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main.go
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main.go
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package main
import (
"fmt"
"io"
"io/ioutil"
"os"
"github.com/ogier/pflag"
)
var (
cmdName = "alita"
cmdVersion = "0.8.0"
)
type CLI struct {
stdin io.Reader
stdout io.Writer
stderr io.Writer
delimiter string
useRegexp bool
count int
margin string
justify string
isHelp bool
isVersion bool
}
func NewCLI(stdin io.Reader, stdout io.Writer, stderr io.Writer) *CLI {
return &CLI{
stdin: stdin,
stdout: stdout,
stderr: stderr,
}
}
func (c *CLI) printUsage() {
fmt.Fprintf(c.stderr, `
Usage: %s [OPTION]... [FILE]...
Align FILE(s), or standard input.
Delimiter control:
-d, --delimiter=DELIM separate lines by DELIM
-r, --regexp DELIM is a regular expression
-c, --count=COUNT separate lines only COUNT times
Output control:
-m, --margin=N[:M] put N or N and M spaces at both ends of DELIM
-j, --justify=[l|c|r]... justify cells to the left, center, or right
Miscellaneous:
-h, --help display this help and exit
--version display version information and exit
`[1:], cmdName)
}
func (c *CLI) printVersion() {
fmt.Fprintf(c.stderr, "%s\n", cmdVersion)
}
func (c *CLI) printErr(err interface{}) {
fmt.Fprintf(c.stderr, "%s: %s\n", cmdName, err)
}
func (c *CLI) guideToHelp() {
fmt.Fprintf(c.stderr, "Try '%s --help' for more information.\n", cmdName)
}
func (c *CLI) parseOption(args []string) (argFiles []string, err error) {
f := pflag.NewFlagSet(cmdName, pflag.ContinueOnError)
f.SetOutput(ioutil.Discard)
f.StringVarP(&c.delimiter, "delimiter", "d", "", "")
f.BoolVarP(&c.useRegexp, "regexp", "r", false, "")
f.IntVarP(&c.count, "count", "c", -1, "")
f.StringVarP(&c.margin, "margin", "m", "", "")
f.StringVarP(&c.justify, "justify", "j", "", "")
f.BoolVarP(&c.isHelp, "help", "h", false, "")
f.BoolVarP(&c.isVersion, "version", "", false, "")
if err := f.Parse(args); err != nil {
return nil, err
}
return f.Args(), nil
}
func (c *CLI) newAligner() (a *Aligner, err error) {
return NewAligner(&Option{
Delimiter: c.delimiter,
UseRegexp: c.useRegexp,
Count: c.count,
Margin: c.margin,
Justify: c.justify,
})
}
func (c *CLI) newArgf(argFiles []string) (r io.Reader, err error) {
switch len(argFiles) {
case 0:
return c.stdin, nil
default:
rs := make([]io.Reader, len(argFiles))
for i, argFile := range argFiles {
f, err := os.Open(argFile)
if err != nil {
return nil, err
}
rs[i] = f
}
return io.MultiReader(rs...), nil
}
}
func (c *CLI) do(a *Aligner, r io.Reader) error {
if err := a.ReadAll(r); err != nil {
return err
}
if err := a.Flush(c.stdout); err != nil {
return err
}
return nil
}
func (c *CLI) Run(args []string) int {
f, err := c.parseOption(args)
if err != nil {
c.printErr(err)
c.guideToHelp()
return 2
}
if c.isHelp {
c.printUsage()
return 0
}
if c.isVersion {
c.printVersion()
return 0
}
a, err := c.newAligner()
if err != nil {
c.printErr(err)
c.guideToHelp()
return 2
}
r, err := c.newArgf(f)
if err != nil {
c.printErr(err)
c.guideToHelp()
return 2
}
if err = c.do(a, r); err != nil {
c.printErr(err)
return 1
}
return 0
}
func main() {
c := NewCLI(os.Stdin, os.Stdout, os.Stderr)
e := c.Run(os.Args[1:])
os.Exit(e)
}