Add NAN and ZERO (#48)

README.md

@@ -16,7 +16,7 @@ println!("{}", timestamp); // Timestamp(1701620628123456789)
 - **Derive trait `StrongType`:** Create a named strong type. 
   - The macro automatically implement common traits like `Clone`, `Debug`, `Default`, `PartialEq`, `PartialOrd`, `Send`, and `Sync`. It also implements `Display` by default, unless overridden by the custom_display attribute. 
   - Conditionally, based on the underlying data type, traits like `Copy`, `Eq`, `Ord`, `Hash` may also be implemented. For primitive data types like `i32` or `bool`, these additional traits will be automatically included.
-  - Numeric types, both integer and floating-point, also implement constants `MIN`, `MAX`. Additionally, for floating-point types, the method `nan()` is implemented.
+  - Numeric types, both integer and floating-point, also implement constants `MIN`, `MAX`, and `ZERO`. Additionally, for floating-point types, `NAN` is implemented.
 
 - **Attributes:** Adding the following attributes to `#[strong_type(...)]` allows for additional features:
   - `auto_operators`: Automatically implements relevant arithmetic (for numeric types) or logical (for boolean types) operators.

strong-type-derive/src/detail/min_max.rs → strong-type-derive/src/detail/constants.rs

@@ -1,11 +1,12 @@
 use proc_macro2::TokenStream;
 use quote::quote;
 
-pub(crate) fn implement_min_max(name: &syn::Ident, value_type: &syn::Ident) -> TokenStream {
+pub(crate) fn implement_constants(name: &syn::Ident, value_type: &syn::Ident) -> TokenStream {
     quote! {
         impl #name {
             const MIN: Self = Self(#value_type::MIN);
             const MAX: Self = Self(#value_type::MAX);
+            const ZERO: Self = Self(0 as #value_type);
         }
     }
 }

strong-type-derive/src/detail/mod.rs

@@ -4,9 +4,9 @@ mod basic_primitive;
 mod basic_string;
 mod bit_ops;
 mod bool_ops;
+mod constants;
 mod display;
 mod hash;
-mod min_max;
 mod nan;
 mod negate;
 mod underlying_type;
@@ -18,9 +18,9 @@ pub(crate) use basic_primitive::implement_basic_primitive;
 pub(crate) use basic_string::implement_basic_string;
 pub(crate) use bit_ops::implement_bit_shift;
 pub(crate) use bool_ops::implement_bool_ops;
+pub(crate) use constants::implement_constants;
 pub(crate) use display::implement_display;
 pub(crate) use hash::implement_hash;
-pub(crate) use min_max::implement_min_max;
 pub(crate) use nan::implement_nan;
 pub(crate) use negate::implement_negate;
 pub(crate) use underlying_type::{get_type_group, get_type_ident, UnderlyingTypeGroup};

strong-type-derive/src/detail/nan.rs

@@ -4,9 +4,7 @@ use quote::quote;
 pub(crate) fn implement_nan(name: &syn::Ident, value_type: &syn::Ident) -> TokenStream {
     quote! {
         impl #name {
-            fn nan() -> Self {
-                Self(#value_type::NAN)
-            }
+            const NAN: Self = Self(#value_type::NAN);
 
             fn is_nan(&self) -> bool {
                 self.0.is_nan()

strong-type-derive/src/strong_type.rs

@@ -1,7 +1,7 @@
 use crate::detail::{
     get_attributes, get_type_group, get_type_ident, implement_arithmetic, implement_basic,
     implement_basic_primitive, implement_basic_string, implement_bit_shift, implement_bool_ops,
-    implement_display, implement_hash, implement_min_max, implement_nan, implement_negate,
+    implement_constants, implement_display, implement_hash, implement_nan, implement_negate,
     is_struct_valid, StrongTypeAttributes, UnderlyingTypeGroup,
 };
 use proc_macro2::TokenStream;
@@ -31,12 +31,12 @@ pub(super) fn expand_strong_type(input: DeriveInput) -> TokenStream {
     match &group {
         UnderlyingTypeGroup::Int | UnderlyingTypeGroup::UInt => {
             ast.extend(implement_basic_primitive(name, value_type));
-            ast.extend(implement_min_max(name, value_type));
+            ast.extend(implement_constants(name, value_type));
             ast.extend(implement_hash(name));
         }
         UnderlyingTypeGroup::Float => {
             ast.extend(implement_basic_primitive(name, value_type));
-            ast.extend(implement_min_max(name, value_type));
+            ast.extend(implement_constants(name, value_type));
             ast.extend(implement_nan(name, value_type));
         }
         UnderlyingTypeGroup::Bool => {

strong-type-tests/tests/strong_type.rs

@@ -96,18 +96,27 @@ mod tests {
     }
 
     #[test]
-    fn test_min_max() {
+    fn test_constants() {
         #[derive(StrongType)]
         struct Second(i32);
 
         assert_eq!(Second::MAX.value(), i32::MAX);
         assert_eq!(Second::MIN.value(), i32::MIN);
+        assert_eq!(Second::ZERO.value(), 0i32);
 
         #[derive(StrongType)]
-        struct Meter(f64);
+        struct State(u8);
+
+        assert_eq!(State::MAX.value(), u8::MAX);
+        assert_eq!(State::MIN.value(), u8::MIN);
+        assert_eq!(State::ZERO.value(), 0u8);
+
+        #[derive(StrongType)]
+        struct Meter(f32);
 
-        assert_eq!(Meter::MAX.value(), f64::MAX);
-        assert_eq!(Meter::MIN.value(), f64::MIN);
+        assert_eq!(Meter::MAX.value(), f32::MAX);
+        assert_eq!(Meter::MIN.value(), f32::MIN);
+        assert_eq!(Meter::ZERO.value(), 0f32);
     }
 
     #[test]
@@ -207,7 +216,7 @@ mod tests {
         #[derive(StrongType)]
         struct Meter(f64);
 
-        let y = Meter::nan();
+        let y = Meter::NAN;
         assert!(y.is_nan());
         assert!(y.value().is_nan());