From 1b107700cf0c1ac39a3fce8409c5caae9bf78bb7 Mon Sep 17 00:00:00 2001
From: Shuhui Luo <107524008+shuhuiluo@users.noreply.github.com>
Date: Mon, 1 Jan 2024 00:59:42 -0800
Subject: [PATCH] Convert functions to `const` in math and tick utils

Functions in the `sqrt_price_math.rs` and `nearest_usable_tick.rs` files, as well as the `constants.rs` file, were changed from regular to `const` functions. This provides the capacity to have these functions evaluated at compile time wherever their usage throughout the codebase makes it possible for constant evaluation. Also, updated the tick comparison in `nearest_usable_tick.rs` which ensures more readability.
---
 src/constants.rs                 | 2 +-
 src/utils/nearest_usable_tick.rs | 4 ++--
 src/utils/sqrt_price_math.rs     | 2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/constants.rs b/src/constants.rs
index acd0e35..aac627c 100644
--- a/src/constants.rs
+++ b/src/constants.rs
@@ -18,7 +18,7 @@ pub enum FeeAmount {
 
 impl FeeAmount {
     /// The default factory tick spacings by fee amount.
-    pub fn tick_spacing(&self) -> i32 {
+    pub const fn tick_spacing(&self) -> i32 {
         match self {
             Self::LOWEST => 1,
             Self::LOW => 10,
diff --git a/src/utils/nearest_usable_tick.rs b/src/utils/nearest_usable_tick.rs
index 11d3d0b..55a54f8 100644
--- a/src/utils/nearest_usable_tick.rs
+++ b/src/utils/nearest_usable_tick.rs
@@ -9,9 +9,9 @@ use super::tick_math::{MAX_TICK, MIN_TICK};
 ///
 /// returns: i32
 ///
-pub fn nearest_usable_tick(tick: i32, tick_spacing: i32) -> i32 {
+pub const fn nearest_usable_tick(tick: i32, tick_spacing: i32) -> i32 {
     assert!(tick_spacing > 0, "TICK_SPACING");
-    assert!((MIN_TICK..=MAX_TICK).contains(&tick), "TICK_BOUND");
+    assert!(tick >= MIN_TICK && tick <= MAX_TICK, "TICK_BOUND");
     let rounded = tick.div_floor(tick_spacing) * tick_spacing;
     let rounded = rounded + (tick - rounded + tick_spacing / 2) / tick_spacing * tick_spacing;
     if rounded < MIN_TICK {
diff --git a/src/utils/sqrt_price_math.rs b/src/utils/sqrt_price_math.rs
index 9da123e..d4cbd25 100644
--- a/src/utils/sqrt_price_math.rs
+++ b/src/utils/sqrt_price_math.rs
@@ -17,7 +17,7 @@ fn to_uint160(x: U256) -> Result<U256, UniswapV3MathError> {
     }
 }
 
-fn to_uint256(x: u128) -> U256 {
+const fn to_uint256(x: u128) -> U256 {
     U256::from_limbs([x as u64, (x >> 64) as u64, 0, 0])
 }