JSON library for Delphi

This is a small and clean library for associative arrays with Boolean / Integer / Float / WideString values. Allows import (export) from (to) JSON text. Extensive error-checking.

Some open-source projects I would like to give credit:

• FunHash by Sokolov Yura
• HatTrie by Daniel C. Jones
• FastInt64 - unknown source
• FastMove by FastCode project

The library was built for the ease of use and clean understandable code - performance was not a first priority so I have not made any benchmarking.

Features

• Numeric and WideString indexes (similar to PHP arrays)
• Boolean / Int64 / Double / WideString item values
• Strict parsing of JSON with descriptive Exception on error
• Simple interface (Add, Delete, Remove, Clear)
• Simple iterators (First, Last, Prev, Next)

Types of node values

Name	Description
jsNull	The NULL value
jsBool	Node value is Boolean
jsInt	Node value is Integer
jsFloat	Node value is Floating-point
jsString	Node value is String
jsArray	Node is an array - has children

Iterators

• TJSONEnum = procedure (Nomer: Integer; Elem: TJSONbase; Data: Pointer; Var Stop: Boolean);
• TJSONEnumObj = procedure (Nomer: Integer; Elem: TJSONbase; Data: Pointer; Var Stop: Boolean) Of Object;

Parsing

function ParseJSON(JSON_str: PAnsiChar): TJSONbase;

Properties

Name	Type	Description
Assoc	Boolean	Whether all keys are Numeric or at least one key is String
Parent	TJSONbase	Where the given node belongs to
FirstChild	TJSONbase	Childs are organized as a double-linked list
LastChild	TJSONbase	Childs are organized as a double-linked list
Next	TJSONbase	Next sibling (by the order of creation)
Prev	TJSONbase	Previous sibling (by the order of creation)
SelfType	TJSONtype	Type of data in the current node
Value	Variant	Value of the current node
Count	Integer	Number of children if the node is non-scalar
Name	WideString	The String key of the current node if this is an associative array
ID	Integer	The Numeric key of the current node if this is non-associative array
Child[Index: Integer]	TJSONbase	Used to access the children of non-associative arrays
Field[Key: WideString]	TJSONbase	Used to access the children of associatve arrays
JsonText	AnsiString	Stringification of the current node as JSON text

Methods

Name	Parameters	Returns	Description
Clear			Remove all children
Delete	Idx: Integer		Delete a child from non-associative array and free the object
Delete	Key: WideString		Delete a child from associative array and free the object
Remove	Idx: Integer	TJSONbase	Removee a child from non-associative array and return the object
Remove	Key: WideString	TJSONbase	Remove a child from associative array and return the object
ForEach	Iterator: TJSONEnum UserData: Pointer		Iterates over the children of non-associative array
ForEach	Iterator: TJSONEnumObj UserData: Pointer		Iterates over the children of associative array
Add	B: Boolean	TJSONbase	Appends a new Boolean child to the node (making it an array if not already, returns the new child)
Add	I: Int64	TJSONbase	Appends a new Integer child to the node (making it an array if not already, returns the new child)
Add	D: Double	TJSONbase	Appends a new Floating-point child to the node (making it an array if not already, returns the new child)
Add	S: WideString	TJSONbase	Appends a new String child to the node (making it an array if not already, returns the new child)
Add	A: TJSONbase		Appends an existing array as a child to the node (making it an array if not already
Add	Key: WideString B: Boolean	TJSONbase	Appends a new Boolean child to the node (making it an array if not already, returns the new child)
Add	Key: WideString I: Int64	TJSONbase	Appends a new Integer child to the node (making it an array if not already, returns the new child)
Add	Key: WideString D: Double	TJSONbase	Appends a new Floating-point child to the node (making it an array if not already, returns the new child)
Add	Key: WideString S: WideString	TJSONbase	Appends a new String child to the node (making it an array if not already, returns the new child)
Add	Key: WideString A: TJSONbase		Appends an existing array as a child to the node (making it an array if not already

Possible errors

• Unsupported assignment of object
• Automatic indexing overflow
• Invalid data type assigned to TJSONbase
• This is an array - it does not have a value by itself
• Index is outside the array
• TJSONbase is not an array and does not support indexes
• Associative arrays do not support empty index
• TJSONbase is not an array and does not have Count property
• Unsupported data type in TJSONbase.JsonText
• Unexpected character at position
• Empty element at position
• Missing closing bracket for array
• Missing closing bracket for object
• Unterminated string at position
• Missing property name/value delimiter (:) at position
• Missing property value at position
• Missing fractional part of a floating-point number at position
• Exponent of the number is not integer at position
• Unquoted property name at position
• Control character encountered at position
• Unrecognized escape sequence at position
• Invalid UNICODE escape sequence at position
• Unescaped symbol at position
• Empty property name at position
• Expected closing bracket or comma at position