style: Refactor mul_by fn into map fn

Refactor the mul_by function on leafs into a more generic map function
that can be used for more operations like abs, signum and mul.

Differential Revision: https://phabricator.services.mozilla.com/D172936

components/style/values/computed/length_percentage.rs

@@ -241,7 +241,7 @@ impl LengthPercentage {
         // TODO: This could in theory take ownership of the calc node in `v` if
         // possible instead of cloning.
         let mut node = v.to_calc_node().into_owned();
-        node.negate();
+        node.map(std::ops::Neg::neg);
 
         let new_node = CalcNode::Sum(
             vec![
@@ -679,10 +679,14 @@ impl calc::CalcNodeLeaf for CalcLengthPercentageLeaf {
         }
     }
 
-    fn mul_by(&mut self, scalar: f32) {
-        match *self {
-            Self::Length(ref mut l) => *l = *l * scalar,
-            Self::Percentage(ref mut p) => p.0 *= scalar,
+    fn map(&mut self, mut op: impl FnMut(f32) -> f32) {
+        match self {
+            CalcLengthPercentageLeaf::Length(value) => {
+                *value = Length::new(op(value.px()));
+            },
+            CalcLengthPercentageLeaf::Percentage(value) => {
+                *value = Percentage(op(value.0));
+            },
         }
     }
 

components/style/values/generics/calc.rs

@@ -232,12 +232,12 @@ pub trait CalcNodeLeaf: Clone + Sized + PartialOrd + PartialEq + ToCss {
     where
         O: Fn(f32, f32) -> f32;
 
-    /// Multiplies the leaf by a given scalar number.
-    fn mul_by(&mut self, scalar: f32);
+    /// Map the value of this node with the given operation.
+    fn map(&mut self, op: impl FnMut(f32) -> f32);
 
     /// Negates the leaf.
     fn negate(&mut self) {
-        self.mul_by(-1.);
+        self.map(std::ops::Neg::neg);
     }
 
     /// Canonicalizes the expression if necessary.
@@ -248,9 +248,9 @@ pub trait CalcNodeLeaf: Clone + Sized + PartialOrd + PartialEq + ToCss {
 }
 
 impl<L: CalcNodeLeaf> CalcNode<L> {
-    /// Negates the node.
-    pub fn negate(&mut self) {
-        self.mul_by(-1.);
+    /// Negates the leaf.
+    fn negate(&mut self) {
+        self.map(std::ops::Neg::neg);
     }
 
     fn sort_key(&self) -> SortKey {
@@ -291,6 +291,47 @@ impl<L: CalcNodeLeaf> CalcNode<L> {
         }
     }
 
+    /// Map the value of this node with the given operation.
+    pub fn map(&mut self, mut op: impl FnMut(f32) -> f32) {
+        fn map_internal<L: CalcNodeLeaf>(node: &mut CalcNode<L>, op: &mut impl FnMut(f32) -> f32) {
+            match node {
+                CalcNode::Leaf(l) => l.map(op),
+                CalcNode::Sum(children) => {
+                    for node in &mut **children {
+                        map_internal(node, op);
+                    }
+                },
+                CalcNode::MinMax(children, _) => {
+                    for node in &mut **children {
+                        map_internal(node, op);
+                    }
+                },
+                CalcNode::Clamp { min, center, max } => {
+                    map_internal(min, op);
+                    map_internal(center, op);
+                    map_internal(max, op);
+                },
+                CalcNode::Round { value, step, .. } => {
+                    map_internal(value, op);
+                    map_internal(step, op);
+                },
+                CalcNode::ModRem {
+                    dividend, divisor, ..
+                } => {
+                    map_internal(dividend, op);
+                    map_internal(divisor, op);
+                },
+                CalcNode::Hypot(children) => {
+                    for node in &mut **children {
+                        map_internal(node, op);
+                    }
+                },
+            }
+        }
+
+        map_internal(self, &mut op);
+    }
+
     /// Convert this `CalcNode` into a `CalcNode` with a different leaf kind.
     pub fn map_leaves<O, F>(&self, mut map: F) -> CalcNode<O>
     where
@@ -573,7 +614,7 @@ impl<L: CalcNodeLeaf> CalcNode<L> {
     /// Multiplies the node by a scalar.
     pub fn mul_by(&mut self, scalar: f32) {
         match *self {
-            Self::Leaf(ref mut l) => l.mul_by(scalar),
+            Self::Leaf(ref mut l) => l.map(|v| v * scalar),
             // Multiplication is distributive across this.
             Self::Sum(ref mut children) => {
                 for node in &mut **children {

components/style/values/specified/calc.rs

@@ -238,31 +238,6 @@ impl generic::CalcNodeLeaf for Leaf {
         }
     }
 
-    fn mul_by(&mut self, scalar: f32) {
-        match *self {
-            Self::Length(ref mut l) => {
-                // FIXME: For consistency this should probably convert absolute
-                // lengths into pixels.
-                *l = *l * scalar;
-            },
-            Self::Number(ref mut n) => {
-                *n *= scalar;
-            },
-            Self::Angle(ref mut a) => {
-                *a = Angle::from_calc(a.degrees() * scalar);
-            },
-            Self::Resolution(ref mut r) => {
-                *r = Resolution::from_dppx(r.dppx() * scalar);
-            },
-            Self::Time(ref mut t) => {
-                *t = Time::from_seconds(t.seconds() * scalar);
-            },
-            Self::Percentage(ref mut p) => {
-                *p *= scalar;
-            },
-        }
-    }
-
     fn sort_key(&self) -> SortKey {
         match *self {
             Self::Number(..) => SortKey::Number,
@@ -416,6 +391,17 @@ impl generic::CalcNodeLeaf for Leaf {
             },
         }
     }
+
+    fn map(&mut self, mut op: impl FnMut(f32) -> f32) {
+        match self {
+            Leaf::Length(one) => *one = one.map(op),
+            Leaf::Angle(one) => *one = specified::Angle::from_calc(op(one.degrees())),
+            Leaf::Time(one) => *one = specified::Time::from_seconds(op(one.seconds())),
+            Leaf::Resolution(one) => *one = specified::Resolution::from_dppx(op(one.dppx())),
+            Leaf::Percentage(one) => *one = op(*one),
+            Leaf::Number(one) => *one = op(*one),
+        }
+    }
 }
 
 /// A calc node representation for specified values.
@@ -738,7 +724,7 @@ impl CalcNode {
                         },
                         Token::Delim('-') => {
                             let mut rhs = Self::parse_product(context, input, allowed_units)?;
-                            rhs.negate();
+                            rhs.mul_by(-1.0);
                             sum.push(rhs);
                         },
                         _ => {

components/style/values/specified/length.rs

@@ -139,6 +139,17 @@ impl FontRelativeLength {
         })
     }
 
+    fn map(&self, mut op: impl FnMut(f32) -> f32) -> Self {
+        match self {
+            FontRelativeLength::Em(x) => FontRelativeLength::Em(op(*x)),
+            FontRelativeLength::Ex(x) => FontRelativeLength::Ex(op(*x)),
+            FontRelativeLength::Ch(x) => FontRelativeLength::Ch(op(*x)),
+            FontRelativeLength::Cap(x) => FontRelativeLength::Cap(op(*x)),
+            FontRelativeLength::Ic(x) => FontRelativeLength::Ic(op(*x)),
+            FontRelativeLength::Rem(x) => FontRelativeLength::Rem(op(*x)),
+        }
+    }
+
     /// Computes the font-relative length.
     pub fn to_computed_value(
         &self,
@@ -513,6 +524,35 @@ impl ViewportPercentageLength {
         })
     }
 
+    fn map(&self, mut op: impl FnMut(f32) -> f32) -> Self {
+        match self {
+            ViewportPercentageLength::Vw(x) => ViewportPercentageLength::Vw(op(*x)),
+            ViewportPercentageLength::Svw(x) => ViewportPercentageLength::Svw(op(*x)),
+            ViewportPercentageLength::Lvw(x) => ViewportPercentageLength::Lvw(op(*x)),
+            ViewportPercentageLength::Dvw(x) => ViewportPercentageLength::Dvw(op(*x)),
+            ViewportPercentageLength::Vh(x) => ViewportPercentageLength::Vh(op(*x)),
+            ViewportPercentageLength::Svh(x) => ViewportPercentageLength::Svh(op(*x)),
+            ViewportPercentageLength::Lvh(x) => ViewportPercentageLength::Lvh(op(*x)),
+            ViewportPercentageLength::Dvh(x) => ViewportPercentageLength::Dvh(op(*x)),
+            ViewportPercentageLength::Vmin(x) => ViewportPercentageLength::Vmin(op(*x)),
+            ViewportPercentageLength::Svmin(x) => ViewportPercentageLength::Svmin(op(*x)),
+            ViewportPercentageLength::Lvmin(x) => ViewportPercentageLength::Lvmin(op(*x)),
+            ViewportPercentageLength::Dvmin(x) => ViewportPercentageLength::Dvmin(op(*x)),
+            ViewportPercentageLength::Vmax(x) => ViewportPercentageLength::Vmax(op(*x)),
+            ViewportPercentageLength::Svmax(x) => ViewportPercentageLength::Svmax(op(*x)),
+            ViewportPercentageLength::Lvmax(x) => ViewportPercentageLength::Lvmax(op(*x)),
+            ViewportPercentageLength::Dvmax(x) => ViewportPercentageLength::Dvmax(op(*x)),
+            ViewportPercentageLength::Vb(x) => ViewportPercentageLength::Vb(op(*x)),
+            ViewportPercentageLength::Svb(x) => ViewportPercentageLength::Svb(op(*x)),
+            ViewportPercentageLength::Lvb(x) => ViewportPercentageLength::Lvb(op(*x)),
+            ViewportPercentageLength::Dvb(x) => ViewportPercentageLength::Dvb(op(*x)),
+            ViewportPercentageLength::Vi(x) => ViewportPercentageLength::Vi(op(*x)),
+            ViewportPercentageLength::Svi(x) => ViewportPercentageLength::Svi(op(*x)),
+            ViewportPercentageLength::Lvi(x) => ViewportPercentageLength::Lvi(op(*x)),
+            ViewportPercentageLength::Dvi(x) => ViewportPercentageLength::Dvi(op(*x)),
+        }
+    }
+
     /// Computes the given viewport-relative length for the given viewport size.
     pub fn to_computed_value(&self, context: &Context) -> CSSPixelLength {
         let (variant, unit, factor) = self.unpack();
@@ -633,6 +673,18 @@ impl AbsoluteLength {
     {
         Ok(Self::Px(op(self.to_px(), other.to_px())))
     }
+
+    fn map(&self, mut op: impl FnMut(f32) -> f32) -> Self {
+        match self {
+            AbsoluteLength::Px(x) => AbsoluteLength::Px(op(*x)),
+            AbsoluteLength::In(x) => AbsoluteLength::In(op(*x)),
+            AbsoluteLength::Cm(x) => AbsoluteLength::Cm(op(*x)),
+            AbsoluteLength::Mm(x) => AbsoluteLength::Mm(op(*x)),
+            AbsoluteLength::Q(x) => AbsoluteLength::Q(op(*x)),
+            AbsoluteLength::Pt(x) => AbsoluteLength::Pt(op(*x)),
+            AbsoluteLength::Pc(x) => AbsoluteLength::Pc(op(*x)),
+        }
+    }
 }
 
 impl ToComputedValue for AbsoluteLength {
@@ -741,6 +793,17 @@ impl ContainerRelativeLength {
         })
     }
 
+    pub(crate) fn map(&self, mut op: impl FnMut(f32) -> f32) -> Self {
+        match self {
+            ContainerRelativeLength::Cqw(x) => ContainerRelativeLength::Cqw(op(*x)),
+            ContainerRelativeLength::Cqh(x) => ContainerRelativeLength::Cqh(op(*x)),
+            ContainerRelativeLength::Cqi(x) => ContainerRelativeLength::Cqi(op(*x)),
+            ContainerRelativeLength::Cqb(x) => ContainerRelativeLength::Cqb(op(*x)),
+            ContainerRelativeLength::Cqmin(x) => ContainerRelativeLength::Cqmin(op(*x)),
+            ContainerRelativeLength::Cqmax(x) => ContainerRelativeLength::Cqmax(op(*x)),
+        }
+    }
+
     /// Computes the given container-relative length.
     pub fn to_computed_value(&self, context: &Context) -> CSSPixelLength {
         let size = context.get_container_size_query();
@@ -1037,6 +1100,20 @@ impl NoCalcLength {
         })
     }
 
+    pub(crate) fn map(&self, mut op: impl FnMut(f32) -> f32) -> Self {
+        use self::NoCalcLength::*;
+
+        match self {
+            Absolute(ref one) => Absolute(one.map(op)),
+            FontRelative(ref one) => FontRelative(one.map(op)),
+            ViewportPercentage(ref one) => ViewportPercentage(one.map(op)),
+            ContainerRelative(ref one) => ContainerRelative(one.map(op)),
+            ServoCharacterWidth(ref one) => {
+                ServoCharacterWidth(CharacterWidth(op(one.0 as f32) as i32))
+            },
+        }
+    }
+
     /// Get a px value without context.
     #[inline]
     pub fn to_computed_pixel_length_without_context(&self) -> Result<CSSFloat, ()> {