class JSON
{
	class parse extends JSON.functor
	{
		call(self, ByRef param_string, param_reviver:="")
		{
			this.rev := isObject(param_reviver) ? param_reviver : false
			; Object keys(and array indices) are temporarily stored in arrays so that
			; we can enumerate them in the order they appear in the string instead
			; of alphabetically. Skip if no reviver function is specified.
			this.keys := this.rev ? {} : false

			static quot := chr(34), bashq := "\" quot
				, json_value := quot "{[01234567890-tfn"
				, json_value_or_array_closing := quot "{[]01234567890-tfn"
				, object_key_or_object_closing := quot "}"

			key := ""
			is_key := false
			root := {}
			stack := [root]
			next := json_value
			pos := 0

			while ((ch := subStr(param_string, ++pos, 1)) != "") {
				if inStr(" `t`r`n", ch) {
					continue
				}
				if !inStr(next, ch, 1) {
					this.parseError(next, param_string, pos)
				}

				holder := stack[1]
				is_array := holder.IsArray

				if inStr(",:", ch) {
					next := (is_key := !is_array && ch == ",") ? quot : json_value

				} else if (inStr("}]", ch)) {
					objRemoveAt(stack, 1)
					next := stack[1]==root ? "" : stack[1].IsArray ? ",]" : ",}"

				} else {
					if (inStr("{[", ch)) {
					; Check if Array() is overridden and if its return value has
					; the 'IsArray' property. If so, Array() will be called normally,
					; otherwise, use a custom base object for arrays
					static json_array := func("Array").isBuiltIn || ![].IsArray ? {IsArray: true} : 0

					; sacrifice readability for minor(actually negligible) performance gain
						(ch == "{")
							? ( is_key := true
							  , value := {}
							  , next := object_key_or_object_closing )
						; ch == "["
							: ( value := json_array ? new json_array : []
							  , next := json_value_or_array_closing )

						ObjInsertAt(stack, 1, value)

						if (this.keys) {
							this.keys[value] := []
						}
					} else {
						if (ch == quot) {
							i := pos
							while (i := inStr(param_string, quot,, i+1)) {
								value := strReplace(subStr(param_string, pos+1, i-pos-1), "\\", "\u005c")

								static tail := A_AhkVersion<"2" ? 0 : -1
								if (subStr(value, tail) != "\") {
									break
								}
							}

							if (!i) {
								this.parseError("'", param_string, pos)
							}

							value := strReplace(value, "\/",  "/")
							, value := strReplace(value, bashq, quot)
							, value := strReplace(value, "\b", "`b")
							, value := strReplace(value, "\f", "`f")
							, value := strReplace(value, "\n", "`n")
							, value := strReplace(value, "\r", "`r")
							, value := strReplace(value, "\t", "`t")

							pos := i ; update pos

							i := 0
							while (i := inStr(value, "\",, i+1)) {
								if (!(subStr(value, i+1, 1) == "u")) {
									this.parseError("\", param_string, pos - strLen(subStr(value, i+1)))
								}

								uffff := Abs("0x" subStr(value, i+2, 4))
								if (A_IsUnicode || uffff < 0x100) {
									value := subStr(value, 1, i-1) chr(uffff) subStr(value, i+6)
								}
							}

							if (is_key) {
								key := value, next := ":"
								continue
							}

						} else {
							value := subStr(param_string, pos, i := regExMatch(param_string, "[\]\},\s]|$",, pos)-pos)

							if value is number
							{
								if value is integer
								{
									value += 0
								}
							}
							else if (value == "true" || value == "false") {
								value := %value% + 0
							} else if (value == "null") {
								value := ""
							} else {
								; we can do more here to pinpoint the actual culprit
								; but that's just too much extra work.
								this.parseError(next, text, pos, i)
							}
							pos += i - 1
						}
						next := holder == root ? "" : is_array ? ",]" : ",}"
					} ; If inStr("{[", ch) { ... } else

					is_array? key := objPush(holder, value) : holder[key] := value

					if (this.keys && this.keys.hasKey(holder)) {
						this.keys[holder].Push(key)
					}
				}
			} ; while ( ... )
			return this.rev ? this.walk(root, "") : root[""]
		}

		parseError(param_expect, ByRef param_string, pos, param_length:=1)
		{
			static quot := chr(34), qurly := quot "}"

			line := strSplit(subStr(param_string, 1, pos), "`n", "`r").length()
			col := pos - inStr(param_string, "`n",, -(strLen(param_string)-pos+1))
			msg := format("{1}`n`nLine:`t{2}`nCol:`t{3}`nChar:`t{4}"
				, (param_expect == "")     ?	"Extra data"
				: (param_expect == "'")    ?	"Unterminated string starting at"
				: (param_expect == "\")    ?	"Invalid \escape"
				: (param_expect == ":")    ?	"Expecting ':' delimiter"
				: (param_expect == quot)   ?	"Expecting object key enclosed in double quotes"
				: (param_expect == qurly)  ?	"Expecting object key enclosed in double quotes or object closing '}'"
				: (param_expect == ",}")   ?	"Expecting ',' delimiter or object closing '}'"
				: (param_expect == ",]")   ?	"Expecting ',' delimiter or array closing ']'"
				: inStr(param_expect, "]") ?	"Expecting JSON value or array closing ']'"
				:								"Expecting JSON value(string, number, true, false, null, object or array)"
			, line, col, pos)

			static offset := A_AhkVersion < "2" ? -3 : -4
			throw Exception(msg, offset, subStr(param_string, pos, param_length))
		}

		walk(param_holder, param_key)
		{
			value := param_holder[param_key]
			if (isObject(value)) {
				for i, k in this.keys[value] {
					; check if objhasKey(value, k) ??
					v := this.walk(value, k)
					if (v != JSON.Undefined) {
						value[k] := v
					} else {
						objDelete(value, k)
					}
				}
			}
			return this.rev.call(param_holder, param_key, value)
		}
	}


	class stringify extends JSON.functor
	{
		call(self, param_value, param_replacer:="", space:="")
		{
			this.rep := isObject(param_replacer) ? param_replacer : ""

			this.gap := ""
			if (space) {
				if space is integer
				{
					loop, % ((n := Abs(space))>10 ? 10 : n) {
						this.gap .= " "
					}
				} else {
					this.gap := subStr(space, 1, 10)
				}
				this.indent := "`n"
			}
			return this.str({"": param_value}, "")
		}

		str(param_holder, param_key)
		{
			param_value := param_holder[param_key]

			if (this.rep) {
				param_value := this.rep.call(param_holder, param_key, objhasKey(param_holder, param_key) ? param_value : JSON.Undefined)
			}

			if isObject(param_value) {
			; Check object type, skip serialization for other object types such as
			; ComObject, Func, BoundFunc, FileObject, RegExMatchObject, Property, etc.
				static type := A_AhkVersion<"2" ? "" : func("Type")
				if (type ? type.call(param_value) == "Object" : objGetCapacity(param_value) != "") {
					if (this.gap) {
						stepback := this.indent
						this.indent .= this.gap
					}

					is_array := param_value.IsArray
					; Array() is not overridden, rollback to old method of
					; identifying array-like objects. Due to the use of a for-loop
					; sparse arrays such as '[1,,3]' are detected as objects({}).
					if (!is_array) {
						for i in param_value {
							is_array := i == A_Index
						}
						until (!is_array)
					}

					str := ""
					if (is_array) {
						loop, % param_value.length() {
							if (this.gap) {
								str .= this.indent
							}
							v := this.str(param_value, A_Index)
							str .= (v != "") ? v "," : "null,"
						}
					} else {
						colon := this.gap ? ": " : ":"
						for k in param_value {
							v := this.str(param_value, k)
							if (v != "") {
								if (this.gap) {
									str .= this.indent
								}
								str .= this.quote(k) colon v ","
							}
						}
					}

					if (str != "") {
						str := rTrim(str, ",")
						if (this.gap) {
							str .= stepback
						}
					}

					if (this.gap) {
						this.indent := stepback
					}
					return is_array ? "[" str "]" : "{" str "}"
				}
			} else {
				; is_number ? param_value : "param_value"
				return objGetCapacity([param_value], 1) == "" ? param_value : this.quote(param_value)
			}
		}

		quote(param_string)
		{
			static quot := chr(34), bashq := "\" quot

			if (param_string != "") {
				param_string := strReplace(param_string,  "\", "\\")
				; , param_string := strReplace(param_string,  "/",  "\/") ; optional in ECMAScript
				, param_string := strReplace(param_string, quot, bashq)
				, param_string := strReplace(param_string, "`b", "\b")
				, param_string := strReplace(param_string, "`f", "\f")
				, param_string := strReplace(param_string, "`n", "\n")
				, param_string := strReplace(param_string, "`r", "\r")
				, param_string := strReplace(param_string, "`t", "\t")

				static rx_escapable := A_AhkVersion<"2" ? "O)[^\x20-\x7e]" : "[^\x20-\x7e]"
				while regExMatch(param_string, rx_escapable, m) {
					param_string := strReplace(param_string, m.Value, format("\u{1:04x}", ord(m.Value)))
				}
			}
			return quot param_string quot
		}
	}

	class test extends JSON.functor
	{
		call(self, param_string:="")
		{
			if (isObject(param_string) || param_string == "") {
				return false
			}

			try {
				JSON.parse(param_string)
			} catch error {
				return false
			}
			return true
		}
	}


	; For use with reviver and replacer functions since AutoHotkey does not
	; have an 'undefined' type. Returning blank("") or 0 won't work since these
	; can't be distnguished from actual JSON values. This leaves us with objects.
	; Replacer() - the caller may return a non-serializable AHK objects such as
	; ComObject, Func, BoundFunc, FileObject, RegExMatchObject, and Property to
	; mimic the behavior of returning 'undefined' in JavaScript but for the sake
	; of code readability and convenience, it's better to do 'return JSON.Undefined'.
	; Internally, the property returns a ComObject with the variant type of VT_EMPTY.
	Undefined[]
	{
		get {
			static empty := {}, vt_empty := ComObject(0, &empty, 1)
			return vt_empty
		}
	}

	class functor
	{
		__call(param_method, ByRef param_args, param_extargs*)
		{
			; When casting to call(), use a new instance of the "function object"
			; so as to avoid directly storing the properties(used across sub-methods)
			; into the "function object" itself.
			if isObject(param_method) {
				return (new this).call(param_method, param_args, param_extargs*)
			} else if (param_method == "") {
				return (new this).call(param_args, param_extargs*)
			}
		}
	}
}