From 664fd72dcbd6abf8a7d01728b3be05de0faefaea Mon Sep 17 00:00:00 2001
From: AmrDeveloper <amr96@programmer.net>
Date: Mon, 3 Jul 2023 16:39:12 +0200
Subject: [PATCH] Add support for Modulus operator

---
 docs/expression/binary.md |  1 +
 src/expression.rs         |  2 ++
 src/parser.rs             | 12 +++++++-----
 src/tokenizer.rs          | 21 ++++++++++++++++++++-
 4 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/docs/expression/binary.md b/docs/expression/binary.md
index 76f3e43e..d4124baa 100644
--- a/docs/expression/binary.md
+++ b/docs/expression/binary.md
@@ -8,6 +8,7 @@ Used to perform arithmetic operators on number types.
 - `-` Subtraction.
 - `*` Multiplication.
 - `/` Division.
+- `%` Modulus.
 
 ### Comparison Expression
 - `=` used to check if field equal to expected value.
diff --git a/src/expression.rs b/src/expression.rs
index d53926ef..166d270d 100644
--- a/src/expression.rs
+++ b/src/expression.rs
@@ -92,6 +92,7 @@ pub enum ArithmeticOperator {
     Minus,
     Star,
     Slash,
+    Modulus,
 }
 
 pub struct ArithmeticExpression {
@@ -109,6 +110,7 @@ impl Expression for ArithmeticExpression {
             ArithmeticOperator::Minus => lhs - rhs,
             ArithmeticOperator::Star => lhs * rhs,
             ArithmeticOperator::Slash => lhs / rhs,
+            ArithmeticOperator::Modulus => lhs % rhs,
         }
         .to_string();
     }
diff --git a/src/parser.rs b/src/parser.rs
index 65582310..83ad952e 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -875,14 +875,16 @@ fn parse_factor_expression(
 
     while *position < tokens.len()
         && (&tokens[*position].kind == &TokenKind::Star
-            || &tokens[*position].kind == &TokenKind::Slash)
+            || &tokens[*position].kind == &TokenKind::Slash
+            || &tokens[*position].kind == &TokenKind::Percentage)
     {
         let operator = &tokens[*position];
         *position += 1;
-        let factor_operator = if operator.kind == TokenKind::Star {
-            ArithmeticOperator::Star
-        } else {
-            ArithmeticOperator::Slash
+
+        let factor_operator = match operator.kind {
+            TokenKind::Star => ArithmeticOperator::Star,
+            TokenKind::Slash => ArithmeticOperator::Slash,
+            _ => ArithmeticOperator::Modulus,
         };
 
         let right_expr = parse_check_expression(tokens, position);
diff --git a/src/tokenizer.rs b/src/tokenizer.rs
index 7bba0d35..5d6eb788 100644
--- a/src/tokenizer.rs
+++ b/src/tokenizer.rs
@@ -45,6 +45,7 @@ pub enum TokenKind {
     Minus,
     Star,
     Slash,
+    Percentage,
 
     Comma,
     Dot,
@@ -206,7 +207,7 @@ pub fn tokenize(script: String) -> Result<Vec<Token>, GQLError> {
             continue;
         }
 
-        // Plus
+        // Slash
         if char == '/' {
             let location = Location {
                 start: column_start,
@@ -224,6 +225,24 @@ pub fn tokenize(script: String) -> Result<Vec<Token>, GQLError> {
             continue;
         }
 
+        // Percentage
+        if char == '%' {
+            let location = Location {
+                start: column_start,
+                end: position,
+            };
+
+            let token = Token {
+                location: location,
+                kind: TokenKind::Percentage,
+                literal: "%".to_owned(),
+            };
+
+            tokens.push(token);
+            position += 1;
+            continue;
+        }
+
         // Or
         if char == '|' {
             let location = Location {