mirror of https://github.com/ergochat/ergo.git
84 lines
1.8 KiB
Go
84 lines
1.8 KiB
Go
// Copyright (c) 2021 Shivaram Lingamneni <slingamn@cs.stanford.edu>
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// released under the MIT license
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package history
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import (
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"sort"
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"time"
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)
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type TargetListing struct {
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CfName string
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Time time.Time
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}
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// Merge `base`, a paging window of targets, with `extras` (the target entries
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// for all joined channels).
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func MergeTargets(base []TargetListing, extra []TargetListing, start, end time.Time, limit int) (results []TargetListing) {
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if len(extra) == 0 {
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return base
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}
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SortCorrespondents(extra)
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start, end, ascending := MinMaxAsc(start, end, time.Time{})
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predicate := func(t time.Time) bool {
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return (start.IsZero() || start.Before(t)) && (end.IsZero() || end.After(t))
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}
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prealloc := len(base) + len(extra)
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if limit < prealloc {
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prealloc = limit
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}
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results = make([]TargetListing, 0, prealloc)
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if !ascending {
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ReverseCorrespondents(base)
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ReverseCorrespondents(extra)
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}
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for len(results) < limit {
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if len(extra) != 0 {
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if !predicate(extra[0].Time) {
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extra = extra[1:]
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continue
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}
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if len(base) != 0 {
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if base[0].Time.Before(extra[0].Time) == ascending {
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results = append(results, base[0])
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base = base[1:]
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} else {
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results = append(results, extra[0])
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extra = extra[1:]
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}
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} else {
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results = append(results, extra[0])
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extra = extra[1:]
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}
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} else if len(base) != 0 {
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results = append(results, base[0])
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base = base[1:]
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} else {
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break
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}
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}
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if !ascending {
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ReverseCorrespondents(results)
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}
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return
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}
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func ReverseCorrespondents(results []TargetListing) {
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// lol, generics when?
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for i, j := 0, len(results)-1; i < j; i, j = i+1, j-1 {
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results[i], results[j] = results[j], results[i]
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}
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}
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func SortCorrespondents(list []TargetListing) {
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sort.Slice(list, func(i, j int) bool {
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return list[i].Time.Before(list[j].Time)
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})
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}
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