SmartEnterprise_v1/Terminalino/TerminalinoCommons/JsonModule.vb

Imports System.Text.RegularExpressions

Public Class JSONObject

#Region "Shared Variables"
    Private Shared ReadOnly reProp As New Regex("(?<=(^|\,)\s*)([^\:]+)\s*\:\s*([^\,]+)", RegexOptions.Compiled)
    Private Shared ReadOnly reReplaced As New Regex("^\$\[\d+\]$", RegexOptions.Compiled)
#End Region

#Region "Shared Functions"

    Private Shared Function TokenizeJSON(ByVal json As String, ByVal l As List(Of String)) As String
        Dim r As String = String.Empty
        Dim nestable As String = "()[]{}"
        Dim stringable As String = """'"
        Dim nested As New Stack(Of Char)
        Dim stringing As Char? = Nothing
        Dim start As Integer = -1
        l.Clear()

        For i As Integer = 0 To json.Length - 1
            Dim c As Char = json(i)
            If stringing IsNot Nothing Then
                If stringing = c Then
                    stringing = Nothing
                    If nested.Count = 0 Then
                        r &= "$[" & l.Count.ToString() & "]"
                        l.Add(json.Substring(start, i - start + 1))
                    End If
                End If
            ElseIf stringable.IndexOf(c) > -1 Then
                stringing = c
                If nested.Count = 0 Then start = i
            ElseIf nestable.IndexOf(c) Mod 2 = 0 Then
                If nested.Count = 0 Then start = i
                nested.Push(c)
            ElseIf nested.Count > 0 Then
                If nestable.IndexOf(nested.Peek()) + 1 = nestable.IndexOf(c) Then
                    nested.Pop()
                    If nested.Count = 0 Then
                        r &= "$[" & l.Count.ToString() & "]"
                        l.Add(json.Substring(start, i - start + 1))
                    End If
                End If
            Else
                r &= If(c = "\" OrElse c = "$", "\" & c, c)
            End If
        Next

        Return r
    End Function

    Private Shared Function ParseJSONObject(ByVal json As String) As Dictionary(Of String, String)
        Dim r As New Dictionary(Of String, String)
        Dim l As New List(Of String)

        'Trim any leading or trailing object delimiters found in JSON objects.
        json = json.TrimStart(" "c).TrimEnd(" "c)
        json = json.Substring(1).Substring(0, json.Length - 2)

        'Tokenize the JSON object.
        json = TokenizeJSON(json, l)

        'Parse the JSON object.
        For Each m As Match In reProp.Matches(json)
            Dim name As String = m.Groups(2).Value.TrimStart()
            Dim value As String = m.Groups(3).Value
            If reReplaced.IsMatch(name) Then name = l(Integer.Parse(name.Substring(2, name.Length - 3)))
            If reReplaced.IsMatch(value) Then value = l(Integer.Parse(value.Substring(2, value.Length - 3)))
            name = name.Trim("'"c, """"c)
            r.Add(name, value)
        Next

        'Return the result.
        Return r
    End Function

    Private Shared Function ParseJSONArray(ByVal json As String) As String()
        Dim l As New List(Of String)
        Dim r As New List(Of String)

        'Trim any leading or trailing array delimiters found in JSON objects, but only one on each side.
        json = json.Trim()
        json = json.Substring(1, json.Length - 2)

        'Tokenize the JSON array.
        json = TokenizeJSON(json, l)

        'Parse and return the JSON array.
        For Each x As String In json.Split(",")
            x = x.Trim()            
            If reReplaced.IsMatch(x) Then
                r.Add(l(Integer.Parse(x.Substring(2, x.Length - 3))))
            Else
                r.Add(x)
            End If
        Next
        Return r.ToArray()
    End Function

#End Region

#Region "Variables"
    Private ReadOnly _properties As Dictionary(Of String, String)
    Private ReadOnly list As New List(Of JSONObject)
#End Region

#Region "Constructor"
    Public Sub New(ByVal json As String)
        If json.Substring(0, 1) = "{" Then
            _properties = JSONObject.ParseJSONObject(json)
        ElseIf json.Substring(0, 1) = "[" Then            
            For Each x As String In JSONObject.ParseJSONArray(json)
                Dim obj As JSONObject = New JSONObject(x)
                list.Add(obj)
            Next
        End If
    End Sub
#End Region

#Region "Methods"

    Public Sub Destroy()
        _properties.Clear()
        list.Clear()
        GC.Collect()
    End Sub

    Public Function GetJsonArray() As List(Of JSONObject)
        Return list
    End Function

    Public Function GetArray(ByVal name As String) As List(Of JSONObject)
        If _properties.ContainsKey(name) Then
            list.Clear()
            Dim prop As String = _properties(name)
            For Each x As String In JSONObject.ParseJSONArray(prop)
                Dim obj As JSONObject = New JSONObject(x)
                list.Add(obj)
            Next
        End If
        Return list
    End Function

    Public Function GetProperty(ByVal name As String) As JSONValue
        If _properties.ContainsKey(name) Then Return Evaluate(_properties(name))

        Return New JSONValue(JSONType.undefined, Nothing)
    End Function

    Private Function Evaluate(ByVal json As String) As JSONValue
        Dim intValue As Integer
        Dim floatValue As Double
        json = json.TrimStart("("c).TrimEnd(")"c)

        If json <> String.Empty Then
            If json(0) = "{"c Then
                Return New JSONValue(JSONType.object, New JSONObject(json))
            ElseIf json(0) = "["c Then
                For Each x As String In JSONObject.ParseJSONArray(json)
                    list.Add(New JSONObject(x))
                Next
            ElseIf json(0) = "'"c OrElse json(0) = """"c Then
                Return New JSONValue(JSONType.string, json.Substring(1, json.Length - 2))
            ElseIf Integer.Parse(json) Then
                intValue = Integer.Parse(json)
                Return New JSONValue(JSONType.int, intValue)
            ElseIf Double.Parse(json) Then
                floatValue = Double.Parse(json)
                Return New JSONValue(JSONType.double, floatValue)
            ElseIf json = "true" Then
                Return New JSONValue(JSONType.bool, True)
            ElseIf json = "false" Then
                Return New JSONValue(JSONType.bool, False)
            ElseIf json = "null" Then
                Return New JSONValue(JSONType.null, Nothing)
            End If
        End If

        Return New JSONValue(JSONType.undefined, Nothing)
    End Function
#End Region

End Class

Public Class JSONValue
    Private _type As JSONType
    Private _value As Object

    Public Sub New(ByVal type As JSONType, ByVal value As Object)
        _type = type
        _value = value
    End Sub

    Public ReadOnly Property Type() As JSONType
        Get
            Return _type
        End Get
    End Property

    Public ReadOnly Property Value() As Object
        Get
            Return _value
        End Get
    End Property

    Public Sub Destroy()
        _value = String.Empty
    End Sub

End Class

Public Enum JSONType
    bool
    int
    [double]
    [string]
    [object]
    array
    null
    undefined
End Enum