Merge pull request #821 from devlights/add-utf8bom-example

Author: devlights

examples/singleapp/utf8bom/Taskfile.yml

@@ -0,0 +1,23 @@
+# https://taskfile.dev
+
+version: '3'
+
+vars:
+  TEST_FILE: test.txt
+
+tasks:
+  default:
+    cmds:
+      - task: run
+  run:
+    cmds:
+      - echo helloworld > {{.TEST_FILE}}
+      - defer: rm -f {{.TEST_FILE}}
+      - nkf -g {{.TEST_FILE}}; hexdump {{.TEST_FILE}}
+      - go run main.go {{.TEST_FILE}}
+      - nkf -g {{.TEST_FILE}}; hexdump {{.TEST_FILE}}
+      - go run main.go -d {{.TEST_FILE}}
+      - nkf -g {{.TEST_FILE}}; hexdump {{.TEST_FILE}}
+  clean:
+    cmds:
+      - rm -rf bin

examples/singleapp/utf8bom/main.go

@@ -0,0 +1,102 @@
+package main
+
+import (
+	"bytes"
+	"flag"
+	"log"
+	"os"
+)
+
+var (
+	BOM = []byte{0xEF, 0xBB, 0xBF}
+)
+
+var (
+	files []string
+	rmBOM bool
+)
+
+func init() {
+	log.SetFlags(0)
+
+	flag.BoolVar(&rmBOM, "d", false, "BOM removal mode")
+	flag.Usage = func() {
+		log.Println("Usage: bom (-d) file-path...")
+		flag.PrintDefaults()
+	}
+}
+
+func main() {
+	flag.Parse()
+
+	if flag.NArg() == 0 {
+		flag.Usage()
+		os.Exit(-1)
+	}
+
+	files = make([]string, len(flag.Args()))
+	copy(files, flag.Args())
+
+	if err := run(); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func run() error {
+	for _, fpath := range files {
+		if err := process(fpath); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func process(fpath string) error {
+	fi, err := os.Stat(fpath)
+	if err != nil {
+		return err
+	}
+
+	data, err := os.ReadFile(fpath)
+	if err != nil {
+		return err
+	}
+
+	if bytes.HasPrefix(data, BOM) {
+		if rmBOM {
+			if err := os.WriteFile(fpath, data[len(BOM):], fi.Mode()); err != nil {
+				return err
+			}
+		}
+
+		return nil
+	}
+
+	if err := os.WriteFile(fpath, append(BOM, data...), fi.Mode()); err != nil {
+		return err
+	}
+
+	return nil
+
+	/*
+	   $ task
+	   task: [run] echo helloworld > test.txt
+	   task: [run] nkf -g test.txt; hexdump test.txt
+	   ASCII
+	   0000000 6568 6c6c 776f 726f 646c 000a
+	   000000b
+	   task: [run] go run main.go test.txt
+	   task: [run] nkf -g test.txt; hexdump test.txt
+	   UTF-8
+	   0000000 bbef 68bf 6c65 6f6c 6f77 6c72 0a64
+	   000000e
+	   task: [run] go run main.go -d test.txt
+	   task: [run] nkf -g test.txt; hexdump test.txt
+	   ASCII
+	   0000000 6568 6c6c 776f 726f 646c 000a
+	   000000b
+	   task: [run] rm -f test.txt
+	*/
+
+}