Implement local variable assignment

demo/demo.rpy

@@ -2,11 +2,12 @@
 if True:
     let x = "3"
     "Bob will be here in [x] seconds."
-    let x = "2"
+    x = "2"
     "Bob will be here in [x] seconds."
     if True:
-        let x = "213"
+        x = "1"
-    let x = "1"
+        let x = "4"
+        "[x]"
     "Bob will be here in [x] seconds."
 "Bob will be here in [x] seconds."
 "Bob" "I will not say anything, [foo]"

renrs/src/lib.rs

@@ -22,6 +22,7 @@ impl State {
         self.script.borrow_mut().next(&self.script)
     }
 }
+
 impl Iterator for State {
     type Item = Event;
     fn next(&mut self) -> Option<Self::Item> {

renrs/src/parser/block.rs

@@ -1,4 +1,5 @@
 use debug_cell::RefCell;
+use core::panic;
 use std::{collections::HashMap, rc::Rc};
 
 use super::{
@@ -71,7 +72,27 @@ impl CommandContext {
                         if let Token::Keyword(_) = value {
                             todo!("assignment variable interpolation isn't implemented");
                         }
-                        todo!("local variable assignment isn't implemented")
+                        let mut block_option = Some(self.context.clone());
+                        let mut modified = false;
+                        while let Some(block) = block_option {
+                            let block = block.borrow();
+                            block
+                                .variables
+                                .borrow_mut()
+                                .entry(variable.clone())
+                                .and_modify(|e| {
+                                    *e = value.clone();
+                                    modified = true;
+                                });
+                            if modified {
+                                break;
+                            }
+                            block_option = block.parent.clone();
+                        }
+                        if !modified {
+                            panic!("undefined variable `{variable}`");
+                        }
+                        return None;
                     }
                 },
                 Eat { .. } => return None,

renrs/src/parser/command.rs

@@ -73,6 +73,11 @@ pub fn parse_command(pair: Pair) -> Command {
             variable: variable.clone(),
             value: value.clone(),
         },
+        [Keyword(variable), Keyword(equals), value] if equals.eq("=") => Assign {
+            assign_type: AssignType::Assign,
+            variable: variable.clone(),
+            value: value.clone()
+        },
         [Keyword(keyword), Str(food), tail @ ..] if keyword.eq("eat") => Eat {
             food: food.to_owned(),
             politely: match tail {