Add switch expression.

tests/switch.rs

@@ -0,0 +1,64 @@
+use rhai::{Engine, EvalAltResult, Scope, INT};
+
+#[test]
+fn test_switch() -> Result<(), Box<EvalAltResult>> {
+    let engine = Engine::new();
+    let mut scope = Scope::new();
+    scope.push("x", 42 as INT);
+
+    assert_eq!(
+        engine.eval_with_scope::<bool>(&mut scope, "switch x { 1 => (), 2 => 'a', 42 => true }")?,
+        true
+    );
+    assert_eq!(
+        engine.eval_with_scope::<bool>(&mut scope, "switch x { 1 => (), 2 => 'a', _ => true }")?,
+        true
+    );
+    assert_eq!(
+        engine.eval_with_scope::<()>(&mut scope, "switch x { 1 => 123, 2 => 'a' }")?,
+        ()
+    );
+    assert_eq!(
+        engine.eval_with_scope::<INT>(
+            &mut scope,
+            "switch x { 1 => 123, 42 => { x / 2 }, _ => 999 }"
+        )?,
+        21
+    );
+    #[cfg(not(feature = "no_index"))]
+    assert_eq!(
+        engine.eval_with_scope::<INT>(
+            &mut scope,
+            r"
+                let y = [1, 2, 3];
+
+                switch y {
+                    42 => 1,
+                    true => 2,
+                    [1, 2, 3] => 3,
+                    _ => 9
+                }
+            "
+        )?,
+        3
+    );
+    #[cfg(not(feature = "no_object"))]
+    assert_eq!(
+        engine.eval_with_scope::<INT>(
+            &mut scope,
+            r"
+                let y = #{a:1, b:true, c:'x'};
+
+                switch y {
+                    42 => 1,
+                    true => 2,
+                    #{b:true, c:'x', a:1} => 3,
+                    _ => 9
+                }
+            "
+        )?,
+        3
+    );
+
+    Ok(())
+}