Accept escaped hyphens, even outside character class

Makefile

@@ -5,9 +5,13 @@ fmt:
 	go fmt ./...
 vet: fmt
 	go vet ./...
-buildLib: vet
+buildLibUnopt: vet
 	go build -gcflags="all=-N -l" ./...
-buildCmd: buildLib
+unopt: buildLibUnopt
 	go build -C kg/ -gcflags="all=-N -l" -o kg ./...
+buildLib: vet
+	go build ./...
+buildCmd: buildLib
+	go build -C kg/ -o kg ./...
 test: buildCmd
 	go test -v ./...

kg/helpers.go

@@ -32,13 +32,21 @@ func genRange[T character](start, end T) []T {
 }
 
 // Returns whether or not the given file contains a NULL character
-func fileContainsNullChar(file *os.File) bool {
+func fileContainsNullChar(filename string) (bool, error) {
+	file, err := os.Open(filename)
+	if err != nil {
+		return true, err
+	}
+	defer file.Close()
 	scanner := bufio.NewScanner(file)
 	for scanner.Scan() {
 		line := scanner.Text()
 		if strings.Contains(line, "\000") {
-			return true
+			return true, nil
 		}
 	}
-	return false
+	if err := scanner.Err(); err != nil {
+		return true, err
+	}
+	return false, nil
 }

kg/main.go

@@ -91,6 +91,7 @@ func main() {
 		inputFilenames := flag.Args()[1:]
 		for _, inputFilename := range inputFilenames {
 			inputFile, err := os.Open(inputFilename)
+			defer inputFile.Close()
 			if err != nil {
 				fmt.Printf("%s: %s: No such file or directory\n", os.Args[0], inputFilename)
 			} else {
@@ -102,8 +103,14 @@ func main() {
 					if fileStat.Mode().IsDir() {
 						fmt.Printf("%s: %s: Is a directory\n", os.Args[0], inputFilename)
 					} else {
-						if fileContainsNullChar(inputFile) {
-							fmt.Printf("%s: %s: Is a binary file\n", os.Args[0], inputFilename)
+						var nullCharPresent bool
+						if nullCharPresent, err = fileContainsNullChar(inputFilename); nullCharPresent {
+							if err != nil {
+								fmt.Printf("%v\n", err)
+								os.Exit(1)
+							} else {
+								fmt.Printf("%s: %s: Is a binary file\n", os.Args[0], inputFilename)
+							}
 						} else {
 							inputFiles = append(inputFiles, inputFile)
 						}

regex/postfixNode.go

@@ -131,13 +131,9 @@ func newEscapedNode(c rune, inCharClass bool) (postfixNode, error) {
 	case 'v': // Vertical tab
 		toReturn.nodetype = characterNode
 		toReturn.contents = append(toReturn.contents, rune(11))
-	case '-': // Literal hyphen - only in character class
-		if inCharClass {
-			toReturn.nodetype = characterNode
-			toReturn.contents = append(toReturn.contents, '-')
-		} else {
-			return postfixNode{}, fmt.Errorf("invalid escape character")
-		}
+	case '-': // Literal hyphen
+		toReturn.nodetype = characterNode
+		toReturn.contents = append(toReturn.contents, '-')
 	default: // None of the above - append it as a regular character
 		if isNormalChar(c) { // Normal characters cannot be escaped
 			return postfixNode{}, fmt.Errorf("invalid escape character")