jfather

README

jfather

Parse JSON with line numbers and more!

This is a JSON parsing module that provides additional information during the unmarshalling process, such as line numbers, columns etc.

You can use jfather to unmarshal JSON just like the encoding/json package, and add your own unmarshalling functionality to gather metadata by implementing the jfather.Umarshaller interface. This requires a single method with the signature UnmarshalJSONWithMetadata(node jfather.Node) error. A full example is below.

You should not use this package unless you need the line/column metadata, as unmarshalling is typically much slower than the encoding/json package:

BenchmarkUnmarshal_JFather-8       	   39483	     34222 ns/op
BenchmarkUnmarshal_Traditional-8   	  176756	      7244 ns/op

Full Example

package main

import (
	"fmt"

	"github.com/liamg/jfather"
)

type ExampleParent struct {
	Child ExampleChild `json:"child"`
}

type ExampleChild struct {
	Name   string
	Line   int
	Column int
}

func (t *ExampleChild) UnmarshalJSONWithMetadata(node jfather.Node) error {
	t.Line = node.Range().Start.Line
	t.Column = node.Range().Start.Column
	return node.Decode(&t.Name)
}

func main() {
	input := []byte(`{
	"child": "secret"
}`)
	var parent ExampleParent
	if err := jfather.Unmarshal(input, &parent); err != nil {
		panic(err)
	}

	fmt.Printf("Child value is at line %d, column %d, and is set to '%s'\n",
		parent.Child.Line, parent.Child.Column, parent.Child.Name)

	// outputs:
	//  Child value is at line 2, column 12, and is set to 'secret'
}

Documentation

Index

• func Unmarshal(data []byte, target interface{}) error
• type Kind
• type Node
• type PeekReader
  • func NewPeekReader(reader io.Reader) *PeekReader
  • func (r *PeekReader) Next() (rune, error)
  • func (r *PeekReader) Peek() (rune, error)
  • func (r *PeekReader) Undo() error
• type Position
• type Range
• type Unmarshaller

Functions

func Unmarshal

func Unmarshal(data []byte, target interface{}) error

Types

type Kind

type Kind uint8

const (
	KindUnknown Kind = iota
	KindNull
	KindNumber
	KindString
	KindBoolean
	KindArray
	KindObject
)

type Node

type Node interface {
	Range() Range
	Decode(target interface{}) error
	Kind() Kind
	Content() []Node
}

type PeekReader

type PeekReader struct {
	// contains filtered or unexported fields
}

func NewPeekReader

func NewPeekReader(reader io.Reader) *PeekReader

func (*PeekReader) Next

func (r *PeekReader) Next() (rune, error)

func (*PeekReader) Peek

func (r *PeekReader) Peek() (rune, error)

func (*PeekReader) Undo

func (r *PeekReader) Undo() error

type Position

type Position struct {
	Line   int
	Column int
}

type Range

type Range struct {
	Start Position
	End   Position
}

type Unmarshaller

type Unmarshaller interface {
	UnmarshalJSONWithMetadata(node Node) error
}