Reduce size of Engine.

src/api/mod.rs

@@ -35,6 +35,7 @@ pub mod definitions;
 
 use crate::{Dynamic, Engine, Identifier};
 
+use std::collections::BTreeSet;
 #[cfg(feature = "no_std")]
 use std::prelude::v1::*;
 
@@ -107,7 +108,9 @@ impl Engine {
     /// ```
     #[inline(always)]
     pub fn disable_symbol(&mut self, symbol: impl Into<Identifier>) -> &mut Self {
-        self.disabled_symbols.insert(symbol.into());
+        self.disabled_symbols
+            .get_or_insert_with(|| BTreeSet::new().into())
+            .insert(symbol.into());
         self
     }
 
@@ -163,18 +166,31 @@ impl Engine {
             // Active standard keywords cannot be made custom
             // Disabled keywords are OK
             Some(token) if token.is_standard_keyword() => {
-                if !self.disabled_symbols.contains(token.literal_syntax()) {
+                if !self
+                    .disabled_symbols
+                    .as_ref()
+                    .map_or(false, |m| m.contains(token.literal_syntax()))
+                {
                     return Err(format!("'{keyword}' is a reserved keyword"));
                 }
             }
             // Active standard symbols cannot be made custom
             Some(token) if token.is_standard_symbol() => {
-                if !self.disabled_symbols.contains(token.literal_syntax()) {
+                if !self
+                    .disabled_symbols
+                    .as_ref()
+                    .map_or(false, |m| m.contains(token.literal_syntax()))
+                {
                     return Err(format!("'{keyword}' is a reserved operator"));
                 }
             }
             // Active standard symbols cannot be made custom
-            Some(token) if !self.disabled_symbols.contains(token.literal_syntax()) => {
+            Some(token)
+                if !self
+                    .disabled_symbols
+                    .as_ref()
+                    .map_or(false, |m| m.contains(token.literal_syntax())) =>
+            {
                 return Err(format!("'{keyword}' is a reserved symbol"))
             }
             // Disabled symbols are OK
@@ -183,6 +199,7 @@ impl Engine {
 
         // Add to custom keywords
         self.custom_keywords
+            .get_or_insert_with(|| std::collections::BTreeMap::new().into())
             .insert(keyword.into(), Some(precedence));
 
         Ok(self)