1 files changed, 59 insertions, 0 deletions
diff --git a/src/gen/field/option_kind.rs b/src/gen/field/option_kind.rs
new file mode 100644
index 0000000..0fde11a
--- /dev/null
+++ b/src/gen/field/option_kind.rs
@@ -0,0 +1,59 @@
+use crate::gen::inside::protobuf_crate_path;
+use crate::gen::rust_types_values::RustType;
+use crate::Customize;
+
+/// Optional fields can be stored are `Option<T>` or `SingularPtrField<T>`.
+#[derive(Copy, Clone, Eq, PartialEq)]
+pub enum OptionKind {
+    /// Field is `Option<T>`
+    Option,
+    /// Field is `SingularPtrField<T>`
+    MessageField,
+}
+
+impl OptionKind {
+    pub(crate) fn wrap_element(&self, element_type: RustType) -> RustType {
+        let element_type = Box::new(element_type);
+        match self {
+            OptionKind::Option => RustType::Option(element_type),
+            OptionKind::MessageField => RustType::MessageField(element_type),
+        }
+    }
+
+    // Type of `as_ref()` operation
+    pub(crate) fn as_ref_type(&self, element_type: RustType) -> RustType {
+        match self {
+            OptionKind::Option => RustType::Option(Box::new(element_type.ref_type())),
+            OptionKind::MessageField => RustType::MessageField(Box::new(element_type.ref_type())),
+        }
+    }
+
+    fn _as_option_ref(&self, v: &str) -> String {
+        match self {
+            OptionKind::Option | OptionKind::MessageField => format!("{}.as_ref()", v),
+        }
+    }
+
+    pub(crate) fn unwrap_or_else(&self, what: &str, default_value: &str) -> String {
+        match self {
+            _ => format!("{}.unwrap_or_else(|| {})", what, default_value),
+        }
+    }
+
+    pub(crate) fn unwrap_ref_or_else(&self, what: &str, default_value: &str) -> String {
+        match self {
+            _ => format!("{}.unwrap_or_else(|| {})", what, default_value),
+        }
+    }
+
+    pub(crate) fn wrap_value(&self, value: &str, customize: &Customize) -> String {
+        match self {
+            OptionKind::Option => format!("::std::option::Option::Some({})", value),
+            OptionKind::MessageField => format!(
+                "{}::MessageField::some({})",
+                protobuf_crate_path(customize),
+                value
+            ),
+        }
+    }
+}