1 // Copyright 2020 Google Inc. All rights reserved. 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 package s2 16 17 // EdgeIterator is an iterator that advances through all edges in an ShapeIndex. 18 // This is different to the ShapeIndexIterator, which advances through the cells in the 19 // ShapeIndex. 20 type EdgeIterator struct { 21 index *ShapeIndex 22 shapeID int32 23 numEdges int32 24 edgeID int32 25 } 26 27 // NewEdgeIterator creates a new edge iterator for the given index. 28 func NewEdgeIterator(index *ShapeIndex) *EdgeIterator { 29 e := &EdgeIterator{ 30 index: index, 31 shapeID: -1, 32 edgeID: -1, 33 } 34 35 e.Next() 36 return e 37 } 38 39 // ShapeID returns the current shape ID. 40 func (e *EdgeIterator) ShapeID() int32 { return e.shapeID } 41 42 // EdgeID returns the current edge ID. 43 func (e *EdgeIterator) EdgeID() int32 { return e.edgeID } 44 45 // ShapeEdgeID returns the current (shapeID, edgeID). 46 func (e *EdgeIterator) ShapeEdgeID() ShapeEdgeID { return ShapeEdgeID{e.shapeID, e.edgeID} } 47 48 // Edge returns the current edge. 49 func (e *EdgeIterator) Edge() Edge { 50 return e.index.Shape(e.shapeID).Edge(int(e.edgeID)) 51 } 52 53 // Done reports if the iterator is positioned at or after the last index edge. 54 func (e *EdgeIterator) Done() bool { return e.shapeID >= int32(len(e.index.shapes)) } 55 56 // Next positions the iterator at the next index edge. 57 func (e *EdgeIterator) Next() { 58 e.edgeID++ 59 for ; e.edgeID >= e.numEdges; e.edgeID++ { 60 e.shapeID++ 61 if e.shapeID >= int32(len(e.index.shapes)) { 62 break 63 } 64 shape := e.index.Shape(e.shapeID) 65 if shape == nil { 66 e.numEdges = 0 67 } else { 68 e.numEdges = int32(shape.NumEdges()) 69 } 70 e.edgeID = -1 71 } 72 } 73