examples/reference/c/eina/src/eina_value.c

#define EFL_BETA_API_SUPPORT 1

#include <stdio.h>

#include <Eina.h>
#include <Efl_Core.h>

/*
 * Eina Value examples.
 *
 * These examples demonstrate how to work with eina_value data and methods.
 * Eina_Value is a way to represent and pass data of varying types and to
 * convert efficiently between them..
 * Eina_Value can even define structs for managing more complex requirements.
 */

static void
_value_int()
{
   Eina_Value int_val;
   char *str;
   int i;

   // Setting up an integer value type
   eina_value_setup(&int_val, EINA_VALUE_TYPE_INT);
   eina_value_set(&int_val, 123);
   eina_value_get(&int_val, &i);
   printf("int_val value is %d\n", i);

   // It can easily be converted it to a string
   str = eina_value_to_string(&int_val);
   printf("int_val to string is \"%s\"\n", str);
   free(str); // it was allocated by eina_value_to_string()
   eina_value_flush(&int_val);
}

static void
_value_string()
{
   Eina_Value str_val;
   const char *str;
   char *newstr;

   // Setting up an integer value type
   eina_value_setup(&str_val, EINA_VALUE_TYPE_STRING);
   eina_value_set(&str_val, "My string");
   eina_value_get(&str_val, &str);
   printf("str_val value is \"%s\" (pointer: %p)\n", str, str);

   // To string here will copy the data, so we still need to free it
   // Notice that the pointer is different on the returned string
   newstr = eina_value_to_string(&str_val);
   printf("str_val to string is \"%s\" (pointer: %p)\n", newstr, newstr);
   free(newstr); // it was allocated by eina_value_to_string()
   eina_value_flush(&str_val);
}

static void
_value_convert()
{
   Eina_Value str_val, int_val;
   int i;
   char *str;

   // set up string and int types to convert between
   eina_value_setup(&str_val, EINA_VALUE_TYPE_STRING);
   eina_value_setup(&int_val, EINA_VALUE_TYPE_INT);

   // convert from int to string:
   eina_value_set(&int_val, 123);
   eina_value_get(&int_val, &i);
   eina_value_convert(&int_val, &str_val);
   eina_value_get(&str_val, &str);
   printf("int_val was %d, converted to string is \"%s\"\n", i, str);

   // and the other way around!
   eina_value_set(&str_val, "33");
   eina_value_get(&str_val, &str);
   eina_value_convert(&str_val, &int_val);
   eina_value_get(&int_val, &i);
   printf("str_val was \"%s\", converted to int is %d\n", str, i);

   eina_value_flush(&str_val);
   eina_value_flush(&int_val);
}

static Eina_Value_Struct_Desc *_STRUCT_DESC = NULL;

static void
_value_struct_define()
{
   typedef struct _Struct {
     int num;
     char chr;
   } Struct;

   static Eina_Value_Struct_Member members[] = {
     // no eina_value_type as they are not constant initializers, see below.
     EINA_VALUE_STRUCT_MEMBER(NULL, Struct, num),
     EINA_VALUE_STRUCT_MEMBER(NULL, Struct, chr)
   };

   // set up the members and describe the struct parameters
   members[0].type = EINA_VALUE_TYPE_INT;
   members[1].type = EINA_VALUE_TYPE_CHAR;
   static Eina_Value_Struct_Desc desc = {
     EINA_VALUE_STRUCT_DESC_VERSION,
     NULL, // no special operations
     members,
     EINA_C_ARRAY_LENGTH(members),
     sizeof(Struct)
   };
   _STRUCT_DESC = &desc;
}

static void
_value_struct_rand(Eina_Value *val)
{
   eina_value_struct_set(val, "num", rand());
   eina_value_struct_set(val, "chr", 32 + rand() % 94);

   // this parameter is not defined but does not error
   eina_value_struct_set(val, "missing", rand());
}

static void
_value_struct_print(Eina_Value *struct_val)
{
   int num;
   char chr;

   eina_value_struct_get(struct_val, "num", &num);
   eina_value_struct_get(struct_val, "chr", &chr);

   printf("Struct content\n");
   printf("  num: %d\n", num);
   printf("  chr: %c\n", chr);

   // we can check if a struct contains a field before working with it
   if (eina_value_struct_get(struct_val, "missing", &num))
     printf(  "missing: %d\n", num);
}

static void
_value_struct()
{
   Eina_Value *struct_val;
   _value_struct_define();

   struct_val = eina_value_struct_new(_STRUCT_DESC);
   _value_struct_rand(struct_val);

   _value_struct_print(struct_val);
   eina_value_free(struct_val);
}

EAPI_MAIN void
efl_main(void *data EINA_UNUSED, const Efl_Event *ev EINA_UNUSED)
{
   _value_int();
   printf("\n");

   _value_string();
   printf("\n");

   _value_convert();
   printf("\n");

   _value_struct();

   efl_exit(0);
}
EFL_MAIN()