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package json
import (
"bytes"
"encoding/json"
"fmt"
"io"
"sort"
"strconv"
)
// A NodeType is the type of a Node.
type NodeType uint
const (
// DocumentNode the root of the document tree.
DocumentNode NodeType = iota
// ElementNode is an element.
ElementNode
// TextNode is the text content of a node.
TextNode
)
var NodeNames = map[NodeType]string{
DocumentNode: "DocumentNode",
ElementNode: "ElementNode",
TextNode: "TextNode",
}
// A Node consists of a NodeType and some Data (tag name for
// element nodes, content for text) and are part of a tree of Nodes.
type Node struct {
Parent, PrevSibling, NextSibling, FirstChild, LastChild *Node
Type NodeType
Data string
DataType string
level int
}
func (n Node) String() string {
return fmt.Sprintf("[%s] %s(%s)", NodeNames[n.Type], n.DataType, n.Data)
}
func (n Node) PrintTree(level int) {
for i := 1; i <= level; i++ {
fmt.Printf(" ")
}
fmt.Println(n)
for _, c := range n.ChildNodes() {
c.PrintTree(level + 1)
}
}
// ChildNodes gets all child nodes of the node.
func (n *Node) ChildNodes() []*Node {
var a []*Node
for nn := n.FirstChild; nn != nil; nn = nn.NextSibling {
a = append(a, nn)
}
return a
}
// InnerText gets the value of the node and all its child nodes.
func (n *Node) InnerText() string {
var output func(*bytes.Buffer, *Node)
output = func(buf *bytes.Buffer, n *Node) {
if n.Type == TextNode {
buf.WriteString(n.Data)
return
}
for child := n.FirstChild; child != nil; child = child.NextSibling {
output(buf, child)
}
}
var buf bytes.Buffer
output(&buf, n)
return buf.String()
}
// SelectElement finds the first of child elements with the
// specified name.
func (n *Node) SelectElement(name string) *Node {
for nn := n.FirstChild; nn != nil; nn = nn.NextSibling {
if nn.Data == name {
return nn
}
}
return nil
}
func parseValue(x interface{}, top *Node, level int) {
addNode := func(n *Node) {
if n.level == top.level {
top.NextSibling = n
n.PrevSibling = top
n.Parent = top.Parent
if top.Parent != nil {
top.Parent.LastChild = n
}
} else if n.level > top.level {
n.Parent = top
if top.FirstChild == nil {
top.FirstChild = n
top.LastChild = n
} else {
t := top.LastChild
t.NextSibling = n
n.PrevSibling = t
top.LastChild = n
}
}
}
// TODO check for null
switch v := x.(type) {
case []interface{}:
for _, vv := range v {
n := &Node{Type: ElementNode, level: level, DataType: "arrayitem"}
addNode(n)
parseValue(vv, n, level+1)
}
case map[string]interface{}:
// The Go’s map iteration order is random.
// (https://blog.golang.org/go-maps-in-action#Iteration-order)
var keys []string
for key := range v {
keys = append(keys, key)
}
sort.Strings(keys)
for _, key := range keys {
n := &Node{Data: key, Type: ElementNode, level: level, DataType: "object"}
addNode(n)
parseValue(v[key], n, level+1)
}
case string:
n := &Node{Data: v, Type: TextNode, level: level, DataType: "string"}
addNode(n)
case float64:
s := strconv.FormatFloat(v, 'f', -1, 64)
n := &Node{Data: s, Type: TextNode, level: level, DataType: "number"}
addNode(n)
case bool:
s := strconv.FormatBool(v)
n := &Node{Data: s, Type: TextNode, level: level, DataType: "boolean"}
addNode(n)
}
}
// Parse JSON document.
func Parse(r io.Reader) (*Node, error) {
var v interface{}
decoder := json.NewDecoder(r)
if err := decoder.Decode(&v); err != nil {
return nil, err
}
doc := &Node{Type: DocumentNode}
parseValue(v, doc, 1)
return doc, nil
}
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