Make mapping error simple with map_err

moreal · moreal · commit c672d8f8b221 · 2022-08-14T03:48:32.000+09:00
diff --git a/vm/src/stdlib/builtins.rs b/vm/src/stdlib/builtins.rs
@@ -262,17 +262,16 @@ mod builtins {
                     ));
                 }
 
-                match std::str::from_utf8(source) {
-                    Ok(s) => Ok(Either::A(vm.ctx.new_str(s))),
-                    Err(err) => {
-                        let msg = format!(
-                            "(unicode error) 'utf-8' codec can't decode byte 0x{:x?} in position {}: invalid start byte",
-                            source[err.valid_up_to()],
-                            err.valid_up_to()
-                        );
-                        Err(vm.new_exception_msg(vm.ctx.exceptions.syntax_error.to_owned(), msg))
-                    }
-                }
+                let source = std::str::from_utf8(source).map_err(|err| {
+                    let msg = format!(
+                        "(unicode error) 'utf-8' codec can't decode byte 0x{:x?} in position {}: invalid start byte",
+                        source[err.valid_up_to()],
+                        err.valid_up_to()
+                    );
+
+                    vm.new_exception_msg(vm.ctx.exceptions.syntax_error.to_owned(), msg)
+                })?;
+                Ok(Either::A(vm.ctx.new_str(source)))
             }
             Either::B(code) => Ok(Either::B(code)),
         }?;
