Fix #344 - Backward scan when `--tiebreak=end`

6 files changed, 112 insertions, 58 deletions

diff --git a/src/algo/algo.go b/src/algo/algo.go
index 03266dd9..ac7bd8b2 100644
--- a/src/algo/algo.go
+++ b/src/algo/algo.go
@@ -15,8 +15,15 @@ import (
  * In short: They try to do as little work as possible.
  */
 
+func runeAt(runes []rune, index int, max int, forward bool) rune {
+	if forward {
+		return runes[index]
+	}
+	return runes[max-index-1]
+}
+
 // FuzzyMatch performs fuzzy-match
-func FuzzyMatch(caseSensitive bool, runes []rune, pattern []rune) (int, int) {
+func FuzzyMatch(caseSensitive bool, forward bool, runes []rune, pattern []rune) (int, int) {
 	if len(pattern) == 0 {
 		return 0, 0
 	}
@@ -34,7 +41,11 @@ func FuzzyMatch(caseSensitive bool, runes []rune, pattern []rune) (int, int) {
 	sidx := -1
 	eidx := -1
 
-	for index, char := range runes {
+	lenRunes := len(runes)
+	lenPattern := len(pattern)
+
+	for index := range runes {
+		char := runeAt(runes, index, lenRunes, forward)
 		// This is considerably faster than blindly applying strings.ToLower to the
 		// whole string
 		if !caseSensitive {
@@ -47,11 +58,12 @@ func FuzzyMatch(caseSensitive bool, runes []rune, pattern []rune) (int, int) {
 				char = unicode.To(unicode.LowerCase, char)
 			}
 		}
-		if char == pattern[pidx] {
+		pchar := runeAt(pattern, pidx, lenPattern, forward)
+		if char == pchar {
 			if sidx < 0 {
 				sidx = index
 			}
-			if pidx++; pidx == len(pattern) {
+			if pidx++; pidx == lenPattern {
 				eidx = index + 1
 				break
 			}
@@ -61,7 +73,7 @@ func FuzzyMatch(caseSensitive bool, runes []rune, pattern []rune) (int, int) {
 	if sidx >= 0 && eidx >= 0 {
 		pidx--
 		for index := eidx - 1; index >= sidx; index-- {
-			char := runes[index]
+			char := runeAt(runes, index, lenRunes, forward)
 			if !caseSensitive {
 				if char >= 'A' && char <= 'Z' {
 					char += 32
@@ -69,14 +81,19 @@ func FuzzyMatch(caseSensitive bool, runes []rune, pattern []rune) (int, int) {
 					char = unicode.To(unicode.LowerCase, char)
 				}
 			}
-			if char == pattern[pidx] {
+
+			pchar := runeAt(pattern, pidx, lenPattern, forward)
+			if char == pchar {
 				if pidx--; pidx < 0 {
 					sidx = index
 					break
 				}
 			}
 		}
-		return sidx, eidx
+		if forward {
+			return sidx, eidx
+		}
+		return lenRunes - eidx, lenRunes - sidx
 	}
 	return -1, -1
 }
@@ -88,20 +105,21 @@ func FuzzyMatch(caseSensitive bool, runes []rune, pattern []rune) (int, int) {
 //
 // We might try to implement better algorithms in the future:
 // http://en.wikipedia.org/wiki/String_searching_algorithm
-func ExactMatchNaive(caseSensitive bool, runes []rune, pattern []rune) (int, int) {
+func ExactMatchNaive(caseSensitive bool, forward bool, runes []rune, pattern []rune) (int, int) {
 	if len(pattern) == 0 {
 		return 0, 0
 	}
 
-	numRunes := len(runes)
-	plen := len(pattern)
-	if numRunes < plen {
+	lenRunes := len(runes)
+	lenPattern := len(pattern)
+
+	if lenRunes < lenPattern {
 		return -1, -1
 	}
 
 	pidx := 0
-	for index := 0; index < numRunes; index++ {
-		char := runes[index]
+	for index := 0; index < lenRunes; index++ {
+		char := runeAt(runes, index, lenRunes, forward)
 		if !caseSensitive {
 			if char >= 'A' && char <= 'Z' {
 				char += 32
@@ -109,10 +127,14 @@ func ExactMatchNaive(caseSensitive bool, runes []rune, pattern []rune) (int, int
 				char = unicode.To(unicode.LowerCase, char)
 			}
 		}
-		if pattern[pidx] == char {
+		pchar := runeAt(pattern, pidx, lenPattern, forward)
+		if pchar == char {
 			pidx++
-			if pidx == plen {
-				return index - plen + 1, index + 1
+			if pidx == lenPattern {
+				if forward {
+					return index - lenPattern + 1, index + 1
+				}
+				return lenRunes - (index + 1), lenRunes - (index - lenPattern + 1)
 			}
 		} else {
 			index -= pidx
@@ -123,7 +145,7 @@ func ExactMatchNaive(caseSensitive bool, runes []rune, pattern []rune) (int, int
 }
 
 // PrefixMatch performs prefix-match
-func PrefixMatch(caseSensitive bool, runes []rune, pattern []rune) (int, int) {
+func PrefixMatch(caseSensitive bool, forward bool, runes []rune, pattern []rune) (int, int) {
 	if len(runes) < len(pattern) {
 		return -1, -1
 	}
@@ -141,7 +163,7 @@ func PrefixMatch(caseSensitive bool, runes []rune, pattern []rune) (int, int) {
 }
 
 // SuffixMatch performs suffix-match
-func SuffixMatch(caseSensitive bool, input []rune, pattern []rune) (int, int) {
+func SuffixMatch(caseSensitive bool, forward bool, input []rune, pattern []rune) (int, int) {
 	runes := util.TrimRight(input)
 	trimmedLen := len(runes)
 	diff := trimmedLen - len(pattern)
@@ -162,7 +184,7 @@ func SuffixMatch(caseSensitive bool, input []rune, pattern []rune) (int, int) {
 }
 
 // EqualMatch performs equal-match
-func EqualMatch(caseSensitive bool, runes []rune, pattern []rune) (int, int) {
+func EqualMatch(caseSensitive bool, forward bool, runes []rune, pattern []rune) (int, int) {
 	if len(runes) != len(pattern) {
 		return -1, -1
 	}
diff --git a/src/algo/algo_test.go b/src/algo/algo_test.go
index db241962..95a020b7 100644
--- a/src/algo/algo_test.go
+++ b/src/algo/algo_test.go
@@ -5,11 +5,11 @@ import (
 	"testing"
 )
 
-func assertMatch(t *testing.T, fun func(bool, []rune, []rune) (int, int), caseSensitive bool, input string, pattern string, sidx int, eidx int) {
+func assertMatch(t *testing.T, fun func(bool, bool, []rune, []rune) (int, int), caseSensitive bool, forward bool, input string, pattern string, sidx int, eidx int) {
 	if !caseSensitive {
 		pattern = strings.ToLower(pattern)
 	}
-	s, e := fun(caseSensitive, []rune(input), []rune(pattern))
+	s, e := fun(caseSensitive, forward, []rune(input), []rune(pattern))
 	if s != sidx {
 		t.Errorf("Invalid start index: %d (expected: %d, %s / %s)", s, sidx, input, pattern)
 	}
@@ -19,33 +19,51 @@ func assertMatch(t *testing.T, fun func(bool, []rune, []rune) (int, int), caseSe
 }
 
 func TestFuzzyMatch(t *testing.T) {
-	assertMatch(t, FuzzyMatch, false, "fooBarbaz", "oBZ", 2, 9)
-	assertMatch(t, FuzzyMatch, true, "fooBarbaz", "oBZ", -1, -1)
-	assertMatch(t, FuzzyMatch, true, "fooBarbaz", "oBz", 2, 9)
-	assertMatch(t, FuzzyMatch, true, "fooBarbaz", "fooBarbazz", -1, -1)
+	assertMatch(t, FuzzyMatch, false, true, "fooBarbaz", "oBZ", 2, 9)
+	assertMatch(t, FuzzyMatch, true, true, "fooBarbaz", "oBZ", -1, -1)
+	assertMatch(t, FuzzyMatch, true, true, "fooBarbaz", "oBz", 2, 9)
+	assertMatch(t, FuzzyMatch, true, true, "fooBarbaz", "fooBarbazz", -1, -1)
+}
+
+func TestFuzzyMatchBackward(t *testing.T) {
+	assertMatch(t, FuzzyMatch, false, true, "foobar fb", "fb", 0, 4)
+	assertMatch(t, FuzzyMatch, false, false, "foobar fb", "fb", 7, 9)
 }
 
 func TestExactMatchNaive(t *testing.T) {
-	assertMatch(t, ExactMatchNaive, false, "fooBarbaz", "oBA", 2, 5)
-	assertMatch(t, ExactMatchNaive, true, "fooBarbaz", "oBA", -1, -1)
-	assertMatch(t, ExactMatchNaive, true, "fooBarbaz", "fooBarbazz", -1, -1)
+	for _, dir := range []bool{true, false} {
+		assertMatch(t, ExactMatchNaive, false, dir, "fooBarbaz", "oBA", 2, 5)
+		assertMatch(t, ExactMatchNaive, true, dir, "fooBarbaz", "oBA", -1, -1)
+		assertMatch(t, ExactMatchNaive, true, dir, "fooBarbaz", "fooBarbazz", -1, -1)
+	}
+}
+
+func TestExactMatchNaiveBackward(t *testing.T) {
+	assertMatch(t, FuzzyMatch, false, true, "foobar foob", "oo", 1, 3)
+	assertMatch(t, FuzzyMatch, false, false, "foobar foob", "oo", 8, 10)
 }
 
 func TestPrefixMatch(t *testing.T) {
-	assertMatch(t, PrefixMatch, false, "fooBarbaz", "Foo", 0, 3)
-	assertMatch(t, PrefixMatch, true, "fooBarbaz", "Foo", -1, -1)
-	assertMatch(t, PrefixMatch, false, "fooBarbaz", "baz", -1, -1)
+	for _, dir := range []bool{true, false} {
+		assertMatch(t, PrefixMatch, false, dir, "fooBarbaz", "Foo", 0, 3)
+		assertMatch(t, PrefixMatch, true, dir, "fooBarbaz", "Foo", -1, -1)
+		assertMatch(t, PrefixMatch, false, dir, "fooBarbaz", "baz", -1, -1)
+	}
 }
 
 func TestSuffixMatch(t *testing.T) {
-	assertMatch(t, SuffixMatch, false, "fooBarbaz", "Foo", -1, -1)
-	assertMatch(t, SuffixMatch, false, "fooBarbaz", "baz", 6, 9)
-	assertMatch(t, SuffixMatch, true, "fooBarbaz", "Baz", -1, -1)
+	for _, dir := range []bool{true, false} {
+		assertMatch(t, SuffixMatch, false, dir, "fooBarbaz", "Foo", -1, -1)
+		assertMatch(t, SuffixMatch, false, dir, "fooBarbaz", "baz", 6, 9)
+		assertMatch(t, SuffixMatch, true, dir, "fooBarbaz", "Baz", -1, -1)
+	}
 }
 
 func TestEmptyPattern(t *testing.T) {
-	assertMatch(t, FuzzyMatch, true, "foobar", "", 0, 0)
-	assertMatch(t, ExactMatchNaive, true, "foobar", "", 0, 0)
-	assertMatch(t, PrefixMatch, true, "foobar", "", 0, 0)
-	assertMatch(t, SuffixMatch, true, "foobar", "", 6, 6)
+	for _, dir := range []bool{true, false} {
+		assertMatch(t, FuzzyMatch, true, dir, "foobar", "", 0, 0)
+		assertMatch(t, ExactMatchNaive, true, dir, "foobar", "", 0, 0)
+		assertMatch(t, PrefixMatch, true, dir, "foobar", "", 0, 0)
+		assertMatch(t, SuffixMatch, true, dir, "foobar", "", 6, 6)
+	}
 }
diff --git a/src/core.go b/src/core.go
index 4f072151..96bfdd4c 100644
--- a/src/core.go
+++ b/src/core.go
@@ -143,7 +143,8 @@ func Run(opts *Options) {
 	// Matcher
 	patternBuilder := func(runes []rune) *Pattern {
 		return BuildPattern(
-			opts.Mode, opts.Case, opts.Nth, opts.Delimiter, runes)
+			opts.Mode, opts.Case, opts.Tiebreak != byEnd,
+			opts.Nth, opts.Delimiter, runes)
 	}
 	matcher := NewMatcher(patternBuilder, sort, opts.Tac, eventBox)
 
diff --git a/src/pattern.go b/src/pattern.go
index cfeb68dc..5466b862 100644
--- a/src/pattern.go
+++ b/src/pattern.go
@@ -39,12 +39,13 @@ type term struct {
 type Pattern struct {
 	mode          Mode
 	caseSensitive bool
+	forward       bool
 	text          []rune
 	terms         []term
 	hasInvTerm    bool
 	delimiter     Delimiter
 	nth           []Range
-	procFun       map[termType]func(bool, []rune, []rune) (int, int)
+	procFun       map[termType]func(bool, bool, []rune, []rune) (int, int)
 }
 
 var (
@@ -70,7 +71,7 @@ func clearChunkCache() {
 }
 
 // BuildPattern builds Pattern object from the given arguments
-func BuildPattern(mode Mode, caseMode Case,
+func BuildPattern(mode Mode, caseMode Case, forward bool,
 	nth []Range, delimiter Delimiter, runes []rune) *Pattern {
 
 	var asString string
@@ -109,12 +110,13 @@ func BuildPattern(mode Mode, caseMode Case,
 	ptr := &Pattern{
 		mode:          mode,
 		caseSensitive: caseSensitive,
+		forward:       forward,
 		text:          []rune(asString),
 		terms:         terms,
 		hasInvTerm:    hasInvTerm,
 		nth:           nth,
 		delimiter:     delimiter,
-		procFun:       make(map[termType]func(bool, []rune, []rune) (int, int))}
+		procFun:       make(map[termType]func(bool, bool, []rune, []rune) (int, int))}
 
 	ptr.procFun[termFuzzy] = algo.FuzzyMatch
 	ptr.procFun[termEqual] = algo.EqualMatch
@@ -288,7 +290,7 @@ func dupItem(item *Item, offsets []Offset) *Item {
 
 func (p *Pattern) fuzzyMatch(item *Item) (int, int) {
 	input := p.prepareInput(item)
-	return p.iter(algo.FuzzyMatch, input, p.caseSensitive, p.text)
+	return p.iter(algo.FuzzyMatch, input, p.caseSensitive, p.forward, p.text)
 }
 
 func (p *Pattern) extendedMatch(item *Item) []Offset {
@@ -296,7 +298,7 @@ func (p *Pattern) extendedMatch(item *Item) []Offset {
 	offsets := []Offset{}
 	for _, term := range p.terms {
 		pfun := p.procFun[term.typ]
-		if sidx, eidx := p.iter(pfun, input, term.caseSensitive, term.text); sidx >= 0 {
+		if sidx, eidx := p.iter(pfun, input, term.caseSensitive, p.forward, term.text); sidx >= 0 {
 			if term.inv {
 				break
 			}
@@ -324,11 +326,11 @@ func (p *Pattern) prepareInput(item *Item) []Token {
 	return ret
 }
 
-func (p *Pattern) iter(pfun func(bool, []rune, []rune) (int, int),
-	tokens []Token, caseSensitive bool, pattern []rune) (int, int) {
+func (p *Pattern) iter(pfun func(bool, bool, []rune, []rune) (int, int),
+	tokens []Token, caseSensitive bool, forward bool, pattern []rune) (int, int) {
 	for _, part := range tokens {
 		prefixLength := part.prefixLength
-		if sidx, eidx := pfun(caseSensitive, part.text, pattern); sidx >= 0 {
+		if sidx, eidx := pfun(caseSensitive, forward, part.text, pattern); sidx >= 0 {
 			return sidx + prefixLength, eidx + prefixLength
 		}
 	}
diff --git a/src/pattern_test.go b/src/pattern_test.go
index 66f5d41d..d5086128 100644
--- a/src/pattern_test.go
+++ b/src/pattern_test.go
@@ -58,10 +58,10 @@ func TestParseTermsEmpty(t *testing.T) {
 func TestExact(t *testing.T) {
 	defer clearPatternCache()
 	clearPatternCache()
-	pattern := BuildPattern(ModeExtended, CaseSmart,
+	pattern := BuildPattern(ModeExtended, CaseSmart, true,
 		[]Range{}, Delimiter{}, []rune("'abc"))
 	sidx, eidx := algo.ExactMatchNaive(
-		pattern.caseSensitive, []rune("aabbcc abc"), pattern.terms[0].text)
+		pattern.caseSensitive, pattern.forward, []rune("aabbcc abc"), pattern.terms[0].text)
 	if sidx != 7 || eidx != 10 {
 		t.Errorf("%s / %d / %d", pattern.terms, sidx, eidx)
 	}
@@ -70,11 +70,11 @@ func TestExact(t *testing.T) {
 func TestEqual(t *testing.T) {
 	defer clearPatternCache()
 	clearPatternCache()
-	pattern := BuildPattern(ModeExtended, CaseSmart, []Range{}, Delimiter{}, []rune("^AbC$"))
+	pattern := BuildPattern(ModeExtended, CaseSmart, true, []Range{}, Delimiter{}, []rune("^AbC$"))
 
 	match := func(str string, sidxExpected int, eidxExpected int) {
 		sidx, eidx := algo.EqualMatch(
-			pattern.caseSensitive, []rune(str), pattern.terms[0].text)
+			pattern.caseSensitive, pattern.forward, []rune(str), pattern.terms[0].text)
 		if sidx != sidxExpected || eidx != eidxExpected {
 			t.Errorf("%s / %d / %d", pattern.terms, sidx, eidx)
 		}
@@ -86,17 +86,17 @@ func TestEqual(t *testing.T) {
 func TestCaseSensitivity(t *testing.T) {
 	defer clearPatternCache()
 	clearPatternCache()
-	pat1 := BuildPattern(ModeFuzzy, CaseSmart, []Range{}, Delimiter{}, []rune("abc"))
+	pat1 := BuildPattern(ModeFuzzy, CaseSmart, true, []Range{}, Delimiter{}, []rune("abc"))
 	clearPatternCache()
-	pat2 := BuildPattern(ModeFuzzy, CaseSmart, []Range{}, Delimiter{}, []rune("Abc"))
+	pat2 := BuildPattern(ModeFuzzy, CaseSmart, true, []Range{}, Delimiter{}, []rune("Abc"))
 	clearPatternCache()
-	pat3 := BuildPattern(ModeFuzzy, CaseIgnore, []Range{}, Delimiter{}, []rune("abc"))
+	pat3 := BuildPattern(ModeFuzzy, CaseIgnore, true, []Range{}, Delimiter{}, []rune("abc"))
 	clearPatternCache()
-	pat4 := BuildPattern(ModeFuzzy, CaseIgnore, []Range{}, Delimiter{}, []rune("Abc"))
+	pat4 := BuildPattern(ModeFuzzy, CaseIgnore, true, []Range{}, Delimiter{}, []rune("Abc"))
 	clearPatternCache()
-	pat5 := BuildPattern(ModeFuzzy, CaseRespect, []Range{}, Delimiter{}, []rune("abc"))
+	pat5 := BuildPattern(ModeFuzzy, CaseRespect, true, []Range{}, Delimiter{}, []rune("abc"))
 	clearPatternCache()
-	pat6 := BuildPattern(ModeFuzzy, CaseRespect, []Range{}, Delimiter{}, []rune("Abc"))
+	pat6 := BuildPattern(ModeFuzzy, CaseRespect, true, []Range{}, Delimiter{}, []rune("Abc"))
 
 	if string(pat1.text) != "abc" || pat1.caseSensitive != false ||
 		string(pat2.text) != "Abc" || pat2.caseSensitive != true ||
@@ -109,7 +109,7 @@ func TestCaseSensitivity(t *testing.T) {
 }
 
 func TestOrigTextAndTransformed(t *testing.T) {
-	pattern := BuildPattern(ModeExtended, CaseSmart, []Range{}, Delimiter{}, []rune("jg"))
+	pattern := BuildPattern(ModeExtended, CaseSmart, true, []Range{}, Delimiter{}, []rune("jg"))
 	tokens := Tokenize([]rune("junegunn"), Delimiter{})
 	trans := Transform(tokens, []Range{Range{1, 1}})
 
diff --git a/test/test_go.rb b/test/test_go.rb
index 377af229..d1f45dc1 100644
--- a/test/test_go.rb
+++ b/test/test_go.rb
@@ -527,6 +527,17 @@ class TestGoFZF < TestBase
     assert_equal output, `cat #{tempname} | #{FZF} -fh -n2 -d:`.split($/)
   end
 
+  def test_tiebreak_end_backward_scan
+    input = %w[
+      foobar-fb
+      fubar
+    ]
+    writelines tempname, input
+
+    assert_equal input.reverse, `cat #{tempname} | #{FZF} -f fb`.split($/)
+    assert_equal input, `cat #{tempname} | #{FZF} -f fb --tiebreak=end`.split($/)
+  end
+
   def test_invalid_cache
     tmux.send_keys "(echo d; echo D; echo x) | #{fzf '-q d'}", :Enter
     tmux.until { |lines| lines[-2].include? '2/3' }