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+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+//! [Calc expressions][calc].
+//!
+//! [calc]: https://drafts.csswg.org/css-values/#calc-notation
+
+use num_traits::Zero;
+use smallvec::SmallVec;
+use std::fmt::{self, Write};
+use std::ops::{Add, Mul, Neg, Rem, Sub};
+use std::{cmp, mem};
+use style_traits::{CssWriter, ToCss};
+
+/// Whether we're a `min` or `max` function.
+#[derive(
+ Clone,
+ Copy,
+ Debug,
+ Deserialize,
+ MallocSizeOf,
+ PartialEq,
+ Serialize,
+ ToAnimatedZero,
+ ToResolvedValue,
+ ToShmem,
+)]
+#[repr(u8)]
+pub enum MinMaxOp {
+ /// `min()`
+ Min,
+ /// `max()`
+ Max,
+}
+
+/// Whether we're a `mod` or `rem` function.
+#[derive(
+ Clone,
+ Copy,
+ Debug,
+ Deserialize,
+ MallocSizeOf,
+ PartialEq,
+ Serialize,
+ ToAnimatedZero,
+ ToResolvedValue,
+ ToShmem,
+)]
+#[repr(u8)]
+pub enum ModRemOp {
+ /// `mod()`
+ Mod,
+ /// `rem()`
+ Rem,
+}
+
+impl ModRemOp {
+ fn apply(self, dividend: f32, divisor: f32) -> f32 {
+ // In mod(A, B) only, if B is infinite and A has opposite sign to B
+ // (including an oppositely-signed zero), the result is NaN.
+ // https://drafts.csswg.org/css-values/#round-infinities
+ if matches!(self, Self::Mod) &&
+ divisor.is_infinite() &&
+ dividend.is_sign_negative() != divisor.is_sign_negative()
+ {
+ return f32::NAN;
+ }
+
+ let (r, same_sign_as) = match self {
+ Self::Mod => (dividend - divisor * (dividend / divisor).floor(), divisor),
+ Self::Rem => (dividend - divisor * (dividend / divisor).trunc(), dividend),
+ };
+ if r == 0.0 && same_sign_as.is_sign_negative() {
+ -0.0
+ } else {
+ r
+ }
+ }
+}
+
+/// The strategy used in `round()`
+#[derive(
+ Clone,
+ Copy,
+ Debug,
+ Deserialize,
+ MallocSizeOf,
+ PartialEq,
+ Serialize,
+ ToAnimatedZero,
+ ToResolvedValue,
+ ToShmem,
+)]
+#[repr(u8)]
+pub enum RoundingStrategy {
+ /// `round(nearest, a, b)`
+ /// round a to the nearest multiple of b
+ Nearest,
+ /// `round(up, a, b)`
+ /// round a up to the nearest multiple of b
+ Up,
+ /// `round(down, a, b)`
+ /// round a down to the nearest multiple of b
+ Down,
+ /// `round(to-zero, a, b)`
+ /// round a to the nearest multiple of b that is towards zero
+ ToZero,
+}
+
+/// This determines the order in which we serialize members of a calc() sum.
+///
+/// See https://drafts.csswg.org/css-values-4/#sort-a-calculations-children
+#[derive(Clone, Copy, Debug, Eq, Ord, PartialEq, PartialOrd)]
+#[allow(missing_docs)]
+pub enum SortKey {
+ Number,
+ Percentage,
+ Cap,
+ Ch,
+ Cqb,
+ Cqh,
+ Cqi,
+ Cqmax,
+ Cqmin,
+ Cqw,
+ Deg,
+ Dppx,
+ Dvb,
+ Dvh,
+ Dvi,
+ Dvmax,
+ Dvmin,
+ Dvw,
+ Em,
+ Ex,
+ Ic,
+ Lh,
+ Lvb,
+ Lvh,
+ Lvi,
+ Lvmax,
+ Lvmin,
+ Lvw,
+ Px,
+ Rem,
+ Rlh,
+ Sec,
+ Svb,
+ Svh,
+ Svi,
+ Svmax,
+ Svmin,
+ Svw,
+ Vb,
+ Vh,
+ Vi,
+ Vmax,
+ Vmin,
+ Vw,
+ Other,
+}
+
+/// A generic node in a calc expression.
+///
+/// FIXME: This would be much more elegant if we used `Self` in the types below,
+/// but we can't because of https://github.com/serde-rs/serde/issues/1565.
+///
+/// FIXME: The following annotations are to workaround an LLVM inlining bug, see
+/// bug 1631929.
+///
+/// cbindgen:destructor-attributes=MOZ_NEVER_INLINE
+/// cbindgen:copy-constructor-attributes=MOZ_NEVER_INLINE
+/// cbindgen:eq-attributes=MOZ_NEVER_INLINE
+#[repr(u8)]
+#[derive(
+ Clone,
+ Debug,
+ Deserialize,
+ MallocSizeOf,
+ PartialEq,
+ Serialize,
+ ToAnimatedZero,
+ ToResolvedValue,
+ ToShmem,
+)]
+pub enum GenericCalcNode<L> {
+ /// A leaf node.
+ Leaf(L),
+ /// A node that negates its child, e.g. Negate(1) == -1.
+ Negate(Box<GenericCalcNode<L>>),
+ /// A node that inverts its child, e.g. Invert(10) == 1 / 10 == 0.1. The child must always
+ /// resolve to a number unit.
+ Invert(Box<GenericCalcNode<L>>),
+ /// A sum node, representing `a + b + c` where a, b, and c are the
+ /// arguments.
+ Sum(crate::OwnedSlice<GenericCalcNode<L>>),
+ /// A product node, representing `a * b * c` where a, b, and c are the
+ /// arguments.
+ Product(crate::OwnedSlice<GenericCalcNode<L>>),
+ /// A `min` or `max` function.
+ MinMax(crate::OwnedSlice<GenericCalcNode<L>>, MinMaxOp),
+ /// A `clamp()` function.
+ Clamp {
+ /// The minimum value.
+ min: Box<GenericCalcNode<L>>,
+ /// The central value.
+ center: Box<GenericCalcNode<L>>,
+ /// The maximum value.
+ max: Box<GenericCalcNode<L>>,
+ },
+ /// A `round()` function.
+ Round {
+ /// The rounding strategy.
+ strategy: RoundingStrategy,
+ /// The value to round.
+ value: Box<GenericCalcNode<L>>,
+ /// The step value.
+ step: Box<GenericCalcNode<L>>,
+ },
+ /// A `mod()` or `rem()` function.
+ ModRem {
+ /// The dividend calculation.
+ dividend: Box<GenericCalcNode<L>>,
+ /// The divisor calculation.
+ divisor: Box<GenericCalcNode<L>>,
+ /// Is the function mod or rem?
+ op: ModRemOp,
+ },
+ /// A `hypot()` function
+ Hypot(crate::OwnedSlice<GenericCalcNode<L>>),
+ /// An `abs()` function.
+ Abs(Box<GenericCalcNode<L>>),
+ /// A `sign()` function.
+ Sign(Box<GenericCalcNode<L>>),
+}
+
+pub use self::GenericCalcNode as CalcNode;
+
+bitflags! {
+ /// Expected units we allow parsing within a `calc()` expression.
+ ///
+ /// This is used as a hint for the parser to fast-reject invalid
+ /// expressions. Numbers are always allowed because they multiply other
+ /// units.
+ #[derive(Clone, Copy, PartialEq, Eq)]
+ pub struct CalcUnits: u8 {
+ /// <length>
+ const LENGTH = 1 << 0;
+ /// <percentage>
+ const PERCENTAGE = 1 << 1;
+ /// <angle>
+ const ANGLE = 1 << 2;
+ /// <time>
+ const TIME = 1 << 3;
+ /// <resolution>
+ const RESOLUTION = 1 << 4;
+
+ /// <length-percentage>
+ const LENGTH_PERCENTAGE = Self::LENGTH.bits() | Self::PERCENTAGE.bits();
+ // NOTE: When you add to this, make sure to make Atan2 deal with these.
+ /// Allow all units.
+ const ALL = Self::LENGTH.bits() | Self::PERCENTAGE.bits() | Self::ANGLE.bits() | Self::TIME.bits() | Self::RESOLUTION.bits();
+ }
+}
+
+impl CalcUnits {
+ /// Returns whether the flags only represent a single unit. This will return true for 0, which
+ /// is a "number" this is also fine.
+ #[inline]
+ fn is_single_unit(&self) -> bool {
+ self.bits() == 0 || self.bits() & (self.bits() - 1) == 0
+ }
+
+ /// Returns true if this unit is allowed to be summed with the given unit, otherwise false.
+ #[inline]
+ fn can_sum_with(&self, other: Self) -> bool {
+ match *self {
+ Self::LENGTH => other.intersects(Self::LENGTH | Self::PERCENTAGE),
+ Self::PERCENTAGE => other.intersects(Self::LENGTH | Self::PERCENTAGE),
+ Self::LENGTH_PERCENTAGE => other.intersects(Self::LENGTH | Self::PERCENTAGE),
+ u => u.is_single_unit() && other == u,
+ }
+ }
+}
+
+/// For percentage resolution, sometimes we can't assume that the percentage basis is positive (so
+/// we don't know whether a percentage is larger than another).
+pub enum PositivePercentageBasis {
+ /// The percent basis is not known-positive, we can't compare percentages.
+ Unknown,
+ /// The percent basis is known-positive, we assume larger percentages are larger.
+ Yes,
+}
+
+macro_rules! compare_helpers {
+ () => {
+ /// Return whether a leaf is greater than another.
+ #[allow(unused)]
+ fn gt(&self, other: &Self, basis_positive: PositivePercentageBasis) -> bool {
+ self.compare(other, basis_positive) == Some(cmp::Ordering::Greater)
+ }
+
+ /// Return whether a leaf is less than another.
+ fn lt(&self, other: &Self, basis_positive: PositivePercentageBasis) -> bool {
+ self.compare(other, basis_positive) == Some(cmp::Ordering::Less)
+ }
+
+ /// Return whether a leaf is smaller or equal than another.
+ fn lte(&self, other: &Self, basis_positive: PositivePercentageBasis) -> bool {
+ match self.compare(other, basis_positive) {
+ Some(cmp::Ordering::Less) => true,
+ Some(cmp::Ordering::Equal) => true,
+ Some(cmp::Ordering::Greater) => false,
+ None => false,
+ }
+ }
+ };
+}
+
+/// A trait that represents all the stuff a valid leaf of a calc expression.
+pub trait CalcNodeLeaf: Clone + Sized + PartialEq + ToCss {
+ /// Returns the unit of the leaf.
+ fn unit(&self) -> CalcUnits;
+
+ /// Returns the unitless value of this leaf.
+ fn unitless_value(&self) -> f32;
+
+ /// Return true if the units of both leaves are equal. (NOTE: Does not take
+ /// the values into account)
+ fn is_same_unit_as(&self, other: &Self) -> bool {
+ std::mem::discriminant(self) == std::mem::discriminant(other)
+ }
+
+ /// Do a partial comparison of these values.
+ fn compare(
+ &self,
+ other: &Self,
+ base_is_positive: PositivePercentageBasis,
+ ) -> Option<cmp::Ordering>;
+ compare_helpers!();
+
+ /// Create a new leaf with a number value.
+ fn new_number(value: f32) -> Self;
+
+ /// Returns a float value if the leaf is a number.
+ fn as_number(&self) -> Option<f32>;
+
+ /// Whether this value is known-negative.
+ fn is_negative(&self) -> bool {
+ self.unitless_value().is_sign_negative()
+ }
+
+ /// Whether this value is infinite.
+ fn is_infinite(&self) -> bool {
+ self.unitless_value().is_infinite()
+ }
+
+ /// Whether this value is zero.
+ fn is_zero(&self) -> bool {
+ self.unitless_value().is_zero()
+ }
+
+ /// Whether this value is NaN.
+ fn is_nan(&self) -> bool {
+ self.unitless_value().is_nan()
+ }
+
+ /// Tries to merge one leaf into another using the sum, that is, perform `x` + `y`.
+ fn try_sum_in_place(&mut self, other: &Self) -> Result<(), ()>;
+
+ /// Try to merge the right leaf into the left by using a multiplication. Return true if the
+ /// merge was successful, otherwise false.
+ fn try_product_in_place(&mut self, other: &mut Self) -> bool;
+
+ /// Tries a generic arithmetic operation.
+ fn try_op<O>(&self, other: &Self, op: O) -> Result<Self, ()>
+ where
+ O: Fn(f32, f32) -> 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.map(std::ops::Neg::neg);
+ }
+
+ /// Canonicalizes the expression if necessary.
+ fn simplify(&mut self);
+
+ /// Returns the sort key for simplification.
+ fn sort_key(&self) -> SortKey;
+
+ /// Create a new leaf containing the sign() result of the given leaf.
+ fn sign_from(leaf: &impl CalcNodeLeaf) -> Self {
+ Self::new_number(if leaf.is_nan() {
+ f32::NAN
+ } else if leaf.is_zero() {
+ leaf.unitless_value()
+ } else if leaf.is_negative() {
+ -1.0
+ } else {
+ 1.0
+ })
+ }
+}
+
+/// The level of any argument being serialized in `to_css_impl`.
+enum ArgumentLevel {
+ /// The root of a calculation tree.
+ CalculationRoot,
+ /// The root of an operand node's argument, e.g. `min(10, 20)`, `10` and `20` will have this
+ /// level, but min in this case will have `TopMost`.
+ ArgumentRoot,
+ /// Any other values serialized in the tree.
+ Nested,
+}
+
+impl<L: CalcNodeLeaf> CalcNode<L> {
+ /// Create a dummy CalcNode that can be used to do replacements of other nodes.
+ fn dummy() -> Self {
+ Self::MinMax(Default::default(), MinMaxOp::Max)
+ }
+
+ /// Change all the leaf nodes to have the given value. This is useful when
+ /// you have `calc(1px * nan)` and you want to replace the product node with
+ /// `calc(nan)`, in which case the unit will be retained.
+ fn coerce_to_value(&mut self, value: f32) {
+ self.map(|_| value);
+ }
+
+ /// Return true if a product is distributive over this node.
+ /// Is distributive: (2 + 3) * 4 = 8 + 12
+ /// Not distributive: sign(2 + 3) * 4 != sign(8 + 12)
+ #[inline]
+ pub fn is_product_distributive(&self) -> bool {
+ match self {
+ Self::Leaf(_) => true,
+ Self::Sum(children) => children.iter().all(|c| c.is_product_distributive()),
+ _ => false,
+ }
+ }
+
+ /// If the node has a valid unit outcome, then return it, otherwise fail.
+ pub fn unit(&self) -> Result<CalcUnits, ()> {
+ Ok(match self {
+ CalcNode::Leaf(l) => l.unit(),
+ CalcNode::Negate(child) | CalcNode::Invert(child) | CalcNode::Abs(child) => {
+ child.unit()?
+ },
+ CalcNode::Sum(children) => {
+ let mut unit = children.first().unwrap().unit()?;
+ for child in children.iter().skip(1) {
+ let child_unit = child.unit()?;
+ if !child_unit.can_sum_with(unit) {
+ return Err(());
+ }
+ unit |= child_unit;
+ }
+ unit
+ },
+ CalcNode::Product(children) => {
+ // Only one node is allowed to have a unit, the rest must be numbers.
+ let mut unit = None;
+ for child in children.iter() {
+ let child_unit = child.unit()?;
+ if child_unit.is_empty() {
+ // Numbers are always allowed in a product, so continue with the next.
+ continue;
+ }
+
+ if unit.is_some() {
+ // We already have a unit for the node, so another unit node is invalid.
+ return Err(());
+ }
+
+ // We have the unit for the node.
+ unit = Some(child_unit);
+ }
+ // We only keep track of specified units, so if we end up with a None and no failure
+ // so far, then we have a number.
+ unit.unwrap_or(CalcUnits::empty())
+ },
+ CalcNode::MinMax(children, _) | CalcNode::Hypot(children) => {
+ let mut unit = children.first().unwrap().unit()?;
+ for child in children.iter().skip(1) {
+ let child_unit = child.unit()?;
+ if !child_unit.can_sum_with(unit) {
+ return Err(());
+ }
+ unit |= child_unit;
+ }
+ unit
+ },
+ CalcNode::Clamp { min, center, max } => {
+ let min_unit = min.unit()?;
+ let center_unit = center.unit()?;
+
+ if !min_unit.can_sum_with(center_unit) {
+ return Err(());
+ }
+
+ let max_unit = max.unit()?;
+
+ if !center_unit.can_sum_with(max_unit) {
+ return Err(());
+ }
+
+ min_unit | center_unit | max_unit
+ },
+ CalcNode::Round { value, step, .. } => {
+ let value_unit = value.unit()?;
+ let step_unit = step.unit()?;
+ if !step_unit.can_sum_with(value_unit) {
+ return Err(());
+ }
+ value_unit | step_unit
+ },
+ CalcNode::ModRem {
+ dividend, divisor, ..
+ } => {
+ let dividend_unit = dividend.unit()?;
+ let divisor_unit = divisor.unit()?;
+ if !divisor_unit.can_sum_with(dividend_unit) {
+ return Err(());
+ }
+ dividend_unit | divisor_unit
+ },
+ CalcNode::Sign(ref child) => {
+ // sign() always resolves to a number, but we still need to make sure that the
+ // child units make sense.
+ let _ = child.unit()?;
+ CalcUnits::empty()
+ },
+ })
+ }
+
+ /// Negate the node inline. If the node is distributive, it is replaced by the result,
+ /// otherwise the node is wrapped in a [`Negate`] node.
+ pub fn negate(&mut self) {
+ /// Node(params) -> Negate(Node(params))
+ fn wrap_self_in_negate<L: CalcNodeLeaf>(s: &mut CalcNode<L>) {
+ let result = mem::replace(s, CalcNode::dummy());
+ *s = CalcNode::Negate(Box::new(result));
+ }
+
+ match *self {
+ CalcNode::Leaf(ref mut leaf) => leaf.negate(),
+ CalcNode::Negate(ref mut value) => {
+ // Don't negate the value here. Replace `self` with it's child.
+ let result = mem::replace(value.as_mut(), Self::dummy());
+ *self = result;
+ },
+ CalcNode::Invert(_) => {
+ // -(1 / -10) == -(-0.1) == 0.1
+ wrap_self_in_negate(self)
+ },
+ CalcNode::Sum(ref mut children) => {
+ for child in children.iter_mut() {
+ child.negate();
+ }
+ },
+ CalcNode::Product(_) => {
+ // -(2 * 3 / 4) == -(1.5)
+ wrap_self_in_negate(self);
+ },
+ CalcNode::MinMax(ref mut children, ref mut op) => {
+ for child in children.iter_mut() {
+ child.negate();
+ }
+
+ // Negating min-max means the operation is swapped.
+ *op = match *op {
+ MinMaxOp::Min => MinMaxOp::Max,
+ MinMaxOp::Max => MinMaxOp::Min,
+ };
+ },
+ CalcNode::Clamp {
+ ref mut min,
+ ref mut center,
+ ref mut max,
+ } => {
+ if min.lte(max, PositivePercentageBasis::Unknown) {
+ min.negate();
+ center.negate();
+ max.negate();
+
+ mem::swap(min, max);
+ } else {
+ wrap_self_in_negate(self);
+ }
+ },
+ CalcNode::Round {
+ ref mut strategy,
+ ref mut value,
+ ref mut step,
+ } => {
+ match *strategy {
+ RoundingStrategy::Nearest => {
+ // Nearest is tricky because we'd have to swap the
+ // behavior at the half-way point from using the upper
+ // to lower bound.
+ // Simpler to just wrap self in a negate node.
+ wrap_self_in_negate(self);
+ return;
+ },
+ RoundingStrategy::Up => *strategy = RoundingStrategy::Down,
+ RoundingStrategy::Down => *strategy = RoundingStrategy::Up,
+ RoundingStrategy::ToZero => (),
+ }
+ value.negate();
+ step.negate();
+ },
+ CalcNode::ModRem {
+ ref mut dividend,
+ ref mut divisor,
+ ..
+ } => {
+ dividend.negate();
+ divisor.negate();
+ },
+ CalcNode::Hypot(ref mut children) => {
+ for child in children.iter_mut() {
+ child.negate();
+ }
+ },
+ CalcNode::Abs(_) => {
+ wrap_self_in_negate(self);
+ },
+ CalcNode::Sign(ref mut child) => {
+ child.negate();
+ },
+ }
+ }
+
+ fn sort_key(&self) -> SortKey {
+ match *self {
+ Self::Leaf(ref l) => l.sort_key(),
+ _ => SortKey::Other,
+ }
+ }
+
+ /// Returns the leaf if we can (if simplification has allowed it).
+ pub fn as_leaf(&self) -> Option<&L> {
+ match *self {
+ Self::Leaf(ref l) => Some(l),
+ _ => None,
+ }
+ }
+
+ /// Tries to merge one node into another using the sum, that is, perform `x` + `y`.
+ fn try_sum_in_place(&mut self, other: &Self) -> Result<(), ()> {
+ match (self, other) {
+ (&mut CalcNode::Leaf(ref mut one), &CalcNode::Leaf(ref other)) => {
+ one.try_sum_in_place(other)
+ },
+ _ => Err(()),
+ }
+ }
+
+ /// Tries to merge one node into another using the product, that is, perform `x` * `y`.
+ pub fn try_product_in_place(&mut self, other: &mut Self) -> bool {
+ if let Ok(resolved) = other.resolve() {
+ if let Some(number) = resolved.as_number() {
+ if number == 1.0 {
+ return true;
+ }
+
+ if self.is_product_distributive() {
+ self.map(|v| v * number);
+ return true;
+ }
+ }
+ }
+
+ if let Ok(resolved) = self.resolve() {
+ if let Some(number) = resolved.as_number() {
+ if number == 1.0 {
+ std::mem::swap(self, other);
+ return true;
+ }
+
+ if other.is_product_distributive() {
+ other.map(|v| v * number);
+ std::mem::swap(self, other);
+ return true;
+ }
+ }
+ }
+
+ false
+ }
+
+ /// Tries to apply a generic arithmetic operator
+ fn try_op<O>(&self, other: &Self, op: O) -> Result<Self, ()>
+ where
+ O: Fn(f32, f32) -> f32,
+ {
+ match (self, other) {
+ (&CalcNode::Leaf(ref one), &CalcNode::Leaf(ref other)) => {
+ Ok(CalcNode::Leaf(one.try_op(other, op)?))
+ },
+ _ => Err(()),
+ }
+ }
+
+ /// 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::Negate(v) | CalcNode::Invert(v) => map_internal(v, op),
+ CalcNode::Sum(children) | CalcNode::Product(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);
+ }
+ },
+ CalcNode::Abs(child) | CalcNode::Sign(child) => {
+ map_internal(child, 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
+ O: CalcNodeLeaf,
+ F: FnMut(&L) -> O,
+ {
+ self.map_leaves_internal(&mut map)
+ }
+
+ fn map_leaves_internal<O, F>(&self, map: &mut F) -> CalcNode<O>
+ where
+ O: CalcNodeLeaf,
+ F: FnMut(&L) -> O,
+ {
+ fn map_children<L, O, F>(
+ children: &[CalcNode<L>],
+ map: &mut F,
+ ) -> crate::OwnedSlice<CalcNode<O>>
+ where
+ L: CalcNodeLeaf,
+ O: CalcNodeLeaf,
+ F: FnMut(&L) -> O,
+ {
+ children
+ .iter()
+ .map(|c| c.map_leaves_internal(map))
+ .collect()
+ }
+
+ match *self {
+ Self::Leaf(ref l) => CalcNode::Leaf(map(l)),
+ Self::Negate(ref c) => CalcNode::Negate(Box::new(c.map_leaves_internal(map))),
+ Self::Invert(ref c) => CalcNode::Invert(Box::new(c.map_leaves_internal(map))),
+ Self::Sum(ref c) => CalcNode::Sum(map_children(c, map)),
+ Self::Product(ref c) => CalcNode::Product(map_children(c, map)),
+ Self::MinMax(ref c, op) => CalcNode::MinMax(map_children(c, map), op),
+ Self::Clamp {
+ ref min,
+ ref center,
+ ref max,
+ } => {
+ let min = Box::new(min.map_leaves_internal(map));
+ let center = Box::new(center.map_leaves_internal(map));
+ let max = Box::new(max.map_leaves_internal(map));
+ CalcNode::Clamp { min, center, max }
+ },
+ Self::Round {
+ strategy,
+ ref value,
+ ref step,
+ } => {
+ let value = Box::new(value.map_leaves_internal(map));
+ let step = Box::new(step.map_leaves_internal(map));
+ CalcNode::Round {
+ strategy,
+ value,
+ step,
+ }
+ },
+ Self::ModRem {
+ ref dividend,
+ ref divisor,
+ op,
+ } => {
+ let dividend = Box::new(dividend.map_leaves_internal(map));
+ let divisor = Box::new(divisor.map_leaves_internal(map));
+ CalcNode::ModRem {
+ dividend,
+ divisor,
+ op,
+ }
+ },
+ Self::Hypot(ref c) => CalcNode::Hypot(map_children(c, map)),
+ Self::Abs(ref c) => CalcNode::Abs(Box::new(c.map_leaves_internal(map))),
+ Self::Sign(ref c) => CalcNode::Sign(Box::new(c.map_leaves_internal(map))),
+ }
+ }
+
+ /// Resolve this node into a value.
+ pub fn resolve(&self) -> Result<L, ()> {
+ self.resolve_map(|l| Ok(l.clone()))
+ }
+
+ /// Resolve this node into a value, given a function that maps the leaf values.
+ pub fn resolve_map<F>(&self, mut leaf_to_output_fn: F) -> Result<L, ()>
+ where
+ F: FnMut(&L) -> Result<L, ()>,
+ {
+ self.resolve_internal(&mut leaf_to_output_fn)
+ }
+
+ fn resolve_internal<F>(&self, leaf_to_output_fn: &mut F) -> Result<L, ()>
+ where
+ F: FnMut(&L) -> Result<L, ()>,
+ {
+ match self {
+ Self::Leaf(l) => leaf_to_output_fn(l),
+ Self::Negate(child) => {
+ let mut result = child.resolve_internal(leaf_to_output_fn)?;
+ result.map(|v| v.neg());
+ Ok(result)
+ },
+ Self::Invert(child) => {
+ let mut result = child.resolve_internal(leaf_to_output_fn)?;
+ result.map(|v| 1.0 / v);
+ Ok(result)
+ },
+ Self::Sum(children) => {
+ let mut result = children[0].resolve_internal(leaf_to_output_fn)?;
+
+ for child in children.iter().skip(1) {
+ let right = child.resolve_internal(leaf_to_output_fn)?;
+ // try_op will make sure we only sum leaves with the same type.
+ result = result.try_op(&right, |left, right| left + right)?;
+ }
+
+ Ok(result)
+ },
+ Self::Product(children) => {
+ let mut result = children[0].resolve_internal(leaf_to_output_fn)?;
+
+ for child in children.iter().skip(1) {
+ let right = child.resolve_internal(leaf_to_output_fn)?;
+ // Mutliply only allowed when either side is a number.
+ match result.as_number() {
+ Some(left) => {
+ // Left side is a number, so we use the right node as the result.
+ result = right;
+ result.map(|v| v * left);
+ },
+ None => {
+ // Left side is not a number, so check if the right side is.
+ match right.as_number() {
+ Some(right) => {
+ result.map(|v| v * right);
+ },
+ None => {
+ // Multiplying with both sides having units.
+ return Err(());
+ },
+ }
+ },
+ }
+ }
+
+ Ok(result)
+ },
+ Self::MinMax(children, op) => {
+ let mut result = children[0].resolve_internal(leaf_to_output_fn)?;
+
+ if result.is_nan() {
+ return Ok(result);
+ }
+
+ for child in children.iter().skip(1) {
+ let candidate = child.resolve_internal(leaf_to_output_fn)?;
+
+ // Leave types must match for each child.
+ if !result.is_same_unit_as(&candidate) {
+ return Err(());
+ }
+
+ if candidate.is_nan() {
+ result = candidate;
+ break;
+ }
+
+ let candidate_wins = match op {
+ MinMaxOp::Min => candidate.lt(&result, PositivePercentageBasis::Yes),
+ MinMaxOp::Max => candidate.gt(&result, PositivePercentageBasis::Yes),
+ };
+
+ if candidate_wins {
+ result = candidate;
+ }
+ }
+
+ Ok(result)
+ },
+ Self::Clamp { min, center, max } => {
+ let min = min.resolve_internal(leaf_to_output_fn)?;
+ let center = center.resolve_internal(leaf_to_output_fn)?;
+ let max = max.resolve_internal(leaf_to_output_fn)?;
+
+ if !min.is_same_unit_as(&center) || !max.is_same_unit_as(&center) {
+ return Err(());
+ }
+
+ if min.is_nan() {
+ return Ok(min);
+ }
+
+ if center.is_nan() {
+ return Ok(center);
+ }
+
+ if max.is_nan() {
+ return Ok(max);
+ }
+
+ let mut result = center;
+ if result.gt(&max, PositivePercentageBasis::Yes) {
+ result = max;
+ }
+ if result.lt(&min, PositivePercentageBasis::Yes) {
+ result = min
+ }
+
+ Ok(result)
+ },
+ Self::Round {
+ strategy,
+ value,
+ step,
+ } => {
+ let mut value = value.resolve_internal(leaf_to_output_fn)?;
+ let step = step.resolve_internal(leaf_to_output_fn)?;
+
+ if !value.is_same_unit_as(&step) {
+ return Err(());
+ }
+
+ let step = step.unitless_value().abs();
+
+ value.map(|value| {
+ // TODO(emilio): Seems like at least a few of these
+ // special-cases could be removed if we do the math in a
+ // particular order.
+ if step.is_zero() {
+ return f32::NAN;
+ }
+
+ if value.is_infinite() {
+ if step.is_infinite() {
+ return f32::NAN;
+ }
+ return value;
+ }
+
+ if step.is_infinite() {
+ match strategy {
+ RoundingStrategy::Nearest | RoundingStrategy::ToZero => {
+ return if value.is_sign_negative() { -0.0 } else { 0.0 }
+ },
+ RoundingStrategy::Up => {
+ return if !value.is_sign_negative() && !value.is_zero() {
+ f32::INFINITY
+ } else if !value.is_sign_negative() && value.is_zero() {
+ value
+ } else {
+ -0.0
+ }
+ },
+ RoundingStrategy::Down => {
+ return if value.is_sign_negative() && !value.is_zero() {
+ -f32::INFINITY
+ } else if value.is_sign_negative() && value.is_zero() {
+ value
+ } else {
+ 0.0
+ }
+ },
+ }
+ }
+
+ let div = value / step;
+ let lower_bound = div.floor() * step;
+ let upper_bound = div.ceil() * step;
+
+ match strategy {
+ RoundingStrategy::Nearest => {
+ // In case of a tie, use the upper bound
+ if value - lower_bound < upper_bound - value {
+ lower_bound
+ } else {
+ upper_bound
+ }
+ },
+ RoundingStrategy::Up => upper_bound,
+ RoundingStrategy::Down => lower_bound,
+ RoundingStrategy::ToZero => {
+ // In case of a tie, use the upper bound
+ if lower_bound.abs() < upper_bound.abs() {
+ lower_bound
+ } else {
+ upper_bound
+ }
+ },
+ }
+ });
+
+ Ok(value)
+ },
+ Self::ModRem {
+ dividend,
+ divisor,
+ op,
+ } => {
+ let mut dividend = dividend.resolve_internal(leaf_to_output_fn)?;
+ let divisor = divisor.resolve_internal(leaf_to_output_fn)?;
+
+ if !dividend.is_same_unit_as(&divisor) {
+ return Err(());
+ }
+
+ let divisor = divisor.unitless_value();
+ dividend.map(|dividend| op.apply(dividend, divisor));
+ Ok(dividend)
+ },
+ Self::Hypot(children) => {
+ let mut result = children[0].resolve_internal(leaf_to_output_fn)?;
+ result.map(|v| v.powi(2));
+
+ for child in children.iter().skip(1) {
+ let child_value = child.resolve_internal(leaf_to_output_fn)?;
+
+ if !result.is_same_unit_as(&child_value) {
+ return Err(());
+ }
+
+ result.map(|v| v + child_value.unitless_value().powi(2));
+ }
+
+ result.map(|v| v.sqrt());
+ Ok(result)
+ },
+ Self::Abs(ref c) => {
+ let mut result = c.resolve_internal(leaf_to_output_fn)?;
+
+ result.map(|v| v.abs());
+
+ Ok(result)
+ },
+ Self::Sign(ref c) => {
+ let result = c.resolve_internal(leaf_to_output_fn)?;
+ Ok(L::sign_from(&result))
+ },
+ }
+ }
+
+ fn is_negative_leaf(&self) -> bool {
+ match *self {
+ Self::Leaf(ref l) => l.is_negative(),
+ _ => false,
+ }
+ }
+
+ fn is_zero_leaf(&self) -> bool {
+ match *self {
+ Self::Leaf(ref l) => l.is_zero(),
+ _ => false,
+ }
+ }
+
+ fn is_infinite_leaf(&self) -> bool {
+ match *self {
+ Self::Leaf(ref l) => l.is_infinite(),
+ _ => false,
+ }
+ }
+
+ /// Visits all the nodes in this calculation tree recursively, starting by
+ /// the leaves and bubbling all the way up.
+ ///
+ /// This is useful for simplification, but can also be used for validation
+ /// and such.
+ pub fn visit_depth_first(&mut self, mut f: impl FnMut(&mut Self)) {
+ self.visit_depth_first_internal(&mut f)
+ }
+
+ fn visit_depth_first_internal(&mut self, f: &mut impl FnMut(&mut Self)) {
+ match *self {
+ Self::Clamp {
+ ref mut min,
+ ref mut center,
+ ref mut max,
+ } => {
+ min.visit_depth_first_internal(f);
+ center.visit_depth_first_internal(f);
+ max.visit_depth_first_internal(f);
+ },
+ Self::Round {
+ ref mut value,
+ ref mut step,
+ ..
+ } => {
+ value.visit_depth_first_internal(f);
+ step.visit_depth_first_internal(f);
+ },
+ Self::ModRem {
+ ref mut dividend,
+ ref mut divisor,
+ ..
+ } => {
+ dividend.visit_depth_first_internal(f);
+ divisor.visit_depth_first_internal(f);
+ },
+ Self::Sum(ref mut children) |
+ Self::Product(ref mut children) |
+ Self::MinMax(ref mut children, _) |
+ Self::Hypot(ref mut children) => {
+ for child in &mut **children {
+ child.visit_depth_first_internal(f);
+ }
+ },
+ Self::Negate(ref mut value) | Self::Invert(ref mut value) => {
+ value.visit_depth_first_internal(f);
+ },
+ Self::Abs(ref mut value) | Self::Sign(ref mut value) => {
+ value.visit_depth_first_internal(f);
+ },
+ Self::Leaf(..) => {},
+ }
+ f(self);
+ }
+
+ /// This function simplifies and sorts the calculation of the specified node. It simplifies
+ /// directly nested nodes while assuming that all nodes below it have already been simplified.
+ /// It is recommended to use this function in combination with `visit_depth_first()`.
+ ///
+ /// This function is necessary only if the node needs to be preserved after parsing,
+ /// specifically for `<length-percentage>` cases where the calculation contains percentages or
+ /// relative units. Otherwise, the node can be evaluated using `resolve()`, which will
+ /// automatically provide a simplified value.
+ ///
+ /// <https://drafts.csswg.org/css-values-4/#calc-simplification>
+ pub fn simplify_and_sort_direct_children(&mut self) {
+ macro_rules! replace_self_with {
+ ($slot:expr) => {{
+ let result = mem::replace($slot, Self::dummy());
+ *self = result;
+ }};
+ }
+
+ macro_rules! value_or_stop {
+ ($op:expr) => {{
+ match $op {
+ Ok(value) => value,
+ Err(_) => return,
+ }
+ }};
+ }
+
+ match *self {
+ Self::Clamp {
+ ref mut min,
+ ref mut center,
+ ref mut max,
+ } => {
+ // NOTE: clamp() is max(min, min(center, max))
+ let min_cmp_center = match min.compare(&center, PositivePercentageBasis::Unknown) {
+ Some(o) => o,
+ None => return,
+ };
+
+ // So if we can prove that min is more than center, then we won,
+ // as that's what we should always return.
+ if matches!(min_cmp_center, cmp::Ordering::Greater) {
+ replace_self_with!(&mut **min);
+ return;
+ }
+
+ // Otherwise try with max.
+ let max_cmp_center = match max.compare(&center, PositivePercentageBasis::Unknown) {
+ Some(o) => o,
+ None => return,
+ };
+
+ if matches!(max_cmp_center, cmp::Ordering::Less) {
+ // max is less than center, so we need to return effectively
+ // `max(min, max)`.
+ let max_cmp_min = match max.compare(&min, PositivePercentageBasis::Unknown) {
+ Some(o) => o,
+ None => {
+ debug_assert!(
+ false,
+ "We compared center with min and max, how are \
+ min / max not comparable with each other?"
+ );
+ return;
+ },
+ };
+
+ if matches!(max_cmp_min, cmp::Ordering::Less) {
+ replace_self_with!(&mut **min);
+ return;
+ }
+
+ replace_self_with!(&mut **max);
+ return;
+ }
+
+ // Otherwise we're the center node.
+ replace_self_with!(&mut **center);
+ },
+ Self::Round {
+ strategy,
+ ref mut value,
+ ref mut step,
+ } => {
+ if step.is_zero_leaf() {
+ value.coerce_to_value(f32::NAN);
+ replace_self_with!(&mut **value);
+ return;
+ }
+
+ if value.is_infinite_leaf() && step.is_infinite_leaf() {
+ value.coerce_to_value(f32::NAN);
+ replace_self_with!(&mut **value);
+ return;
+ }
+
+ if value.is_infinite_leaf() {
+ replace_self_with!(&mut **value);
+ return;
+ }
+
+ if step.is_infinite_leaf() {
+ match strategy {
+ RoundingStrategy::Nearest | RoundingStrategy::ToZero => {
+ value.coerce_to_value(0.0);
+ replace_self_with!(&mut **value);
+ return;
+ },
+ RoundingStrategy::Up => {
+ if !value.is_negative_leaf() && !value.is_zero_leaf() {
+ value.coerce_to_value(f32::INFINITY);
+ replace_self_with!(&mut **value);
+ return;
+ } else if !value.is_negative_leaf() && value.is_zero_leaf() {
+ replace_self_with!(&mut **value);
+ return;
+ } else {
+ value.coerce_to_value(0.0);
+ replace_self_with!(&mut **value);
+ return;
+ }
+ },
+ RoundingStrategy::Down => {
+ if value.is_negative_leaf() && !value.is_zero_leaf() {
+ value.coerce_to_value(f32::INFINITY);
+ replace_self_with!(&mut **value);
+ return;
+ } else if value.is_negative_leaf() && value.is_zero_leaf() {
+ replace_self_with!(&mut **value);
+ return;
+ } else {
+ value.coerce_to_value(0.0);
+ replace_self_with!(&mut **value);
+ return;
+ }
+ },
+ }
+ }
+
+ if step.is_negative_leaf() {
+ step.negate();
+ }
+
+ let remainder = value_or_stop!(value.try_op(step, Rem::rem));
+ if remainder.is_zero_leaf() {
+ replace_self_with!(&mut **value);
+ return;
+ }
+
+ let (mut lower_bound, mut upper_bound) = if value.is_negative_leaf() {
+ let upper_bound = value_or_stop!(value.try_op(&remainder, Sub::sub));
+ let lower_bound = value_or_stop!(upper_bound.try_op(&step, Sub::sub));
+
+ (lower_bound, upper_bound)
+ } else {
+ let lower_bound = value_or_stop!(value.try_op(&remainder, Sub::sub));
+ let upper_bound = value_or_stop!(lower_bound.try_op(&step, Add::add));
+
+ (lower_bound, upper_bound)
+ };
+
+ match strategy {
+ RoundingStrategy::Nearest => {
+ let lower_diff = value_or_stop!(value.try_op(&lower_bound, Sub::sub));
+ let upper_diff = value_or_stop!(upper_bound.try_op(value, Sub::sub));
+ // In case of a tie, use the upper bound
+ if lower_diff.lt(&upper_diff, PositivePercentageBasis::Unknown) {
+ replace_self_with!(&mut lower_bound);
+ } else {
+ replace_self_with!(&mut upper_bound);
+ }
+ },
+ RoundingStrategy::Up => {
+ replace_self_with!(&mut upper_bound);
+ },
+ RoundingStrategy::Down => {
+ replace_self_with!(&mut lower_bound);
+ },
+ RoundingStrategy::ToZero => {
+ let mut lower_diff = lower_bound.clone();
+ let mut upper_diff = upper_bound.clone();
+
+ if lower_diff.is_negative_leaf() {
+ lower_diff.negate();
+ }
+
+ if upper_diff.is_negative_leaf() {
+ upper_diff.negate();
+ }
+
+ // In case of a tie, use the upper bound
+ if lower_diff.lt(&upper_diff, PositivePercentageBasis::Unknown) {
+ replace_self_with!(&mut lower_bound);
+ } else {
+ replace_self_with!(&mut upper_bound);
+ }
+ },
+ };
+ },
+ Self::ModRem {
+ ref dividend,
+ ref divisor,
+ op,
+ } => {
+ let mut result = value_or_stop!(dividend.try_op(divisor, |a, b| op.apply(a, b)));
+ replace_self_with!(&mut result);
+ },
+ Self::MinMax(ref mut children, op) => {
+ let winning_order = match op {
+ MinMaxOp::Min => cmp::Ordering::Less,
+ MinMaxOp::Max => cmp::Ordering::Greater,
+ };
+
+ let mut result = 0;
+ for i in 1..children.len() {
+ let o = match children[i]
+ .compare(&children[result], PositivePercentageBasis::Unknown)
+ {
+ // We can't compare all the children, so we can't
+ // know which one will actually win. Bail out and
+ // keep ourselves as a min / max function.
+ //
+ // TODO: Maybe we could simplify compatible children,
+ // see https://github.com/w3c/csswg-drafts/issues/4756
+ None => return,
+ Some(o) => o,
+ };
+
+ if o == winning_order {
+ result = i;
+ }
+ }
+
+ replace_self_with!(&mut children[result]);
+ },
+ Self::Sum(ref mut children_slot) => {
+ let mut sums_to_merge = SmallVec::<[_; 3]>::new();
+ let mut extra_kids = 0;
+ for (i, child) in children_slot.iter().enumerate() {
+ if let Self::Sum(ref children) = *child {
+ extra_kids += children.len();
+ sums_to_merge.push(i);
+ }
+ }
+
+ // If we only have one kid, we've already simplified it, and it
+ // doesn't really matter whether it's a sum already or not, so
+ // lift it up and continue.
+ if children_slot.len() == 1 {
+ replace_self_with!(&mut children_slot[0]);
+ return;
+ }
+
+ let mut children = mem::take(children_slot).into_vec();
+
+ if !sums_to_merge.is_empty() {
+ children.reserve(extra_kids - sums_to_merge.len());
+ // Merge all our nested sums, in reverse order so that the
+ // list indices are not invalidated.
+ for i in sums_to_merge.drain(..).rev() {
+ let kid_children = match children.swap_remove(i) {
+ Self::Sum(c) => c,
+ _ => unreachable!(),
+ };
+
+ // This would be nicer with
+ // https://github.com/rust-lang/rust/issues/59878 fixed.
+ children.extend(kid_children.into_vec());
+ }
+ }
+
+ debug_assert!(children.len() >= 2, "Should still have multiple kids!");
+
+ // Sort by spec order.
+ children.sort_unstable_by_key(|c| c.sort_key());
+
+ // NOTE: if the function returns true, by the docs of dedup_by,
+ // a is removed.
+ children.dedup_by(|a, b| b.try_sum_in_place(a).is_ok());
+
+ if children.len() == 1 {
+ // If only one children remains, lift it up, and carry on.
+ replace_self_with!(&mut children[0]);
+ } else {
+ // Else put our simplified children back.
+ *children_slot = children.into_boxed_slice().into();
+ }
+ },
+ Self::Product(ref mut children_slot) => {
+ let mut products_to_merge = SmallVec::<[_; 3]>::new();
+ let mut extra_kids = 0;
+ for (i, child) in children_slot.iter().enumerate() {
+ if let Self::Product(ref children) = *child {
+ extra_kids += children.len();
+ products_to_merge.push(i);
+ }
+ }
+
+ // If we only have one kid, we've already simplified it, and it
+ // doesn't really matter whether it's a product already or not,
+ // so lift it up and continue.
+ if children_slot.len() == 1 {
+ replace_self_with!(&mut children_slot[0]);
+ return;
+ }
+
+ let mut children = mem::take(children_slot).into_vec();
+
+ if !products_to_merge.is_empty() {
+ children.reserve(extra_kids - products_to_merge.len());
+ // Merge all our nested sums, in reverse order so that the
+ // list indices are not invalidated.
+ for i in products_to_merge.drain(..).rev() {
+ let kid_children = match children.swap_remove(i) {
+ Self::Product(c) => c,
+ _ => unreachable!(),
+ };
+
+ // This would be nicer with
+ // https://github.com/rust-lang/rust/issues/59878 fixed.
+ children.extend(kid_children.into_vec());
+ }
+ }
+
+ debug_assert!(children.len() >= 2, "Should still have multiple kids!");
+
+ // NOTE: if the function returns true, by the docs of dedup_by,
+ // a is removed.
+ children.dedup_by(|right, left| left.try_product_in_place(right));
+
+ if children.len() == 1 {
+ // If only one children remains, lift it up, and carry on.
+ replace_self_with!(&mut children[0]);
+ } else {
+ // Else put our simplified children back.
+ *children_slot = children.into_boxed_slice().into();
+ }
+ },
+ Self::Hypot(ref children) => {
+ let mut result = value_or_stop!(children[0].try_op(&children[0], Mul::mul));
+
+ for child in children.iter().skip(1) {
+ let square = value_or_stop!(child.try_op(&child, Mul::mul));
+ result = value_or_stop!(result.try_op(&square, Add::add));
+ }
+
+ result = value_or_stop!(result.try_op(&result, |a, _| a.sqrt()));
+
+ replace_self_with!(&mut result);
+ },
+ Self::Abs(ref mut child) => {
+ if let CalcNode::Leaf(leaf) = child.as_mut() {
+ leaf.map(|v| v.abs());
+ replace_self_with!(&mut **child);
+ }
+ },
+ Self::Sign(ref mut child) => {
+ if let CalcNode::Leaf(leaf) = child.as_mut() {
+ let mut result = Self::Leaf(L::sign_from(leaf));
+ replace_self_with!(&mut result);
+ }
+ },
+ Self::Negate(ref mut child) => {
+ // Step 6.
+ match &mut **child {
+ CalcNode::Leaf(_) => {
+ // 1. If root’s child is a numeric value, return an equivalent numeric value, but
+ // with the value negated (0 - value).
+ child.negate();
+ replace_self_with!(&mut **child);
+ },
+ CalcNode::Negate(value) => {
+ // 2. If root’s child is a Negate node, return the child’s child.
+ replace_self_with!(&mut **value);
+ },
+ _ => {
+ // 3. Return root.
+ },
+ }
+ },
+ Self::Invert(ref mut child) => {
+ // Step 7.
+ match &mut **child {
+ CalcNode::Leaf(leaf) => {
+ // 1. If root’s child is a number (not a percentage or dimension) return the
+ // reciprocal of the child’s value.
+ if leaf.unit().is_empty() {
+ child.map(|v| 1.0 / v);
+ replace_self_with!(&mut **child);
+ }
+ },
+ CalcNode::Invert(value) => {
+ // 2. If root’s child is an Invert node, return the child’s child.
+ replace_self_with!(&mut **value);
+ },
+ _ => {
+ // 3. Return root.
+ },
+ }
+ },
+ Self::Leaf(ref mut l) => {
+ l.simplify();
+ },
+ }
+ }
+
+ /// Simplifies and sorts the kids in the whole calculation subtree.
+ pub fn simplify_and_sort(&mut self) {
+ self.visit_depth_first(|node| node.simplify_and_sort_direct_children())
+ }
+
+ fn to_css_impl<W>(&self, dest: &mut CssWriter<W>, level: ArgumentLevel) -> fmt::Result
+ where
+ W: Write,
+ {
+ let write_closing_paren = match *self {
+ Self::MinMax(_, op) => {
+ dest.write_str(match op {
+ MinMaxOp::Max => "max(",
+ MinMaxOp::Min => "min(",
+ })?;
+ true
+ },
+ Self::Clamp { .. } => {
+ dest.write_str("clamp(")?;
+ true
+ },
+ Self::Round { strategy, .. } => {
+ match strategy {
+ RoundingStrategy::Nearest => dest.write_str("round("),
+ RoundingStrategy::Up => dest.write_str("round(up, "),
+ RoundingStrategy::Down => dest.write_str("round(down, "),
+ RoundingStrategy::ToZero => dest.write_str("round(to-zero, "),
+ }?;
+
+ true
+ },
+ Self::ModRem { op, .. } => {
+ dest.write_str(match op {
+ ModRemOp::Mod => "mod(",
+ ModRemOp::Rem => "rem(",
+ })?;
+
+ true
+ },
+ Self::Hypot(_) => {
+ dest.write_str("hypot(")?;
+ true
+ },
+ Self::Abs(_) => {
+ dest.write_str("abs(")?;
+ true
+ },
+ Self::Sign(_) => {
+ dest.write_str("sign(")?;
+ true
+ },
+ Self::Negate(_) => {
+ // We never generate a [`Negate`] node as the root of a calculation, only inside
+ // [`Sum`] nodes as a child. Because negate nodes are handled by the [`Sum`] node
+ // directly (see below), this node will never be serialized.
+ debug_assert!(
+ false,
+ "We never serialize Negate nodes as they are handled inside Sum nodes."
+ );
+ dest.write_str("(-1 * ")?;
+ true
+ },
+ Self::Invert(_) => {
+ dest.write_str("(1 / ")?;
+ true
+ },
+ Self::Sum(_) | Self::Product(_) => match level {
+ ArgumentLevel::CalculationRoot => {
+ dest.write_str("calc(")?;
+ true
+ },
+ ArgumentLevel::ArgumentRoot => false,
+ ArgumentLevel::Nested => {
+ dest.write_str("(")?;
+ true
+ },
+ },
+ Self::Leaf(_) => match level {
+ ArgumentLevel::CalculationRoot => {
+ dest.write_str("calc(")?;
+ true
+ },
+ ArgumentLevel::ArgumentRoot | ArgumentLevel::Nested => false,
+ },
+ };
+
+ match *self {
+ Self::MinMax(ref children, _) | Self::Hypot(ref children) => {
+ let mut first = true;
+ for child in &**children {
+ if !first {
+ dest.write_str(", ")?;
+ }
+ first = false;
+ child.to_css_impl(dest, ArgumentLevel::ArgumentRoot)?;
+ }
+ },
+ Self::Negate(ref value) | Self::Invert(ref value) => {
+ value.to_css_impl(dest, ArgumentLevel::Nested)?
+ },
+ Self::Sum(ref children) => {
+ let mut first = true;
+ for child in &**children {
+ if !first {
+ match child {
+ Self::Leaf(l) => {
+ if l.is_negative() {
+ dest.write_str(" - ")?;
+ let mut negated = l.clone();
+ negated.negate();
+ negated.to_css(dest)?;
+ } else {
+ dest.write_str(" + ")?;
+ l.to_css(dest)?;
+ }
+ },
+ Self::Negate(n) => {
+ dest.write_str(" - ")?;
+ n.to_css_impl(dest, ArgumentLevel::Nested)?;
+ },
+ _ => {
+ dest.write_str(" + ")?;
+ child.to_css_impl(dest, ArgumentLevel::Nested)?;
+ },
+ }
+ } else {
+ first = false;
+ child.to_css_impl(dest, ArgumentLevel::Nested)?;
+ }
+ }
+ },
+ Self::Product(ref children) => {
+ let mut first = true;
+ for child in &**children {
+ if !first {
+ match child {
+ Self::Invert(n) => {
+ dest.write_str(" / ")?;
+ n.to_css_impl(dest, ArgumentLevel::Nested)?;
+ },
+ _ => {
+ dest.write_str(" * ")?;
+ child.to_css_impl(dest, ArgumentLevel::Nested)?;
+ },
+ }
+ } else {
+ first = false;
+ child.to_css_impl(dest, ArgumentLevel::Nested)?;
+ }
+ }
+ },
+ Self::Clamp {
+ ref min,
+ ref center,
+ ref max,
+ } => {
+ min.to_css_impl(dest, ArgumentLevel::ArgumentRoot)?;
+ dest.write_str(", ")?;
+ center.to_css_impl(dest, ArgumentLevel::ArgumentRoot)?;
+ dest.write_str(", ")?;
+ max.to_css_impl(dest, ArgumentLevel::ArgumentRoot)?;
+ },
+ Self::Round {
+ ref value,
+ ref step,
+ ..
+ } => {
+ value.to_css_impl(dest, ArgumentLevel::ArgumentRoot)?;
+ dest.write_str(", ")?;
+ step.to_css_impl(dest, ArgumentLevel::ArgumentRoot)?;
+ },
+ Self::ModRem {
+ ref dividend,
+ ref divisor,
+ ..
+ } => {
+ dividend.to_css_impl(dest, ArgumentLevel::ArgumentRoot)?;
+ dest.write_str(", ")?;
+ divisor.to_css_impl(dest, ArgumentLevel::ArgumentRoot)?;
+ },
+ Self::Abs(ref v) | Self::Sign(ref v) => {
+ v.to_css_impl(dest, ArgumentLevel::ArgumentRoot)?
+ },
+ Self::Leaf(ref l) => l.to_css(dest)?,
+ }
+
+ if write_closing_paren {
+ dest.write_char(')')?;
+ }
+ Ok(())
+ }
+
+ fn compare(
+ &self,
+ other: &Self,
+ basis_positive: PositivePercentageBasis,
+ ) -> Option<cmp::Ordering> {
+ match (self, other) {
+ (&CalcNode::Leaf(ref one), &CalcNode::Leaf(ref other)) => {
+ one.compare(other, basis_positive)
+ },
+ _ => None,
+ }
+ }
+
+ compare_helpers!();
+}
+
+impl<L: CalcNodeLeaf> ToCss for CalcNode<L> {
+ /// <https://drafts.csswg.org/css-values/#calc-serialize>
+ fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+ where
+ W: Write,
+ {
+ self.to_css_impl(dest, ArgumentLevel::CalculationRoot)
+ }
+}
+
+#[cfg(test)]
+mod tests {
+ use super::*;
+
+ #[test]
+ fn can_sum_with_checks() {
+ assert!(CalcUnits::LENGTH.can_sum_with(CalcUnits::LENGTH));
+ assert!(CalcUnits::LENGTH.can_sum_with(CalcUnits::PERCENTAGE));
+ assert!(CalcUnits::LENGTH.can_sum_with(CalcUnits::LENGTH_PERCENTAGE));
+
+ assert!(CalcUnits::PERCENTAGE.can_sum_with(CalcUnits::LENGTH));
+ assert!(CalcUnits::PERCENTAGE.can_sum_with(CalcUnits::PERCENTAGE));
+ assert!(CalcUnits::PERCENTAGE.can_sum_with(CalcUnits::LENGTH_PERCENTAGE));
+
+ assert!(CalcUnits::LENGTH_PERCENTAGE.can_sum_with(CalcUnits::LENGTH));
+ assert!(CalcUnits::LENGTH_PERCENTAGE.can_sum_with(CalcUnits::PERCENTAGE));
+ assert!(CalcUnits::LENGTH_PERCENTAGE.can_sum_with(CalcUnits::LENGTH_PERCENTAGE));
+
+ assert!(!CalcUnits::ANGLE.can_sum_with(CalcUnits::TIME));
+ assert!(CalcUnits::ANGLE.can_sum_with(CalcUnits::ANGLE));
+
+ assert!(!(CalcUnits::ANGLE | CalcUnits::TIME).can_sum_with(CalcUnits::ANGLE));
+ assert!(!CalcUnits::ANGLE.can_sum_with(CalcUnits::ANGLE | CalcUnits::TIME));
+ assert!(
+ !(CalcUnits::ANGLE | CalcUnits::TIME).can_sum_with(CalcUnits::ANGLE | CalcUnits::TIME)
+ );
+ }
+}
generated by cgit v1.2.3 (git 2.39.1) at 2025-02-16 13:37:51 +0000