elements.go

package parser

const (
	ElementTextNode = "text"
)

in.json

[
    {
        "element": "html",
        "attributes": [
            {
                "key": "lang",
                "value": "en"
            }
        ],
        "children": [
            {
                "element": "head",
                "children": [
                    {
                        "element": "meta",
                        "attributes": [
                            {
                                "key": "charset",
                                "value": "UTF-8"
                            }
                        ]
                    },
                    {
                        "element": "meta",
                        "attributes": [
                            {
                                "key": "name",
                                "value": "viewport"
                            },
                            {
                                "key": "content",
                                "value": "width=device-width, initial-scale=1.0"
                            }
                        ]
                    },
                    {
                        "element": "title",
                        "children": [
                            {
                                "element": "text",
                                "value": "Fuck you Somto"
                            }
                        ]
                    }
                ]
            },
            {
                "element": "body",
                "children": [
                    {
                        "element": "h1",
                        "children": [
                            {
                                "element": "text",
                                "value": "Methods"
                            }
                        ]
                    },
                    {
                        "element": "p",
                        "children": [
                            {
                                "element": "text",
                                "value": "Although this is better than the first version of this code, we can improve it significantly by using a special type of function known as a method"
                            }
                        ]
                    }
                ]
            }
        ]
    }
]

main.go

package main

import (
	"calhoun/appscript/parser"
	"fmt"
	"os"
)

func main() {
	file, _ := os.Open("in.json")
	defer file.Close()

	fmt.Println(parser.Parse(file))
}

parser.go

package parser

import (
	"encoding/json"
	"fmt"
	"html"
	"os"
	"strings"
	"sync"
)

type DomNode struct {
	Element    string
	Value      string
	Attributes []AttrNode
	Css        []CssNode
	Children   []DomNode
}

type CssNode struct {
	Property string
	Value    string
}

type AttrNode struct {
	Key   string
	Value string
}

type Stringer interface {
	String() string
}

func (c CssNode) String() string {
	return fmt.Sprintf("%s: %s;", c.Property, c.Value)
}

func (a AttrNode) String() string {
	return fmt.Sprintf("%s=\"%s\"", a.Key, a.Value)
}

func Parse(f *os.File) (r string, err error) {
	var domTree []DomNode
	var wg sync.WaitGroup

	decoder := json.NewDecoder(f)
	err = decoder.Decode(&domTree)

	if err != nil {
		return
	}

	for _, node := range domTree {
		wg.Add(1)
		go func() {
			r += node.parse()
			wg.Done()
		}()
	}
	wg.Wait()
	return
}

func (t *DomNode) parse() string {
	if t.Element == ElementTextNode {
		return t.Value
	}

	var style string
	var attributes string
	var wg sync.WaitGroup
	tag := html.EscapeString(t.Element)
	html := "<" + tag

	if len(t.Css) > 0 {
		style = GenerateStringable(" ", t.Css...)
		html += " style=\"" + style + "\""
	}

	if len(t.Attributes) > 0 {
		attributes = GenerateStringable(" ", t.Attributes...)
		html += attributes
	}

	if len(t.Children) == 0 {
		html += "/>"
		return html
	}

	html += ">"

	for _, node := range t.Children {
		wg.Add(1)
		go func() {
			html += node.parse()
			wg.Done()
		}()
		wg.Wait()
	}

	html += "</" + tag + ">"

	return html
}

func GenerateStringable(separator string, s ...Stringer) string {
	var list []string
	for _, kv := range s {
		list = append(list, kv.String())
	}
	return strings.Join(list[:], separator)
}