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use super::{CoordPos, Direction, Edge, EdgeEnd, GeometryGraph, IntersectionMatrix, Label};
use crate::{Coord, GeoFloat};
/// A collection of [`EdgeEnds`](EdgeEnd) which obey the following invariant:
/// They originate at the same node and have the same direction.
///
/// This is based on [JTS's `EdgeEndBundle` as of 1.18.1](https://github.com/locationtech/jts/blob/jts-1.18.1/modules/core/src/main/java/org/locationtech/jts/operation/relate/EdgeEndBundle.java)
#[derive(Clone, Debug)]
pub(crate) struct EdgeEndBundle<F>
where
F: GeoFloat,
{
coordinate: Coord<F>,
edge_ends: Vec<EdgeEnd<F>>,
}
impl<F> EdgeEndBundle<F>
where
F: GeoFloat,
{
pub(crate) fn new(coordinate: Coord<F>) -> Self {
Self {
coordinate,
edge_ends: vec![],
}
}
fn edge_ends_iter(&self) -> impl Iterator<Item = &EdgeEnd<F>> {
self.edge_ends.iter()
}
fn edge_ends_iter_mut(&mut self) -> impl Iterator<Item = &mut EdgeEnd<F>> {
self.edge_ends.iter_mut()
}
pub(crate) fn insert(&mut self, edge_end: EdgeEnd<F>) {
self.edge_ends.push(edge_end);
}
pub(crate) fn into_labeled(mut self) -> LabeledEdgeEndBundle<F> {
let is_area = self
.edge_ends_iter()
.any(|edge_end| edge_end.label().is_area());
let mut label = if is_area {
Label::empty_area()
} else {
Label::empty_line_or_point()
};
for i in 0..2 {
self.compute_label_on(&mut label, i);
if is_area {
self.compute_label_side(&mut label, i, Direction::Left);
self.compute_label_side(&mut label, i, Direction::Right);
}
}
LabeledEdgeEndBundle {
label,
edge_end_bundle: self,
}
}
/// Compute the overall ON position for the list of EdgeEnds.
/// (This is essentially equivalent to computing the self-overlay of a single Geometry)
///
/// EdgeEnds can be either on the boundary (e.g. Polygon edge)
/// OR in the interior (e.g. segment of a LineString)
/// of their parent Geometry.
///
/// In addition, GeometryCollections use a boundary node rule to determine whether a segment is
/// on the boundary or not.
///
/// Finally, in GeometryCollections it can occur that an edge is both
/// on the boundary and in the interior (e.g. a LineString segment lying on
/// top of a Polygon edge.) In this case the Boundary is given precedence.
///
/// These observations result in the following rules for computing the ON location:
/// - if there are an odd number of Bdy edges, the attribute is Bdy
/// - if there are an even number >= 2 of Bdy edges, the attribute is Int
/// - if there are any Int edges, the attribute is Int
/// - otherwise, the attribute is None
///
fn compute_label_on(&mut self, label: &mut Label, geom_index: usize) {
let mut boundary_count = 0;
let mut found_interior = false;
for edge_end in self.edge_ends_iter() {
match edge_end.label().on_position(geom_index) {
Some(CoordPos::OnBoundary) => {
boundary_count += 1;
}
Some(CoordPos::Inside) => {
found_interior = true;
}
None | Some(CoordPos::Outside) => {}
}
}
let mut position = None;
if found_interior {
position = Some(CoordPos::Inside);
}
if boundary_count > 0 {
position = Some(GeometryGraph::<'_, F>::determine_boundary(boundary_count));
}
if let Some(location) = position {
label.set_on_position(geom_index, location);
} else {
// This is technically a diversion from JTS, but I don't think we'd ever
// get here, unless `l.on_location` was *already* None, in which cases this is a
// no-op, so assert that assumption.
// If this assert is rightfully triggered, we may need to add a method like
// `l.clear_on_location(geom_index)`
debug_assert!(
label.on_position(geom_index).is_none(),
"diverging from JTS, which would have replaced the existing Location with None"
);
}
}
/// To compute the summary label for a side, the algorithm is:
/// FOR all edges
/// IF any edge's location is INTERIOR for the side, side location = INTERIOR
/// ELSE IF there is at least one EXTERIOR attribute, side location = EXTERIOR
/// ELSE side location = NULL
/// Note that it is possible for two sides to have apparently contradictory information
/// i.e. one edge side may indicate that it is in the interior of a geometry, while
/// another edge side may indicate the exterior of the same geometry. This is
/// not an incompatibility - GeometryCollections may contain two Polygons that touch
/// along an edge. This is the reason for Interior-primacy rule above - it
/// results in the summary label having the Geometry interior on _both_ sides.
fn compute_label_side(&mut self, label: &mut Label, geom_index: usize, side: Direction) {
let mut position = None;
for edge_end in self.edge_ends_iter_mut() {
if edge_end.label().is_area() {
match edge_end.label_mut().position(geom_index, side) {
Some(CoordPos::Inside) => {
position = Some(CoordPos::Inside);
break;
}
Some(CoordPos::Outside) => {
position = Some(CoordPos::Outside);
}
None | Some(CoordPos::OnBoundary) => {}
}
}
}
if let Some(position) = position {
label.set_position(geom_index, side, position);
}
}
}
/// An [`EdgeEndBundle`] whose topological relationships have been aggregated into a single
/// [`Label`].
///
/// `update_intersection_matrix` applies this aggregated topology to an `IntersectionMatrix`.
#[derive(Clone, Debug)]
pub(crate) struct LabeledEdgeEndBundle<F>
where
F: GeoFloat,
{
label: Label,
edge_end_bundle: EdgeEndBundle<F>,
}
impl<F> LabeledEdgeEndBundle<F>
where
F: GeoFloat,
{
pub fn label(&self) -> &Label {
&self.label
}
pub fn label_mut(&mut self) -> &mut Label {
&mut self.label
}
pub fn update_intersection_matrix(&self, intersection_matrix: &mut IntersectionMatrix) {
Edge::<F>::update_intersection_matrix(self.label(), intersection_matrix);
}
pub fn coordinate(&self) -> &Coord<F> {
&self.edge_end_bundle.coordinate
}
}