Lazy calculate indexer call hashes.

src/engine.rs

@@ -3,7 +3,7 @@
 use crate::ast::{Expr, FnCallExpr, Ident, OpAssignment, Stmt, AST_OPTION_FLAGS::*};
 use crate::custom_syntax::CustomSyntax;
 use crate::dynamic::{map_std_type_name, AccessMode, Union, Variant};
-use crate::fn_hash::{calc_fn_hash, get_hasher};
+use crate::fn_hash::get_hasher;
 use crate::fn_native::{
     CallableFunction, IteratorFn, OnDebugCallback, OnParseTokenCallback, OnPrintCallback,
     OnVarCallback,
@@ -682,6 +682,9 @@ pub struct EvalState {
     /// Embedded module resolver.
     #[cfg(not(feature = "no_module"))]
     pub embedded_module_resolver: Option<Shared<crate::module::resolvers::StaticModuleResolver>>,
+    /// Function call hashes to FN_IDX_GET and FN_IDX_SET
+    #[cfg(any(not(feature = "no_index"), not(feature = "no_object")))]
+    fn_hash_indexing: (u64, u64),
 }
 
 impl EvalState {
@@ -698,6 +701,8 @@ impl EvalState {
             #[cfg(not(feature = "no_module"))]
             embedded_module_resolver: None,
             fn_resolution_caches: StaticVec::new(),
+            #[cfg(any(not(feature = "no_index"), not(feature = "no_object")))]
+            fn_hash_indexing: (0, 0),
         }
     }
     /// Is the state currently at global (root) level?
@@ -735,6 +740,32 @@ impl EvalState {
             .pop()
             .expect("at least one function resolution cache");
     }
+    /// Get the pre-calculated index getter hash.
+    #[cfg(any(not(feature = "no_index"), not(feature = "no_object")))]
+    #[must_use]
+    pub fn fn_hash_idx_get(&mut self) -> u64 {
+        if self.fn_hash_indexing != (0, 0) {
+            self.fn_hash_indexing.0
+        } else {
+            let n1 = crate::calc_fn_hash(FN_IDX_GET, 2);
+            let n2 = crate::calc_fn_hash(FN_IDX_SET, 3);
+            self.fn_hash_indexing = (n1, n2);
+            n1
+        }
+    }
+    /// Get the pre-calculated index setter hash.
+    #[cfg(any(not(feature = "no_index"), not(feature = "no_object")))]
+    #[must_use]
+    pub fn fn_hash_idx_set(&mut self) -> u64 {
+        if self.fn_hash_indexing != (0, 0) {
+            self.fn_hash_indexing.1
+        } else {
+            let n1 = crate::calc_fn_hash(FN_IDX_GET, 2);
+            let n2 = crate::calc_fn_hash(FN_IDX_SET, 3);
+            self.fn_hash_indexing = (n1, n2);
+            n2
+        }
+    }
 }
 
 /// _(internals)_ A type containing all the limits imposed by the [`Engine`].
@@ -804,31 +835,6 @@ impl Default for Limits {
     }
 }
 
-/// A type containing useful constants for the [`Engine`].
-#[derive(Debug)]
-pub struct GlobalConstants {
-    /// An empty [`ImmutableString`] for cloning purposes.
-    pub(crate) empty_string: ImmutableString,
-    /// Function call hash to FN_IDX_GET
-    #[cfg(any(not(feature = "no_index"), not(feature = "no_object")))]
-    pub(crate) fn_hash_idx_get: u64,
-    /// Function call hash to FN_IDX_SET
-    #[cfg(any(not(feature = "no_index"), not(feature = "no_object")))]
-    pub(crate) fn_hash_idx_set: u64,
-}
-
-impl Default for GlobalConstants {
-    fn default() -> Self {
-        Self {
-            empty_string: Default::default(),
-            #[cfg(any(not(feature = "no_index"), not(feature = "no_object")))]
-            fn_hash_idx_get: calc_fn_hash(FN_IDX_GET, 2),
-            #[cfg(any(not(feature = "no_index"), not(feature = "no_object")))]
-            fn_hash_idx_set: calc_fn_hash(FN_IDX_SET, 3),
-        }
-    }
-}
-
 /// Context of a script evaluation process.
 #[derive(Debug)]
 pub struct EvalContext<'a, 'x, 'px, 'm, 's, 'b, 't, 'pt> {
@@ -950,8 +956,8 @@ pub struct Engine {
     /// A map mapping type names to pretty-print names.
     pub(crate) type_names: BTreeMap<Identifier, Box<Identifier>>,
 
-    /// Useful constants
+    /// An empty [`ImmutableString`] for cloning purposes.
-    pub(crate) constants: GlobalConstants,
+    pub(crate) empty_string: ImmutableString,
 
     /// A set of symbols to disable.
     pub(crate) disabled_symbols: BTreeSet<Identifier>,
@@ -1081,7 +1087,7 @@ impl Engine {
             module_resolver: None,
 
             type_names: Default::default(),
-            constants: Default::default(),
+            empty_string: Default::default(),
             disabled_symbols: Default::default(),
             custom_keywords: Default::default(),
             custom_syntax: Default::default(),
@@ -1116,7 +1122,7 @@ impl Engine {
     #[inline(always)]
     #[must_use]
     pub fn const_empty_string(&self) -> ImmutableString {
-        self.constants.empty_string.clone()
+        self.empty_string.clone()
     }
 
     /// Search for a module within an imports stack.
@@ -1328,8 +1334,7 @@ impl Engine {
 
                         if let Some(mut new_val) = try_setter {
                             // Try to call index setter if value is changed
-                            let hash_set =
+                            let hash_set = FnCallHashes::from_native(state.fn_hash_idx_set());
-                                FnCallHashes::from_native(self.constants.fn_hash_idx_set);
                             let args = &mut [target, &mut idx_val_for_setter, &mut new_val];
 
                             if let Err(err) = self.exec_fn_call(
@@ -1376,8 +1381,7 @@ impl Engine {
 
                         if let Some(mut new_val) = try_setter {
                             // Try to call index setter
-                            let hash_set =
+                            let hash_set = FnCallHashes::from_native(state.fn_hash_idx_set());
-                                FnCallHashes::from_native(self.constants.fn_hash_idx_set);
                             let args = &mut [target, &mut idx_val_for_setter, &mut new_val];
 
                             self.exec_fn_call(
@@ -1508,8 +1512,7 @@ impl Engine {
                             // Try an indexer if property does not exist
                             EvalAltResult::ErrorDotExpr(_, _) => {
                                 let args = &mut [target, &mut name.into(), &mut new_val];
-                                let hash_set =
+                                let hash_set = FnCallHashes::from_native(state.fn_hash_idx_set());
-                                    FnCallHashes::from_native(self.constants.fn_hash_idx_set);
                                 let pos = Position::NONE;
 
                                 self.exec_fn_call(
@@ -1668,7 +1671,7 @@ impl Engine {
                                                 let args =
                                                     &mut [target.as_mut(), &mut name.into(), val];
                                                 let hash_set = FnCallHashes::from_native(
-                                                    self.constants.fn_hash_idx_set,
+                                                    state.fn_hash_idx_set(),
                                                 );
                                                 self.exec_fn_call(
                                                     mods, state, lib, FN_IDX_SET, hash_set, args,
@@ -2072,7 +2075,7 @@ impl Engine {
 
             _ if use_indexers => {
                 let args = &mut [target, &mut idx];
-                let hash_get = FnCallHashes::from_native(self.constants.fn_hash_idx_get);
+                let hash_get = FnCallHashes::from_native(state.fn_hash_idx_get());
                 let idx_pos = Position::NONE;
 
                 self.exec_fn_call(
@@ -3096,7 +3099,7 @@ impl Engine {
             // Concentrate all empty strings into one instance to save memory
             if let Dynamic(crate::dynamic::Union::Str(s, _, _)) = r {
                 if s.is_empty() {
-                    if !s.ptr_eq(&self.constants.empty_string) {
+                    if !s.ptr_eq(&self.empty_string) {
                         *s = self.const_empty_string();
                     }
                     return result;