vjson is very simple and very fast JSON parser.

pros:

• maybe fastest in the world
• small memory footprint (28 bytes per value on x86)
• small code footprint
• easy to modify

• parsing only utf-8
• not support surrogate pairs in \uXXXX escape sequences
• can parse some not valid json's

Installation

Clone repository and add this files to you project:

• json.h
• json.cpp
• block_allocator.h
• block_allocator.cpp

Test project

Under windows:

1. Run command promt and go to vjson project folder
2. mkdir build
3. cd build
4. cmake ..
5. Open created solution in Visual Studio

1. Open terminal and go to vjson project folder
2. mkdir build; cd build; cmake ..; make

Using

Include "json.h" and just call json_parse(). Example:

char *errorPos = 0;
char *errorDesc = 0;
int errorLine = 0;
block_allocator allocator(1 << 10); // 1 KB per block
	
json_value *root = json_parse(source, &errorPos, &errorDesc, &errorLine, &allocator);

Warning: vjson is destructive parser, i.e. you source buffer will be modyfied.

Return value is root json_value object or NULL if error occured.

Parameters explanation:

• char *source - null terminated json source
• char **errorPos - pointer to source where error occurs
• char **errorDesc - error description
• int *line - line number in source where error occurs
• block_allocator *allocator - json_value allocator

Now you can access values by simple iteration over resulting document:

for (json_value *it = root->first_child; it; it = it->next_sibling)
{
	if (value->name)
	{
		printf("%s = ", value->name);
	}

	switch(value->type)
	{
	case JSON_NULL:
		printf("null\n");
		break;
	case JSON_STRING:
		printf("\"%s\"\n", value->string_value);
		break;
	case JSON_INT:
		printf("%d\n", value->int_value);
		break;
	case JSON_FLOAT:
		printf("%f\n", value->float_value);
		break;
	case JSON_BOOL:
		printf(value->int_value ? "true\n" : "false\n");
		break;
	}
}

Root node lifetime is equals to block allocator lifetime. For easy loading you maybe want write something like SampleDocumentClass using own file\logging functions.

Modifying

You can replace allocator. Just change json_parse() signature and json_alloc()

Or create XML SAX like parsing by adding callback to json_parse() and call them instead of json_append()

License

Distributed under the MIT license. Copyright (c) 2010, Ivan Vashchaev