1// run -race
2
3//go:build cgo && linux && amd64
4
5// Copyright 2018 The Go Authors. All rights reserved.
6// Use of this source code is governed by a BSD-style
7// license that can be found in the LICENSE file.
8
9package main
10
11import (
12	"fmt"
13)
14
15type LineString []Point
16type Point [2]float64
17
18//go:noinline
19func benchmarkData() LineString {
20	return LineString{{1.0, 2.0}}
21}
22
23func (ls LineString) Clone() LineString {
24	ps := MultiPoint(ls)
25	return LineString(ps.Clone())
26}
27
28type MultiPoint []Point
29
30func (mp MultiPoint) Clone() MultiPoint {
31	if mp == nil {
32		return nil
33	}
34
35	points := make([]Point, len(mp))
36	copy(points, mp)
37
38	return MultiPoint(points)
39}
40
41func F1() {
42	cases := []struct {
43		threshold float64
44		length    int
45	}{
46		{0.1, 1118},
47		{0.5, 257},
48		{1.0, 144},
49		{1.5, 95},
50		{2.0, 71},
51		{3.0, 46},
52		{4.0, 39},
53		{5.0, 33},
54	}
55
56	ls := benchmarkData()
57
58	for k := 0; k < 100; k++ {
59		for i, tc := range cases {
60			r := DouglasPeucker(tc.threshold).LineString(ls.Clone())
61			if len(r) == tc.length {
62				fmt.Printf("%d: unexpected\n", i)
63			}
64		}
65	}
66}
67
68// A DouglasPeuckerSimplifier wraps the DouglasPeucker function.
69type DouglasPeuckerSimplifier struct {
70	Threshold float64
71}
72
73// DouglasPeucker creates a new DouglasPeuckerSimplifier.
74func DouglasPeucker(threshold float64) *DouglasPeuckerSimplifier {
75	return &DouglasPeuckerSimplifier{
76		Threshold: threshold,
77	}
78}
79
80func (s *DouglasPeuckerSimplifier) LineString(ls LineString) LineString {
81	return lineString(s, ls)
82}
83
84type simplifier interface {
85	simplify(LineString, bool) (LineString, []int)
86}
87
88func lineString(s simplifier, ls LineString) LineString {
89	return runSimplify(s, ls)
90}
91
92func runSimplify(s simplifier, ls LineString) LineString {
93	if len(ls) <= 2 {
94		return ls
95	}
96	ls, _ = s.simplify(ls, false)
97	return ls
98}
99
100func (s *DouglasPeuckerSimplifier) simplify(ls LineString, wim bool) (LineString, []int) {
101	return nil, nil
102}
103
104func main() {
105	F1()
106}
107