From 2265e7eb748b5a1aadb1c47859b2a3dd0bc1451e Mon Sep 17 00:00:00 2001
From: Connor Skees <connor1skees@gmail.com>
Date: Sun, 26 Jul 2020 21:22:10 -0400
Subject: [PATCH] implement builtin function `math.sqrt`

---
 src/builtin/modules/math.rs | 25 ++++++++++++++++++++++-
 src/lib.rs                  |  1 +
 src/value/number/mod.rs     | 16 ++++++++++++++-
 tests/math-module.rs        | 40 +++++++++++++++++++++++++++++++++++++
 4 files changed, 80 insertions(+), 2 deletions(-)

diff --git a/src/builtin/modules/math.rs b/src/builtin/modules/math.rs
index fd55a8a..643beaa 100644
--- a/src/builtin/modules/math.rs
+++ b/src/builtin/modules/math.rs
@@ -115,7 +115,29 @@ fn pow(mut args: CallArgs, parser: &mut Parser<'_>) -> SassResult<Value> {
 
 fn sqrt(mut args: CallArgs, parser: &mut Parser<'_>) -> SassResult<Value> {
     args.max_args(1)?;
-    todo!()
+    let number = args.get_err(0, "number")?;
+
+    Ok(match number {
+        Value::Dimension(Some(n), Unit::None, ..) => Value::Dimension(n.sqrt(), Unit::None, true),
+        v @ Value::Dimension(Some(..), ..) => {
+            return Err((
+                format!(
+                    "$number: Expected {} to have no units.",
+                    v.inspect(args.span())?
+                ),
+                args.span(),
+            )
+                .into())
+        }
+        Value::Dimension(None, ..) => Value::Dimension(None, Unit::None, true),
+        v => {
+            return Err((
+                format!("$number: {} is not a number.", v.inspect(args.span())?),
+                args.span(),
+            )
+                .into())
+        }
+    })
 }
 
 fn cos(mut args: CallArgs, parser: &mut Parser<'_>) -> SassResult<Value> {
@@ -165,6 +187,7 @@ pub(crate) fn declare(f: &mut Module) {
     f.insert_builtin("unit", unit);
     f.insert_builtin("percentage", percentage);
     f.insert_builtin("clamp", clamp);
+    f.insert_builtin("sqrt", sqrt);
     #[cfg(feature = "random")]
     f.insert_builtin("random", random);
 
diff --git a/src/lib.rs b/src/lib.rs
index 32f4c41..dbea119 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -50,6 +50,7 @@ grass input.scss
     clippy::unknown_clippy_lints,
     clippy::replace_consts,
     clippy::single_match,
+    clippy::float_arithmetic,
 
     // temporarily allowed while under heavy development.
     // eventually these allows should be refactored away
diff --git a/src/value/number/mod.rs b/src/value/number/mod.rs
index 9cbb4ed..8e95bf9 100644
--- a/src/value/number/mod.rs
+++ b/src/value/number/mod.rs
@@ -8,7 +8,9 @@ use std::{
 
 use num_bigint::BigInt;
 use num_rational::{BigRational, Rational64};
-use num_traits::{CheckedAdd, CheckedDiv, CheckedMul, CheckedSub, Num, One, Signed, Zero};
+use num_traits::{
+    CheckedAdd, CheckedDiv, CheckedMul, CheckedSub, Num, One, Signed, ToPrimitive, Zero,
+};
 
 use integer::Integer;
 
@@ -106,6 +108,18 @@ impl Number {
 
         self
     }
+
+    #[allow(clippy::cast_precision_loss)]
+    pub fn sqrt(self) -> Option<Self> {
+        Some(match self {
+            Number::Small(n) => Number::Big(Box::new(BigRational::from_float(
+                ((*n.numer() as f64) / (*n.denom() as f64)).sqrt(),
+            )?)),
+            Number::Big(n) => Number::Big(Box::new(BigRational::from_float(
+                ((n.numer().to_f64()?) / (n.denom().to_f64()?)).sqrt(),
+            )?)),
+        })
+    }
 }
 
 impl Default for Number {
diff --git a/tests/math-module.rs b/tests/math-module.rs
index 50030df..f5beefe 100644
--- a/tests/math-module.rs
+++ b/tests/math-module.rs
@@ -38,3 +38,43 @@ error!(
     "@use 'sass:math';\na {\n  color: math.clamp(0mm, 1cm, 2);\n}\n",
     "Error: $min has unit mm but $max is unitless. Arguments must all have units or all be unitless."
 );
+test!(
+    sqrt_zero,
+    "@use 'sass:math';\na {\n  color: math.sqrt(0);\n}\n",
+    "a {\n  color: 0;\n}\n"
+);
+test!(
+    sqrt_small_positive,
+    "@use 'sass:math';\na {\n  color: math.sqrt(99);\n}\n",
+    "a {\n  color: 9.9498743711;\n}\n"
+);
+test!(
+    sqrt_small_negative,
+    "@use 'sass:math';\na {\n  color: math.sqrt(-99);\n}\n",
+    "a {\n  color: NaN;\n}\n"
+);
+test!(
+    sqrt_big_positive,
+    "@use 'sass:math';\na {\n  color: math.sqrt(9999999999999999999999999999999999999999999999999);\n}\n",
+    "a {\n  color: 3162277660168379038695424;\n}\n"
+);
+test!(
+    sqrt_big_negative,
+    "@use 'sass:math';\na {\n  color: math.sqrt(-9999999999999999999999999999999999999999999999999);\n}\n",
+    "a {\n  color: NaN;\n}\n"
+);
+test!(
+    sqrt_irrational,
+    "@use 'sass:math';\na {\n  color: math.sqrt(2);\n}\n",
+    "a {\n  color: 1.4142135624;\n}\n"
+);
+test!(
+    sqrt_of_nan,
+    "@use 'sass:math';\na {\n  color: math.sqrt((0 / 0));\n}\n",
+    "a {\n  color: NaN;\n}\n"
+);
+error!(
+    sqrt_with_units,
+    "@use 'sass:math';\na {\n  color: math.sqrt(1px);\n}\n",
+    "Error: $number: Expected 1px to have no units."
+);