Switch height to a function and not a variable

Sources/FunctionalTableData/TableSectionHeaderFooter.swift

@@ -17,13 +17,28 @@ public protocol TableHeaderFooterConfigType: TableItemConfigType {
 	func dequeueHeaderFooter(from tableView: UITableView) -> UITableViewHeaderFooterView?
 	func isEqual(_ other: TableHeaderFooterConfigType?) -> Bool
 	var height: CGFloat { get }
+	func height(given width: CGFloat) -> CGFloat?
+}
+
+extension TableHeaderFooterConfigType {
+	public func height(given width: CGFloat) -> CGFloat? {
+		nil
+	}
 }
 
 public protocol TableHeaderFooterStateType: Equatable {
 	var insets: UIEdgeInsets { get }
 	var height: CGFloat { get }
 	var topSeparatorHidden: Bool { get }
 	var bottomSeparatorHidden: Bool { get }
+
+	func height(given width: CGFloat) -> CGFloat?
+}
+
+extension TableHeaderFooterStateType {
+	public func height(given width: CGFloat) -> CGFloat? {
+		nil
+	}
 }
 
 public struct TableSectionHeaderFooter<ViewType: UIView, Layout: TableItemLayout, S: TableHeaderFooterStateType>: TableHeaderFooterConfigType {
@@ -53,7 +68,11 @@ public struct TableSectionHeaderFooter<ViewType: UIView, Layout: TableItemLayout
 	}
 
 	public var height: CGFloat {
-		return state?.height ?? 0
+		state?.height ?? 0
+	}
+
+	public func height(given width: CGFloat) -> CGFloat? {
+		return state?.height(given: width) ?? height
 	}
 
 	// MARK: - TableHeaderFooterConfigType

Sources/FunctionalTableData/TableView/FunctionalTableData+UITableViewDelegate.swift

@@ -49,15 +49,15 @@ extension FunctionalTableData {
 				// When given a height of zero grouped style UITableView's use their default value instead of zero. By returning CGFloat.min we get around this behavior and force UITableView to end up using a height of zero after all.
 				return tableView.style == .grouped ? CGFloat.leastNormalMagnitude : 0
 			}
-			return header.height
+			return header.height(given: tableView.frame.width) ?? header.height
 		}
 
 		public func tableView(_ tableView: UITableView, heightForFooterInSection section: Int) -> CGFloat {
 			guard let footer = data.sections[section].footer else {
 				// When given a height of zero grouped style UITableView's use their default value instead of zero. By returning CGFloat.min we get around this behavior and force UITableView to end up using a height of zero after all.
 				return tableView.style == .grouped ? CGFloat.leastNormalMagnitude : 0
 			}
-			return footer.height
+			return footer.height(given: tableView.frame.width) ?? footer.height
 		}
 
 		public func tableView(_ tableView: UITableView, estimatedHeightForRowAt indexPath: IndexPath) -> CGFloat {

Tests/FunctionalTableDataTests/CollectionSectionChangeSetTests.swift

@@ -654,7 +654,7 @@ fileprivate struct TestHeaderFooter: TableHeaderFooterConfigType, CollectionSupp
 		guard let other = other as? TestHeaderFooter else { return false }
 		return state == other.state
 	}
-
+	
 	var height: CGFloat {
 		return state?.height ?? 0
 	}