Fix prefix/suffix/equal matcher to trim whitespaces

- Prefix matcher will trim leading whitespaces only when the pattern
  doesn't start with a whitespace
- Suffix matcher will trim trailing whitespaces only when the pattern
  doesn't end with a whitespace
- Equal matcher will trim leading whitespaces only when the pattern
  doesn't start with a whitespace, and trim trailing whitespaces only
  when the pattern doesn't end with a whitespace

Previously, only suffix matcher would trim whitespaces unconditionally.

Fix #1894

4 files changed, 60 insertions, 9 deletions

diff --git a/src/algo/algo.go b/src/algo/algo.go
index a627514c..b3f29e66 100644
--- a/src/algo/algo.go
+++ b/src/algo/algo.go
@@ -773,12 +773,17 @@ func PrefixMatch(caseSensitive bool, normalize bool, forward bool, text *util.Ch
 		return Result{0, 0, 0}, nil
 	}
 
-	if text.Length() < len(pattern) {
+	trimmedLen := 0
+	if !unicode.IsSpace(pattern[0]) {
+		trimmedLen = text.LeadingWhitespaces()
+	}
+
+	if text.Length()-trimmedLen < len(pattern) {
 		return Result{-1, -1, 0}, nil
 	}
 
 	for index, r := range pattern {
-		char := text.Get(index)
+		char := text.Get(trimmedLen + index)
 		if !caseSensitive {
 			char = unicode.ToLower(char)
 		}
@@ -790,14 +795,17 @@ func PrefixMatch(caseSensitive bool, normalize bool, forward bool, text *util.Ch
 		}
 	}
 	lenPattern := len(pattern)
-	score, _ := calculateScore(caseSensitive, normalize, text, pattern, 0, lenPattern, false)
-	return Result{0, lenPattern, score}, nil
+	score, _ := calculateScore(caseSensitive, normalize, text, pattern, trimmedLen, trimmedLen+lenPattern, false)
+	return Result{trimmedLen, trimmedLen + lenPattern, score}, nil
 }
 
 // SuffixMatch performs suffix-match
 func SuffixMatch(caseSensitive bool, normalize bool, forward bool, text *util.Chars, pattern []rune, withPos bool, slab *util.Slab) (Result, *[]int) {
 	lenRunes := text.Length()
-	trimmedLen := lenRunes - text.TrailingWhitespaces()
+	trimmedLen := lenRunes
+	if len(pattern) == 0 || !unicode.IsSpace(pattern[len(pattern)-1]) {
+		trimmedLen -= text.TrailingWhitespaces()
+	}
 	if len(pattern) == 0 {
 		return Result{trimmedLen, trimmedLen, 0}, nil
 	}
@@ -828,14 +836,30 @@ func SuffixMatch(caseSensitive bool, normalize bool, forward bool, text *util.Ch
 // EqualMatch performs equal-match
 func EqualMatch(caseSensitive bool, normalize bool, forward bool, text *util.Chars, pattern []rune, withPos bool, slab *util.Slab) (Result, *[]int) {
 	lenPattern := len(pattern)
-	if text.Length() != lenPattern {
+	if lenPattern == 0 {
+		return Result{-1, -1, 0}, nil
+	}
+
+	// Strip leading whitespaces
+	trimmedLen := 0
+	if !unicode.IsSpace(pattern[0]) {
+		trimmedLen = text.LeadingWhitespaces()
+	}
+
+	// Strip trailing whitespaces
+	trimmedEndLen := 0
+	if !unicode.IsSpace(pattern[lenPattern-1]) {
+		trimmedEndLen = text.TrailingWhitespaces()
+	}
+
+	if text.Length()-trimmedLen-trimmedEndLen != lenPattern {
 		return Result{-1, -1, 0}, nil
 	}
 	match := true
 	if normalize {
 		runes := text.ToRunes()
 		for idx, pchar := range pattern {
-			char := runes[idx]
+			char := runes[trimmedLen+idx]
 			if !caseSensitive {
 				char = unicode.To(unicode.LowerCase, char)
 			}
@@ -845,14 +869,15 @@ func EqualMatch(caseSensitive bool, normalize bool, forward bool, text *util.Cha
 			}
 		}
 	} else {
-		runesStr := text.ToString()
+		runes := text.ToRunes()
+		runesStr := string(runes[trimmedLen : len(runes)-trimmedEndLen])
 		if !caseSensitive {
 			runesStr = strings.ToLower(runesStr)
 		}
 		match = runesStr == string(pattern)
 	}
 	if match {
-		return Result{0, lenPattern, (scoreMatch+bonusBoundary)*lenPattern +
+		return Result{trimmedLen, trimmedLen + lenPattern, (scoreMatch+bonusBoundary)*lenPattern +
 			(bonusFirstCharMultiplier-1)*bonusBoundary}, nil
 	}
 	return Result{-1, -1, 0}, nil
diff --git a/src/algo/algo_test.go b/src/algo/algo_test.go
index 610c30e5..d8f40cdf 100644
--- a/src/algo/algo_test.go
+++ b/src/algo/algo_test.go
@@ -136,6 +136,10 @@ func TestPrefixMatch(t *testing.T) {
 		assertMatch(t, PrefixMatch, false, dir, "fooBarbaz", "Foo", 0, 3, score)
 		assertMatch(t, PrefixMatch, false, dir, "foOBarBaZ", "foo", 0, 3, score)
 		assertMatch(t, PrefixMatch, false, dir, "f-oBarbaz", "f-o", 0, 3, score)
+
+		assertMatch(t, PrefixMatch, false, dir, " fooBar", "foo", 1, 4, score)
+		assertMatch(t, PrefixMatch, false, dir, " fooBar", " fo", 0, 3, score)
+		assertMatch(t, PrefixMatch, false, dir, "     fo", "foo", -1, -1, 0)
 	}
 }
 
@@ -148,6 +152,13 @@ func TestSuffixMatch(t *testing.T) {
 			scoreMatch*3+bonusConsecutive*2)
 		assertMatch(t, SuffixMatch, false, dir, "fooBarBaZ", "baz", 6, 9,
 			(scoreMatch+bonusCamel123)*3+bonusCamel123*(bonusFirstCharMultiplier-1))
+
+		// Strip trailing white space from the string
+		assertMatch(t, SuffixMatch, false, dir, "fooBarbaz ", "baz", 6, 9,
+			scoreMatch*3+bonusConsecutive*2)
+		// Only when the pattern doesn't end with a space
+		assertMatch(t, SuffixMatch, false, dir, "fooBarbaz ", "baz ", 6, 10,
+			scoreMatch*4+bonusConsecutive*2+bonusNonWord)
 	}
 }
 
diff --git a/src/pattern_test.go b/src/pattern_test.go
index bfadf5d8..5a622952 100644
--- a/src/pattern_test.go
+++ b/src/pattern_test.go
@@ -98,6 +98,9 @@ func TestEqual(t *testing.T) {
 	}
 	match("ABC", -1, -1)
 	match("AbC", 0, 3)
+	match("AbC  ", 0, 3)
+	match(" AbC ", 1, 4)
+	match("  AbC", 2, 5)
 }
 
 func TestCaseSensitivity(t *testing.T) {
diff --git a/src/util/chars.go b/src/util/chars.go
index a57ba4bb..41de9243 100644
--- a/src/util/chars.go
+++ b/src/util/chars.go
@@ -130,6 +130,18 @@ func (chars *Chars) TrimLength() uint16 {
 	return chars.trimLength
 }
 
+func (chars *Chars) LeadingWhitespaces() int {
+	whitespaces := 0
+	for i := 0; i < chars.Length(); i++ {
+		char := chars.Get(i)
+		if !unicode.IsSpace(char) {
+			break
+		}
+		whitespaces++
+	}
+	return whitespaces
+}
+
 func (chars *Chars) TrailingWhitespaces() int {
 	whitespaces := 0
 	for i := chars.Length() - 1; i >= 0; i-- {