mirror of https://github.com/DaveGamble/cJSON.git
updated README markdown, gitignore, added the Makefile and fixed weird comments in test.c
This commit is contained in:
Kevin Branigan
parent
4cc55858fd
commit
ebba183f1e
|
|
@ -0,0 +1,3 @@
|
|||
a.out
|
||||
.svn
|
||||
*.o
|
||||
|
|
@ -0,0 +1,3 @@
|
|||
all: cJSON.o
|
||||
cc -Wall cJSON.c -c -o cJSON.o
|
||||
cc -Wall cJSON.o test.c -lm
|
||||
191
README.md
191
README.md
|
|
@ -21,6 +21,7 @@
|
|||
*/
|
||||
|
||||
Welcome to cJSON.
|
||||
-----------------
|
||||
|
||||
cJSON aims to be the dumbest possible parser that you can get your job done with.
|
||||
It's a single file of C, and a single header file.
|
||||
|
|
@ -29,68 +30,68 @@ JSON is described best here: http://www.json.org/
|
|||
It's like XML, but fat-free. You use it to move data around, store things, or just
|
||||
generally represent your program's state.
|
||||
|
||||
|
||||
First up, how do I build?
|
||||
Add cJSON.c to your project, and put cJSON.h somewhere in the header search path.
|
||||
For example, to build the test app:
|
||||
|
||||
gcc cJSON.c test.c -o test -lm
|
||||
./test
|
||||
|
||||
gcc cJSON.c test.c -o test -lm
|
||||
./test
|
||||
|
||||
As a library, cJSON exists to take away as much legwork as it can, but not get in your way.
|
||||
As a point of pragmatism (i.e. ignoring the truth), I'm going to say that you can use it
|
||||
in one of two modes: Auto and Manual. Let's have a quick run-through.
|
||||
|
||||
|
||||
I lifted some JSON from this page: http://www.json.org/fatfree.html
|
||||
That page inspired me to write cJSON, which is a parser that tries to share the same
|
||||
philosophy as JSON itself. Simple, dumb, out of the way.
|
||||
|
||||
Some JSON:
|
||||
{
|
||||
"name": "Jack (\"Bee\") Nimble",
|
||||
"format": {
|
||||
"type": "rect",
|
||||
"width": 1920,
|
||||
"height": 1080,
|
||||
"interlace": false,
|
||||
"frame rate": 24
|
||||
----------
|
||||
|
||||
{
|
||||
"name": "Jack (\"Bee\") Nimble",
|
||||
"format": {
|
||||
"type": "rect",
|
||||
"width": 1920,
|
||||
"height": 1080,
|
||||
"interlace": false,
|
||||
"frame rate": 24
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
Assume that you got this from a file, a webserver, or magic JSON elves, whatever,
|
||||
you have a char * to it. Everything is a cJSON struct.
|
||||
Get it parsed:
|
||||
cJSON *root = cJSON_Parse(my_json_string);
|
||||
|
||||
cJSON *root = cJSON_Parse(my_json_string);
|
||||
|
||||
This is an object. We're in C. We don't have objects. But we do have structs.
|
||||
What's the framerate?
|
||||
|
||||
cJSON *format = cJSON_GetObjectItem(root,"format");
|
||||
int framerate = cJSON_GetObjectItem(format,"frame rate")->valueint;
|
||||
cJSON *format = cJSON_GetObjectItem(root,"format");
|
||||
int framerate = cJSON_GetObjectItem(format,"frame rate")->valueint;
|
||||
|
||||
|
||||
Want to change the framerate?
|
||||
cJSON_GetObjectItem(format,"frame rate")->valueint=25;
|
||||
|
||||
cJSON_GetObjectItem(format,"frame rate")->valueint=25;
|
||||
|
||||
Back to disk?
|
||||
char *rendered=cJSON_Print(root);
|
||||
char *rendered=cJSON_Print(root);
|
||||
|
||||
Finished? Delete the root (this takes care of everything else).
|
||||
cJSON_Delete(root);
|
||||
cJSON_Delete(root);
|
||||
|
||||
That's AUTO mode. If you're going to use Auto mode, you really ought to check pointers
|
||||
before you dereference them. If you want to see how you'd build this struct in code?
|
||||
cJSON *root,*fmt;
|
||||
root=cJSON_CreateObject();
|
||||
cJSON_AddItemToObject(root, "name", cJSON_CreateString("Jack (\"Bee\") Nimble"));
|
||||
cJSON_AddItemToObject(root, "format", fmt=cJSON_CreateObject());
|
||||
cJSON_AddStringToObject(fmt,"type", "rect");
|
||||
cJSON_AddNumberToObject(fmt,"width", 1920);
|
||||
cJSON_AddNumberToObject(fmt,"height", 1080);
|
||||
cJSON_AddFalseToObject (fmt,"interlace");
|
||||
cJSON_AddNumberToObject(fmt,"frame rate", 24);
|
||||
cJSON *root,*fmt;
|
||||
root=cJSON_CreateObject();
|
||||
cJSON_AddItemToObject(root, "name", cJSON_CreateString("Jack (\"Bee\") Nimble"));
|
||||
cJSON_AddItemToObject(root, "format", fmt=cJSON_CreateObject());
|
||||
cJSON_AddStringToObject(fmt,"type", "rect");
|
||||
cJSON_AddNumberToObject(fmt,"width", 1920);
|
||||
cJSON_AddNumberToObject(fmt,"height", 1080);
|
||||
cJSON_AddFalseToObject (fmt,"interlace");
|
||||
cJSON_AddNumberToObject(fmt,"frame rate", 24);
|
||||
|
||||
Hopefully we can agree that's not a lot of code? There's no overhead, no unnecessary setup.
|
||||
Look at test.c for a bunch of nice examples, mostly all ripped off the json.org site, and
|
||||
|
|
@ -111,18 +112,20 @@ Sibling hs type False, name "interlace", and a sibling:
|
|||
Sibling has type Number, name "frame rate", value 24
|
||||
|
||||
Here's the structure:
|
||||
typedef struct cJSON {
|
||||
struct cJSON *next,*prev;
|
||||
struct cJSON *child;
|
||||
---------------------
|
||||
|
||||
int type;
|
||||
typedef struct cJSON {
|
||||
struct cJSON *next,*prev;
|
||||
struct cJSON *child;
|
||||
|
||||
char *valuestring;
|
||||
int valueint;
|
||||
double valuedouble;
|
||||
int type;
|
||||
|
||||
char *string;
|
||||
} cJSON;
|
||||
char *valuestring;
|
||||
int valueint;
|
||||
double valuedouble;
|
||||
|
||||
char *string;
|
||||
} cJSON;
|
||||
|
||||
By default all values are 0 unless set by virtue of being meaningful.
|
||||
|
||||
|
|
@ -146,59 +149,59 @@ the root object, and traverse the structure (which is, formally, an N-tree),
|
|||
and tokenise as you please. If you wanted to build a callback style parser, this is how
|
||||
you'd do it (just an example, since these things are very specific):
|
||||
|
||||
void parse_and_callback(cJSON *item,const char *prefix)
|
||||
{
|
||||
while (item)
|
||||
{
|
||||
char *newprefix=malloc(strlen(prefix)+strlen(item->name)+2);
|
||||
sprintf(newprefix,"%s/%s",prefix,item->name);
|
||||
int dorecurse=callback(newprefix, item->type, item);
|
||||
if (item->child && dorecurse) parse_and_callback(item->child,newprefix);
|
||||
item=item->next;
|
||||
free(newprefix);
|
||||
}
|
||||
}
|
||||
void parse_and_callback(cJSON *item,const char *prefix)
|
||||
{
|
||||
while (item)
|
||||
{
|
||||
char *newprefix=malloc(strlen(prefix)+strlen(item->name)+2);
|
||||
sprintf(newprefix,"%s/%s",prefix,item->name);
|
||||
int dorecurse=callback(newprefix, item->type, item);
|
||||
if (item->child && dorecurse) parse_and_callback(item->child,newprefix);
|
||||
item=item->next;
|
||||
free(newprefix);
|
||||
}
|
||||
}
|
||||
|
||||
The prefix process will build you a separated list, to simplify your callback handling.
|
||||
The 'dorecurse' flag would let the callback decide to handle sub-arrays on it's own, or
|
||||
let you invoke it per-item. For the item above, your callback might look like this:
|
||||
|
||||
int callback(const char *name,int type,cJSON *item)
|
||||
{
|
||||
if (!strcmp(name,"name")) { /* populate name */ }
|
||||
else if (!strcmp(name,"format/type") { /* handle "rect" */ }
|
||||
else if (!strcmp(name,"format/width") { /* 800 */ }
|
||||
else if (!strcmp(name,"format/height") { /* 600 */ }
|
||||
else if (!strcmp(name,"format/interlace") { /* false */ }
|
||||
else if (!strcmp(name,"format/frame rate") { /* 24 */ }
|
||||
return 1;
|
||||
}
|
||||
int callback(const char *name,int type,cJSON *item)
|
||||
{
|
||||
if (!strcmp(name,"name")) { /* populate name */ }
|
||||
else if (!strcmp(name,"format/type") { /* handle "rect" */ }
|
||||
else if (!strcmp(name,"format/width") { /* 800 */ }
|
||||
else if (!strcmp(name,"format/height") { /* 600 */ }
|
||||
else if (!strcmp(name,"format/interlace") { /* false */ }
|
||||
else if (!strcmp(name,"format/frame rate") { /* 24 */ }
|
||||
return 1;
|
||||
}
|
||||
|
||||
Alternatively, you might like to parse iteratively.
|
||||
You'd use:
|
||||
|
||||
void parse_object(cJSON *item)
|
||||
{
|
||||
int i; for (i=0;i<cJSON_GetArraySize(item);i++)
|
||||
{
|
||||
cJSON *subitem=cJSON_GetArrayItem(item,i);
|
||||
// handle subitem.
|
||||
}
|
||||
}
|
||||
void parse_object(cJSON *item)
|
||||
{
|
||||
int i; for (i=0;i<cJSON_GetArraySize(item);i++)
|
||||
{
|
||||
cJSON *subitem=cJSON_GetArrayItem(item,i);
|
||||
// handle subitem.
|
||||
}
|
||||
}
|
||||
|
||||
Or, for PROPER manual mode:
|
||||
|
||||
void parse_object(cJSON *item)
|
||||
{
|
||||
cJSON *subitem=item->child;
|
||||
while (subitem)
|
||||
{
|
||||
// handle subitem
|
||||
if (subitem->child) parse_object(subitem->child);
|
||||
|
||||
subitem=subitem->next;
|
||||
}
|
||||
}
|
||||
void parse_object(cJSON *item)
|
||||
{
|
||||
cJSON *subitem=item->child;
|
||||
while (subitem)
|
||||
{
|
||||
// handle subitem
|
||||
if (subitem->child) parse_object(subitem->child);
|
||||
|
||||
subitem=subitem->next;
|
||||
}
|
||||
}
|
||||
|
||||
Of course, this should look familiar, since this is just a stripped-down version
|
||||
of the callback-parser.
|
||||
|
|
@ -212,20 +215,20 @@ You can, of course, hand your sub-objects to other functions to populate.
|
|||
Also, if you find a use for it, you can manually build the objects.
|
||||
For instance, suppose you wanted to build an array of objects?
|
||||
|
||||
cJSON *objects[24];
|
||||
cJSON *objects[24];
|
||||
|
||||
cJSON *Create_array_of_anything(cJSON **items,int num)
|
||||
{
|
||||
int i;cJSON *prev, *root=cJSON_CreateArray();
|
||||
for (i=0;i<24;i++)
|
||||
{
|
||||
if (!i) root->child=objects[i];
|
||||
else prev->next=objects[i], objects[i]->prev=prev;
|
||||
prev=objects[i];
|
||||
}
|
||||
return root;
|
||||
}
|
||||
|
||||
cJSON *Create_array_of_anything(cJSON **items,int num)
|
||||
{
|
||||
int i;cJSON *prev, *root=cJSON_CreateArray();
|
||||
for (i=0;i<24;i++)
|
||||
{
|
||||
if (!i) root->child=objects[i];
|
||||
else prev->next=objects[i], objects[i]->prev=prev;
|
||||
prev=objects[i];
|
||||
}
|
||||
return root;
|
||||
}
|
||||
|
||||
and simply: Create_array_of_anything(objects,24);
|
||||
|
||||
cJSON doesn't make any assumptions about what order you create things in.
|
||||
|
|
@ -235,7 +238,6 @@ of those objects.
|
|||
As soon as you call cJSON_Print, it renders the structure to text.
|
||||
|
||||
|
||||
|
||||
The test.c code shows how to handle a bunch of typical cases. If you uncomment
|
||||
the code, it'll load, parse and print a bunch of test files, also from json.org,
|
||||
which are more complex than I'd care to try and stash into a const char array[].
|
||||
|
|
@ -243,5 +245,4 @@ which are more complex than I'd care to try and stash into a const char array[].
|
|||
|
||||
Enjoy cJSON!
|
||||
|
||||
|
||||
- Dave Gamble, Aug 2009
|
||||
|
|
|
|||
4
test.c
4
test.c
|
|
@ -69,7 +69,7 @@ void create_objects()
|
|||
cJSON_AddFalseToObject (fmt,"interlace");
|
||||
cJSON_AddNumberToObject(fmt,"frame rate", 24);
|
||||
|
||||
out=cJSON_Print(root); cJSON_Delete(root); printf("%s\n",out); free(out); /* Print to text, Delete the cJSON, print it, release the string.
|
||||
out=cJSON_Print(root); cJSON_Delete(root); printf("%s\n",out); free(out); /* Print to text, Delete the cJSON, print it, release the string. */
|
||||
|
||||
/* Our "days of the week" array: */
|
||||
const char *strings[7]={"Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday"};
|
||||
|
|
@ -142,7 +142,7 @@ int main (int argc, const char * argv[]) {
|
|||
doit(text4);
|
||||
doit(text5);
|
||||
|
||||
/* Parse standard testfiles:
|
||||
/* Parse standard testfiles: */
|
||||
/* dofile("../../tests/test1"); */
|
||||
/* dofile("../../tests/test2"); */
|
||||
/* dofile("../../tests/test3"); */
|
||||
|
|
|
|||
Loading…
Reference in New Issue