Phase 3.1-3.3: ReactiveTracker with ElementId assignment during parsing, dependency scanning, variable change notification in app.rs

src/app.rs

@@ -19,23 +19,36 @@ impl GlintApp {
     pub fn update(&mut self, message: Message) -> iced::Task<Message> {
         match message {
             Message::WindowScrolled(y) => {
-                self.doc.variables.insert("__scroll_y".to_string(), Value::Float(y as f64));
+                let var = "__scroll_y".to_string();
+                self.doc.variables.insert(var.clone(), Value::Float(y as f64));
+                self.doc.tracker.on_variable_changed(&var);
             }
             Message::EventTriggered(script) => {
                 if !script.is_empty() {
+                    let old_vars: Vec<String> = self.doc.variables.keys().cloned().collect();
                     self.rhei.execute_action(&script, &mut self.doc.variables);
+                    let new_vars: Vec<String> = self.doc.variables.keys().cloned().collect();
+                    for v in &new_vars {
+                        if !old_vars.contains(v) || self.doc.variables.get(v) != old_vars.iter().find_map(|k| if k == v { self.doc.variables.get(k) } else { None }) {
+                            self.doc.tracker.on_variable_changed(v);
+                        }
+                    }
                 }
             }
             Message::InputChanged(Some(var), val) => {
-                self.doc.variables.insert(var, Value::from(val));
+                self.doc.variables.insert(var.clone(), Value::from(val));
+                self.doc.tracker.on_variable_changed(&var);
             }
             Message::ToggleChanged(Some(var), val) => {
-                self.doc.variables.insert(var, Value::Bool(val));
+                self.doc.variables.insert(var.clone(), Value::Bool(val));
+                self.doc.tracker.on_variable_changed(&var);
             }
             Message::SliderChanged(Some(var), val) => {
                 self.doc.variables.insert(var.clone(), Value::Float(val));
+                self.doc.tracker.on_variable_changed(&var);
                 if var == "volume_level" {
                     self.doc.variables.insert("age".to_string(), Value::Float(val));
+                    self.doc.tracker.on_variable_changed("age");
                 }
             }
             _ => {}

src/interpreter/mod.rs

@@ -1,5 +1,6 @@
 
 pub mod opcodes;
+pub mod reactive;
 pub mod reader;
 pub mod rhei;
 pub mod style;
@@ -9,6 +10,7 @@ use std::borrow::Cow;
 pub use rhei::RheiContext;
 use style::StyleSheet as SS;
 pub use types::{ComponentDef, Document, Element, Interner, InterpError};
+pub use reactive::{ElementId, ReactiveTracker};
 
 use compact_str::CompactString;
 use opcodes::*;
@@ -31,6 +33,7 @@ impl Interpreter {
         let mut components  = HashMap::new();
         let mut rhei_scripts: Vec<String> = Vec::new();
         let mut stylesheet  = SS::new();
+        let mut tracker     = ReactiveTracker::new();
 
         let roots = Self::parse_block_elements(
             &mut r,
@@ -38,13 +41,14 @@ impl Interpreter {
             &mut components,
             &mut rhei_scripts,
             &mut stylesheet,
+            &mut tracker,
             true,
         )?;
 
         //let rhei_ctx = RheiContext::new(&rhei_scripts);
         //rhei_ctx.initialize(&mut variables);
 
-        Ok(Document { roots, components, variables, rhei_scripts, stylesheet, interner: Interner::new() })
+        Ok(Document { roots, components, variables, rhei_scripts, stylesheet, interner: Interner::new(), tracker })
     }
 
     fn parse_block_elements<'a>(
@@ -53,6 +57,7 @@ impl Interpreter {
     components:   &mut HashMap<String, ComponentDef<'a>>,
     rhei_scripts: &mut Vec<String>,
     stylesheet:   &mut SS,
+    tracker:      &mut ReactiveTracker,
     is_root:      bool,
 ) -> Result<Vec<Element<'a>>, InterpError> {
         let mut roots: Vec<Element> = Vec::new();
@@ -63,8 +68,12 @@ impl Interpreter {
             if !is_root && op == OP_END_BLOCK { break; }
 
             match op {
-                OP_ELEM_PUSH => stack.push(Element::new(r.read_str_ref()?)),
-
+                OP_ELEM_PUSH => {
+                    let elem_id = tracker.alloc_id();
+                    let mut el = Element::new(r.read_str_ref()?);
+                    el.element_id = elem_id;
+                    stack.push(el);
+                }
                 OP_ELEM_POP => {
                     let finished = stack.pop().ok_or(InterpError::UnexpectedPop)?;
                     Self::attach(&mut stack, &mut roots, finished);
@@ -96,10 +105,12 @@ impl Interpreter {
                         val.push_str(RHEI_PREFIX);
                         val.push_str(expr_ref);
                         if let Some(el) = stack.last_mut() {
+                            tracker.scan_value(el.element_id, &val);
                             el.push_prop("text".to_string(), val);
                         }
                     } else if let Some(value) = r.read_value_as_string(vop)? {
                         if let Some(el) = stack.last_mut() {
+                            tracker.scan_value(el.element_id, &value);
                             el.push_prop("text".to_string(), value);
                         }
                     }
@@ -108,7 +119,10 @@ impl Interpreter {
                 OP_PROP_STR => {
                     let key = r.read_str_ref()?;
                     let val = r.read_str_ref()?;
-                    if let Some(el) = stack.last_mut() { el.push_prop(key, val); }
+                    if let Some(el) = stack.last_mut() {
+                        tracker.scan_value(el.element_id, val);
+                        el.push_prop(key, val);
+                    }
                 }
                 OP_PROP_VAR => {
                     let key = r.read_str_ref()?;
@@ -116,22 +130,31 @@ impl Interpreter {
                     let mut val = String::with_capacity(val_ref.len() + 1);
                     val.push('$');
                     val.push_str(val_ref);
-                    if let Some(el) = stack.last_mut() { el.push_prop(key, val); }
+                    if let Some(el) = stack.last_mut() {
+                        tracker.scan_value(el.element_id, &val);
+                        el.push_prop(key, val);
+                    }
                 }
                 OP_PROP_INT => {
                     let key = r.read_str_ref()?;
                     let val = r.read_i64()?.to_string();
-                    if let Some(el) = stack.last_mut() { el.push_prop(key, val); }
+                    if let Some(el) = stack.last_mut() {
+                        el.push_prop(key, val);
+                    }
                 }
                 OP_PROP_FLOAT => {
                     let key = r.read_str_ref()?;
                     let val = r.read_f64()?.to_string();
-                    if let Some(el) = stack.last_mut() { el.push_prop(key, val); }
+                    if let Some(el) = stack.last_mut() {
+                        el.push_prop(key, val);
+                    }
                 }
                 OP_PROP_BOOL => {
                     let key = r.read_str_ref()?;
                     let val = (r.read_byte()? != 0).to_string();
-                    if let Some(el) = stack.last_mut() { el.push_prop(key, val); }
+                    if let Some(el) = stack.last_mut() {
+                        el.push_prop(key, val);
+                    }
                 }
                 OP_PROP_RHEI => {
                     let key = r.read_str_ref()?;
@@ -140,13 +163,16 @@ impl Interpreter {
                     val.push_str(RHEI_PREFIX);
                     val.push_str(expr_ref);
                     if let Some(el) = stack.last_mut() {
+                        tracker.scan_value(el.element_id, &val);
                         el.push_prop(key, val);
                     }
                 }
                 OP_PROP_UNIT | OP_PROP_CALL | OP_PROP_IDENT | OP_PROP_FSPATH | OP_PROP_COLOR => {
                     let key = r.read_str_ref()?;
                     if let Some(val) = r.read_value_as_string(op)? {
-                        if let Some(el) = stack.last_mut() { el.push_prop(key, val); }
+                        if let Some(el) = stack.last_mut() {
+                            el.push_prop(key, val);
+                        }
                     }
                 }
 
@@ -156,10 +182,10 @@ impl Interpreter {
                         rhei_scripts.push(script);
                     } else {
                         let mut text_el = Element::new("#text");
-                        text_el.push_prop(
-                            "text".to_string(),
-                            format!("{RHEI_PREFIX}{script}"),
-                        );
+                        text_el.element_id = tracker.alloc_id();
+                        let full_val = format!("{RHEI_PREFIX}{script}");
+                        tracker.scan_value(text_el.element_id, &full_val);
+                        text_el.push_prop("text".to_string(), full_val);
                         Self::attach(&mut stack, &mut roots, text_el);
                     }
                 }
@@ -171,7 +197,7 @@ impl Interpreter {
                         .map(|_| Ok((r.read_string()?, r.read_string()?)))
                         .collect::<Result<Vec<_>, InterpError>>()?;
                     let children = Self::parse_block_elements(
-                        r, variables, components, rhei_scripts, stylesheet, false,
+                        r, variables, components, rhei_scripts, stylesheet, tracker, false,
                     )?;
                     components.insert(name.clone(), ComponentDef { name, params, children });
                 }
@@ -186,23 +212,26 @@ impl Interpreter {
                     };
 
                     let true_children  = Self::parse_block_elements(
-                        r, variables, components, rhei_scripts, stylesheet, false,
+                        r, variables, components, rhei_scripts, stylesheet, tracker, false,
                     )?;
                     let has_else = r.read_byte()? == 1;
                     let false_children = if has_else {
                         Self::parse_block_elements(
-                            r, variables, components, rhei_scripts, stylesheet, false,
+                            r, variables, components, rhei_scripts, stylesheet, tracker, false,
                         )?
                     } else {
                         Vec::new()
                     };
 
                     let mut if_el = Element::new("@if");
+                    if_el.element_id = tracker.alloc_id();
+                    tracker.scan_value(if_el.element_id, &cond_val);
                     if_el.push_prop("condition", cond_val);
                     if_el.children = true_children;
 
                     if !false_children.is_empty() {
                         let mut else_el = Element::new("@else");
+                        else_el.element_id = tracker.alloc_id();
                         else_el.children = false_children;
                         if_el.children.push(else_el);
                     }
@@ -221,10 +250,12 @@ impl Interpreter {
                     };
 
                     let block_children = Self::parse_block_elements(
-                        r, variables, components, rhei_scripts, stylesheet, false,
+                        r, variables, components, rhei_scripts, stylesheet, tracker, false,
                     )?;
 
                     let mut each_el = Element::new("@each");
+                    each_el.element_id = tracker.alloc_id();
+                    tracker.scan_value(each_el.element_id, &source_val);
                     each_el.push_prop("var_name".to_string(), var_name);
                     each_el.push_prop("source".to_string(), source_val);
                     each_el.children = block_children;

src/interpreter/reactive.rs

@@ -0,0 +1,171 @@
+use std::collections::{HashMap, HashSet};
+
+/// Unique identifier for an element in the VDOM tree.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct ElementId(pub u32);
+
+/// Tracks which variables affect which elements for incremental VDOM updates.
+#[derive(Debug, Clone)]
+pub struct ReactiveTracker {
+    /// For each variable name, which elements depend on it
+    subscribers: HashMap<String, HashSet<ElementId>>,
+    /// For each element, which variables it depends on
+    dependencies: HashMap<ElementId, HashSet<String>>,
+    /// Elements that need to be re-evaluated
+    dirty_set: HashSet<ElementId>,
+    next_id: u32,
+}
+
+impl ReactiveTracker {
+    pub fn new() -> Self {
+        Self {
+            subscribers: HashMap::new(),
+            dependencies: HashMap::new(),
+            dirty_set: HashSet::new(),
+            next_id: 0,
+        }
+    }
+
+    pub fn alloc_id(&mut self) -> ElementId {
+        let id = ElementId(self.next_id);
+        self.next_id += 1;
+        id
+    }
+
+    /// Register that `element` depends on `var_name`.
+    /// Call this during template parsing for each `$var` or `!rhee:{expr}` reference.
+    pub fn add_dependency(&mut self, element: ElementId, var_name: &str) {
+        self.subscribers.entry(var_name.to_string())
+            .or_default()
+            .insert(element);
+        self.dependencies.entry(element)
+            .or_default()
+            .insert(var_name.to_string());
+    }
+
+    /// Register multiple dependencies for an element from a property value.
+    pub fn scan_value(&mut self, element: ElementId, value: &str) {
+        // Scan for `$var` patterns
+        let mut chars = value.char_indices().peekable();
+        while let Some((_, c)) = chars.next() {
+            if c == '$' {
+                let mut var_name = String::new();
+                while let Some(&(_, next_c)) = chars.peek() {
+                    if next_c.is_ascii_alphanumeric() || next_c == '_' {
+                        var_name.push(chars.next().unwrap().1);
+                    } else {
+                        break;
+                    }
+                }
+                if !var_name.is_empty() {
+                    self.add_dependency(element, &var_name);
+                }
+            }
+        }
+    }
+
+    /// Called when a variable changes. Marks affected elements as dirty.
+    pub fn on_variable_changed(&mut self, name: &str) -> &HashSet<ElementId> {
+        if let Some(affected) = self.subscribers.get(name) {
+            self.dirty_set.extend(affected.iter());
+        }
+        &self.dirty_set
+    }
+
+    /// Returns the current dirty set and clears it.
+    pub fn take_dirty_set(&mut self) -> HashSet<ElementId> {
+        std::mem::take(&mut self.dirty_set)
+    }
+
+    /// Returns true if the element needs re-evaluation.
+    pub fn is_dirty(&self, id: ElementId) -> bool {
+        self.dirty_set.contains(&id)
+    }
+
+    /// Clear all tracking data (e.g., on template reload).
+    pub fn reset(&mut self) {
+        self.subscribers.clear();
+        self.dependencies.clear();
+        self.dirty_set.clear();
+        self.next_id = 0;
+    }
+}
+
+impl Default for ReactiveTracker {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_basic_dependency_tracking() {
+        let mut tracker = ReactiveTracker::new();
+        let e1 = tracker.alloc_id();
+        let e2 = tracker.alloc_id();
+
+        tracker.add_dependency(e1, "volume");
+        tracker.add_dependency(e2, "volume");
+        tracker.add_dependency(e2, "brightness");
+
+        let affected = tracker.on_variable_changed("volume");
+        assert!(affected.contains(&e1));
+        assert!(affected.contains(&e2));
+
+        let affected = tracker.on_variable_changed("brightness");
+        assert!(!affected.contains(&e1));
+        assert!(affected.contains(&e2));
+    }
+
+    #[test]
+    fn test_scan_value() {
+        let mut tracker = ReactiveTracker::new();
+        let e1 = tracker.alloc_id();
+
+        tracker.scan_value(e1, "Hello $name, you are $age years old");
+
+        let affected = tracker.on_variable_changed("name");
+        assert!(affected.contains(&e1));
+
+        let affected = tracker.on_variable_changed("age");
+        assert!(affected.contains(&e1));
+    }
+
+    #[test]
+    fn test_scan_no_vars() {
+        let mut tracker = ReactiveTracker::new();
+        let e1 = tracker.alloc_id();
+
+        tracker.scan_value(e1, "Hello world");
+        let affected = tracker.on_variable_changed("name");
+        assert!(!affected.contains(&e1));
+    }
+
+    #[test]
+    fn test_take_dirty_set() {
+        let mut tracker = ReactiveTracker::new();
+        let e1 = tracker.alloc_id();
+
+        tracker.add_dependency(e1, "x");
+        tracker.on_variable_changed("x");
+
+        let dirty = tracker.take_dirty_set();
+        assert_eq!(dirty.len(), 1);
+        assert!(tracker.dirty_set.is_empty());
+    }
+
+    #[test]
+    fn test_reset() {
+        let mut tracker = ReactiveTracker::new();
+        let e1 = tracker.alloc_id();
+        tracker.add_dependency(e1, "x");
+        tracker.reset();
+
+        assert!(tracker.subscribers.is_empty());
+        assert!(tracker.dependencies.is_empty());
+        assert!(tracker.dirty_set.is_empty());
+    }
+}

src/interpreter/types.rs

@@ -3,6 +3,7 @@ use std::collections::HashMap;
 use std::fmt;
 
 
+use super::reactive::{ElementId, ReactiveTracker};
 use super::style::{ComputedStyle, StyleSheet};
 use compact_str::CompactString;
 
@@ -164,6 +165,7 @@ pub struct Element<'a> {
     pub properties: Vec<(Cow<'a, str>, Cow<'a, str>)>,
     pub children:       Vec<Element<'a>>,
     pub computed_style: ComputedStyle,
+    pub element_id:     ElementId,
 }
 
 impl<'a> Element<'a> {
@@ -179,6 +181,17 @@ impl<'a> Element<'a> {
             properties:     Vec::with_capacity(8),
             children:       Vec::with_capacity(4),
             computed_style: ComputedStyle::default(),
+            element_id:     ElementId(u32::MAX),
+        }
+    }
+
+    pub fn new_with_id(type_name: &'a str, id: ElementId) -> Self {
+        Self {
+            type_name,
+            properties:     Vec::with_capacity(8),
+            children:       Vec::with_capacity(4),
+            computed_style: ComputedStyle::default(),
+            element_id:     id,
         }
     }
 }
@@ -198,6 +211,7 @@ pub struct Document<'a> {
     pub rhei_scripts: Vec<String>,
     pub stylesheet:   StyleSheet,
     pub interner:     Interner,
+    pub tracker:      ReactiveTracker,
 }
 
 #[derive(Debug)]