Allow initialization of EvalState tag and separate debugger state into separate variable.

CHANGELOG.md

@@ -21,6 +21,8 @@ Enhancements
 ------------
 
 * `EvalAltResult::IndexNotFound` is added to aid in raising errors for indexers.
+* `Engine::def_tag`, `Engine::def_tag_mut` and `Engine::set_tag` are added to manage a default value for the custom evaluation state, accessible via `EvalState::tag()` (which is the same as `NativeCallContext::tag()`).
+* Originally, the debugger's custom state uses the same state as `EvalState::tag()` (which is the same as `NativeCallContext::tag()`).  It is now split into its own variable accessible under `Debugger::state()`.
 
 
 Version 1.7.0

src/api/compile.rs

@@ -201,7 +201,7 @@ impl Engine {
         scope: &Scope,
         scripts: impl AsRef<[S]>,
     ) -> ParseResult<AST> {
-        self.compile_with_scope_and_optimization_level(scope, scripts, self.optimization_level)
+        self.compile_with_scope_and_optimization_level(scope, scripts, self.optimization_level())
     }
     /// Join a list of strings and compile into an [`AST`] using own scope at a specific optimization level.
     ///
@@ -292,6 +292,6 @@ impl Engine {
 
         let mut peekable = stream.peekable();
         let mut state = ParseState::new(self, scope, tokenizer_control);
-        self.parse_global_expr(&mut peekable, &mut state, self.optimization_level)
+        self.parse_global_expr(&mut peekable, &mut state, self.optimization_level())
     }
 }

src/api/eval.rs

@@ -67,7 +67,7 @@ impl Engine {
         let ast = self.compile_with_scope_and_optimization_level(
             scope,
             &[script],
-            self.optimization_level,
+            self.optimization_level(),
         )?;
         self.eval_ast_with_scope(scope, &ast)
     }

src/api/mod.rs

@@ -30,7 +30,7 @@ pub mod deprecated;
 
 use crate::engine::Precedence;
 use crate::tokenizer::Token;
-use crate::{Engine, Identifier};
+use crate::{Dynamic, Engine, Identifier};
 
 #[cfg(feature = "no_std")]
 use std::prelude::v1::*;
@@ -195,4 +195,23 @@ impl Engine {
 
         Ok(self)
     }
+
+    /// Get the default value of the custom state for each evaluation run.
+    #[inline(always)]
+    #[must_use]
+    pub fn default_tag(&self) -> &Dynamic {
+        &self.def_tag
+    }
+    /// Get a mutable reference to the default value of the custom state for each evaluation run.
+    #[inline(always)]
+    #[must_use]
+    pub fn default_tag_mut(&mut self) -> &mut Dynamic {
+        &mut self.def_tag
+    }
+    /// Set the default value of the custom state for each evaluation run.
+    #[inline(always)]
+    pub fn set_default_tag(&mut self, value: impl Into<Dynamic>) -> &mut Self {
+        self.def_tag = value.into();
+        self
+    }
 }

src/api/run.rs

@@ -26,7 +26,11 @@ impl Engine {
             self.lex_raw(&scripts, self.token_mapper.as_ref().map(Box::as_ref));
         let mut state = ParseState::new(self, scope, tokenizer_control);
 
-        let ast = self.parse(&mut stream.peekable(), &mut state, self.optimization_level)?;
+        let ast = self.parse(
+            &mut stream.peekable(),
+            &mut state,
+            self.optimization_level(),
+        )?;
 
         self.run_ast_with_scope(scope, &ast)
     }

src/bin/rhai-dbg.rs

@@ -60,7 +60,12 @@ fn print_current_source(
     lines: &[String],
     window: (usize, usize),
 ) {
-    let current_source = &mut *context.tag_mut().write_lock::<ImmutableString>().unwrap();
+    let current_source = &mut *context
+        .global_runtime_state_mut()
+        .debugger
+        .state_mut()
+        .write_lock::<ImmutableString>()
+        .unwrap();
     let src = source.unwrap_or("");
     if src != current_source {
         println!(

src/engine.rs

@@ -132,8 +132,11 @@ pub struct Engine {
     /// Language options.
     pub(crate) options: LangOptions,
 
+    /// Default value for the custom state.
+    pub(crate) def_tag: Dynamic,
+
     /// Script optimization level.
-    pub optimization_level: OptimizationLevel,
+    pub(crate) optimization_level: OptimizationLevel,
 
     /// Max limits.
     #[cfg(not(feature = "unchecked"))]
@@ -280,6 +283,8 @@ impl Engine {
 
             options: LangOptions::new(),
 
+            def_tag: Dynamic::UNIT,
+
             #[cfg(not(feature = "no_optimize"))]
             optimization_level: OptimizationLevel::Simple,
             #[cfg(feature = "no_optimize")]

src/eval/debugger.rs

@@ -253,17 +253,20 @@ pub struct Debugger {
     break_points: Vec<BreakPoint>,
     /// The current function call stack.
     call_stack: Vec<CallStackFrame>,
+    /// The current state.
+    state: Dynamic,
 }
 
 impl Debugger {
     /// Create a new [`Debugger`].
     #[inline(always)]
     #[must_use]
-    pub fn new(status: DebuggerStatus) -> Self {
+    pub fn new(status: DebuggerStatus, state: Dynamic) -> Self {
         Self {
             status,
             break_points: Vec::new(),
             call_stack: Vec::new(),
+            state,
         }
     }
     /// Get the current call stack.
@@ -374,6 +377,23 @@ impl Debugger {
     pub fn break_points_mut(&mut self) -> &mut Vec<BreakPoint> {
         &mut self.break_points
     }
+    /// Get the custom state.
+    #[inline(always)]
+    #[must_use]
+    pub fn state(&self) -> &Dynamic {
+        &self.state
+    }
+    /// Get a mutable reference to the custom state.
+    #[inline(always)]
+    #[must_use]
+    pub fn state_mut(&mut self) -> &mut Dynamic {
+        &mut self.state
+    }
+    /// Set the custom state.
+    #[inline(always)]
+    pub fn set_state(&mut self, state: impl Into<Dynamic>) {
+        self.state = state.into();
+    }
 }
 
 impl Engine {

src/eval/global_state.rs

@@ -78,8 +78,6 @@ impl GlobalRuntimeState<'_> {
     #[inline(always)]
     #[must_use]
     pub fn new(engine: &Engine) -> Self {
-        let _engine = engine;
-
         Self {
             #[cfg(not(feature = "no_module"))]
             keys: crate::StaticVec::new_const(),
@@ -98,21 +96,21 @@ impl GlobalRuntimeState<'_> {
             #[cfg(not(feature = "no_function"))]
             constants: None,
 
-            #[cfg(not(feature = "debugging"))]
-            tag: Dynamic::UNIT,
+            tag: engine.default_tag().clone(),
+
             #[cfg(feature = "debugging")]
-            tag: if let Some((ref init, ..)) = engine.debugger {
+            debugger: crate::eval::Debugger::new(
+                if engine.debugger.is_some() {
+                    crate::eval::DebuggerStatus::Init
+                } else {
+                    crate::eval::DebuggerStatus::CONTINUE
+                },
+                if let Some((ref init, ..)) = engine.debugger {
                     init()
                 } else {
                     Dynamic::UNIT
                 },
-
-            #[cfg(feature = "debugging")]
-            debugger: crate::eval::Debugger::new(if engine.debugger.is_some() {
-                crate::eval::DebuggerStatus::Init
-            } else {
-                crate::eval::DebuggerStatus::CONTINUE
-            }),
+            ),
 
             dummy: PhantomData::default(),
         }

tests/debugging.rs

@@ -57,10 +57,18 @@ fn test_debugger_state() -> Result<(), Box<EvalAltResult>> {
         },
         |mut context, _, _, _, _| {
             // Print debugger state - which is an object map
-            println!("Current state = {}", context.tag());
+            println!(
+                "Current state = {}",
+                context.global_runtime_state_mut().debugger.state()
+            );
 
             // Modify state
-            let mut state = context.tag_mut().write_lock::<Map>().unwrap();
+            let mut state = context
+                .global_runtime_state_mut()
+                .debugger
+                .state_mut()
+                .write_lock::<Map>()
+                .unwrap();
             let hello = state.get("hello").unwrap().as_int().unwrap();
             state.insert("hello".into(), (hello + 1).into());
             state.insert("foo".into(), true.into());