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// Copyright 2020 Google Inc. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package s2
// EdgeIterator is an iterator that advances through all edges in an ShapeIndex.
// This is different to the ShapeIndexIterator, which advances through the cells in the
// ShapeIndex.
type EdgeIterator struct {
index *ShapeIndex
shapeID int32
numEdges int32
edgeID int32
}
// NewEdgeIterator creates a new edge iterator for the given index.
func NewEdgeIterator(index *ShapeIndex) *EdgeIterator {
e := &EdgeIterator{
index: index,
shapeID: -1,
edgeID: -1,
}
e.Next()
return e
}
// ShapeID returns the current shape ID.
func (e *EdgeIterator) ShapeID() int32 { return e.shapeID }
// EdgeID returns the current edge ID.
func (e *EdgeIterator) EdgeID() int32 { return e.edgeID }
// ShapeEdgeID returns the current (shapeID, edgeID).
func (e *EdgeIterator) ShapeEdgeID() ShapeEdgeID { return ShapeEdgeID{e.shapeID, e.edgeID} }
// Edge returns the current edge.
func (e *EdgeIterator) Edge() Edge {
return e.index.Shape(e.shapeID).Edge(int(e.edgeID))
}
// Done reports if the iterator is positioned at or after the last index edge.
func (e *EdgeIterator) Done() bool { return e.shapeID >= int32(len(e.index.shapes)) }
// Next positions the iterator at the next index edge.
func (e *EdgeIterator) Next() {
e.edgeID++
for ; e.edgeID >= e.numEdges; e.edgeID++ {
e.shapeID++
if e.shapeID >= int32(len(e.index.shapes)) {
break
}
shape := e.index.Shape(e.shapeID)
if shape == nil {
e.numEdges = 0
} else {
e.numEdges = int32(shape.NumEdges())
}
e.edgeID = -1
}
}
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