jsonpp.go

package main

import (
	"io"
	"fmt"
	"bufio"
	"os"
	"flag"

	"github.com/tidwall/gjson"
	p "github.com/tanishiking/prettier"
)

func main() {
	var (
		width int
	)
	flag.IntVar(&width, "w", 80, "width")
	flag.Parse()

	reader := bufio.NewReader(os.Stdin)
	var output []rune
	for {
		input, _, err := reader.ReadRune()
		if err != nil && err == io.EOF {
			break
		}
		output = append(output, input)
	}
	json := string(output)
	if (!gjson.Valid(json)) {
		panic("error")
	}
	result := gjson.Parse(json)
	doc := gjsonResultToDoc(result)
	// fmt.Println(doc.String())
	fmt.Println(p.Pretty(width, doc))
}

func gjsonResultToDoc(r gjson.Result) p.Doc {
	switch r.Type {
	default:
		return p.Empty()
	case gjson.Null:
		return p.Text("null")
	case gjson.False:
		return p.Text("false")
	case gjson.Number:
		return p.Text(fmt.Sprintf("%v", r.Num))
	case gjson.String:
		return p.Text(fmt.Sprintf("\"%v\"", r.Str))
	case gjson.True:
		return p.Text("true")
	case gjson.JSON:
		if (r.IsArray()) {
			rs := r.Array()
			ds := make([]p.Doc, len(rs))
			comma := p.Text(",")
			for i, r := range rs {
				ds[i] = p.Group(p.Concat([]p.Doc{p.Line(), gjsonResultToDoc(r)}))
			}
			parts := p.Intercalate(comma, ds)
			return p.Concat([]p.Doc{
				p.Text("["),
				p.Nest(uint(2), p.Concat([]p.Doc{parts, p.Text("]")})),
			})
		} else {
			var kvs []p.Doc
			r.ForEach(func (k gjson.Result, v gjson.Result) bool {
				value := gjsonResultToDoc(v)
				kv := p.Concat([]p.Doc{
					p.Text(k.Str),
					p.Text(":"),
					p.Nest(uint(2), p.Concat([]p.Doc{p.LineOrSpace(), value})),
				})
				kvs = append(kvs, kv)
				return true
			})
			parts := p.Fill(p.Text(","), kvs)
			return p.TightBracketBy(
				p.Text("{"),
				p.Text("}"),
				parts,
				uint(2),
			)
		}
	}
}