Add no_object feature to disable objects.

Cargo.toml

@@ -20,13 +20,14 @@ categories = [ "no-std", "embedded", "parser-implementations" ]
 num-traits = "0.2.11"
 
 [features]
-#default = ["no_function", "no_index", "no_float", "only_i32", "no_stdlib", "unchecked", "no_optimize"]
+#default = ["no_function", "no_index", "no_object", "no_float", "only_i32", "no_stdlib", "unchecked", "no_optimize"]
 default = []
 unchecked = []      # unchecked arithmetic
 no_stdlib = []      # no standard library of utility functions
 no_index = []       # no arrays and indexing
 no_float = []       # no floating-point
 no_function = []    # no script-defined functions
+no_object = []      # no custom objects
 no_optimize = []    # no script optimizer
 optimize_full = []  # set optimization level to Full (default is Simple) - this is a feature used only to simplify testing
 only_i32 = []       # set INT=i32 (useful for 32-bit systems)

README.md

@@ -62,6 +62,7 @@ Optional features
 | `unchecked`   | Exclude arithmetic checking (such as overflows and division by zero). Beware that a bad script may panic the entire system!                              |
 | `no_function` | Disable script-defined functions if not needed.                                                                                                          |
 | `no_index`    | Disable arrays and indexing features if not needed.                                                                                                      |
+| `no_object`   | Disable support for custom types and objects.                                                                                                            |
 | `no_float`    | Disable floating-point numbers and math if not needed.                                                                                                   |
 | `no_optimize` | Disable the script optimizer.                                                                                                                            |
 | `only_i32`    | Set the system integer type to `i32` and disable all other integer types. `INT` is set to `i32`.                                                         |
@@ -76,6 +77,7 @@ Excluding unneeded functionalities can result in smaller, faster builds as well
 [`no_index`]: #optional-features
 [`no_float`]: #optional-features
 [`no_function`]: #optional-features
+[`no_object`]: #optional-features
 [`no_optimize`]: #optional-features
 [`only_i32`]: #optional-features
 [`only_i64`]: #optional-features
@@ -294,7 +296,7 @@ type_of('c') == "char";
 type_of(42) == "i64";
 
 let x = 123;
-x.type_of();                // error - 'type_of' cannot use postfix notation
+x.type_of();                // error - 'type_of' cannot use method-call style
 type_of(x) == "i64";
 
 x = 99.999;
@@ -496,6 +498,7 @@ fn main() -> Result<(), EvalAltResult>
 ```
 
 All custom types must implement `Clone`.  This allows the [`Engine`] to pass by value.
+You can turn off support for custom types via the [`no_object`] feature.
 
 ```rust
 #[derive(Clone)]
@@ -522,7 +525,8 @@ let mut engine = Engine::new();
 engine.register_type::<TestStruct>();
 ```
 
-To use methods and functions with the [`Engine`], we need to register them.  There are some convenience functions to help with this.  Below I register update and new with the [`Engine`].
+To use methods and functions with the [`Engine`], we need to register them. There are some convenience functions to help with this.
+Below I register update and new with the [`Engine`].
 
 *Note: [`Engine`] follows the convention that methods use a `&mut` first parameter so that invoking methods can update the value in memory.*
 
@@ -531,7 +535,8 @@ engine.register_fn("update", TestStruct::update);   // registers 'update(&mut ts
 engine.register_fn("new_ts", TestStruct::new);      // registers 'new'
 ```
 
-Finally, we call our script.  The script can see the function and method we registered earlier.  We need to get the result back out from script land just as before, this time casting to our custom struct type.
+Finally, we call our script.  The script can see the function and method we registered earlier.
+We need to get the result back out from script land just as before, this time casting to our custom struct type.
 
 ```rust
 let result = engine.eval::<TestStruct>("let x = new_ts(); x.update(); x")?;
@@ -539,7 +544,8 @@ let result = engine.eval::<TestStruct>("let x = new_ts(); x.update(); x")?;
 println!("result: {}", result.field);               // prints 42
 ```
 
-In fact, any function with a first argument (either by copy or via a `&mut` reference) can be used as a method-call on that type because internally they are the same thing: methods on a type is implemented as a functions taking an first argument.
+In fact, any function with a first argument (either by copy or via a `&mut` reference) can be used as a method-call on that type because internally they are the same thing:
+methods on a type is implemented as a functions taking an first argument.
 
 ```rust
 fn foo(ts: &mut TestStruct) -> i64 {
@@ -553,7 +559,15 @@ let result = engine.eval::<i64>("let x = new_ts(); x.foo()")?;
 println!("result: {}", result);                     // prints 1
 ```
 
-[`type_of()`] works fine with custom types and returns the name of the type. If `register_type_with_name` is used to register the custom type
+If the [`no_object`] feature is turned on, however, the _method_ style of function calls (i.e. calling a function as an object-method) is no longer supported.
+
+```rust
+// Below is a syntax error under 'no_object' because 'len' cannot be called in method style.
+let result = engine.eval::<i64>("let x = [1, 2, 3]; x.len()")?;
+```
+
+[`type_of()`] works fine with custom types and returns the name of the type.
+If `register_type_with_name` is used to register the custom type
 with a special "pretty-print" name, [`type_of()`] will return that name instead.
 
 ```rust
@@ -605,6 +619,9 @@ let result = engine.eval::<i64>("let a = new_ts(); a.xyz = 42; a.xyz")?;
 println!("Answer: {}", result);                     // prints 42
 ```
 
+Needless to say, `register_type`, `register_type_with_name`, `register_get`, `register_set` and `register_get_set`
+are not available when the [`no_object`] feature is turned on.
+
 Initializing and maintaining state
 ---------------------------------
 
@@ -1326,6 +1343,8 @@ a.update();             // method call
 update(a);              // this works, but 'a' is unchanged because only a COPY of 'a' is passed to 'update' by VALUE
 ```
 
+Custom types, properties and methods can be disabled via the [`no_object`] feature.
+
 `print` and `debug`
 -------------------
 
@@ -1606,7 +1625,7 @@ eval("{ let z = y }");          // to keep a variable local, use a statement blo
 
 print("z = " + z);              // error - variable 'z' not found
 
-"print(42)".eval();             // nope - just like 'type_of' postfix notation doesn't work
+"print(42)".eval();             // nope - just like 'type_of', method-call style doesn't work
 ```
 
 Script segments passed to `eval` execute inside the current [`Scope`], so they can access and modify _everything_,

examples/arrays_and_structs.rs

@@ -15,6 +15,8 @@ impl TestStruct {
     }
 }
 
+#[cfg(not(feature = "no_index"))]
+#[cfg(not(feature = "no_object"))]
 fn main() {
     let mut engine = Engine::new();
 
@@ -32,3 +34,6 @@ fn main() {
         engine.eval::<TestStruct>("let x = [new_ts()]; x[0].update(); x[0]")
     );
 }
+
+#[cfg(any(feature = "no_index", feature = "no_object"))]
+fn main() {}

examples/custom_types_and_methods.rs

@@ -15,6 +15,7 @@ impl TestStruct {
     }
 }
 
+#[cfg(not(feature = "no_object"))]
 fn main() -> Result<(), EvalAltResult> {
     let mut engine = Engine::new();
 
@@ -29,3 +30,6 @@ fn main() -> Result<(), EvalAltResult> {
 
     Ok(())
 }
+
+#[cfg(feature = "no_object")]
+fn main() {}

src/api.rs

@@ -75,6 +75,7 @@ impl<'e> Engine<'e> {
     /// # Ok(())
     /// # }
     /// ```
+    #[cfg(not(feature = "no_object"))]
     pub fn register_type<T: Any + Clone>(&mut self) {
         self.register_type_with_name::<T>(type_name::<T>());
     }
@@ -122,6 +123,7 @@ impl<'e> Engine<'e> {
     /// # Ok(())
     /// # }
     /// ```
+    #[cfg(not(feature = "no_object"))]
     pub fn register_type_with_name<T: Any + Clone>(&mut self, name: &str) {
         // Add the pretty-print type name into the map
         self.type_names
@@ -173,6 +175,7 @@ impl<'e> Engine<'e> {
     /// # Ok(())
     /// # }
     /// ```
+    #[cfg(not(feature = "no_object"))]
     pub fn register_get<T: Any + Clone, U: Any + Clone>(
         &mut self,
         name: &str,
@@ -215,6 +218,7 @@ impl<'e> Engine<'e> {
     /// # Ok(())
     /// # }
     /// ```
+    #[cfg(not(feature = "no_object"))]
     pub fn register_set<T: Any + Clone, U: Any + Clone>(
         &mut self,
         name: &str,
@@ -262,6 +266,7 @@ impl<'e> Engine<'e> {
     /// # Ok(())
     /// # }
     /// ```
+    #[cfg(not(feature = "no_object"))]
     pub fn register_get_set<T: Any + Clone, U: Any + Clone>(
         &mut self,
         name: &str,
@@ -864,7 +869,7 @@ impl<'e> Engine<'e> {
     /// let mut engine = Engine::new();
     ///
     /// // Set 'retain_functions' in 'consume' to keep the function definitions
-    /// engine.consume(true, "fn add(x, y) { x.len() + y }")?;
+    /// engine.consume(true, "fn add(x, y) { len(x) + y }")?;
     ///
     /// // Call the script-defined function
     /// let result: i64 = engine.call_fn("add", (String::from("abc"), 123_i64))?;

src/engine.rs

@@ -344,6 +344,7 @@ impl Engine<'_> {
     ///
     /// Otherwise, if `src` is `Some`, then it holds a name and index into `scope`; using `get_mut` on
     /// `scope` can retrieve a mutable reference to the variable's value to use as `this`.
+    #[cfg(not(feature = "no_object"))]
     fn get_dot_val_helper(
         &mut self,
         scope: &mut Scope,
@@ -487,6 +488,7 @@ impl Engine<'_> {
     }
 
     /// Evaluate a dot chain getter
+    #[cfg(not(feature = "no_object"))]
     fn get_dot_val(
         &mut self,
         scope: &mut Scope,
@@ -741,6 +743,7 @@ impl Engine<'_> {
     }
 
     /// Chain-evaluate a dot setter
+    #[cfg(not(feature = "no_object"))]
     fn set_dot_val_helper(
         &mut self,
         scope: &mut Scope,
@@ -858,6 +861,7 @@ impl Engine<'_> {
     }
 
     // Evaluate a dot chain setter
+    #[cfg(not(feature = "no_object"))]
     fn set_dot_val(
         &mut self,
         scope: &mut Scope,
@@ -1021,6 +1025,7 @@ impl Engine<'_> {
                     }
 
                     // dot_lhs.dot_rhs = rhs
+                    #[cfg(not(feature = "no_object"))]
                     Expr::Dot(dot_lhs, dot_rhs, _) => self.set_dot_val(
                         scope,
                         dot_lhs,
@@ -1041,6 +1046,7 @@ impl Engine<'_> {
                 }
             }
 
+            #[cfg(not(feature = "no_object"))]
             Expr::Dot(lhs, rhs, _) => self.get_dot_val(scope, lhs, rhs, level),
 
             #[cfg(not(feature = "no_index"))]

src/optimize.rs

@@ -334,6 +334,7 @@ fn optimize_expr<'a>(expr: Expr, state: &mut State<'a>) -> Expr {
             expr => Expr::Assignment(id, Box::new(optimize_expr(expr, state)), pos),
         },
         // lhs.rhs
+        #[cfg(not(feature = "no_object"))]
         Expr::Dot(lhs, rhs, pos) => Expr::Dot(
             Box::new(optimize_expr(*lhs, state)),
             Box::new(optimize_expr(*rhs, state)),

src/parser.rs

@@ -357,6 +357,7 @@ pub enum Expr {
     /// expr = expr
     Assignment(Box<Expr>, Box<Expr>, Position),
     /// lhs.rhs
+    #[cfg(not(feature = "no_object"))]
     Dot(Box<Expr>, Box<Expr>, Position),
     /// expr[expr]
     #[cfg(not(feature = "no_index"))]
@@ -443,10 +444,12 @@ impl Expr {
             | Expr::False(pos)
             | Expr::Unit(pos) => *pos,
 
-            Expr::Assignment(expr, _, _)
-            | Expr::Dot(expr, _, _)
-            | Expr::And(expr, _)
-            | Expr::Or(expr, _) => expr.position(),
+            Expr::Assignment(expr, _, _) | Expr::And(expr, _) | Expr::Or(expr, _) => {
+                expr.position()
+            }
+
+            #[cfg(not(feature = "no_object"))]
+            Expr::Dot(expr, _, _) => expr.position(),
 
             #[cfg(not(feature = "no_float"))]
             Expr::FloatConstant(_, pos) => *pos,
@@ -1767,6 +1770,7 @@ fn parse_assignment(lhs: Expr, rhs: Expr, pos: Position) -> Result<Expr, ParseEr
             },
 
             // dot_lhs.dot_rhs
+            #[cfg(not(feature = "no_object"))]
             Expr::Dot(dot_lhs, dot_rhs, _) => match dot_lhs.as_ref() {
                 // var.dot_rhs
                 Expr::Variable(_, _) if is_top => valid_assignment_chain(dot_rhs, false),
@@ -1875,6 +1879,7 @@ fn parse_binary_op<'a>(
                 Token::PlusAssign => parse_op_assignment("+", current_lhs, rhs, pos)?,
                 Token::MinusAssign => parse_op_assignment("-", current_lhs, rhs, pos)?,
 
+                #[cfg(not(feature = "no_object"))]
                 Token::Period => {
                     fn change_var_to_property(expr: Expr) -> Expr {
                         match expr {

tests/arrays.rs

@@ -16,6 +16,7 @@ fn test_arrays() -> Result<(), EvalAltResult> {
 }
 
 #[test]
+#[cfg(not(feature = "no_object"))]
 fn test_array_with_structs() -> Result<(), EvalAltResult> {
     #[derive(Clone)]
     struct TestStruct {

tests/expressions.rs

@@ -27,6 +27,7 @@ fn test_expressions() -> Result<(), EvalAltResult> {
 
 /// This example taken from https://github.com/jonathandturner/rhai/issues/115
 #[test]
+#[cfg(not(feature = "no_object"))]
 fn test_expressions_eval() -> Result<(), EvalAltResult> {
     #[derive(Debug, Clone)]
     struct AGENT {

tests/float.rs

@@ -21,6 +21,7 @@ fn test_float() -> Result<(), EvalAltResult> {
 }
 
 #[test]
+#[cfg(not(feature = "no_object"))]
 fn struct_with_float() -> Result<(), EvalAltResult> {
     #[derive(Clone)]
     struct TestStruct {

tests/get_set.rs

@@ -1,3 +1,5 @@
+#![cfg(not(feature = "no_object"))]
+
 use rhai::{Engine, EvalAltResult, RegisterFn, INT};
 
 #[test]

tests/math.rs

@@ -12,12 +12,12 @@ fn test_math() -> Result<(), EvalAltResult> {
 
     #[cfg(not(feature = "only_i32"))]
     assert_eq!(
-        engine.eval::<INT>("(-9223372036854775807).abs()")?,
+        engine.eval::<INT>("abs(-9223372036854775807)")?,
         9_223_372_036_854_775_807
     );
 
     #[cfg(feature = "only_i32")]
-    assert_eq!(engine.eval::<INT>("(-2147483647).abs()")?, 2147483647);
+    assert_eq!(engine.eval::<INT>("abs(-2147483647)")?, 2147483647);
 
     // Overflow/underflow/division-by-zero errors
     #[cfg(not(feature = "unchecked"))]
@@ -26,7 +26,7 @@ fn test_math() -> Result<(), EvalAltResult> {
         {
             assert!(matches!(
                 engine
-                    .eval::<INT>("(-9223372036854775808).abs()")
+                    .eval::<INT>("abs(-9223372036854775808)")
                     .expect_err("expects negation overflow"),
                 EvalAltResult::ErrorArithmetic(_, _)
             ));

tests/method_call.rs

@@ -1,3 +1,5 @@
+#![cfg(not(feature = "no_object"))]
+
 use rhai::{Engine, EvalAltResult, RegisterFn, INT};
 
 #[test]

tests/mismatched_op.rs

@@ -12,6 +12,7 @@ fn test_mismatched_op() {
 }
 
 #[test]
+#[cfg(not(feature = "no_object"))]
 fn test_mismatched_op_custom_type() {
     #[derive(Clone)]
     struct TestStruct {

tests/side_effects.rs

@@ -1,3 +1,5 @@
+#![cfg(not(feature = "no_object"))]
+
 ///! This test simulates an external command object that is driven by a script.
 use rhai::{Engine, EvalAltResult, RegisterFn, Scope, INT};
 use std::cell::RefCell;