fasterjson - the faster json parser

1.Overview
2.Compiling and installation
3.Basic Use
4.Performance
5.Finally

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1.Overview

Fasterjson is a fast JSON(SAX) parser. It directly parse JSON text, call registered event functions, fast access JSON content of your interest.
Fasterjson is used in access JSON data read-only, such as parsing JSON configuration file, or unpacking large JSON. Because it is not like the DOM model need to construct a complete document tree, so the speed is very fast, almost close to the performance of strlen(). 
Fasterjson is very small, the entire source code consists of a pair fasterjson.h and fasterjson.c,500 lines,13KB,not depend on any other libraries, easily embedded in your project.

2.Compiling and installation

for example, Linux
[code]
$ cd src
$ make -f makefile.Linux install
gcc -g -fPIC -O2 -Wall -Werror -fno-strict-aliasing -I.  -c fasterjson.c
gcc -g -fPIC -O2 -Wall -Werror -fno-strict-aliasing -o libfasterjson.so fasterjson.o -shared -L.
cp -f libfasterjson.so $HOME/lib/exlib/
cp -f fasterjson.h $HOME/include/fasterjson/
[/code]

3.Basic Use

Only three interface functions in fasterjson

[code]
typedef int funcCallbackOnJsonNode( int type , char *jpath , int jpath_len , int jpath_size , char *node , int node_len , char *content , int content_len , void *p );
int TravelJsonBuffer( char *json_buffer , char *jpath , int jpath_size
		, funcCallbackOnJsonNode *pfuncCallbackOnJsonNode
		, void *p );
int TravelJsonBuffer4( char *json_buffer , char *jpath , int jpath_size
		, funcCallbackOnJsonNode *pfuncCallbackOnEnterJsonBranch
		, funcCallbackOnJsonNode *pfuncCallbackOnLeaveJsonBranch
		, funcCallbackOnJsonNode *pfuncCallbackOnEnterJsonArray
		, funcCallbackOnJsonNode *pfuncCallbackOnLeaveJsonArray
		, funcCallbackOnJsonNode *pfuncCallbackOnJsonLeaf
		, void *p );
[/code]
Function TravelJsonBuffer() read JSON text and fast parsing, call pfuncCallbackOnJsonNode() when accessing JSON branches or leaves , application can be determined branches or leaves events by type and jpath, visit data interested.
Function TravelJsonBuffer4 is event subdivided version.

The following is a simple example
[code]
funcCallbackOnJsonNode CallbackOnJsonNode ;
int CallbackOnJsonNode( int type , char *jpath , int jpath_len , int jpath_size , char *nodename , int nodename_len , char *content , int content_len , void *p )
{
	if( type & FASTERJSON_NODE_BRANCH )
	{
		if( type & FASTERJSON_NODE_ENTER )
		{
			printf( "ENTER-BRANCH p[%s] jpath[%.*s] nodename[%.*s]\n" , (char*)p , jpath_len , jpath , nodename_len , nodename );
		}
		else if( type & FASTERJSON_NODE_LEAVE )
		{
			printf( "LEAVE-BRANCH p[%s] jpath[%.*s] nodename[%.*s]\n" , (char*)p , jpath_len , jpath , nodename_len , nodename );
		}
	}
	else if( type & FASTERJSON_NODE_ARRAY )
	{
		if( type & FASTERJSON_NODE_ENTER )
		{
			printf( "ENTER-ARRAY  p[%s] jpath[%.*s] nodename[%.*s]\n" , (char*)p , jpath_len , jpath , nodename_len , nodename );
		}
		else if( type & FASTERJSON_NODE_LEAVE )
		{
			printf( "LEAVE-ARRAY  p[%s] jpath[%.*s] nodename[%.*s]\n" , (char*)p , jpath_len , jpath , nodename_len , nodename );
		}
	}
	else if( type & FASTERJSON_NODE_LEAF )
	{
		printf( "LEAF         p[%s] jpath[%.*s] nodename[%.*s] content[%.*s]\n" , (char*)p , jpath_len , jpath , nodename_len , nodename , content_len , content );
	}
	
	return 0;
}

...
char	jpath[ 1024 + 1 ] ;
char	*json_buffer = NULL ;
char	*p = "hello world" ;

memset( jpath , 0x00 , sizeof(jpath) );
nret = TravelJsonBuffer( json_buffer , jpath , sizeof(jpath) , & CallbackOnJsonNode , p ) ;
free( json_buffer );
if( nret && nret != FASTJSON_INFO_END_OF_BUFFER )
{
	printf( "TravelJsonTree failed[%d]\n" , nret );
	return nret;
}
...
[/code]

For output
[code]
$ cat test_basic.json
{
       root :
       {
               leaf : content ,
               sub_branch:
               {
                       sub_leaf:sub_content ,
                       "sub_leaf 2":"sub_content 2"
               }
       } ,
       "root2" : "leaf2"
}
$ ./test_fasterjson test_basic.json
ENTER-BRANCH p[hello world] jpath[/root] nodename[root]
LEAF         p[hello world] jpath[/root/leaf] nodename[leaf] content[content]
ENTER-BRANCH p[hello world] jpath[/root/sub_branch] nodename[sub_branch]
LEAF         p[hello world] jpath[/root/sub_branch/sub_leaf] nodename[sub_leaf] content[sub_content]
LEAF         p[hello world] jpath[/root/sub_branch/sub_leaf 2] nodename[sub_leaf 2] content[sub_content 2]
LEAVE-BRANCH p[hello world] jpath[/root/sub_branch] nodename[sub_branch]
LEAVE-BRANCH p[hello world] jpath[/root] nodename[root]
LEAF         p[hello world] jpath[/root2] nodename[root2] content[leaf2]
[/code]

You can transform event callback function, rapid access JSON nodes, for example, according to certain JPATH then fill c struct members.

To multi-byte , set global var g_fasterjson_encoding to change encoding , such as FASTERJSON_ENCODING_UTF8 and FASTERJSON_ENCODING_GB18030 , and default for UTF8.
for example : g_fasterjson_encoding = FASTERJSON_ENCODING_GB18030 ;

4.Performance

Fastjson's performance is very high, below is fasterjson and rapidjson pressure measurement
[code]
~/exsrc/fasterjson-1.0.0/test $ ls -l test_big_and_lang.json
-rw-r--r-- 1 calvin calvin 622511 Sep 21 10:51 test_big_and_lang.json
~/exsrc/fasterjson-1.0.0/test $ wc test_big_and_lang.json
17870  26332 622511 test_big_and_lang.json
[/code]

fasterjson runs 10 times, get the best results
[code]
~/exsrc/fasterjson-1.0.0/test $ time ./press_fastjson test_big.json 1000000
Elapse 3 seconds

real    0m3.445s
user    0m3.401s
sys     0m0.010s
[/code]
Iterates through all leaves and branches on 1000 times, it took about 3 seconds.

rapidjson runs 10 times, get the best results
[code]
~/exsrc/fasterjson-1.0.0/test_rapidjson $ time ./press_rapidjson ../test/test_big.json 1000000
Elapse 10 seconds

real    0m9.733s
user    0m9.623s
sys     0m0.017s
[/code]
Iterates through all leaves and branches on 1000000 times, it took about 10 seconds.

fasterjson is faster than rapidjson about 3 times.

5.Finally

Welcome to use fasterjson, if you have any problems, please tell me, thank you ^_^
Project home page : [url]https://github.com/calvinwilliams/fasterjson[/url]
Author email      : calvinwilliams.c@gmail.com