From 929784da8375751edb3a2daafcef4691478f43da Mon Sep 17 00:00:00 2001
From: milarin <milaring@proton.me>
Date: Mon, 20 Mar 2023 11:07:09 +0100
Subject: [PATCH] added -0 paramter for better compability with xargs

---
 main.go | 61 +++++++++++++++++++++++++++++++++++----------------------
 1 file changed, 38 insertions(+), 23 deletions(-)

diff --git a/main.go b/main.go
index 1494bcc..9a6dc01 100644
--- a/main.go
+++ b/main.go
@@ -14,7 +14,7 @@ import (
 	"git.milar.in/milarin/buildinfo"
 )
 
-var (
+var ( //flags
 	// regex with sub groups
 	input = flag.String("i", `^(.|\n)*?$`, "input pattern")
 
@@ -49,6 +49,12 @@ var (
 
 	showVersion = flag.Bool("v", false, "show version and exit")
 
+	OutputNullByte = flag.Bool("0", false, "use nullbyte instead of newline as line separator for printing output")
+)
+
+var ( // globals
+	LineSeparator string = "\n"
+
 	replacePattern     = regexp.MustCompile(`\{(\d+)(?::(.*?))?(?::(.*?))?(?::(.*?))?\}`)
 	numMutationPattern = regexp.MustCompile(`([+\-*/])(\d+|\((\d+)\))`)
 )
@@ -61,6 +67,10 @@ func main() {
 		return
 	}
 
+	if *OutputNullByte {
+		LineSeparator = string(rune(0))
+	}
+
 	pattern, err := regexp.Compile(*input)
 	if err != nil {
 		panic(err)
@@ -73,12 +83,12 @@ func main() {
 
 		if len(matches) == 0 {
 			if *keepUnmatched {
-				fmt.Println(line)
+				fmt.Print(line, LineSeparator)
 			}
 			continue
 		}
 
-		fmt.Println(replaceVars(escapedOutput, matches...))
+		fmt.Print(replaceVars(escapedOutput, matches...), LineSeparator)
 	}
 }
 
@@ -87,32 +97,15 @@ func readLines(r io.Reader) <-chan string {
 
 	go func(out chan<- string, source io.Reader) {
 		defer close(out)
-
 		r := bufio.NewReader(source)
 
 		for {
-			var line string
-			var err error
-			lines := make([]string, 0, *lineParseAmount)
-			for line, err = r.ReadString('\n'); ; line, err = r.ReadString('\n') {
-				if rn, size := utf8.DecodeLastRuneInString(line); rn == '\n' {
-					line = line[:len(line)-size]
-				}
-
-				lines = append(lines, line)
-
-				// stop reading as soon as lineParseAmount is reached or an error occured (most likely EOF)
-				if len(lines) == cap(lines) || err != nil {
-					break
-				}
-			}
-
-			linesCombined := strings.Join(lines, "\n")
+			line, err := ReadLine(r)
 
 			// use data as line if reading was successfull or EOF has been reached
 			// in the latter case: only use data if something could be read until EOF
-			if err == nil || err == io.EOF && linesCombined != "" {
-				out <- linesCombined
+			if err == nil || err == io.EOF && line != "" {
+				out <- line
 			}
 
 			if err != nil {
@@ -124,6 +117,28 @@ func readLines(r io.Reader) <-chan string {
 	return ch
 }
 
+func ReadLine(r *bufio.Reader) (string, error) {
+	lines := make([]string, 0, *lineParseAmount)
+
+	var line string
+	var err error
+	for line, err = r.ReadString('\n'); ; line, err = r.ReadString('\n') {
+		if rn, size := utf8.DecodeLastRuneInString(line); rn == '\n' {
+			line = line[:len(line)-size]
+		}
+
+		lines = append(lines, line)
+
+		// stop reading as soon as lineParseAmount is reached or an error occured (most likely EOF)
+		if len(lines) == cap(lines) || err != nil {
+			break
+		}
+	}
+
+	linesCombined := strings.Join(lines, "\n")
+	return linesCombined, err
+}
+
 func replaceVars(format string, vars ...string) string {
 	replacements := replacePattern.FindAllStringSubmatch(format, -1)