rs

@@ -40,6 +40,14 @@ cfg_if! {
                 }
             })
         }
+
+        fn unintern_str(key: &str) {
+            CACHE.with(|cache| {
+                let mut cache = cache.entries.borrow_mut();
+
+                cache.remove(key);
+            })
+        }
     }
 }
 
@@ -80,3 +88,16 @@ pub fn intern(s: &str) -> &str {
 
     s
 }
+
+
+/// Removes a Rust string from the intern cache.
+///
+/// This does the opposite of the [`intern`](fn.intern.html) function.
+///
+/// If the [`intern`](fn.intern.html) function is called again then it will re-intern the string.
+#[allow(unused_variables)]
+#[inline]
+pub fn unintern(s: &str) {
+    #[cfg(feature = "enable-interning")]
+    unintern_str(s);
+}

src/lib.rs

@@ -70,7 +70,7 @@ if_std! {
     mod anyref;
 
     mod cache;
-    pub use cache::intern::intern;
+    pub use cache::intern::{intern, unintern};
 }
 
 /// Representation of an object owned by JS.

tests/wasm/simple.rs

@@ -1,5 +1,5 @@
 use wasm_bindgen::prelude::*;
-use wasm_bindgen::JsCast;
+use wasm_bindgen::{JsCast, intern, unintern};
 use wasm_bindgen_test::*;
 
 #[wasm_bindgen(module = "tests/wasm/simple.js")]
@@ -157,6 +157,9 @@ fn binding_to_unimplemented_apis_doesnt_break_everything() {
 fn optional_slices() {
     optional_str_none(None);
     optional_str_some(Some("x"));
+    optional_str_some(Some(intern("x")));
+    unintern("x");
+    optional_str_some(Some("x"));
     optional_slice_none(None);
     optional_slice_some(Some(&[1, 2, 3]));
     optional_string_none(None);