1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
|
// Copyright 2019 The Hugo Authors. 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 page
import (
"errors"
"fmt"
"html/template"
"math"
"reflect"
"github.com/gohugoio/hugo/config"
"github.com/spf13/cast"
)
// PaginatorProvider provides two ways to create a page paginator.
type PaginatorProvider interface {
Paginator(options ...interface{}) (*Pager, error)
Paginate(seq interface{}, options ...interface{}) (*Pager, error)
}
// Pager represents one of the elements in a paginator.
// The number, starting on 1, represents its place.
type Pager struct {
number int
*Paginator
}
func (p Pager) String() string {
return fmt.Sprintf("Pager %d", p.number)
}
type paginatedElement interface {
Len() int
}
type pagers []*Pager
var (
paginatorEmptyPages Pages
paginatorEmptyPageGroups PagesGroup
)
type Paginator struct {
paginatedElements []paginatedElement
pagers
paginationURLFactory
total int
size int
}
type paginationURLFactory func(int) string
// PageNumber returns the current page's number in the pager sequence.
func (p *Pager) PageNumber() int {
return p.number
}
// URL returns the URL to the current page.
func (p *Pager) URL() template.HTML {
return template.HTML(p.paginationURLFactory(p.PageNumber()))
}
// Pages returns the Pages on this page.
// Note: If this return a non-empty result, then PageGroups() will return empty.
func (p *Pager) Pages() Pages {
if len(p.paginatedElements) == 0 {
return paginatorEmptyPages
}
if pages, ok := p.element().(Pages); ok {
return pages
}
return paginatorEmptyPages
}
// PageGroups return Page groups for this page.
// Note: If this return non-empty result, then Pages() will return empty.
func (p *Pager) PageGroups() PagesGroup {
if len(p.paginatedElements) == 0 {
return paginatorEmptyPageGroups
}
if groups, ok := p.element().(PagesGroup); ok {
return groups
}
return paginatorEmptyPageGroups
}
func (p *Pager) element() paginatedElement {
if len(p.paginatedElements) == 0 {
return paginatorEmptyPages
}
return p.paginatedElements[p.PageNumber()-1]
}
// page returns the Page with the given index
func (p *Pager) page(index int) (Page, error) {
if pages, ok := p.element().(Pages); ok {
if pages != nil && len(pages) > index {
return pages[index], nil
}
return nil, nil
}
// must be PagesGroup
// this construction looks clumsy, but ...
// ... it is the difference between 99.5% and 100% test coverage :-)
groups := p.element().(PagesGroup)
i := 0
for _, v := range groups {
for _, page := range v.Pages {
if i == index {
return page, nil
}
i++
}
}
return nil, nil
}
// NumberOfElements gets the number of elements on this page.
func (p *Pager) NumberOfElements() int {
return p.element().Len()
}
// HasPrev tests whether there are page(s) before the current.
func (p *Pager) HasPrev() bool {
return p.PageNumber() > 1
}
// Prev returns the pager for the previous page.
func (p *Pager) Prev() *Pager {
if !p.HasPrev() {
return nil
}
return p.pagers[p.PageNumber()-2]
}
// HasNext tests whether there are page(s) after the current.
func (p *Pager) HasNext() bool {
return p.PageNumber() < len(p.paginatedElements)
}
// Next returns the pager for the next page.
func (p *Pager) Next() *Pager {
if !p.HasNext() {
return nil
}
return p.pagers[p.PageNumber()]
}
// First returns the pager for the first page.
func (p *Pager) First() *Pager {
return p.pagers[0]
}
// Last returns the pager for the last page.
func (p *Pager) Last() *Pager {
return p.pagers[len(p.pagers)-1]
}
// Pagers returns a list of pagers that can be used to build a pagination menu.
func (p *Paginator) Pagers() pagers {
return p.pagers
}
// PageSize returns the size of each paginator page.
func (p *Paginator) PageSize() int {
return p.size
}
// TotalPages returns the number of pages in the paginator.
func (p *Paginator) TotalPages() int {
return len(p.paginatedElements)
}
// TotalNumberOfElements returns the number of elements on all pages in this paginator.
func (p *Paginator) TotalNumberOfElements() int {
return p.total
}
func splitPages(pages Pages, size int) []paginatedElement {
var split []paginatedElement
for low, j := 0, len(pages); low < j; low += size {
high := int(math.Min(float64(low+size), float64(len(pages))))
split = append(split, pages[low:high])
}
return split
}
func splitPageGroups(pageGroups PagesGroup, size int) []paginatedElement {
type keyPage struct {
key interface{}
page Page
}
var (
split []paginatedElement
flattened []keyPage
)
for _, g := range pageGroups {
for _, p := range g.Pages {
flattened = append(flattened, keyPage{g.Key, p})
}
}
num
|