Add is_shared function.

doc/src/appendix/keywords.md

@@ -9,6 +9,7 @@ Keywords List
 |        `false`        | Boolean false literal                    |                 |      No      |
 |         `let`         | Variable declaration                     |                 |      No      |
 |        `const`        | Constant declaration                     |                 |      No      |
+|      `is_shared`      | Is a value shared?                       |                 |      No      |
 |       `shared`        | Share value                              |  [`no_shared`]  |      No      |
 |        `take`         | Un-share value                           |  [`no_shared`]  |      No      |
 |         `if`          | If statement                             |                 |      No      |

doc/src/language/keywords.md

@@ -9,7 +9,7 @@ The following are reserved keywords in Rhai:
 | ------------------------------------------------- | ------------------------------------------------ | --------------------- | :--------------------: |
 | `true`, `false`                                   |                                                  | Boolean constants     |                        |
 | `let`, `const`                                    | `var`, `static`                                  | Variable declarations |                        |
-| `shared`, `take`                                  |                                                  | Shared values         |     [`no_shared`]      |
+| `shared`, `take`, `is_shared`                     |                                                  | Shared values         |     [`no_shared`]      |
 | `if`, `else`                                      | `then`, `goto`, `exit`                           | Control flow          |                        |
 |                                                   | `switch`, `match`, `case`                        | Matching              |                        |
 | `while`, `loop`, `for`, `in`, `continue`, `break` | `do`, `each`                                     | Looping               |                        |
@@ -23,4 +23,3 @@ The following are reserved keywords in Rhai:
 |                                                   | `default`, `void`, `null`, `nil`                 | Special values        |                        |
 
 Keywords cannot become the name of a [function] or [variable], even when they are disabled.
-

src/engine.rs

@@ -99,6 +99,7 @@ pub const KEYWORD_FN_PTR_CALL: &str = "call";
 pub const KEYWORD_FN_PTR_CURRY: &str = "curry";
 pub const KEYWORD_SHARED: &str = "shared";
 pub const KEYWORD_TAKE: &str = "take";
+pub const KEYWORD_IS_SHARED: &str = "is_shared";
 pub const KEYWORD_THIS: &str = "this";
 pub const FN_TO_STRING: &str = "to_string";
 #[cfg(not(feature = "no_object"))]

src/fn_call.rs

@@ -4,8 +4,8 @@ use crate::any::Dynamic;
 use crate::calc_fn_hash;
 use crate::engine::{
     search_imports, search_namespace, search_scope_only, Engine, Imports, State, KEYWORD_DEBUG,
-    KEYWORD_EVAL, KEYWORD_FN_PTR, KEYWORD_FN_PTR_CALL, KEYWORD_FN_PTR_CURRY, KEYWORD_PRINT,
+    KEYWORD_EVAL, KEYWORD_FN_PTR, KEYWORD_FN_PTR_CALL, KEYWORD_FN_PTR_CURRY, KEYWORD_IS_SHARED,
-    KEYWORD_SHARED, KEYWORD_TAKE, KEYWORD_TYPE_OF,
+    KEYWORD_PRINT, KEYWORD_SHARED, KEYWORD_TAKE, KEYWORD_TYPE_OF,
 };
 use crate::error::ParseErrorType;
 use crate::fn_native::{FnCallArgs, FnPtr};
@@ -451,6 +451,12 @@ impl Engine {
                 )))
             }
 
+            // Fn
+            KEYWORD_IS_SHARED if args.len() == 1 => Err(Box::new(EvalAltResult::ErrorRuntime(
+                "'is_shared' should not be called in method style. Try is_shared(...);".into(),
+                Position::none(),
+            ))),
+
             // eval - reaching this point it must be a method-style call
             KEYWORD_EVAL
                 if args.len() == 1 && !self.has_override(lib, hash_fn, hash_script, pub_only) =>
@@ -783,6 +789,15 @@ impl Engine {
             .into());
         }
 
+        // Handle is_shared()
+        #[cfg(not(feature = "no_shared"))]
+        if name == KEYWORD_IS_SHARED && args_expr.len() == 1 {
+            let expr = args_expr.get(0).unwrap();
+            let value = self.eval_expr(scope, mods, state, lib, this_ptr, expr, level)?;
+
+            return Ok(value.is_shared().into());
+        }
+
         // Handle shared()
         #[cfg(not(feature = "no_shared"))]
         if name == KEYWORD_SHARED && args_expr.len() == 1 {

src/token.rs

@@ -2,7 +2,7 @@
 
 use crate::engine::{
     Engine, KEYWORD_DEBUG, KEYWORD_EVAL, KEYWORD_FN_PTR, KEYWORD_FN_PTR_CALL, KEYWORD_FN_PTR_CURRY,
-    KEYWORD_PRINT, KEYWORD_SHARED, KEYWORD_TAKE, KEYWORD_THIS, KEYWORD_TYPE_OF,
+    KEYWORD_IS_SHARED, KEYWORD_PRINT, KEYWORD_SHARED, KEYWORD_TAKE, KEYWORD_THIS, KEYWORD_TYPE_OF,
 };
 
 use crate::error::LexError;
@@ -1431,28 +1431,22 @@ fn get_identifier(
 /// Is this keyword allowed as a function?
 #[inline(always)]
 pub fn is_keyword_function(name: &str) -> bool {
+    match name {
         #[cfg(not(feature = "no_shared"))]
-    if name == KEYWORD_SHARED || name == KEYWORD_TAKE {
+        KEYWORD_SHARED | KEYWORD_TAKE | KEYWORD_IS_SHARED => true,
-        return true;
+        KEYWORD_PRINT | KEYWORD_DEBUG | KEYWORD_TYPE_OF | KEYWORD_EVAL | KEYWORD_FN_PTR
+        | KEYWORD_FN_PTR_CALL | KEYWORD_FN_PTR_CURRY => true,
+        _ => false,
     }
-
-    name == KEYWORD_PRINT
-        || name == KEYWORD_DEBUG
-        || name == KEYWORD_TYPE_OF
-        || name == KEYWORD_EVAL
-        || name == KEYWORD_FN_PTR
-        || name == KEYWORD_FN_PTR_CALL
-        || name == KEYWORD_FN_PTR_CURRY
 }
 
 /// Can this keyword be overridden as a function?
 #[inline(always)]
 pub fn can_override_keyword(name: &str) -> bool {
-    name == KEYWORD_PRINT
+    match name {
-        || name == KEYWORD_DEBUG
+        KEYWORD_PRINT | KEYWORD_DEBUG | KEYWORD_TYPE_OF | KEYWORD_EVAL | KEYWORD_FN_PTR => true,
-        || name == KEYWORD_TYPE_OF
+        _ => false,
-        || name == KEYWORD_EVAL
+    }
-        || name == KEYWORD_FN_PTR
 }
 
 pub fn is_valid_identifier(name: impl Iterator<Item = char>) -> bool {

tests/shared.rs

@@ -18,6 +18,11 @@ fn test_shared() -> Result<(), Box<EvalAltResult>> {
 
     assert_eq!(engine.eval::<char>("shared('x')")?, 'x');
 
+    assert!(engine.eval::<bool>("is_shared(shared(42))")?);
+
+    #[cfg(not(feature = "no_object"))]
+    assert!(engine.eval::<bool>("shared(42).is_shared()")?);
+
     #[cfg(not(feature = "no_index"))]
     {
         assert_eq!(