Simplify grepper interface

extended_grep.go

@@ -4,25 +4,19 @@ import (
 	"io"
 	"log"
 	"os"
-	"sync"
 )
 
 type extendedGrep struct {
 	lineGrep
 	pattern pattern
 }
 
-func (g extendedGrep) grep(path string, sem chan struct{}, wg *sync.WaitGroup) {
+func (g extendedGrep) grep(path string) {
 	f, err := getFileHandler(path)
 	if err != nil {
 		log.Fatalf("open: %s\n", err)
 	}
-
-	defer func() {
-		f.Close()
-		<-sem
-		wg.Done()
-	}()
+	defer f.Close()
 
 	if f == os.Stdin {
 		// TODO: File type is fixed in ASCII because it can not determine the character code.

fixed_grep.go

@@ -6,25 +6,19 @@ import (
 	"io/ioutil"
 	"log"
 	"os"
-	"sync"
 )
 
 type fixedGrep struct {
 	lineGrep
 	pattern pattern
 }
 
-func (g fixedGrep) grep(path string, sem chan struct{}, wg *sync.WaitGroup) {
+func (g fixedGrep) grep(path string) {
 	f, err := getFileHandler(path)
 	if err != nil {
 		log.Fatalf("open: %s\n", err)
 	}
-
-	defer func() {
-		f.Close()
-		<-sem
-		wg.Done()
-	}()
+	defer f.Close()
 
 	if f == os.Stdin {
 		// TODO: File type is fixed in ASCII because it can not determine the character code.

grep.go

@@ -31,14 +31,18 @@ func (g grep) start() {
 	for path := range g.in {
 		sem <- struct{}{}
 		wg.Add(1)
-		go g.grepper.grep(path, sem, wg)
+		go func(path string) {
+			defer wg.Done()
+			defer func() { <-sem }()
+			g.grepper.grep(path)
+		}(path)
 	}
 	wg.Wait()
 	g.done <- struct{}{}
 }
 
 type grepper interface {
-	grep(path string, sem chan struct{}, wg *sync.WaitGroup)
+	grep(path string)
 }
 
 func newGrepper(pattern pattern, printer printer, opts Option) grepper {

passthrough_grep.go

@@ -1,16 +1,10 @@
 package the_platinum_searcher
 
-import "sync"
-
 type passthroughGrep struct {
 	printer printer
 }
 
-func (g passthroughGrep) grep(path string, sem chan struct{}, wg *sync.WaitGroup) {
-	defer func() {
-		<-sem
-		wg.Done()
-	}()
+func (g passthroughGrep) grep(path string) {
 	match := match{path: path, lines: []line{line{}}}
 	g.printer.print(match)
 }