gist/kore_json_construct.c

#include <PublicDomain.txt>

// Simple function I wrote to make my life easier while playing with Kore C web server
//
// Should be easily portable to not use any json libraries at all if you really wanna to
//
// I know that it uses ?: GCC extension but in this file it can be expanded to standard C ternary operator with simple
// sed expression, everything for your closed-source "can't add useful features to my compiler" needs :)
//
// Usage:
// N-th variadic argument starts new context with one of the json types
// N+1 sets the name of object if current context is not an array, can be NULL
// N+2 sets the object value
// N+M marks the end with JSON_END flag if the context was object or array
//
// Example:
//	root = json_construct( NULL,
//		JSON_TYPE_OBJECT, NULL,
//			JSON_TYPE_STRING, "version", "2.1",
//			JSON_TYPE_OBJECT, "software",
//				JSON_TYPE_STRING, "name", "apserv",
//				JSON_TYPE_STRING, "version", "0.0.1",
//				JSON_TYPE_STRING, "repository", "https://git.mentality.rip/FWGS/apserv",
//				JSON_TYPE_STRING, "homepage", "https://git.mentality.rip/FWGS/apserv",
//			JSON_END,
//			JSON_TYPE_ARRAY, "protocols",
//				JSON_TYPE_STRING, "activitypub",
//			JSON_END,
//			JSON_TYPE_OBJECT, "services",
//				JSON_TYPE_ARRAY, "inbound", JSON_END,
//				JSON_TYPE_ARRAY, "outbound", JSON_END,
//			JSON_END,
//			JSON_TYPE_LITERAL, "openRegistrations", APSERV_OPEN_REGISTRATIONS ? JSON_TRUE : JSON_FALSE,
//			JSON_TYPE_OBJECT, "usage",
//				JSON_TYPE_OBJECT, "users",
//					JSON_TYPE_U64, "total", 0,
//					JSON_TYPE_U64, "activeHalfyear", 0,
//					JSON_TYPE_U64, "activeMonth", 0,
//				JSON_END,
//			JSON_END,
//			JSON_TYPE_OBJECT, "metadata",
//			JSON_END,
//		JSON_END);
//
// This generates an object below:
// {
//  "version": "2.1",
//  "software": {
//    "name": "apserv",
//    "version": "0.0.1",
//    "repository": "https://git.mentality.rip/FWGS/apserv",
//    "homepage": "https://git.mentality.rip/FWGS/apserv"
//  },
//  "protocols": [
//    "activitypub"
//  ],
//  "services": {
//    "inbound": [],
//    "outbound": []
//  },
//  "openRegistrations": false,
//  "usage": {
//    "users": {
//      "total": 0,
//      "activeHalfyear": 0,
//      "activeMonth": 0
//    }
//  },
//  "metadata": {}
// }
//


#include <stdarg.h>
#include <inttypes.h>
#include <stdbool.h>
#include <kore/kore.h>

#define JSON_END         0
#define JSON_TYPE_OBJECT KORE_JSON_TYPE_OBJECT
#define JSON_TYPE_ARRAY  KORE_JSON_TYPE_ARRAY
#define JSON_TYPE_STRING KORE_JSON_TYPE_STRING
#define JSON_TYPE_NUMBER KORE_JSON_TYPE_NUMBER
#define JSON_TYPE_LITERAL KORE_JSON_TYPE_LITERAL
#define JSON_TYPE_I32    (1U<<31)
#define JSON_TYPE_U32    (1U<<30)
#define JSON_TYPE_I64    KORE_JSON_TYPE_INTEGER
#define JSON_TYPE_U64    KORE_JSON_TYPE_INTEGER_U64

#define JSON_FALSE KORE_JSON_FALSE
#define JSON_TRUE  KORE_JSON_TRUE
#define JSON_NULL  KORE_JSON_NULL

struct kore_json_item *json_construct( struct kore_json_item *parent, int type, ... );

#define JSON_CONSTRUCT_DEBUG

#ifdef JSON_CONSTRUCT_DEBUG
#define CONSTRUCT_DEBUG(...) kore_log( LOG_DEBUG, __VA_ARGS__ )
#else
#define CONSTRUCT_DEBUG(...)
#endif

static struct kore_json_item *json_construct_onev( struct kore_json_item *parent, bool skipname, int type, va_list ap )
{
	struct kore_json_item *ret = NULL;
	const char *name, *parent_name;

	if( type == JSON_END )
	{
		fatal( "%s: this shouldn't happen", __func__ );
		return NULL;
	}

	if( parent )
	{
		if( parent->name )
			parent_name = parent->name;
		else parent_name = "(noname)";
	}
	else parent_name = "(noparent)";

	if( !skipname )
		name = va_arg( ap, const char * );
	else name = NULL;

	if( type == JSON_TYPE_OBJECT || type == JSON_TYPE_ARRAY )
	{
		const char *strtype = type == JSON_TYPE_OBJECT ? "object" : "array";
		struct kore_json_item *f;

		f = kore_json_create_item( parent, name, type );
		if( !ret ) ret = f;

		CONSTRUCT_DEBUG( "(%s) creating %s \"%s\"", parent_name, strtype, name ?: "" );

		for( ;; )
		{
			int nexttype = va_arg( ap, int );
			if( nexttype == JSON_END )
			{
				CONSTRUCT_DEBUG( "(%s) closing %s \"%s\"", parent_name, strtype, name ?: "" );
				return ret;
			}

			json_construct_onev( f, type == JSON_TYPE_ARRAY, nexttype, ap );
		}
	}

	switch( type )
	{
	case JSON_TYPE_STRING:
	{
		const char *szValue = va_arg( ap, const char * );

		CONSTRUCT_DEBUG( "(%s) creating string object \"%s\": \"%s\"", parent_name, name ?: "", szValue );

		ret = kore_json_create_string( parent, name, szValue );
		break;
	}
	case JSON_TYPE_NUMBER:
	{
		double flValue = va_arg( ap, double );

		CONSTRUCT_DEBUG( "(%s) creating number parameter \"%s\": %f", parent_name, name ?: "", flValue );

		ret = kore_json_create_number( parent, name, flValue );
		break;
	}
	case JSON_TYPE_LITERAL:
	{
		int32_t iValue = va_arg( ap, int );
		const char *szValue;

		switch( iValue )
		{
		case JSON_FALSE: szValue = "false"; break;
		case JSON_TRUE: szValue = "true"; break;
		case JSON_NULL: szValue = "null"; break;
		default: fatal("illegal value %d for literal type", iValue );
		}

		CONSTRUCT_DEBUG( "(%s) creating literal parameter \"%s\": %s", parent_name, name ?: "", szValue );

		ret = kore_json_create_literal( parent, name, iValue );
		break;
	}
	case JSON_TYPE_I32:
	{
		int32_t iValue = va_arg( ap, int32_t );

		CONSTRUCT_DEBUG( "(%s) creating int32 parameter \"%s\": %d", parent_name, name ?: "", iValue );

		ret = kore_json_create_integer( parent, name, iValue );
		break;
	}
	case JSON_TYPE_U32:
	{
		uint32_t uValue = va_arg( ap, uint32_t );

		CONSTRUCT_DEBUG( "(%s) creating uint32 parameter \"%s\": %u", parent_name, name ?: "", uValue );

		ret = kore_json_create_integer( parent, name, uValue );
		break;
	}
	case JSON_TYPE_I64:
	{
		int64_t lValue = va_arg( ap, int64_t );

		CONSTRUCT_DEBUG( "(%s) creating int64 parameter \"%s\": " PRId64, parent_name, name ?: "", lValue );

		ret = kore_json_create_integer( parent, name, lValue );
		break;
	}
	case JSON_TYPE_U64:
	{
		uint64_t ulValue = va_arg( ap, uint64_t );

		CONSTRUCT_DEBUG( "(%s) creating uint64 parameter \"%s\": " PRIu64, parent_name, name ?: "", ulValue );

		ret = kore_json_create_integer_u64( parent, name, ulValue );
		break;
	}
	}

	return ret;
}

struct kore_json_item *json_construct( struct kore_json_item *parent, int type, ... )
{
	va_list ap;

	va_start( ap, type );
	parent = json_construct_onev( parent, type == JSON_TYPE_ARRAY, type, ap );
	va_end( ap );

	return parent;
}