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pagination.go
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/
pagination.go
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package app
/* pagination helpers; ported from python code in github.com/jmoiron/jmoiron.net */
import (
"github.com/jmoiron/monet/template"
"math"
"strconv"
)
type Link struct {
Url string
Num string
HasUrl bool
Inter bool
}
type Paginator struct {
Page int
PerPage int
Skip int
Limit int
Begin int
End int
Link string
WindowSize int
HasPrev bool
HasNext bool
NumPages int
Inter string
}
var defaultLink = ""
var defaultWindowSize = 10
func NewPaginator(page, perPage int) *Paginator {
if page < 1 {
return nil
}
p := new(Paginator)
p.Page = page
p.PerPage = perPage
p.Skip = (page - 1) * perPage
p.Begin = p.Skip
p.End = p.Skip + perPage
p.Limit = perPage
p.Link = defaultLink
p.WindowSize = defaultWindowSize
p.Inter = "..."
return p
}
/* given a maximum number of items, render pagination */
func (p *Paginator) Render(objCount int) string {
if p.Begin > objCount {
return ""
}
if p.Page > 1 {
p.HasPrev = true
}
if p.End < objCount {
p.HasNext = true
}
p.NumPages = int(math.Ceil(float64(objCount) / float64(p.PerPage)))
if p.Page > p.NumPages {
return ""
}
context := p.Context(p.NumPages)
links := []Link{}
for _, c := range context {
v, _ := strconv.Atoi(c)
if c == "..." {
links = append(links, Link{Num: p.Inter, Inter: true})
} else if v == p.Page {
links = append(links, Link{Num: c})
} else {
links = append(links, Link{Num: c, Url: p.Link + c, HasUrl: true})
}
}
return template.Render("paginator.mandira", M{"Pages": links}, p,
M{
"NextPageUrl": p.Link + itoa(p.Page+1),
"PrevPageUrl": p.Link + itoa(p.Page-1),
})
}
/* shortcut */
var itoa = strconv.Itoa
func strRange(begin, end int) []string {
r := []string{}
for i := begin; i < end; i++ {
r = append(r, itoa(i))
}
return r
}
func makeWindow(center, size int) []string {
lpad := size / 2
rpad := size / 2
if size%2 >= 0 {
lpad = size/2 - 1
}
return strRange(center-lpad, center+rpad+1)
}
func (p *Paginator) Context(pageCount int) []string {
padArea := int(2 + math.Ceil(float64(p.WindowSize-4)/2.0))
middle := p.WindowSize - 4
if pageCount < p.WindowSize {
return strRange(1, pageCount+1)
}
if p.Page <= padArea {
r := strRange(1, 2+middle+1)
for _, s := range []string{p.Inter, itoa(pageCount - 1), itoa(pageCount)} {
r = append(r, s)
}
return r
}
if pageCount-padArea <= p.Page && p.Page <= pageCount {
r := strRange(1, 3)
r = append(r, p.Inter)
for _, s := range strRange(pageCount-middle-1, pageCount+1) {
r = append(r, s)
}
return r
}
r := strRange(1, 3)
r = append(r, p.Inter)
for _, s := range makeWindow(p.Page, middle) {
r = append(r, s)
}
r = append(r, p.Inter)
r = append(r, itoa(pageCount-1))
r = append(r, itoa(pageCount))
return r
}