gotosocial/internal/paging/boundary.go

150 lines
4.1 KiB
Go

// GoToSocial
// Copyright (C) GoToSocial Authors admin@gotosocial.org
// SPDX-License-Identifier: AGPL-3.0-or-later
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
package paging
// EitherMinID returns an ID boundary with given min ID value,
// using either the `since_id`,"DESC" name,ordering or
// `min_id`,"ASC" name,ordering depending on which is set.
func EitherMinID(minID, sinceID string) Boundary {
/*
Paging with `since_id` vs `min_id`:
limit = 4 limit = 4
+----------+ +----------+
max_id--> |xxxxxxxxxx| | | <-- max_id
+----------+ +----------+
|xxxxxxxxxx| | |
+----------+ +----------+
|xxxxxxxxxx| | |
+----------+ +----------+
|xxxxxxxxxx| |xxxxxxxxxx|
+----------+ +----------+
| | |xxxxxxxxxx|
+----------+ +----------+
| | |xxxxxxxxxx|
+----------+ +----------+
since_id--> | | |xxxxxxxxxx| <-- min_id
+----------+ +----------+
| | | |
+----------+ +----------+
*/
switch {
case minID != "":
return MinID(minID)
default:
// default min is `since_id`
return SinceID(sinceID)
}
}
// SinceID ...
func SinceID(sinceID string) Boundary {
return Boundary{
Name: "since_id",
Value: sinceID,
Order: OrderDescending,
}
}
// MinID ...
func MinID(minID string) Boundary {
return Boundary{
Name: "min_id",
Value: minID,
Order: OrderAscending,
}
}
// MaxID returns an ID boundary with given max
// ID value, and the "max_id" query key set.
func MaxID(maxID string) Boundary {
return Boundary{
Name: "max_id",
Value: maxID,
Order: OrderDescending,
}
}
// MinShortcodeDomain returns a boundary with the given minimum emoji
// shortcode@domain, and the "min_shortcode_domain" query key set.
func MinShortcodeDomain(min string) Boundary {
return Boundary{
Name: "min_shortcode_domain",
Value: min,
Order: OrderAscending,
}
}
// MaxShortcodeDomain returns a boundary with the given maximum emoji
// shortcode@domain, and the "max_shortcode_domain" query key set.
func MaxShortcodeDomain(max string) Boundary {
return Boundary{
Name: "max_shortcode_domain",
Value: max,
Order: OrderDescending,
}
}
// Boundary represents the upper or lower limit in a page slice.
type Boundary struct {
Name string // i.e. query key
Value string
Order Order // NOTE: see Order type for explanation
}
// new creates a new Boundary with the same ordering and name
// as the original (receiving), but with the new provided value.
func (b Boundary) new(value string) Boundary {
return Boundary{
Name: b.Name,
Value: value,
Order: b.Order,
}
}
// Find finds the boundary's set value in input slice, or returns -1.
func (b Boundary) Find(in []string) int {
if b.Value == "" {
return -1
}
for i := range in {
if in[i] == b.Value {
return i
}
}
return -1
}
// Boundary_FindFunc is functionally equivalent to Boundary{}.Find() but for an arbitrary type with ID.
// Note: this is not a Boundary{} method as Go generics are not supported in method receiver functions.
func Boundary_FindFunc[T any](b Boundary, in []T, get func(T) string) int { //nolint:revive
if get == nil {
panic("nil function")
}
if b.Value == "" {
return -1
}
for i := range in {
if get(in[i]) == b.Value {
return i
}
}
return -1
}