LibWeb: Parse min() css math function

Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp

@@ -3434,6 +3434,45 @@ ErrorOr<RefPtr<CalculatedStyleValue>> Parser::parse_calculated_value(Vector<Comp
     return CalculatedStyleValue::create(calculation_tree.release_nonnull(), calc_type.release_value());
 }
 
+ErrorOr<OwnPtr<CalculationNode>> Parser::parse_min_function(Function const& function)
+{
+    TokenStream stream { function.values() };
+    auto parameters = parse_a_comma_separated_list_of_component_values(stream);
+
+    if (parameters.size() == 0) {
+        dbgln_if(CSS_PARSER_DEBUG, "min() must have at least 1 parameter"sv);
+        return nullptr;
+    }
+
+    Vector<NonnullOwnPtr<CalculationNode>> calculated_parameters;
+    calculated_parameters.ensure_capacity(parameters.size());
+
+    CalculatedStyleValue::ResolvedType type;
+    bool first = true;
+    for (auto& parameter : parameters) {
+        auto calculation_node = TRY(parse_a_calculation(parameter));
+
+        if (!calculation_node) {
+            dbgln_if(CSS_PARSER_DEBUG, "min() parameters must be valid calculations"sv);
+            return nullptr;
+        }
+
+        if (first) {
+            type = calculation_node->resolved_type().value();
+            first = false;
+        }
+
+        if (calculation_node->resolved_type().value() != type) {
+            dbgln_if(CSS_PARSER_DEBUG, "min() parameters must all be of the same type"sv);
+            return nullptr;
+        }
+
+        calculated_parameters.append(calculation_node.release_nonnull());
+    }
+
+    return TRY(MinCalculationNode::create(move(calculated_parameters)));
+}
+
 ErrorOr<RefPtr<StyleValue>> Parser::parse_dynamic_value(ComponentValue const& component_value)
 {
     if (component_value.is_function()) {
@@ -3460,6 +3499,9 @@ ErrorOr<OwnPtr<CalculationNode>> Parser::parse_a_calc_function_node(Function con
     if (function.name().equals_ignoring_ascii_case("calc"sv))
         return TRY(parse_a_calculation(function.values()));
 
+    if (function.name().equals_ignoring_ascii_case("min"sv))
+        return TRY(parse_min_function(function));
+
     dbgln_if(CSS_PARSER_DEBUG, "We didn't implement `{}` function yet", function.name());
     return nullptr;
 }

Userland/Libraries/LibWeb/CSS/Parser/Parser.h

@@ -290,6 +290,7 @@ private:
     ErrorOr<RefPtr<StyleValue>> parse_dynamic_value(ComponentValue const&);
     ErrorOr<RefPtr<CalculatedStyleValue>> parse_calculated_value(Vector<ComponentValue> const&);
     ErrorOr<OwnPtr<CalculationNode>> parse_a_calc_function_node(Function const&);
+    ErrorOr<OwnPtr<CalculationNode>> parse_min_function(Function const&);
     ErrorOr<RefPtr<StyleValue>> parse_dimension_value(ComponentValue const&);
     ErrorOr<RefPtr<StyleValue>> parse_integer_value(TokenStream<ComponentValue>&);
     ErrorOr<RefPtr<StyleValue>> parse_number_value(TokenStream<ComponentValue>&);

Userland/Libraries/LibWeb/CSS/StyleValues/CalculatedStyleValue.cpp

@@ -24,6 +24,17 @@ static bool is_dimension(CalculatedStyleValue::ResolvedType type)
         && type != CalculatedStyleValue::ResolvedType::Percentage;
 }
 
+static double resolve_value(CalculatedStyleValue::CalculationResult::Value value, Layout::Node const* layout_node)
+{
+    return value.visit(
+        [](Number const& number) { return number.value(); },
+        [](Angle const& angle) { return angle.to_degrees(); },
+        [](Frequency const& frequency) { return frequency.to_hertz(); },
+        [layout_node](Length const& length) { return length.to_px(*layout_node).value(); },
+        [](Percentage const& percentage) { return percentage.value(); },
+        [](Time const& time) { return time.to_seconds(); });
+};
+
 CalculationNode::CalculationNode(Type type)
     : m_type(type)
 {
@@ -390,6 +401,84 @@ ErrorOr<void> InvertCalculationNode::dump(StringBuilder& builder, int indent) co
     return {};
 }
 
+ErrorOr<NonnullOwnPtr<MinCalculationNode>> MinCalculationNode::create(Vector<NonnullOwnPtr<Web::CSS::CalculationNode>> values)
+{
+    return adopt_nonnull_own_or_enomem(new (nothrow) MinCalculationNode(move(values)));
+}
+
+MinCalculationNode::MinCalculationNode(Vector<NonnullOwnPtr<CalculationNode>> values)
+    : CalculationNode(Type::Min)
+    , m_values(move(values))
+{
+}
+
+MinCalculationNode::~MinCalculationNode() = default;
+
+ErrorOr<String> MinCalculationNode::to_string() const
+{
+    StringBuilder builder;
+    TRY(builder.try_append("min("sv));
+    for (size_t i = 0; i < m_values.size(); ++i) {
+        if (i != 0)
+            TRY(builder.try_append(", "sv));
+        TRY(builder.try_append(TRY(m_values[i]->to_string())));
+    }
+    TRY(builder.try_append(")"sv));
+    return builder.to_string();
+}
+
+Optional<CalculatedStyleValue::ResolvedType> MinCalculationNode::resolved_type() const
+{
+    // NOTE: We check during parsing that all values have the same type.
+    return m_values[0]->resolved_type();
+}
+
+bool MinCalculationNode::contains_percentage() const
+{
+    for (auto const& value : m_values) {
+        if (value->contains_percentage())
+            return true;
+    }
+
+    return false;
+}
+
+CalculatedStyleValue::CalculationResult MinCalculationNode::resolve(Layout::Node const* layout_node, CalculatedStyleValue::PercentageBasis const& percentage_basis) const
+{
+    CalculatedStyleValue::CalculationResult smallest_node = m_values.first()->resolve(layout_node, percentage_basis);
+    auto smallest_value = resolve_value(smallest_node.value(), layout_node);
+
+    for (size_t i = 1; i < m_values.size(); i++) {
+        auto child_resolved = m_values[i]->resolve(layout_node, percentage_basis);
+        auto child_value = resolve_value(child_resolved.value(), layout_node);
+
+        if (child_value < smallest_value) {
+            smallest_value = child_value;
+            smallest_node = child_resolved;
+        }
+    }
+
+    return smallest_node;
+}
+
+ErrorOr<void> MinCalculationNode::for_each_child_node(Function<ErrorOr<void>(NonnullOwnPtr<CalculationNode>&)> const& callback)
+{
+    for (auto& value : m_values) {
+        TRY(value->for_each_child_node(callback));
+        TRY(callback(value));
+    }
+
+    return {};
+}
+
+ErrorOr<void> MinCalculationNode::dump(StringBuilder& builder, int indent) const
+{
+    TRY(builder.try_appendff("{: >{}}MIN:\n", "", indent));
+    for (auto const& value : m_values)
+        TRY(value->dump(builder, indent + 2));
+    return {};
+}
+
 void CalculatedStyleValue::CalculationResult::add(CalculationResult const& other, Layout::Node const* layout_node, PercentageBasis const& percentage_basis)
 {
     add_or_subtract_internal(SumOperation::Add, other, layout_node, percentage_basis);

Userland/Libraries/LibWeb/CSS/StyleValues/CalculatedStyleValue.h

@@ -119,8 +119,11 @@ public:
         // NOTE: Currently, any value with a `var()` or `attr()` function in it is always an
         //       UnresolvedStyleValue so we do not have to implement a NonMathFunction type here.
 
-        // Operator nodes
-        // https://www.w3.org/TR/css-values-4/#calculation-tree-operator-nodes
+        // Comparison function nodes, a sub-type of operator node
+        // https://drafts.csswg.org/css-values-4/#comp-func
+        Min,
+        Max,
+        Clamp,
 
         // Calc-operator nodes, a sub-type of operator node
         // https://www.w3.org/TR/css-values-4/#calculation-tree-calc-operator-nodes
@@ -253,4 +256,22 @@ private:
     NonnullOwnPtr<CalculationNode> m_value;
 };
 
+class MinCalculationNode final : public CalculationNode {
+public:
+    static ErrorOr<NonnullOwnPtr<MinCalculationNode>> create(Vector<NonnullOwnPtr<CalculationNode>>);
+    ~MinCalculationNode();
+
+    virtual ErrorOr<String> to_string() const override;
+    virtual Optional<CalculatedStyleValue::ResolvedType> resolved_type() const override;
+    virtual bool contains_percentage() const override;
+    virtual CalculatedStyleValue::CalculationResult resolve(Layout::Node const*, CalculatedStyleValue::PercentageBasis const&) const override;
+    virtual ErrorOr<void> for_each_child_node(Function<ErrorOr<void>(NonnullOwnPtr<CalculationNode>&)> const&) override;
+
+    virtual ErrorOr<void> dump(StringBuilder&, int indent) const override;
+
+private:
+    explicit MinCalculationNode(Vector<NonnullOwnPtr<CalculationNode>>);
+    Vector<NonnullOwnPtr<CalculationNode>> m_values;
+};
+
 }