Fix _NegateMatcher bug in grepper

Unlike positive matchers that is valid on first match, the exit criteria
is met when all matchers are matched.

Negate matchers must be tested with the whole file and none of negate
matchers can be matched. So it's different logic than testing with
finder. Because finder only test with one line of file path, grepper
needs the whole file.

internal/finder.go

@@ -26,10 +26,11 @@ func newFinder(queries ...string) *_Finder {
 	finder := &_Finder{
 		matchers: matchers,
 		walker:   make(chan string),
-		done:     make(chan bool),
+		done:     make(chan bool, 1),
 	}
 
 	go func() {
+		defer close(finder.walker)
 		_ = filepath.Walk(".", func(path string, info os.FileInfo, err error) error {
 			if finder.shouldSkip(info.Name()) {
 				if info.IsDir() {
@@ -59,8 +60,6 @@ func newFinder(queries ...string) *_Finder {
 
 			return nil
 		})
-		close(finder.walker)
-		close(finder.done)
 	}()
 
 	return finder
@@ -72,6 +71,7 @@ func (f *_Finder) channel() <-chan string {
 
 func (f *_Finder) reset() {
 	f.done <- true
+	close(f.done)
 }
 
 func (f *_Finder) shouldSkip(basematcher string) bool {

internal/grepper.go

@@ -13,13 +13,18 @@ func newGrepper() *_Grepper {
 }
 
 func (g *_Grepper) grep(file string, keywords ...string) (bool, error) {
-	matchers := make(map[string]_Matcher, len(keywords))
+	matchers := make(map[string]_Matcher)
+	negateMatchers := make(map[string]_Matcher)
 	for _, keyword := range keywords {
 		matcher, err := newMatcher(keyword)
 		if err != nil {
 			continue
 		}
-		matchers[keyword] = matcher
+		if _, ok := matcher.(*_NegateMatcher); ok {
+			negateMatchers[keyword] = matcher
+		} else {
+			matchers[keyword] = matcher
+		}
 	}
 
 	f, err := os.Open(file)
@@ -40,7 +45,12 @@ func (g *_Grepper) grep(file string, keywords ...string) (bool, error) {
 				delete(matchers, keyword)
 			}
 		}
-		if len(matchers) == 0 {
+		for _, negateMatcher := range negateMatchers {
+			if !negateMatcher.Matches(scanner.Text()) {
+				return false, nil
+			}
+		}
+		if len(matchers) == 0 && len(negateMatchers) == 0 {
 			break
 		}
 	}

internal/grepper_test.go

@@ -2,17 +2,18 @@ package internal
 
 import (
 	"testing"
+
+	"github.com/stretchr/testify/assert"
 )
 
 func TestGrep(t *testing.T) {
 	grepper := newGrepper()
+
 	match, err := grepper.grep("grepper_test.go", "package", "func", "NewGrepper")
-	if err != nil {
-		t.Fatal(err)
-	}
+	assert.Nil(t, err)
+	assert.True(t, match)
 
-	t.Log(match)
-	if !match {
-		t.Fatal("expected main.go to match")
-	}
+	match, err = grepper.grep("grepper_test.go", "package", "func", "-NewGrepper")
+	assert.Nil(t, err)
+	assert.False(t, match)
 }

internal/matcher.go

@@ -8,6 +8,7 @@ import (
 
 type _Matcher interface {
 	Matches(input string) bool
+	String() string
 }
 
 type _StringMatcher struct {
@@ -48,6 +49,10 @@ func (m _StringMatcher) Matches(input string) bool {
 	return strings.Contains(lower, m.pattern)
 }
 
+func (m _StringMatcher) String() string {
+	return m.pattern
+}
+
 type _RegexpMatcher struct {
 	pattern *regexp.Regexp
 }
@@ -65,6 +70,10 @@ func (m _RegexpMatcher) Matches(input string) bool {
 	return m.pattern.FindStringSubmatch(input) != nil
 }
 
+func (m *_RegexpMatcher) String() string {
+	return m.pattern.String()
+}
+
 type _NegateMatcher struct {
 	original _Matcher
 }
@@ -76,3 +85,7 @@ func newNegateMatcher(matcher _Matcher) *_NegateMatcher {
 func (m _NegateMatcher) Matches(input string) bool {
 	return !m.original.Matches(input)
 }
+
+func (m _NegateMatcher) String() string {
+	return "-" + m.original.String()
+}