177 lines
4.1 KiB
Go
177 lines
4.1 KiB
Go
// Fuzzy searching allows for flexibly matching a string with partial input,
|
|
// useful for filtering data very quickly based on lightweight user input.
|
|
package fuzzy
|
|
|
|
import (
|
|
"unicode"
|
|
"unicode/utf8"
|
|
)
|
|
|
|
var noop = func(r rune) rune { return r }
|
|
|
|
// Match returns true if source matches target using a fuzzy-searching
|
|
// algorithm. Note that it doesn't implement Levenshtein distance (see
|
|
// RankMatch instead), but rather a simplified version where there's no
|
|
// approximation. The method will return true only if each character in the
|
|
// source can be found in the target and occurs after the preceding matches.
|
|
func Match(source, target string) bool {
|
|
return match(source, target, noop)
|
|
}
|
|
|
|
// MatchFold is a case-insensitive version of Match.
|
|
func MatchFold(source, target string) bool {
|
|
return match(source, target, unicode.ToLower)
|
|
}
|
|
|
|
func match(source, target string, fn func(rune) rune) bool {
|
|
lenDiff := len(target) - len(source)
|
|
|
|
if lenDiff < 0 {
|
|
return false
|
|
}
|
|
|
|
if lenDiff == 0 && source == target {
|
|
return true
|
|
}
|
|
|
|
Outer:
|
|
for _, r1 := range source {
|
|
for i, r2 := range target {
|
|
if fn(r1) == fn(r2) {
|
|
target = target[i+utf8.RuneLen(r2):]
|
|
continue Outer
|
|
}
|
|
}
|
|
return false
|
|
}
|
|
|
|
return true
|
|
}
|
|
|
|
// Find will return a list of strings in targets that fuzzy matches source.
|
|
func Find(source string, targets []string) []string {
|
|
return find(source, targets, noop)
|
|
}
|
|
|
|
// FindFold is a case-insensitive version of Find.
|
|
func FindFold(source string, targets []string) []string {
|
|
return find(source, targets, unicode.ToLower)
|
|
}
|
|
|
|
func find(source string, targets []string, fn func(rune) rune) []string {
|
|
var matches []string
|
|
|
|
for _, target := range targets {
|
|
if match(source, target, fn) {
|
|
matches = append(matches, target)
|
|
}
|
|
}
|
|
|
|
return matches
|
|
}
|
|
|
|
// RankMatch is similar to Match except it will measure the Levenshtein
|
|
// distance between the source and the target and return its result. If there
|
|
// was no match, it will return -1.
|
|
// Given the requirements of match, RankMatch only needs to perform a subset of
|
|
// the Levenshtein calculation, only deletions need be considered, required
|
|
// additions and substitutions would fail the match test.
|
|
func RankMatch(source, target string) int {
|
|
return rank(source, target, noop)
|
|
}
|
|
|
|
// RankMatchFold is a case-insensitive version of RankMatch.
|
|
func RankMatchFold(source, target string) int {
|
|
return rank(source, target, unicode.ToLower)
|
|
}
|
|
|
|
func rank(source, target string, fn func(rune) rune) int {
|
|
lenDiff := len(target) - len(source)
|
|
|
|
if lenDiff < 0 {
|
|
return -1
|
|
}
|
|
|
|
if lenDiff == 0 && source == target {
|
|
return 0
|
|
}
|
|
|
|
runeDiff := 0
|
|
|
|
Outer:
|
|
for _, r1 := range source {
|
|
for i, r2 := range target {
|
|
if fn(r1) == fn(r2) {
|
|
target = target[i+utf8.RuneLen(r2):]
|
|
continue Outer
|
|
} else {
|
|
runeDiff++
|
|
}
|
|
}
|
|
return -1
|
|
}
|
|
|
|
// Count up remaining char
|
|
for len(target) > 0 {
|
|
target = target[utf8.RuneLen(rune(target[0])):]
|
|
runeDiff++
|
|
}
|
|
|
|
return runeDiff
|
|
}
|
|
|
|
// RankFind is similar to Find, except it will also rank all matches using
|
|
// Levenshtein distance.
|
|
func RankFind(source string, targets []string) Ranks {
|
|
var r Ranks
|
|
|
|
for index, target := range targets {
|
|
if match(source, target, noop) {
|
|
distance := LevenshteinDistance(source, target)
|
|
r = append(r, Rank{source, target, distance, index})
|
|
}
|
|
}
|
|
return r
|
|
}
|
|
|
|
// RankFindFold is a case-insensitive version of RankFind.
|
|
func RankFindFold(source string, targets []string) Ranks {
|
|
var r Ranks
|
|
|
|
for index, target := range targets {
|
|
if match(source, target, unicode.ToLower) {
|
|
distance := LevenshteinDistance(source, target)
|
|
r = append(r, Rank{source, target, distance, index})
|
|
}
|
|
}
|
|
return r
|
|
}
|
|
|
|
type Rank struct {
|
|
// Source is used as the source for matching.
|
|
Source string
|
|
|
|
// Target is the word matched against.
|
|
Target string
|
|
|
|
// Distance is the Levenshtein distance between Source and Target.
|
|
Distance int
|
|
|
|
// Location of Target in original list
|
|
OriginalIndex int
|
|
}
|
|
|
|
type Ranks []Rank
|
|
|
|
func (r Ranks) Len() int {
|
|
return len(r)
|
|
}
|
|
|
|
func (r Ranks) Swap(i, j int) {
|
|
r[i], r[j] = r[j], r[i]
|
|
}
|
|
|
|
func (r Ranks) Less(i, j int) bool {
|
|
return r[i].Distance < r[j].Distance
|
|
}
|