Change fast_ops to options.

CHANGELOG.md

@@ -30,9 +30,9 @@ New features
 * `if`-expressions are allowed in `Engine::eval_expression` and `Engine::compile_expression` provided that both statement blocks each contain at most a single expression.
 * `switch`-expressions are allowed in `Engine::eval_expression` and `Engine::compile_expression` provided that match actions are expressions only.
 
-### `fast_ops` feature
+### Fast operators
 
-* A new feature `fast_ops` is introduced that short-circuits all built-in operators of built-in types for higher speed. New user overloads are ignored.
+* A new option `Engine::fast_operators` is introduced that short-circuits all built-in operators of built-in types for higher speed. User overloads are ignored. For operator-heavy scripts, this may yield substantial speed-up's.
 
 Enhancements
 ------------

Cargo.toml

@@ -39,10 +39,9 @@ serde_bytes = "0.11"
 serde_json = { version = "1.0", default-features = false, features = ["alloc"] }
 
 [features]
-default = ["std", "fast_ops"]
+default = ["std"]
 std = ["ahash/std", "ahash/runtime-rng", "num-traits/std", "smartstring/std"]
 unchecked = []                  # unchecked arithmetic
-fast_ops = []                   # ignore overloaded standard operators
 sync = []                       # restrict to only types that implement Send + Sync
 no_position = []                # do not track position in the parser
 no_optimize = []                # no script optimizer

src/api/options.rs

@@ -7,26 +7,28 @@ use std::prelude::v1::*;
 
 bitflags! {
     /// Bit-flags containing all language options for the [`Engine`].
-    pub struct LangOptions: u8 {
+    pub struct LangOptions: u16 {
         /// Is `if`-expression allowed?
-        const IF_EXPR = 0b_0000_0001;
+        const IF_EXPR = 0b_0000_0000_0001;
         /// Is `switch` expression allowed?
-        const SWITCH_EXPR = 0b_0000_0010;
+        const SWITCH_EXPR = 0b_0000_0000_0010;
         /// Is statement-expression allowed?
-        const STMT_EXPR = 0b_0000_0100;
+        const STMT_EXPR = 0b_0000_0000_0100;
         /// Is anonymous function allowed?
         #[cfg(not(feature = "no_function"))]
-        const ANON_FN = 0b_0000_1000;
+        const ANON_FN = 0b_0000_0000_1000;
         /// Is looping allowed?
-        const LOOPING = 0b_0001_0000;
+        const LOOPING = 0b_0000_0001_0000;
         /// Is variables shadowing allowed?
-        const SHADOW = 0b_0010_0000;
+        const SHADOW = 0b_0000_0010_0000;
         /// Strict variables mode?
-        const STRICT_VAR = 0b_0100_0000;
+        const STRICT_VAR = 0b_0000_0100_0000;
         /// Raise error if an object map property does not exist?
         /// Returns `()` if `false`.
         #[cfg(not(feature = "no_object"))]
-        const FAIL_ON_INVALID_MAP_PROPERTY = 0b_1000_0000;
+        const FAIL_ON_INVALID_MAP_PROPERTY = 0b_0000_1000_0000;
+        /// Fast operators mode?
+        const FAST_OPS = 0b_0001_0000_0000;
     }
 }
 
@@ -158,4 +160,16 @@ impl Engine {
         self.options
             .set(LangOptions::FAIL_ON_INVALID_MAP_PROPERTY, enable);
     }
+    /// Is fast operators mode enabled?
+    /// Default is `false`.
+    #[inline(always)]
+    #[must_use]
+    pub const fn fast_operators(&self) -> bool {
+        self.options.contains(LangOptions::FAST_OPS)
+    }
+    /// Set whether fast operators mode is enabled.
+    #[inline(always)]
+    pub fn set_fast_operators(&mut self, enable: bool) {
+        self.options.set(LangOptions::FAST_OPS, enable);
+    }
 }

src/eval/expr.rs

@@ -228,8 +228,7 @@ impl Engine {
             ..
         } = expr;
 
-        #[cfg(feature = "fast_ops")]
-        if *std_ops {
+        if *std_ops && self.fast_operators() {
             let mut lhs = self
                 .get_arg_value(scope, global, caches, lib, this_ptr, &args[0], level)?
                 .0

src/optimizer.rs

@@ -1181,7 +1181,7 @@ fn optimize_expr(expr: &mut Expr, state: &mut OptimizerState, _chaining: bool) {
                     return;
                 }
                 // Overloaded operators can override built-in.
-                _ if x.args.len() == 2 && (cfg!(feature = "fast_ops") || !has_native_fn_override(state.engine, x.hashes.native, &arg_types)) => {
+                _ if x.args.len() == 2 && (state.engine.fast_operators() || !has_native_fn_override(state.engine, x.hashes.native, &arg_types)) => {
                     if let Some(result) = get_builtin_binary_op_fn(&x.name, &arg_values[0], &arg_values[1])
                         .and_then(|f| {
                             #[cfg(not(feature = "no_function"))]

tests/native.rs

@@ -77,19 +77,22 @@ fn test_native_overload() -> Result<(), Box<EvalAltResult>> {
 
     assert_eq!(
         engine.eval::<String>(r#"let x = "hello"; let y = "world"; x + y"#)?,
-        if cfg!(not(feature = "fast_ops")) {
         "hello***world"
-        } else {
-            "helloworld"
-        }
     );
     assert_eq!(
         engine.eval::<String>(r#"let x = "hello"; let y = (); x + y"#)?,
-        if cfg!(not(feature = "fast_ops")) {
         "hello Foo!"
-        } else {
+    );
+
+    engine.set_fast_operators(true);
+
+    assert_eq!(
+        engine.eval::<String>(r#"let x = "hello"; let y = "world"; x + y"#)?,
+        "helloworld"
+    );
+    assert_eq!(
+        engine.eval::<String>(r#"let x = "hello"; let y = (); x + y"#)?,
         "hello"
-        }
     );
 
     Ok(())

tests/optimizer.rs

@@ -49,8 +49,6 @@ fn test_optimizer_run() -> Result<(), Box<EvalAltResult>> {
     run_test(&mut engine)?;
 
     // Override == operator
-    #[cfg(not(feature = "fast_ops"))]
-    {
     engine.register_fn("==", |_x: INT, _y: INT| false);
 
     engine.set_optimization_level(OptimizationLevel::Simple);
@@ -66,7 +64,6 @@ fn test_optimizer_run() -> Result<(), Box<EvalAltResult>> {
         engine.eval::<INT>("if 1 == 1 || 2 > 3 { 42 } else { 123 }")?,
         123
     );
-    }
 
     Ok(())
 }

tests/plugins.rs

@@ -128,14 +128,7 @@ fn test_plugins_package() -> Result<(), Box<EvalAltResult>> {
     assert_eq!(engine.eval::<INT>("let a = [1, 2, 3]; test(a, 2)")?, 6);
     assert_eq!(engine.eval::<INT>("let a = [1, 2, 3]; hi(a, 2)")?, 6);
     assert_eq!(engine.eval::<INT>("let a = [1, 2, 3]; test(a, 2)")?, 6);
-    assert_eq!(
-        engine.eval::<INT>("2 + 2")?,
-        if cfg!(not(feature = "fast_ops")) {
-            5
-        } else {
-            4
-        }
-    );
+    assert_eq!(engine.eval::<INT>("2 + 2")?, 5);
     assert_eq!(
         engine.eval::<String>("let a = [1, 2, 3]; greet(test(a, 2))")?,
         "6 kitties"