54 lines
1.1 KiB
Go
54 lines
1.1 KiB
Go
// +build ignore
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package main
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import (
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"bytes"
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"encoding/json"
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"io/ioutil"
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"log"
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"os"
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)
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func init() {
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log.SetPrefix("fmtjson: ")
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log.SetFlags(0)
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}
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func main() {
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if len(os.Args) < 1 {
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log.Fatal(`usage: go run jsonfmt.go [files...]
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This is a small utility that standardizes the formatting of JSON files.
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`)
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}
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for _, path := range os.Args[1:] {
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data, err := ioutil.ReadFile(path)
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if err != nil {
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log.Fatalf("reading file %s: %v", path, err)
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}
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buff := new(bytes.Buffer)
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if err := json.Indent(buff, data, "", " "); err != nil {
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if err, ok := err.(*json.SyntaxError); ok {
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// Calculate line number and column of error.
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data := data[:err.Offset]
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lineNum := 1 + bytes.Count(data, []byte{'\n'})
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lastIndex := bytes.LastIndex(data, []byte{'\n'})
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colNum := err.Offset
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if lastIndex > -1 {
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colNum = int64(len(data) - lastIndex)
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}
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log.Fatalf("file %s: invalid json at line %d, column %d: %v", path, lineNum, colNum, err)
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}
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log.Fatalf("file %s: invalid json: %v", path, err)
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}
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if err := ioutil.WriteFile(path, buff.Bytes(), 0644); err != nil {
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log.Fatalf("write file %s: %v", path, err)
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}
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}
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}
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