Implement builtin functions ceil() and floor()

src/builtin/math.rs

@@ -18,4 +18,16 @@ pub(crate) fn register(f: &mut BTreeMap<String, Builtin>) {
             _ => todo!("expected number in builtin function `round()`")
         }
     });
+    decl!(f "ceil", |args, _| {
+        match arg!(args, 0, "number").eval() {
+            Value::Dimension(n, u) => Some(Value::Dimension(n.ceil(), u)),
+            _ => todo!("expected number in builtin function `ceil()`")
+        }
+    });
+    decl!(f "floor", |args, _| {
+        match arg!(args, 0, "number").eval() {
+            Value::Dimension(n, u) => Some(Value::Dimension(n.floor(), u)),
+            _ => todo!("expected number in builtin function `floor()`")
+        }
+    });
 }

src/value/number.rs

@@ -30,6 +30,18 @@ impl Number {
             val: self.val.round(),
         }
     }
+
+    pub fn ceil(self) -> Self {
+        Number {
+            val: self.val.ceil(),
+        }
+    }
+
+    pub fn floor(self) -> Self {
+        Number {
+            val: self.val.floor(),
+        }
+    }
 }
 
 impl fmt::LowerHex for Number {

tests/math.rs

@@ -28,3 +28,23 @@ test!(
     "a {\n  color: round(10.6px);\n}\n",
     "a {\n  color: 11px;\n}\n"
 );
+test!(
+    floor_below_pt_5,
+    "a {\n  color: floor(10.4px);\n}\n",
+    "a {\n  color: 10px;\n}\n"
+);
+test!(
+    floor_above_pt_5,
+    "a {\n  color: floor(10.6px);\n}\n",
+    "a {\n  color: 10px;\n}\n"
+);
+test!(
+    ceil_below_pt_5,
+    "a {\n  color: ceil(10.4px);\n}\n",
+    "a {\n  color: 11px;\n}\n"
+);
+test!(
+    ceil_above_pt_5,
+    "a {\n  color: ceil(10.6px);\n}\n",
+    "a {\n  color: 11px;\n}\n"
+);