better way to convert from u64 to i64

Author: anihamde

pyth-sdk/src/error.rs

@@ -9,5 +9,7 @@ pub enum LiquidityOracleError {
     #[error("final discount rate should not be greater than the discount precision")]
     FinalDiscountExceedsPrecision,
     #[error("None encountered")]
-    NoneEncountered
+    NoneEncountered,
+    #[error("i64 try from error")]
+    I64ConversionError,
 }

pyth-sdk/src/price.rs

@@ -135,13 +135,13 @@ impl Price {
             return Err(LiquidityOracleError::FinalDiscountExceedsPrecision.into());
         }
 
-        let remaining_depositable = (max_deposits-deposits) as i64;
-        let diff_discount_precision_initial = (discount_precision-discount_initial) as i64;
-        let diff_discount_precision_final = (discount_precision-discount_final) as i64;
+        let remaining_depositable = utils::u64_to_i64(max_deposits-deposits)?;
+        let diff_discount_precision_initial = utils::u64_to_i64(discount_precision-discount_initial)?;
+        let diff_discount_precision_final = utils::u64_to_i64(discount_precision-discount_final)?;
 
         // get fractions for deposits
         let deposits_as_price = Price {
-            price: deposits as i64,
+            price: utils::u64_to_i64(deposits)?,
             conf: 0,
             expo: 0,
             publish_time: 0,
@@ -153,7 +153,7 @@ impl Price {
             publish_time: 0,
         };
         let max_deposits_as_price = Price {
-            price: max_deposits as i64,
+            price: utils::u64_to_i64(max_deposits)?,
             conf: 1,
             expo: 0,
             publish_time: 0,
@@ -176,7 +176,7 @@ impl Price {
             publish_time: 0,
         };
         let discount_precision_as_price = Price {
-            price: discount_precision as i64,
+            price: utils::u64_to_i64(discount_precision)?,
             conf: 1,
             expo: 0,
             publish_time: 0,

pyth-sdk/src/utils.rs

@@ -1,3 +1,7 @@
+use std::convert::TryFrom;
+
+use crate::error::LiquidityOracleError;
+
 /// This module helps serde to serialize deserialize some fields as String
 ///
 /// The reason this is added is that `#[serde(with = "String")]` does not work
@@ -30,3 +34,7 @@ pub mod as_string {
             .map_err(|_| D::Error::custom("Input is not valid"))
     }
 }
+
+pub fn u64_to_i64(value: u64) -> Result<i64, LiquidityOracleError> {
+    i64::try_from(value).map_err(|_| LiquidityOracleError::I64ConversionError)
+}