Fix stack overflow

CHANGELOG.md

@@ -16,12 +16,14 @@ Bug fixes
 * Fixed stack overflow when calling closures recursively (thanks [`@MageWeiG`](https://github.com/MageWeiG) [880](https://github.com/rhaiscript/rhai/issues/880)).
 * `Engine::call_fn` and `Engine::call_fn_with_options` now correctly use the `AST`'s `source` field.
 * (Fuzzing) Fixed crash when using `..=` in strings.
+* A recursive stack-overflow bug in `Dynamic::is_hashable` is fixed.
 
 New features
 ------------
 
 * The `break`, `continue`, `return` and `throw` statements can now follow the `??` operator to short-circuit operations where the value is `()`.
 * A new symbol, `$func$`, is added to custom syntax to allow parsing of anonymous functions.
+* The `filter`, `drain` and `retain` methods are added to object maps.
 
 
 Version 1.18.0

src/api/register.rs

@@ -68,11 +68,10 @@ impl Engine {
         const X: bool,
         R: Variant + Clone,
         const F: bool,
-        FUNC: RhaiNativeFunc<A, N, X, R, F> + SendSync + 'static,
     >(
         &mut self,
         name: impl AsRef<str> + Into<Identifier>,
-        func: FUNC,
+        func: impl RhaiNativeFunc<A, N, X, R, F> + SendSync + 'static,
     ) -> &mut Self {
         FuncRegistration::new(name.into()).register_into_engine(self, func);
 

src/packages/map_basic.rs

@@ -2,7 +2,9 @@
 
 use crate::engine::OP_EQUALS;
 use crate::plugin::*;
-use crate::{def_package, Dynamic, ImmutableString, Map, NativeCallContext, RhaiResultOf, INT};
+use crate::{
+    def_package, Dynamic, FnPtr, ImmutableString, Map, NativeCallContext, RhaiResultOf, INT,
+};
 #[cfg(feature = "no_std")]
 use std::prelude::v1::*;
 
@@ -293,6 +295,162 @@ mod map_functions {
 
         map.values().cloned().collect()
     }
+    /// Iterate through all the elements in the object map, applying a `filter` function to each
+    /// and return a new collection of all elements that return `true` as a new object map.
+    ///
+    /// # Function Parameters
+    ///
+    /// * `key`: current key
+    /// * `value` _(optional)_: copy of element (bound to `this` if omitted)
+    ///
+    /// # Example
+    ///
+    /// ```rhai
+    /// let x = #{a:1, b:2, c:3, d:4, e:5};
+    ///
+    /// let y = x.filter(|k| this >= 3);
+    ///
+    /// print(y);       // prints #{"c":3, "d":4, "e":5}
+    ///
+    /// let y = x.filter(|k, v| k != "d" && v < 5);
+    ///
+    /// print(y);       // prints #{"a":1, "b":2, "c":3}
+    /// ```
+    #[rhai_fn(return_raw)]
+    pub fn filter(ctx: NativeCallContext, map: &mut Map, filter: FnPtr) -> RhaiResultOf<Map> {
+        if map.is_empty() {
+            return Ok(Map::new());
+        }
+
+        let mut result = Map::new();
+
+        for (key, item) in map.iter_mut() {
+            if filter
+                .call_raw_with_extra_args("filter", &ctx, Some(item), [key.into()], [], Some(1))?
+                .as_bool()
+                .unwrap_or(false)
+            {
+                result.insert(key.clone(), item.clone());
+            }
+        }
+
+        Ok(result)
+    }
+    /// Remove all elements in the object map that return `true` when applied the `filter` function and
+    /// return them as a new object map.
+    ///
+    /// # Function Parameters
+    ///
+    /// * `key`: current key
+    /// * `value` _(optional)_: copy of element (bound to `this` if omitted)
+    ///
+    /// # Example
+    ///
+    /// ```rhai
+    /// let x = #{a:1, b:2, c:3, d:4, e:5};
+    ///
+    /// let y = x.drain(|k| this < 3);
+    ///
+    /// print(x);       // prints #{"c":3, "d":4, "e":5]
+    ///
+    /// print(y);       // prints #{"a":1, "b"2}
+    ///
+    /// let z = x.drain(|k, v| k == "c" || v >= 5);
+    ///
+    /// print(x);       // prints #{"d":4}
+    ///
+    /// print(z);       // prints #{"c":3, "e":5}
+    /// ```
+    #[rhai_fn(return_raw)]
+    pub fn drain(ctx: NativeCallContext, map: &mut Map, filter: FnPtr) -> RhaiResultOf<Map> {
+        if map.is_empty() {
+            return Ok(Map::new());
+        }
+
+        let mut drained = Map::new();
+        let mut retained = Map::new();
+
+        for (key, mut value) in mem::take(map).into_iter() {
+            if filter
+                .call_raw_with_extra_args(
+                    "drain",
+                    &ctx,
+                    Some(&mut value),
+                    [key.clone().into()],
+                    [],
+                    Some(1),
+                )?
+                .as_bool()
+                .unwrap_or(false)
+            {
+                drained.insert(key, value);
+            } else {
+                retained.insert(key, value);
+            }
+        }
+
+        *map = retained;
+
+        Ok(drained)
+    }
+    /// Remove all elements in the object map that do not return `true` when applied the `filter` function and
+    /// return them as a new object map.
+    ///
+    /// # Function Parameters
+    ///
+    /// * `key`: current key
+    /// * `value` _(optional)_: copy of element (bound to `this` if omitted)
+    ///
+    /// # Example
+    ///
+    /// ```rhai
+    /// let x = #{a:1, b:2, c:3, d:4, e:5};
+    ///
+    /// let y = x.retain(|k| this < 3);
+    ///
+    /// print(x);       // prints #{"a":1, "b"2}
+    ///
+    /// print(y);       // prints #{"c":3, "d":4, "e":5]
+    ///
+    /// let z = y.retain(|k, v| k == "c" || v >= 5);
+    ///
+    /// print(y);       // prints #{"c":3, "e":5}
+    ///
+    /// print(z);       // prints #{"d":4}
+    /// ```
+    #[rhai_fn(return_raw)]
+    pub fn retain(ctx: NativeCallContext, map: &mut Map, filter: FnPtr) -> RhaiResultOf<Map> {
+        if map.is_empty() {
+            return Ok(Map::new());
+        }
+
+        let mut drained = Map::new();
+        let mut retained = Map::new();
+
+        for (key, mut value) in mem::take(map).into_iter() {
+            if filter
+                .call_raw_with_extra_args(
+                    "retain",
+                    &ctx,
+                    Some(&mut value),
+                    [key.clone().into()],
+                    [],
+                    Some(1),
+                )?
+                .as_bool()
+                .unwrap_or(false)
+            {
+                retained.insert(key, value);
+            } else {
+                drained.insert(key, value);
+            }
+        }
+
+        *map = retained;
+
+        Ok(drained)
+    }
+
     /// Return the JSON representation of the object map.
     ///
     /// # Data types

src/types/dynamic.rs

@@ -741,7 +741,6 @@ impl fmt::Debug for Dynamic {
                     dict: &mut HashSet<*const Dynamic>,
                 ) -> fmt::Result {
                     match value.0 {
-                        #[cfg(not(feature = "no_closure"))]
                         Union::Shared(ref cell, ..) => match crate::func::locked_read(cell) {
                             Some(v) => {
                                 if dict.insert(value) {
@@ -1267,8 +1266,27 @@ impl Dynamic {
             }
 
             #[cfg(not(feature = "no_closure"))]
-            Union::Shared(ref cell, ..) => {
-                crate::func::locked_read(cell).map_or(false, |v| v.is_hashable())
+            Union::Shared(..) => {
+                #[cfg(feature = "no_std")]
+                use hashbrown::HashSet;
+                #[cfg(not(feature = "no_std"))]
+                use std::collections::HashSet;
+
+                // Avoid infinite recursion for shared values in a reference loop.
+                fn checked_is_hashable(
+                    value: &Dynamic,
+                    dict: &mut HashSet<*const Dynamic>,
+                ) -> bool {
+                    match value.0 {
+                        Union::Shared(ref cell, ..) => match crate::func::locked_read(cell) {
+                            Some(v) => dict.insert(value) && checked_is_hashable(&v, dict),
+                            _ => false,
+                        },
+                        _ => value.is_hashable(),
+                    }
+                }
+
+                checked_is_hashable(self, &mut <_>::default())
             }
         }
     }

tests/build_type.rs

@@ -1,5 +1,6 @@
 #![cfg(not(feature = "no_object"))]
 use rhai::{CustomType, Engine, EvalAltResult, Position, TypeBuilder, INT};
+use std::cmp::Ordering;
 
 #[test]
 fn test_build_type() {
@@ -32,7 +33,7 @@
         fn set_z(&mut self, z: INT) {
             self.z = z
         }
         fn get_component(&mut self, idx: INT) -> Result<INT, Box<EvalAltResult>> {
             match idx {
                 0 => Ok(self.x),
                 1 => Ok(self.y),
@@ -219,3 +220,31 @@
         }
     );
 }
+
+#[test]
+fn test_build_type_operators() {
+    #[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord)]
+    struct XYZ(INT);
+
+    impl CustomType for XYZ {
+        fn build(mut tb: TypeBuilder<Self>) {
+            tb.with_fn("new_xyz", XYZ)
+                .with_fn("<", |a: XYZ, b: XYZ| Self::cmp(&a, &b) == Ordering::Less)
+                .with_fn(">", |a: XYZ, b: XYZ| Self::cmp(&a, &b) == Ordering::Greater)
+                .with_fn("<=", |a: XYZ, b: XYZ| Self::cmp(&a, &b) != Ordering::Greater)
+                .with_fn(">=", |a: XYZ, b: XYZ| Self::cmp(&a, &b) != Ordering::Less)
+                .with_fn("!=", |a: XYZ, b: XYZ| Self::cmp(&a, &b) != Ordering::Equal)
+                .with_fn("==", |a: XYZ, b: XYZ| Self::cmp(&a, &b) == Ordering::Equal);
+        }
+    }
+
+    let mut engine = Engine::new();
+    engine.build_type::<XYZ>();
+
+    assert!(!engine.eval::<bool>("let a = new_xyz(1); let b = new_xyz(2); a == b").unwrap());
+    assert!(engine.eval::<bool>("let a = new_xyz(1); let b = new_xyz(2); a != b").unwrap());
+    assert!(engine.eval::<bool>("let a = new_xyz(1); let b = new_xyz(2); a < b").unwrap());
+    assert!(engine.eval::<bool>("let a = new_xyz(1); let b = new_xyz(2); a <= b").unwrap());
+    assert!(!engine.eval::<bool>("let a = new_xyz(1); let b = new_xyz(2); a > b").unwrap());
+    assert!(!engine.eval::<bool>("let a = new_xyz(1); let b = new_xyz(2); a >= b").unwrap());
+}