Add console.log, avoid printing undefined result

valuescript_vm/src/builtins/console_builtin.rs

@@ -0,0 +1,52 @@
+use std::fmt;
+use std::rc::Rc;
+
+use crate::native_function::{native_fn, NativeFunction};
+use crate::vs_class::VsClass;
+use crate::vs_value::{LoadFunctionResult, ToVal, Val};
+
+use super::builtin_object::BuiltinObject;
+
+pub struct ConsoleBuiltin {}
+
+impl BuiltinObject for ConsoleBuiltin {
+  fn bo_name() -> &'static str {
+    "console"
+  }
+
+  fn bo_sub(key: &str) -> Val {
+    match key {
+      "log" => LOG.to_val(),
+
+      _ => Val::Undefined,
+    }
+  }
+
+  fn bo_load_function() -> LoadFunctionResult {
+    LoadFunctionResult::NotAFunction
+  }
+
+  fn bo_as_class_data() -> Option<Rc<VsClass>> {
+    None
+  }
+}
+
+impl fmt::Display for ConsoleBuiltin {
+  fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+    write!(f, "[object console]")
+  }
+}
+
+static LOG: NativeFunction = native_fn(|_this, params| {
+  for (i, p) in params.iter().enumerate() {
+    if i > 0 {
+      print!(" ");
+    }
+
+    print!("{}", p);
+  }
+
+  println!();
+
+  Ok(Val::Undefined)
+});

valuescript_vm/src/builtins/mod.rs

@@ -2,6 +2,7 @@ mod array_builtin;
 mod bigint_builtin;
 mod boolean_builtin;
 mod builtin_object;
+mod console_builtin;
 mod debug_builtin;
 pub mod error_builtin;
 pub mod internal_error_builtin;
@@ -21,7 +22,7 @@ use crate::{
 
 use self::{
   array_builtin::ArrayBuiltin, bigint_builtin::BigIntBuiltin, boolean_builtin::BooleanBuiltin,
-  debug_builtin::DebugBuiltin, error_builtin::ErrorBuiltin,
+  console_builtin::ConsoleBuiltin, debug_builtin::DebugBuiltin, error_builtin::ErrorBuiltin,
   internal_error_builtin::InternalErrorBuiltin, math_builtin::MathBuiltin,
   number_builtin::NumberBuiltin, range_error_builtin::RangeErrorBuiltin,
   string_builtin::StringBuiltin, symbol_builtin::SymbolBuiltin,
@@ -46,4 +47,5 @@ pub static BUILTIN_VALS: [fn() -> Val; BUILTIN_COUNT] = [
   || SymbolBuiltin {}.to_val(),
   || VsSymbol::ITERATOR.to_val(),
   || BigIntBuiltin {}.to_val(),
+  || ConsoleBuiltin {}.to_val(),
 ];