Store layout attributes separately

src/layout_abstract_syntax.rs

@@ -20,6 +20,7 @@ impl LayoutAbstractNode {
 pub struct LayoutAbstractTag {
 	pub namespace: String,
 	pub name: String,
+	pub layout_attributes: LayoutAttributes,
 	pub attributes: Vec<Attribute>,
 }
 
@@ -28,12 +29,27 @@ impl LayoutAbstractTag {
 		Self {
 			namespace,
 			name,
+			layout_attributes: Default::default(),
 			attributes: Vec::new(),
 		}
 	}
 
 	pub fn add_attribute(&mut self, attribute: Attribute) {
-		self.attributes.push(attribute);
+		match &attribute.name[..] {
+			// Layout attributes, stored separately
+			"width" => self.layout_attributes.width = attribute.dimension(),
+			"height" => self.layout_attributes.height = attribute.dimension(),
+			"x-align" => self.layout_attributes.x_align = attribute.percent(),
+			"y-align" => self.layout_attributes.y_align = attribute.percent(),
+			"x-padding" => self.layout_attributes.padding.set_horizontal(attribute.dimension()),
+			"y-padding" => self.layout_attributes.padding.set_vertical(attribute.dimension()),
+			"padding" => self.layout_attributes.padding = attribute.box_dimensions(),
+			"x-spacing" => self.layout_attributes.spacing.set_horizontal(attribute.dimension()),
+			"y-spacing" => self.layout_attributes.spacing.set_vertical(attribute.dimension()),
+			"spacing" => self.layout_attributes.spacing = attribute.box_dimensions(),
+			// Non-layout attribute
+			_ => self.attributes.push(attribute),
+		}
 	}
 }
 
@@ -47,6 +63,65 @@ impl Attribute {
 	pub fn new(name: String, value: AttributeValue) -> Self {
 		Self { name, value }
 	}
+
+	/// Extracts this attribute's values as typed values.
+	fn values(self) -> Vec<TypeValue> {
+		if let AttributeValue::TypeValue(values) = self.value {
+			values
+				.into_iter()
+				.map(|value| {
+					if let TypeValueOrArgument::TypeValue(value) = value {
+						value
+					}
+					else {
+						todo!("variable arguments are note yet supported")
+					}
+				})
+				.collect()
+		}
+		else {
+			todo!("variable arguments are not yet supported")
+		}
+	}
+
+	/// Converts this attribute's value into a single dimension.
+	fn dimension(self) -> Dimension {
+		let values = self.values();
+		assert_eq!(values.len(), 1, "expected a single value");
+		values[0].expect_dimension()
+	}
+
+	/// Extracts a percentage from this attribute's value.
+	fn percent(self) -> f32 {
+		match self.dimension() {
+			Dimension::Percent(value) => value,
+			_ => panic!("expected a percentage"),
+		}
+	}
+
+	/// Converts this attribute's values into box dimensions.
+	fn box_dimensions(self) -> BoxDimensions {
+		let values = self.values();
+		match values.len() {
+			1 => {
+				let value = values[0].expect_dimension();
+				BoxDimensions::all(value)
+			},
+			2 => {
+				let vertical = values[0].expect_dimension();
+				let horizontal = values[1].expect_dimension();
+				BoxDimensions::symmetric(vertical, horizontal)
+			},
+			4 => {
+				let top = values[0].expect_dimension();
+				let right = values[1].expect_dimension();
+				let bottom = values[2].expect_dimension();
+				let left = values[3].expect_dimension();
+				BoxDimensions::new(top, right, bottom, left)
+			},
+			_ => panic!("expected 1, 2 or 4 values"),
+		}
+	}
 }
 
 #[derive(Debug, Clone, PartialEq)]
@@ -54,3 +129,28 @@ pub enum AttributeValue {
 	VariableParameter(VariableParameter),
 	TypeValue(Vec<TypeValueOrArgument>),
 }
+
+/// Layout-specific attributes.
+#[derive(Clone, Debug, PartialEq)]
+pub struct LayoutAttributes {
+	pub width: Dimension,
+	pub height: Dimension,
+	pub x_align: f32,
+	pub y_align: f32,
+	pub spacing: BoxDimensions,
+	pub padding: BoxDimensions,
+}
+
+impl Default for LayoutAttributes {
+	fn default() -> Self {
+		let zero_box = BoxDimensions::all(Dimension::AbsolutePx(0.0));
+		Self {
+			width: Dimension::Inner,
+			height: Dimension::Inner,
+			x_align: 0.0,
+			y_align: 0.0,
+			spacing: zero_box,
+			padding: zero_box,
+		}
+	}
+}

src/layout_abstract_types.rs

@@ -49,20 +49,80 @@ pub enum TypeValue {
 	Layout(Vec<ComponentAst>),
 	Integer(i64),
 	Decimal(f64),
-	AbsolutePx(f32),
-	Percent(f32),
-	PercentRemainder(f32),
-	Inner,
-	Width,
-	Height,
+	Dimension(Dimension),
 	TemplateString(Vec<TemplateStringSegment>),
 	Color(Color),
 	Bool(bool),
 	None,
 }
 
+impl TypeValue {
+	/// Converts this to a dimension, panics if not possible.
+	pub fn expect_dimension(&self) -> Dimension {
+		match self {
+			Self::Dimension(dimension) => *dimension,
+			_ => panic!("expected a dimension"),
+		}
+	}
+}
+
 #[derive(Debug, Clone, PartialEq)]
 pub enum TemplateStringSegment {
 	String(String),
 	Argument(TypeValueOrArgument),
 }
+
+/// A dimension is a measure along an axis.
+#[derive(Copy, Clone, Debug, PartialEq)]
+pub enum Dimension {
+	/// Absolute value in pixels.
+	AbsolutePx(f32),
+	/// Percent of parent container size along the same axis.
+	Percent(f32),
+	/// Percent of free space remaining in parent container.
+	PercentRemainder(f32),
+	/// Minimum size required to fit the children.
+	Inner,
+	/// Size relative to the width of this component.
+	Width,
+	/// Size relative to the height of this component.
+	Height,
+}
+
+/// Dimensions along a box's four sides.
+#[derive(Copy, Clone, Debug, PartialEq)]
+pub struct BoxDimensions {
+	pub top: Dimension,
+	pub right: Dimension,
+	pub bottom: Dimension,
+	pub left: Dimension,
+}
+
+impl BoxDimensions {
+	/// Construct new box dimensions, with values given for each side.
+	pub fn new(top: Dimension, right: Dimension, bottom: Dimension, left: Dimension) -> Self {
+		Self { top, right, bottom, left }
+	}
+
+	/// Construct new box dimensions, with same values used for top-bottom and left-right.
+	pub fn symmetric(vertical: Dimension, horizontal: Dimension) -> Self {
+		Self::new(vertical, horizontal, vertical, horizontal)
+	}
+
+	/// Construct new box dimensions with the same value for all sides.
+	pub fn all(value: Dimension) -> Self {
+		Self::new(value, value, value, value)
+	}
+
+	/// Sets the padding on the top and bottom sides.
+	pub fn set_vertical(&mut self, value: Dimension) {
+		self.top = value;
+		self.bottom = value;
+	}
+
+	/// Sets the padding on the left and right sides.
+	pub fn set_horizontal(&mut self, value: Dimension) {
+		self.left = value;
+		self.right = value;
+	}
+}

src/layout_attribute_parser.rs

@@ -130,28 +130,31 @@ impl AttributeParser {
 				let pixels = value
 					.parse::<f32>()
 					.expect(&format!("Invalid value `{}` specified in the attribute type`{}` when parsing XML layout", value, attribute_type)[..]);
-				TypeValueOrArgument::TypeValue(TypeValue::AbsolutePx(pixels))
+				let dimension = Dimension::AbsolutePx(pixels);
+				TypeValueOrArgument::TypeValue(TypeValue::Dimension(dimension))
 			},
 			// Percent: ?%
 			Some([value, "%"]) => {
 				let percent = value
 					.parse::<f32>()
 					.expect(&format!("Invalid value `{}` specified in the attribute type `{}` when parsing XML layout", value, attribute_type)[..]);
-				TypeValueOrArgument::TypeValue(TypeValue::Percent(percent))
+				let dimension = Dimension::Percent(percent);
+				TypeValueOrArgument::TypeValue(TypeValue::Dimension(dimension))
 			},
 			// PercentRemainder: ?@
 			Some([value, "@"]) => {
 				let percent_remainder = value
 					.parse::<f32>()
 					.expect(&format!("Invalid value `{}` specified in the attribute type `{}` when parsing XML layout", value, attribute_type)[..]);
-				TypeValueOrArgument::TypeValue(TypeValue::PercentRemainder(percent_remainder))
+				let dimension = Dimension::PercentRemainder(percent_remainder);
+				TypeValueOrArgument::TypeValue(TypeValue::Dimension(dimension))
 			},
 			// Inner: inner
-			Some([inner]) if inner.eq_ignore_ascii_case("inner") => TypeValueOrArgument::TypeValue(TypeValue::Inner),
+			Some([inner]) if inner.eq_ignore_ascii_case("inner") => TypeValueOrArgument::TypeValue(TypeValue::Dimension(Dimension::Inner)),
 			// Width: width
-			Some([width]) if width.eq_ignore_ascii_case("width") => TypeValueOrArgument::TypeValue(TypeValue::Width),
+			Some([width]) if width.eq_ignore_ascii_case("width") => TypeValueOrArgument::TypeValue(TypeValue::Dimension(Dimension::Width)),
 			// Height: height
-			Some([height]) if height.eq_ignore_ascii_case("height") => TypeValueOrArgument::TypeValue(TypeValue::Height),
+			Some([height]) if height.eq_ignore_ascii_case("height") => TypeValueOrArgument::TypeValue(TypeValue::Dimension(Dimension::Height)),
 			// TemplateString: `? ... {{?}} ...`
 			Some(["`", string, "`"]) => {
 				let mut segments = Vec::<TemplateStringSegment>::new();