Andreas Deininger
89 lines
1.7 KiB
Go
89 lines
1.7 KiB
Go
package cli
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import (
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"bytes"
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"errors"
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"flag"
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"fmt"
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"io"
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"io/ioutil"
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"os"
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"github.com/pelletier/go-toml/v2"
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)
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type ConvertFn func(r io.Reader, w io.Writer) error
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type Program struct {
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Usage string
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Fn ConvertFn
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// Inplace allows the command to take more than one file as argument and
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// perform conversion in place on each provided file.
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Inplace bool
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}
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func (p *Program) Execute() {
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flag.Usage = func() { fmt.Fprintf(os.Stderr, p.Usage) }
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flag.Parse()
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os.Exit(p.main(flag.Args(), os.Stdin, os.Stdout, os.Stderr))
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}
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func (p *Program) main(files []string, input io.Reader, output, error io.Writer) int {
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err := p.run(files, input, output)
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if err != nil {
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var derr *toml.DecodeError
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if errors.As(err, &derr) {
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fmt.Fprintln(error, derr.String())
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row, col := derr.Position()
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fmt.Fprintln(error, "error occurred at row", row, "column", col)
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} else {
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fmt.Fprintln(error, err.Error())
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}
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return -1
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}
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return 0
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}
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func (p *Program) run(files []string, input io.Reader, output io.Writer) error {
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if len(files) > 0 {
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if p.Inplace {
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return p.runAllFilesInPlace(files)
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}
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f, err := os.Open(files[0])
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if err != nil {
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return err
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}
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defer f.Close()
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input = f
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}
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return p.Fn(input, output)
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}
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func (p *Program) runAllFilesInPlace(files []string) error {
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for _, path := range files {
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err := p.runFileInPlace(path)
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if err != nil {
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return err
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}
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}
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return nil
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}
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func (p *Program) runFileInPlace(path string) error {
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in, err := ioutil.ReadFile(path)
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if err != nil {
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return err
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}
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out := new(bytes.Buffer)
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err = p.Fn(bytes.NewReader(in), out)
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if err != nil {
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return err
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}
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return ioutil.WriteFile(path, out.Bytes(), 0600)
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}
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