Merge pull request #19 from invariant-labs/add-checked_big_div

Add checked big div
invariant-labs · Oct 11, 2023 · 0755759 · 0755759
2 parents 9d4992b + 39bd3d2
commit 0755759
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Showing 3 changed files with 36 additions and 1 deletion.
diff --git a/decimal_core/src/big_ops.rs b/decimal_core/src/big_ops.rs
@@ -82,6 +82,27 @@ pub fn generate_big_ops(characteristics: DecimalCharacteristics) -> proc_macro::
                 )
             }
 
+            fn checked_big_div(self, rhs: T) -> std::result::Result<Self, String> {
+                Ok(
+                    Self::new(
+                        #big_type::try_from(self.get())
+                            .map_err(|_| format!("decimal: lhs value can't fit into `{}` type in {}::big_div()", #big_str, #name_str))?
+                            .checked_mul(
+                                T::one()
+                            )
+                            .ok_or_else(|| format!("decimal: overflow in method {}::big_div()", #name_str))?
+                            .checked_div(
+                                rhs.get()
+                                    .try_into()
+                                    .map_err(|_| format!("decimal: rhs value can't fit into `{}` type in {}::big_div()", #big_str, #name_str))?
+                            )
+                            .ok_or_else(|| format!("decimal: overflow in method {}::big_div()", #name_str))?
+                            .try_into()
+                            .map_err(|_| format!("decimal: overflow casting result to `{}` type in method {}::big_div()", #underlying_str, #name_str))?
+                    )
+                )
+            }
+
             fn big_div_up(self, rhs: T) -> Self {
                 Self::new(
                     #big_type::try_from(self.get())
@@ -133,6 +154,14 @@ pub fn generate_big_ops(characteristics: DecimalCharacteristics) -> proc_macro::
                 assert_eq!(a.big_div(b), #struct_name::new(2));
             }
 
+
+            #[test]
+            fn test_checked_big_div () {
+                let a = #struct_name::new(29);
+                let b = #struct_name::new(#struct_name::one());
+                assert_eq!(a.big_div(b), #struct_name::new(29));
+            }
+
             #[test]
             fn test_big_div_up () {
                 let a = #struct_name::new(2);

diff --git a/src/traits.rs b/src/traits.rs
@@ -16,10 +16,11 @@ pub trait Decimal {
     fn almost_one<T: TryFrom<u128>>() -> T;
 }
 
-pub trait BigOps<T> {
+pub trait BigOps<T>: Sized {
     fn big_mul(self, rhs: T) -> Self;
     fn big_mul_up(self, rhs: T) -> Self;
     fn big_div(self, rhs: T) -> Self;
+    fn checked_big_div(self, rhs: T) -> std::result::Result<Self, String>;
     fn big_div_up(self, rhs: T) -> Self;
 }
 

diff --git a/src/walkthrough.rs b/src/walkthrough.rs
@@ -86,6 +86,11 @@ mod walkthrough {
             let result = percentage.checked_sub(Percentage::new(10));
             assert_eq!(result, Ok(Percentage::new(90)));
         }
+        // checked big div
+        {
+            let price = Price::max_instance().checked_big_div(Price::new(50000));
+            assert_eq!(price, Ok(Price::new(68056473384187692692674921486353642291)));
+        }
 
         // checked_from_scale
         {