LibWeb: Parse clamp() css math function

Author: https://github.com/stelar7
Commit: 2ef6aa5f3d
Pull-request: https://github.com/SerenityOS/serenity/pull/19158
Reviewed-by: https://github.com/AtkinsSJ ✅

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

@@ -3512,6 +3512,45 @@ ErrorOr<OwnPtr<CalculationNode>> Parser::parse_max_function(Function const& func
     return TRY(MaxCalculationNode::create(move(calculated_parameters)));
 }
 
+ErrorOr<OwnPtr<CalculationNode>> Parser::parse_clamp_function(Function const& function)
+{
+    TokenStream stream { function.values() };
+    auto parameters = parse_a_comma_separated_list_of_component_values(stream);
+
+    if (parameters.size() != 3) {
+        dbgln_if(CSS_PARSER_DEBUG, "clamp() must have exactly three parameters"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, "clamp() 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, "clamp() parameters must all be of same type"sv);
+            return nullptr;
+        }
+
+        calculated_parameters.append(calculation_node.release_nonnull());
+    }
+
+    return TRY(ClampCalculationNode::create(move(calculated_parameters[0]), move(calculated_parameters[1]), move(calculated_parameters[2])));
+}
+
 ErrorOr<RefPtr<StyleValue>> Parser::parse_dynamic_value(ComponentValue const& component_value)
 {
     if (component_value.is_function()) {
@@ -3544,6 +3583,9 @@ ErrorOr<OwnPtr<CalculationNode>> Parser::parse_a_calc_function_node(Function con
     if (function.name().equals_ignoring_ascii_case("max"sv))
         return TRY(parse_max_function(function));
 
+    if (function.name().equals_ignoring_ascii_case("clamp"sv))
+        return TRY(parse_clamp_function(function));
+
     dbgln_if(CSS_PARSER_DEBUG, "We didn't implement `{}` function yet", function.name());
     return nullptr;
 }

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

@@ -292,6 +292,7 @@ private:
     ErrorOr<OwnPtr<CalculationNode>> parse_a_calc_function_node(Function const&);
     ErrorOr<OwnPtr<CalculationNode>> parse_min_function(Function const&);
     ErrorOr<OwnPtr<CalculationNode>> parse_max_function(Function const&);
+    ErrorOr<OwnPtr<CalculationNode>> parse_clamp_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

@@ -557,6 +557,88 @@ ErrorOr<void> MaxCalculationNode::dump(StringBuilder& builder, int indent) const
     return {};
 }
 
+ErrorOr<NonnullOwnPtr<ClampCalculationNode>> ClampCalculationNode::create(NonnullOwnPtr<CalculationNode> min, NonnullOwnPtr<CalculationNode> center, NonnullOwnPtr<CalculationNode> max)
+{
+    return adopt_nonnull_own_or_enomem(new (nothrow) ClampCalculationNode(move(min), move(center), move(max)));
+}
+
+ClampCalculationNode::ClampCalculationNode(NonnullOwnPtr<CalculationNode> min, NonnullOwnPtr<CalculationNode> center, NonnullOwnPtr<CalculationNode> max)
+    : CalculationNode(Type::Clamp)
+    , m_min_value(move(min))
+    , m_center_value(move(center))
+    , m_max_value(move(max))
+{
+}
+
+ClampCalculationNode::~ClampCalculationNode() = default;
+
+ErrorOr<String> ClampCalculationNode::to_string() const
+{
+    StringBuilder builder;
+    TRY(builder.try_append("clamp("sv));
+    TRY(builder.try_append(TRY(m_min_value->to_string())));
+    TRY(builder.try_append(", "sv));
+    TRY(builder.try_append(TRY(m_center_value->to_string())));
+    TRY(builder.try_append(", "sv));
+    TRY(builder.try_append(TRY(m_max_value->to_string())));
+    TRY(builder.try_append(")"sv));
+    return builder.to_string();
+}
+
+Optional<CalculatedStyleValue::ResolvedType> ClampCalculationNode::resolved_type() const
+{
+    // NOTE: We check during parsing that all values have the same type.
+    return m_min_value->resolved_type();
+}
+
+bool ClampCalculationNode::contains_percentage() const
+{
+    return m_min_value->contains_percentage() || m_center_value->contains_percentage() || m_max_value->contains_percentage();
+}
+
+CalculatedStyleValue::CalculationResult ClampCalculationNode::resolve(Layout::Node const* layout_node, CalculatedStyleValue::PercentageBasis const& percentage_basis) const
+{
+    auto min_node = m_min_value->resolve(layout_node, percentage_basis);
+    auto center_node = m_center_value->resolve(layout_node, percentage_basis);
+    auto max_node = m_max_value->resolve(layout_node, percentage_basis);
+
+    auto min_value = resolve_value(min_node.value(), layout_node);
+    auto center_value = resolve_value(center_node.value(), layout_node);
+    auto max_value = resolve_value(max_node.value(), layout_node);
+
+    // NOTE: The value should be returned as "max(MIN, min(VAL, MAX))"
+    auto chosen_value = max(min_value, min(center_value, max_value));
+    if (chosen_value == min_value)
+        return min_node;
+    if (chosen_value == center_value)
+        return center_node;
+    if (chosen_value == max_value)
+        return max_node;
+
+    VERIFY_NOT_REACHED();
+}
+
+ErrorOr<void> ClampCalculationNode::for_each_child_node(Function<ErrorOr<void>(NonnullOwnPtr<CalculationNode>&)> const& callback)
+{
+    TRY(m_min_value->for_each_child_node(callback));
+    TRY(m_center_value->for_each_child_node(callback));
+    TRY(m_max_value->for_each_child_node(callback));
+    TRY(callback(m_min_value));
+    TRY(callback(m_center_value));
+    TRY(callback(m_max_value));
+
+    return {};
+}
+
+ErrorOr<void> ClampCalculationNode::dump(StringBuilder& builder, int indent) const
+{
+    TRY(builder.try_appendff("{: >{}}CLAMP:\n", "", indent));
+    TRY(m_min_value->dump(builder, indent + 2));
+    TRY(m_center_value->dump(builder, indent + 2));
+    TRY(m_max_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

@@ -292,4 +292,24 @@ private:
     Vector<NonnullOwnPtr<CalculationNode>> m_values;
 };
 
+class ClampCalculationNode final : public CalculationNode {
+public:
+    static ErrorOr<NonnullOwnPtr<ClampCalculationNode>> create(NonnullOwnPtr<CalculationNode>, NonnullOwnPtr<CalculationNode>, NonnullOwnPtr<CalculationNode>);
+    ~ClampCalculationNode();
+
+    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 ClampCalculationNode(NonnullOwnPtr<CalculationNode>, NonnullOwnPtr<CalculationNode>, NonnullOwnPtr<CalculationNode>);
+    NonnullOwnPtr<CalculationNode> m_min_value;
+    NonnullOwnPtr<CalculationNode> m_center_value;
+    NonnullOwnPtr<CalculationNode> m_max_value;
+};
+
 }