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package util
import (
"iter"
"math"
"strings"
"time"
)
func ParseDateTime(s string) (time.Time, error) {
dateFormats := []string{
"Jan _2, 2006",
"January 2, 2006",
"January 2 2006",
"Jan 2 2006",
"2006 January 2",
time.DateOnly,
time.DateTime,
time.Layout,
time.ANSIC,
time.UnixDate,
time.RubyDate,
time.RFC822,
time.RFC822Z,
time.RFC850,
time.RFC1123,
time.RFC1123Z,
time.RFC3339,
}
var t time.Time
var err error
for _, layout := range dateFormats {
if t, err = time.Parse(layout, s); err == nil {
return t, nil
}
}
return time.Time{}, err
}
// Estimate an interval around a time which is still "meaningful"
//
// Ex: 2025-06-14 -> [2025-06-10, 2025-06-18]
// Ex: 2025-06-14T12:00 -> [2025-06-14T8:00, 2025-06-14T16:00]
func FuzzDatetime(t time.Time) (start time.Time, stop time.Time) {
hour, minute, sec := t.Clock()
_, month, day := t.Date()
var d time.Duration
if sec != 0 {
d = 5 * time.Minute
} else if minute != 0 {
d = 30 * time.Minute
} else if hour != 0 {
d = 4 * time.Hour
} else if day != 1 {
d = 84 * time.Hour // +- 3.5 days
} else if month != time.January {
d = 336 * time.Hour // +- .5 months
} else {
d = 4380 * time.Hour // search +- 6months
}
return t.Add(-d), t.Add(d)
}
// Create a copy of a slice with all values that satisfy cond
func Fitler[E any](s []E, cond func(e E) bool) []E {
filtered := make([]E, 0, len(s))
for _, e := range s {
if cond(e) {
filtered = append(filtered, e)
}
}
return filtered
}
// Create an iterator of index and element for all values in a slice which satisfy cond.
func FilterIter[E any](s []E, cond func(e E) bool) iter.Seq2[int, E] {
return func(yield func(int, E) bool) {
for i, e := range s {
if cond(e) {
if !yield(i, e) {
return
}
}
}
}
}
// FilterIter but backwards
func BackwardsFilterIter[E any](s []E, cond func(e E) bool) iter.Seq2[int, E] {
return func(yield func(int, E) bool) {
for i := len(s) - 1; i >= 0; i-- {
if cond(s[i]) {
if !yield(i, s[i]) {
return
}
}
}
}
}
// A Levenshtein distance implementation based off of
//
// https://en.wikipedia.org/wiki/Levenshtein_distance#Iterative_with_full_matrix
// PERF: more performant implementations exist
func LevensteinDistance(s, t string) int {
m, n := len(s), len(t)
d := make([][]int, m+1)
for i := range m + 1 {
d[i] = make([]int, n+1)
}
for i := range m {
d[i+1][0] = i
}
for j := range n {
d[0][j+1] = j
}
var subCost int
for j := range n {
for i := range m {
if s[i] == t[j] {
subCost = 0
} else {
subCost = 1
}
del := d[i][j+1] + 1
insert := d[i+1][j] + 1
sub := d[i][j] + subCost
d[i+1][j+1] = min(del, insert, sub)
}
}
return d[m][n]
}
// Find nearest element of a slice using cmp, returns the found element and
// if the distance is below ceil
func Nearest[E any](candidate E, valid []E, cmp func(E, E) int, ceil int) (E, bool) {
minDistance := math.MaxInt
minIdx := -1
var d int
for i, e := range valid {
if sd := cmp(candidate, e); sd < 0 {
d = -sd
} else {
d = sd
}
if d < minDistance {
minDistance = d
minIdx = i
}
}
if minIdx < 0 {
return candidate, false
}
return valid[minIdx], minDistance < ceil
}
// Check if substr[left:right] is a substring of S.
// If left > len(substr) use 0
// If right < 0 use 0
func ContainsSliced(s, substr string, left, right int) bool {
return strings.Contains(s, substr[min(left, len(substr)):max(right, 0)])
}
|
