118 lines
2.6 KiB
Go
118 lines
2.6 KiB
Go
// Copyright (c) 2025-2026 Probo Inc <hello@getprobo.com>.
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//
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// Permission to use, copy, modify, and/or distribute this software for any
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// purpose with or without fee is hereby granted, provided that the above
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// copyright notice and this permission notice appear in all copies.
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//
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// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
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// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
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// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
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// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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// PERFORMANCE OF THIS SOFTWARE.
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package page
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type (
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Paginable[T OrderField] interface {
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CursorKey(orderBy T) CursorKey
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}
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PageInfo struct {
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HasNext bool
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HasPrev bool
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}
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Page[T Paginable[U], U OrderField] struct {
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Info *PageInfo
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Cursor *Cursor[U]
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Data []T
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}
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)
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func (p *Page[T, U]) First() T {
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if len(p.Data) == 0 {
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var zero T
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return zero
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}
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return p.Data[0]
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}
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func (p *Page[T, U]) Last() T {
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if len(p.Data) == 0 {
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var zero T
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return zero
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}
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return p.Data[len(p.Data)-1]
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}
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func NewPage[T Paginable[U], U OrderField](data []T, c *Cursor[U]) *Page[T, U] {
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pi := &PageInfo{}
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if len(data) == 0 {
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return &Page[T, U]{
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Info: pi,
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Data: data,
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}
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}
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edges := data
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firstFromData := data[0]
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switch c.Position {
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case Head:
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if c.Key != nil {
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if len(edges) == c.Size+2 {
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edges = edges[1 : len(edges)-1]
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} else {
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edges = edges[1:]
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}
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} else if c.Key == nil && len(edges) == c.Size+1 {
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edges = edges[0 : len(edges)-1]
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}
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if c.Key != nil && c.Key.String() == firstFromData.CursorKey(c.OrderBy.Field).String() {
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pi.HasPrev = true
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}
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if c.Key != nil && c.Size+2 == len(data) {
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pi.HasNext = true
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} else if c.Key == nil && c.Size+1 == len(data) {
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pi.HasNext = true
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}
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case Tail:
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for i, j := 0, len(edges)-1; i < j; i, j = i+1, j-1 {
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edges[i], edges[j] = edges[j], edges[i]
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}
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if c.Key != nil {
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if len(edges) == c.Size+2 {
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edges = edges[1 : len(edges)-1]
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} else {
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edges = edges[0 : len(edges)-1]
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}
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} else if c.Key == nil && len(edges) == c.Size+1 {
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edges = edges[1:]
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}
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if c.Key != nil && c.Key.String() == firstFromData.CursorKey(c.OrderBy.Field).String() {
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pi.HasNext = true
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}
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if c.Key != nil && c.Size+2 == len(data) {
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pi.HasPrev = true
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} else if c.Key == nil && c.Size+1 == len(data) {
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pi.HasPrev = true
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}
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}
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return &Page[T, U]{
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Info: pi,
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Cursor: c,
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Data: edges,
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}
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}
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