Implement builtin function ie-hex-str()

src/builtin/color/other.rs

@@ -2,6 +2,7 @@ use std::collections::BTreeMap;
 
 use super::Builtin;
 use crate::color::Color;
+use crate::common::QuoteKind;
 use crate::units::Unit;
 use crate::value::{Number, Value};
 
@@ -172,6 +173,13 @@ pub(crate) fn register(f: &mut BTreeMap<String, Builtin>) {
             color
         }))
     });
+    decl!(f "ie-hex-str", |args, _| {
+        let color = match arg!(args, 0, "color").eval() {
+            Value::Color(c) => c.clone(),
+            _ => todo!("non-color given to builtin function `ie-hex-str()`")
+        };
+        Some(Value::Ident(color.to_ie_hex_str(), QuoteKind::None))
+    });
 }
 
 fn scale(val: Number, by: Number, max: Number) -> Number {

src/color/mod.rs

@@ -396,6 +396,21 @@ impl Color {
     }
 }
 
+/// Other color functions
+impl Color {
+    pub fn to_ie_hex_str(&self) -> String {
+        format!(
+            "#{:02X}{:02X}{:02X}{:02X}",
+            (self.alpha.clone() * Number::from(255))
+                .round()
+                .to_integer(),
+            self.red.to_integer(),
+            self.green.to_integer(),
+            self.blue.to_integer()
+        )
+    }
+}
+
 /// Get the proper representation from RGBA values
 fn repr(red: &Number, green: &Number, blue: &Number, alpha: &Number) -> String {
     macro_rules! into_u8 {

tests/color.rs

@@ -441,3 +441,18 @@ test!(
     "a {\n  color: scale-color(sienna, $alpha: -70%);\n}\n",
     "a {\n  color: rgba(160, 82, 45, 0.3);\n}\n"
 );
+test!(
+    ie_hex_str_hex_3,
+    "a {\n  color: ie-hex-str(#abc);\n}\n",
+    "a {\n  color: #FFAABBCC;\n}\n"
+);
+test!(
+    ie_hex_str_hex_6,
+    "a {\n  color: ie-hex-str(#3322BB);\n}\n",
+    "a {\n  color: #FF3322BB;\n}\n"
+);
+test!(
+    ie_hex_str_rgb,
+    "a {\n  color: ie-hex-str(rgba(0, 255, 0, 0.5));\n}\n",
+    "a {\n  color: #8000FF00;\n}\n"
+);