From 4c1ceac6eb5ddbc382d7fa7f6d306a467df3a186 Mon Sep 17 00:00:00 2001
From: Finn Bear <finnbearlabs@gmail.com>
Date: Mon, 23 Oct 2023 06:37:21 -0700
Subject: [PATCH] Feature #2720 - add remainder aka modulo operator. (#2868)

---
 lib/src/err/mod.rs         |  4 ++++
 lib/src/fnc/operate.rs     | 12 +++++-------
 lib/src/sql/expression.rs  |  1 +
 lib/src/sql/number.rs      |  5 +++--
 lib/src/sql/operator.rs    |  5 +++++
 lib/src/sql/value/value.rs | 17 +++++++++++++++++
 6 files changed, 35 insertions(+), 9 deletions(-)

diff --git a/lib/src/err/mod.rs b/lib/src/err/mod.rs
index 9f88b9e1..cd2e25a7 100644
--- a/lib/src/err/mod.rs
+++ b/lib/src/err/mod.rs
@@ -547,6 +547,10 @@ pub enum Error {
 	#[error("Cannot perform division with '{0}' and '{1}'")]
 	TryDiv(String, String),
 
+	/// Cannot perform remainder
+	#[error("Cannot perform remainder with '{0}' and '{1}'")]
+	TryRem(String, String),
+
 	/// Cannot perform power
 	#[error("Cannot raise the value '{0}' with '{1}'")]
 	TryPow(String, String),
diff --git a/lib/src/fnc/operate.rs b/lib/src/fnc/operate.rs
index 9d4cfc73..9f6e719c 100644
--- a/lib/src/fnc/operate.rs
+++ b/lib/src/fnc/operate.rs
@@ -3,13 +3,7 @@ use crate::dbs::Transaction;
 use crate::doc::CursorDoc;
 use crate::err::Error;
 use crate::idx::planner::executor::QueryExecutor;
-use crate::sql::value::TryAdd;
-use crate::sql::value::TryDiv;
-use crate::sql::value::TryMul;
-use crate::sql::value::TryNeg;
-use crate::sql::value::TryPow;
-use crate::sql::value::TrySub;
-use crate::sql::value::Value;
+use crate::sql::value::{TryAdd, TryDiv, TryMul, TryNeg, TryPow, TryRem, TrySub, Value};
 use crate::sql::{Expression, Thing};
 
 pub fn neg(a: Value) -> Result<Value, Error> {
@@ -64,6 +58,10 @@ pub fn div(a: Value, b: Value) -> Result<Value, Error> {
 	a.try_div(b)
 }
 
+pub fn rem(a: Value, b: Value) -> Result<Value, Error> {
+	a.try_rem(b)
+}
+
 pub fn pow(a: Value, b: Value) -> Result<Value, Error> {
 	a.try_pow(b)
 }
diff --git a/lib/src/sql/expression.rs b/lib/src/sql/expression.rs
index f302adfd..45faae2a 100644
--- a/lib/src/sql/expression.rs
+++ b/lib/src/sql/expression.rs
@@ -164,6 +164,7 @@ impl Expression {
 			Operator::Sub => fnc::operate::sub(l, r),
 			Operator::Mul => fnc::operate::mul(l, r),
 			Operator::Div => fnc::operate::div(l, r),
+			Operator::Rem => fnc::operate::rem(l, r),
 			Operator::Pow => fnc::operate::pow(l, r),
 			Operator::Equal => fnc::operate::equal(&l, &r),
 			Operator::Exact => fnc::operate::exact(&l, &r),
diff --git a/lib/src/sql/number.rs b/lib/src/sql/number.rs
index 3f30eda5..5d645178 100644
--- a/lib/src/sql/number.rs
+++ b/lib/src/sql/number.rs
@@ -1,4 +1,4 @@
-use super::value::{TryAdd, TryDiv, TryMul, TryNeg, TryPow, TrySub};
+use super::value::{TryAdd, TryDiv, TryMul, TryNeg, TryPow, TryRem, TrySub};
 use crate::err::Error;
 use crate::sql::ending::number as ending;
 use crate::sql::error::{IResult, ParseError};
@@ -17,7 +17,7 @@ use std::fmt::{self, Display, Formatter};
 use std::hash;
 use std::iter::Product;
 use std::iter::Sum;
-use std::ops::{self, Add, Div, Mul, Neg, Sub};
+use std::ops::{self, Add, Div, Mul, Neg, Rem, Sub};
 use std::str::FromStr;
 
 pub(crate) const TOKEN: &str = "$surrealdb::private::sql::Number";
@@ -504,6 +504,7 @@ impl_simple_try_op!(TryAdd, try_add, add, checked_add);
 impl_simple_try_op!(TrySub, try_sub, sub, checked_sub);
 impl_simple_try_op!(TryMul, try_mul, mul, checked_mul);
 impl_simple_try_op!(TryDiv, try_div, div, checked_div);
+impl_simple_try_op!(TryRem, try_rem, rem, checked_rem);
 
 impl TryPow for Number {
 	type Output = Self;
diff --git a/lib/src/sql/operator.rs b/lib/src/sql/operator.rs
index f7a43d48..aaa5300a 100644
--- a/lib/src/sql/operator.rs
+++ b/lib/src/sql/operator.rs
@@ -70,6 +70,8 @@ pub enum Operator {
 	Intersects,
 	//
 	Knn(u32), // <{k}>
+	//
+	Rem, // %
 }
 
 impl Default for Operator {
@@ -90,6 +92,7 @@ impl Operator {
 			Self::Add => 7,
 			Self::Mul => 8,
 			Self::Div => 9,
+			Self::Rem => 10,
 			_ => 5,
 		}
 	}
@@ -108,6 +111,7 @@ impl fmt::Display for Operator {
 			Self::Sub => f.write_char('-'),
 			Self::Mul => f.write_char('*'),
 			Self::Div => f.write_char('/'),
+			Self::Rem => f.write_char('%'),
 			Self::Pow => f.write_str("**"),
 			Self::Inc => f.write_str("+="),
 			Self::Dec => f.write_str("-="),
@@ -213,6 +217,7 @@ pub fn binary_symbols(i: &str) -> IResult<&str, Operator> {
 			value(Operator::Mul, char('∙')),
 			value(Operator::Div, char('/')),
 			value(Operator::Div, char('÷')),
+			value(Operator::Rem, char('%')),
 		)),
 		alt((
 			value(Operator::Contain, char('∋')),
diff --git a/lib/src/sql/value/value.rs b/lib/src/sql/value/value.rs
index 5795eb52..bd3006ca 100644
--- a/lib/src/sql/value/value.rs
+++ b/lib/src/sql/value/value.rs
@@ -2694,6 +2694,23 @@ impl TryDiv for Value {
 
 // ------------------------------
 
+pub(crate) trait TryRem<Rhs = Self> {
+	type Output;
+	fn try_rem(self, v: Self) -> Result<Self::Output, Error>;
+}
+
+impl TryRem for Value {
+	type Output = Self;
+	fn try_rem(self, other: Self) -> Result<Self, Error> {
+		Ok(match (self, other) {
+			(Self::Number(v), Self::Number(w)) => Self::Number(v.try_rem(w)?),
+			(v, w) => return Err(Error::TryRem(v.to_raw_string(), w.to_raw_string())),
+		})
+	}
+}
+
+// ------------------------------
+
 pub(crate) trait TryPow<Rhs = Self> {
 	type Output;
 	fn try_pow(self, v: Self) -> Result<Self::Output, Error>;