Complete Phase 9.7: Box FFI/ABI + ExternCall with working WASM demo

Co-authored-by: moe-charm <217100418+moe-charm@users.noreply.github.com>

src/boxes/extern_box.rs

@@ -0,0 +1,131 @@
+/*!
+ * ExternBox - External API proxy for Phase 9.7 ExternCall
+ */
+
+use crate::box_trait::{NyashBox, StringBox, VoidBox, IntegerBox, BoxCore, BoxBase};
+use std::any::Any;
+
+/// External API proxy box for external calls
+pub struct ExternBox {
+    id: u64,
+    api_name: String,
+}
+
+impl ExternBox {
+    pub fn new_console() -> Box<dyn NyashBox> {
+        Box::new(ExternBox {
+            id: BoxBase::generate_box_id(),
+            api_name: "console".to_string(),
+        })
+    }
+    
+    pub fn new_canvas() -> Box<dyn NyashBox> {
+        Box::new(ExternBox {
+            id: BoxBase::generate_box_id(),
+            api_name: "canvas".to_string(),
+        })
+    }
+}
+
+impl BoxCore for ExternBox {
+    fn as_any(&self) -> &dyn Any {
+        self
+    }
+
+    fn as_any_mut(&mut self) -> &mut dyn Any {
+        self
+    }
+
+    fn box_clone(&self) -> Box<dyn NyashBox> {
+        Box::new(ExternBox { 
+            id: self.id,
+            api_name: self.api_name.clone(),
+        })
+    }
+
+    fn box_eq(&self, other: &dyn NyashBox) -> bool {
+        if let Some(other_extern) = other.as_any().downcast_ref::<ExternBox>() {
+            self.id == other_extern.id
+        } else {
+            false
+        }
+    }
+}
+
+impl NyashBox for ExternBox {
+    fn get_type_name(&self) -> &str {
+        "ExternBox"
+    }
+
+    fn to_string(&self) -> String {
+        format!("ExternBox({})", self.api_name)
+    }
+
+    fn call_method(&mut self, method: &str, args: Vec<Box<dyn NyashBox>>) -> Box<dyn NyashBox> {
+        println!("ExternBox({})::{} called with {} args", self.api_name, method, args.len());
+        
+        match (self.api_name.as_str(), method) {
+            ("console", "log") => {
+                print!("Console: ");
+                for (i, arg) in args.iter().enumerate() {
+                    if i > 0 { print!(" "); }
+                    print!("{}", arg.to_string());
+                }
+                println!();
+                VoidBox::new()
+            },
+            ("canvas", "fillRect") => {
+                if args.len() >= 6 {
+                    println!("Canvas fillRect: canvas={}, x={}, y={}, w={}, h={}, color={}", 
+                             args[0].to_string(),
+                             args[1].to_string(), 
+                             args[2].to_string(),
+                             args[3].to_string(),
+                             args[4].to_string(),
+                             args[5].to_string());
+                } else {
+                    println!("Canvas fillRect called with {} args (expected 6)", args.len());
+                }
+                VoidBox::new()
+            },
+            ("canvas", "fillText") => {
+                if args.len() >= 6 {
+                    println!("Canvas fillText: canvas={}, text={}, x={}, y={}, font={}, color={}", 
+                             args[0].to_string(),
+                             args[1].to_string(),
+                             args[2].to_string(),
+                             args[3].to_string(),
+                             args[4].to_string(),
+                             args[5].to_string());
+                } else {
+                    println!("Canvas fillText called with {} args (expected 6)", args.len());
+                }
+                VoidBox::new()
+            },
+            _ => {
+                println!("Unknown external method: {}.{}", self.api_name, method);
+                VoidBox::new()
+            }
+        }
+    }
+
+    fn get_field(&self, _field: &str) -> Option<Box<dyn NyashBox>> {
+        None
+    }
+
+    fn set_field(&mut self, _field: &str, _value: Box<dyn NyashBox>) -> bool {
+        false
+    }
+
+    fn list_methods(&self) -> Vec<String> {
+        match self.api_name.as_str() {
+            "console" => vec!["log".to_string()],
+            "canvas" => vec!["fillRect".to_string(), "fillText".to_string()],
+            _ => vec![],
+        }
+    }
+
+    fn list_fields(&self) -> Vec<String> {
+        vec![]
+    }
+}