complete rewrite, added basic documentation

README.md

@@ -0,0 +1,28 @@
+togo
+====
+togo converts files to Go source code as a byte array.
+togo is based on (but is a complete rewrite of)
+[Franco Lazzarino's togo](https://github.com/flazz/togo).
+
+
+usage
+-----
+togo is designed to be embedded in your Go project for a dependency free
+way to manage assets.
+
+First, copy `main.go` from togo into a subdirectory in your
+project (for example, a subdirectory named `togo`.)
+
+Next, add comments to indicate to go generate that you wish to run
+your local copy of togo to build assets.
+
+    //go:generate go run ./togo -n Favicon_ico -i assets/favicon.ico -p static -o static/favicon_ico.go
+
+togo takes some basic arguments:
+
+Argument | Description
+-------- | -----------
+-p | generated package name
+-n | generated variable name
+-i | input file name
+-o | output file name

main.go

@@ -1,111 +1,88 @@
 package main
 
 import (
-	"bytes"
 	"flag"
-	"go/format"
+	"fmt"
 	"io"
-	"io/ioutil"
 	"log"
 	"os"
-	"text/template"
+	"time"
 )
 
-const chunkSize = 0x10
-
-const tmpl = `
-package {{.Pkg}}
-
-var {{.Name}} = []byte{
-    // {{ len .Value }} bytes from {{ .InputPath }}
-	{{ range .Chunks -}}
-		{{ range . }} {{ printf "0x%02x" . }}, {{ end }}
-	{{ end }}
-}
-`
-
-var t *template.Template
-
-func init() {
-	t = template.Must(template.New("constfile").Parse(tmpl))
-}
-
-type file struct {
-	Pkg, Name, InputPath string
-	Value                []byte
-}
-
-func (f *file) Chunks() [][]byte {
-	return chunks(f.Value, chunkSize)
-}
-
-func chunks(b []byte, n int) [][]byte {
-	var c [][]byte
-
-	nChks := len(b) / n
-
-	for i := 0; i < nChks; i++ {
-		m := i * n
-		c = append(c, b[m:m+n])
-	}
-
-	if r := len(b) % n; r > 0 {
-		m := n * nChks
-		c = append(c, b[m:m+r])
-	}
-
-	return c
-}
-
-func (f *file) Read() (err error) {
-	f.Value, err = ioutil.ReadFile(f.InputPath)
-	return
-}
-
-func (f *file) Render(w io.Writer) error {
-	outputPath := f.InputPath + ".go"
-	var buf bytes.Buffer
-	if err := t.Execute(&buf, &f); err != nil {
-		return err
-	}
-
-	b, err := format.Source(buf.Bytes())
-	if err != nil {
-		log.Fatal(err)
-	}
-
-	if err := ioutil.WriteFile(outputPath, b, os.ModePerm); err != nil {
-		return err
-	}
-
-	return nil
-}
-
 func main() {
-
-	var f file
-	flag.StringVar(&f.Pkg, "pkg", "", "package")
-	flag.StringVar(&f.Name, "name", "", "const name")
-	flag.StringVar(&f.InputPath, "input", "", "input file")
+	pkg := flag.String("p", "", "package")
+	name := flag.String("n", "", "const name")
+	inputfn := flag.String("i", "", "input file")
+	outputfn := flag.String("o", "", "output file")
 	flag.Parse()
 
-	if f.Pkg == "" {
+	if *pkg == "" {
 		log.Fatal("pkg required")
 	}
 
-	if f.Name == "" {
+	if *name == "" {
 		log.Fatal("name required")
 	}
 
-	if f.InputPath == "" {
+	if *inputfn == "" {
 		log.Fatal("input file required")
 	}
 
-	if err := f.Read(); err != nil {
-		log.Fatal(err)
+	if *outputfn == "" {
+		*outputfn = *inputfn + ".go"
 	}
 
-	if err := f.Render(os.Stdout); err != nil {
+	omod := fmod(*outputfn)
+	imod := fmod(*inputfn)
+	if omod.After(imod) {
+		log.Printf("Refusing to update %s\n", *outputfn)
+		return
+	}
+
+	ifile, err := os.Open(*inputfn)
+	if err != nil {
 		log.Fatal(err)
 	}
+	defer ifile.Close()
+
+	ofile, err := os.OpenFile(*outputfn, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0660)
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer ofile.Close()
+
+	fmt.Fprintf(ofile, "package %s\n\nvar %s = []byte{", *pkg, *name)
+
+	buf := make([]byte, 4096)
+	for c := 0; ; {
+		i, err := ifile.Read(buf)
+		if err != nil {
+			if err != io.EOF {
+				log.Fatal(err)
+			}
+			break
+		}
+
+		for j := 0; j < i; j++ {
+			if (c % 13) == 0 {
+				fmt.Fprintf(ofile, "\n\t")
+			} else {
+				fmt.Fprintf(ofile, " ")
+			}
+			fmt.Fprintf(ofile, "0x%02x,", buf[j])
+			c++
+		}
+	}
+	fmt.Fprintf(ofile, "\n}\n")
+}
+
+func fmod(fn string) time.Time {
+	fi, err := os.Stat(fn)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return time.Time{}
+		}
+		log.Fatal(err)
+	}
+	return fi.ModTime()
 }