From 0d7cf0a069b96e3b16bd16a5ab14416f124f9b08 Mon Sep 17 00:00:00 2001
From: Dmitry Dodzin <d.dodzin@gmail.com>
Date: Wed, 18 Jun 2025 20:59:54 +0300
Subject: [PATCH] Update a more correct math evaluation

---
 src/lib.rs            |  4 ++++
 src/transform/expr.rs | 26 ++++++++++++++++++--------
 2 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index 502f439..4cb0d7f 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1214,6 +1214,10 @@ mod tests {
   #[case("1 + 2 / 2 + 1", "3")]
   #[case("3.12 * 2", "6.24")]
   #[case("\"3.12\" + \".2\"", "\"3.12.2\"")]
+  #[case("22 - 18", "4")]
+  #[case("22 - 18 - 1", "3")]
+  #[case("16 / 2", "8")]
+  #[case("16 / 2 / 2", "4")]
   #[case("true and true", "true")]
   #[case("true or false", "true")]
   #[case("false or false", "false")]
diff --git a/src/transform/expr.rs b/src/transform/expr.rs
index 259ba87..d70cfc4 100644
--- a/src/transform/expr.rs
+++ b/src/transform/expr.rs
@@ -122,11 +122,20 @@ pub struct OperatorExprTransformer {
 
 macro_rules! impl_operator_parse {
   ($ident:ident, $op:ident) => {
-    if let Some((index, _)) = $ident
-      .iter()
-      .enumerate()
-      .find(|(_, pair)| matches!(pair.as_rule(), Rule::$op))
-    {
+    impl_operator_parse!($ident, $op, false)
+  };
+  ($ident:ident, $op:ident, $invert:literal) => {
+    let found_rule = {
+      let matcher = |(_, pair): &(_, &Pair<Rule>)| matches!(pair.as_rule(), Rule::$op);
+
+      if $invert {
+        $ident.iter().enumerate().rev().find(matcher)
+      } else {
+        $ident.iter().enumerate().find(matcher)
+      }
+    };
+
+    if let Some((index, _)) = found_rule {
       let mut right = $ident.split_off(index).split_off(1);
 
       let lhs = if $ident.len() == 1 {
@@ -168,10 +177,11 @@ impl OperatorExprTransformer {
     impl_operator_parse!(pairs, Lte);
     impl_operator_parse!(pairs, Equal);
     impl_operator_parse!(pairs, NotEqual);
-    impl_operator_parse!(pairs, Add);
-    impl_operator_parse!(pairs, Sub);
+
     impl_operator_parse!(pairs, Mul);
-    impl_operator_parse!(pairs, Div);
+    impl_operator_parse!(pairs, Add);
+    impl_operator_parse!(pairs, Div, true);
+    impl_operator_parse!(pairs, Sub, true);
 
     Err(JsltError::InvalidInput(format!(
       "Could not evaluate the expession {pairs:#?}",