Revise ranking algorithm

src/options.go

@@ -8,6 +8,7 @@ import (
 	"strings"
 	"unicode/utf8"
 
+	"github.com/junegunn/fzf/src/algo"
 	"github.com/junegunn/fzf/src/curses"
 
 	"github.com/junegunn/go-shellwords"
@@ -19,6 +20,7 @@ const usage = `usage: fzf [options]
     -x, --extended        Extended-search mode
                           (enabled by default; +x or --no-extended to disable)
     -e, --exact           Enable Exact-match
+    --algo=TYPE           Fuzzy matching algorithm: [v1|v2] (default: v2)
     -i                    Case-insensitive match (default: smart-case match)
     +i                    Case-sensitive match
     -n, --nth=N[,..]      Comma-separated list of field index expressions
@@ -94,8 +96,7 @@ const (
 type criterion int
 
 const (
-	byMatchLen criterion = iota
-	byBonus
+	byScore criterion = iota
 	byLength
 	byBegin
 	byEnd
@@ -129,6 +130,7 @@ type previewOpts struct {
 // Options stores the values of command-line options
 type Options struct {
 	Fuzzy       bool
+	FuzzyAlgo   algo.Algo
 	Extended    bool
 	Case        Case
 	Nth         []Range
@@ -172,6 +174,7 @@ type Options struct {
 func defaultOptions() *Options {
 	return &Options{
 		Fuzzy:       true,
+		FuzzyAlgo:   algo.FuzzyMatchV2,
 		Extended:    true,
 		Case:        CaseSmart,
 		Nth:         make([]Range, 0),
@@ -179,7 +182,7 @@ func defaultOptions() *Options {
 		Delimiter:   Delimiter{},
 		Sort:        1000,
 		Tac:         false,
-		Criteria:    []criterion{byMatchLen, byBonus, byLength},
+		Criteria:    []criterion{byScore, byLength},
 		Multi:       false,
 		Ansi:        false,
 		Mouse:       true,
@@ -322,6 +325,18 @@ func isAlphabet(char uint8) bool {
 	return char >= 'a' && char <= 'z'
 }
 
+func parseAlgo(str string) algo.Algo {
+	switch str {
+	case "v1":
+		return algo.FuzzyMatchV1
+	case "v2":
+		return algo.FuzzyMatchV2
+	default:
+		errorExit("invalid algorithm (expected: v1 or v2)")
+	}
+	return algo.FuzzyMatchV2
+}
+
 func parseKeyChords(str string, message string) map[int]string {
 	if len(str) == 0 {
 		errorExit(message)
@@ -407,7 +422,7 @@ func parseKeyChords(str string, message string) map[int]string {
 }
 
 func parseTiebreak(str string) []criterion {
-	criteria := []criterion{byMatchLen, byBonus}
+	criteria := []criterion{byScore}
 	hasIndex := false
 	hasLength := false
 	hasBegin := false
@@ -834,6 +849,8 @@ func parseOptions(opts *Options, allArgs []string) {
 		case "-f", "--filter":
 			filter := nextString(allArgs, &i, "query string required")
 			opts.Filter = &filter
+		case "--algo":
+			opts.FuzzyAlgo = parseAlgo(nextString(allArgs, &i, "algorithm required (v1|v2)"))
 		case "--expect":
 			opts.Expect = parseKeyChords(nextString(allArgs, &i, "key names required"), "key names required")
 		case "--tiebreak":
@@ -962,7 +979,9 @@ func parseOptions(opts *Options, allArgs []string) {
 		case "--version":
 			opts.Version = true
 		default:
-			if match, value := optString(arg, "-q", "--query="); match {
+			if match, value := optString(arg, "--algo="); match {
+				opts.FuzzyAlgo = parseAlgo(value)
+			} else if match, value := optString(arg, "-q", "--query="); match {
 				opts.Query = value
 			} else if match, value := optString(arg, "-f", "--filter="); match {
 				opts.Filter = &value