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// nolint: golint, dupl
package main
import (
"os"
"github.com/alecthomas/kong"
"github.com/alecthomas/participle/v2"
"github.com/alecthomas/participle/v2/lexer"
)
var (
jsonLexer = lexer.MustSimple([]lexer.SimpleRule{
{Name: "Comment", Pattern: `\/\/[^\n]*`},
{Name: "String", Pattern: `"(\\"|[^"])*"`},
{Name: "Number", Pattern: `[-+]?(\d*\.)?\d+`},
{Name: "Punct", Pattern: `[-[!@#$%^&*()+_={}\|:;"'<,>.?/]|]`},
{Name: "Null", Pattern: "null"},
{Name: "True", Pattern: "true"},
{Name: "False", Pattern: "false"},
{Name: "EOL", Pattern: `[\n\r]+`},
{Name: "Whitespace", Pattern: `[ \t]+`},
})
jsonParser = participle.MustBuild[Json](
participle.Lexer(jsonLexer),
participle.Unquote("String"),
participle.Elide("Whitespace", "EOL"),
participle.UseLookahead(2),
)
cli struct {
File string `arg:"" type:"existingfile" help:"File to parse."`
}
)
// Parse a Json string.
func Parse(data []byte) (*Json, error) {
json, err := jsonParser.ParseBytes("", data)
if err != nil {
return nil, err
}
return json, nil
}
type Json struct {
Pos lexer.Position
Object *Object `parser:"@@ |"`
Array *Array `parser:"@@ |"`
Number *string `parser:"@Number |"`
String *string `parser:"@String |"`
False *string `parser:"@False |"`
True *string `parser:"@True |"`
Null *string `parser:"@Null"`
}
type Object struct {
Pos lexer.Position
Pairs []*Pair `parser:"'{' @@ (',' @@)* '}'"`
}
type Pair struct {
Pos lexer.Position
Key string `parser:"@String ':'"`
Value *Json `parser:"@@"`
}
type Array struct {
Pos lexer.Position
Items []*Json `parser:"'[' @@ (',' @@)* ']'"`
}
func main() {
ctx := kong.Parse(&cli)
data, err := os.ReadFile(cli.File)
ctx.FatalIfErrorf(err)
res, err := Parse(data)
ctx.FatalIfErrorf(err)
ctx.Printf("res is: %v", res)
}
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