eina: strbuf - Add strftime related functions

eina_strbuf_append_strftime()
eina_strbuf_insert_strftime()
eina_strbuf_prepend_strftime() - macro

We need these functions for implementing generic format function
interface especially for calander.

Ref T6204

src/examples/eina/eina_strbuf_02.c

@@ -0,0 +1,35 @@
+//Compile with:
+//gcc -Wall -o eina_strbuf_02 eina_strbuf_02c `pkg-config --cflags --libs eina`
+
+#include <stdio.h>
+#include <Eina.h>
+
+int main(int argc EINA_UNUSED, char **argv EINA_UNUSED)
+{
+   Eina_Strbuf *buf;
+   time_t curr_time;
+   struct tm *info;
+
+   eina_init();
+
+   curr_time = time(NULL);
+   info = localtime(&curr_time);
+
+   buf = eina_strbuf_new();
+   eina_strbuf_append_strftime(buf, "%I:%M%p", info);
+   printf("current time: %s\n", eina_strbuf_string_get(buf));
+   eina_strbuf_reset(buf);
+
+   buf = eina_strbuf_new();
+   eina_strbuf_append(buf, "Hours: Minutes");
+   //insert hour at ^Hours: Minutes where ^ is the position
+   eina_strbuf_prepend_strftime(buf, "%I ", info);
+   //insert hour at hhhHours: ^Minutes where ^ is the position
+   eina_strbuf_insert_strftime(buf, "%M ", info, 10);
+   printf("%s\n", eina_strbuf_string_get(buf));
+
+   eina_strbuf_free(buf);
+   eina_shutdown();
+
+   return 0;
+}

src/lib/eina/eina_strbuf.c

@@ -220,6 +220,34 @@ eina_strbuf_substr_get(Eina_Strbuf *buf, size_t pos, size_t len)
    return eina_strbuf_manage_new(str);
 }
 
+EAPI Eina_Bool
+eina_strbuf_append_strftime(Eina_Strbuf *buf, const char *format, const struct tm *tm)
+{
+   char *outputbuf;
+
+   outputbuf = eina_strftime(format, tm);
+   if (!outputbuf) return EINA_FALSE;
+
+   eina_strbuf_append(buf, outputbuf);
+   free(outputbuf);
+
+   return EINA_TRUE;
+}
+
+EAPI Eina_Bool
+eina_strbuf_insert_strftime(Eina_Strbuf *buf, const char *format, const struct tm *tm, size_t pos)
+{
+   char *outputbuf;
+
+   outputbuf = eina_strftime(format, tm);
+   if (!outputbuf) return EINA_FALSE;
+
+   eina_strbuf_insert_length(buf, outputbuf, strlen(outputbuf), pos);
+   free(outputbuf);
+
+   return EINA_TRUE;
+}
+
 /* Unicode */
 
 #include "eina_strbuf_template_c.x"

src/lib/eina/eina_strbuf.h

@@ -737,6 +737,74 @@ EAPI Eina_Rw_Slice eina_strbuf_rw_slice_get(const Eina_Strbuf *buf) EINA_WARN_UN
  */
 EAPI char* eina_strbuf_release(Eina_Strbuf *buf) EINA_WARN_UNUSED_RESULT EINA_ARG_NONNULL(1);
 
+/**
+ * @brief append the given buffer based on strftime output.
+ *
+ * @param tm Pointer to a tm structure needed by strftime.
+ * @param fmt String containing format specifiers needed by strftime.
+ * @return #EINA_TRUE on success, #EINA_FALSE on failure.
+ *
+ * This will add append buffer of exact required size based on strftime output
+ *
+ * Example usage:
+ * @code
+ * time_t curr_time;
+ * struct tm *info;
+ * Eina_Strbuf *buf = eina_strbuf_new();
+ * curr_time = time(NULL);
+ * info = localtime(&curr_time);
+ * eina_strbuf_append_strftime(buf, "%I:%M%p", info);
+ * //after use
+ * eina_strbuf_free(buf);
+ * @endcode #EINA_TRUE on success, #EINA_FALSE on failure.
+ *
+ * @since 1.21
+ */
+EAPI Eina_Bool eina_strbuf_append_strftime(Eina_Strbuf *buf, const char *fmt, const struct tm *tm);
+
+/**
+ * @brief insert the given buffer based on strftime output at given position
+ *
+ * @param buf The string buffer to prepend to.
+ * @param fmt String containing format specifiers needed by strftime.
+ * @param tm Pointer to a tm structure needed by strftime.
+ * @return #EINA_TRUE on success, #EINA_FALSE on failure.
+ *
+ * This will add append buffer of exact required size based on strftime output
+ *
+ * Example usage:
+ * @code
+ * time_t curr_time;
+ * struct tm *info;
+ * Eina_Strbuf *buf = eina_strbuf_new();
+ * curr_time = time(NULL);
+ * info = localtime(&curr_time);
+ * eina_strbuf_insert_strftime(buf, "%I:%M%p", info, 2);
+ * //after use
+ * eina_strbuf_free(buf);
+ * @endcode
+ *
+ * @since 1.21
+ */
+EAPI Eina_Bool eina_strbuf_insert_strftime(Eina_Strbuf *buf, const char *fmt, const struct tm *tm, size_t pos);
+
+/**
+ * @def eina_strbuf_prepend_strftime(buf, fmt, tm)
+ * @brief Prepends the given string to the given buffer.
+ *
+ * @param buf The string buffer to prepend to.
+ * @param fmt The string to prepend.
+ * @param tm The variable arguments.
+ * @return #EINA_TRUE on success, #EINA_FALSE on failure.
+ *
+ * This macro is calling eina_strbuf_insert_strftime() at position 0. If @p buf
+ * can't prepend it, #EINA_FALSE is returned, otherwise #EINA_TRUE is
+ * returned.
+ *
+ * @since 1.21
+ */
+#define eina_strbuf_prepend_strftime(buf, fmt, tm)                eina_strbuf_insert_strftime(buf, fmt, tm, 0)
+
 /**
  * @}
  */

src/tests/eina/eina_test_strbuf.c

@@ -660,6 +660,36 @@ START_TEST(strbuf_release_test)
 }
 END_TEST
 
+START_TEST(strbuf_strftime_test)
+{
+   Eina_Strbuf *buf;
+   time_t curr_time;
+   struct tm *info;
+   char cbuf[32];
+   const char *str;
+
+   curr_time = time(NULL);
+   info = localtime(&curr_time);
+
+   strftime(cbuf, 32, "%I:%M%p", info);
+
+   buf = eina_strbuf_new();
+   eina_strbuf_append_strftime(buf, "%I:%M%p", info);
+   str = eina_strbuf_string_get(buf);
+   fail_if(str == NULL || strcmp(str, cbuf) != 0);
+   eina_strbuf_reset(buf);
+
+   buf = eina_strbuf_new();
+   eina_strbuf_append(buf, "Hours: Minutes");
+   eina_strbuf_prepend_strftime(buf, "%I ", info);
+   eina_strbuf_insert_strftime(buf, "%M ", info, 10);
+   strftime(cbuf, 32, "%I Hours: %M Minutes", info);
+   str = eina_strbuf_string_get(buf);
+   fail_if(str == NULL || strcmp(str, cbuf) != 0);
+
+   eina_strbuf_free(buf);
+}
+
 void
 eina_test_strbuf(TCase *tc)
 {
@@ -677,4 +707,5 @@ eina_test_strbuf(TCase *tc)
    tcase_add_test(tc, strbuf_substr_get);
    tcase_add_test(tc, strbuf_prepend_print);
    tcase_add_test(tc, strbuf_release_test);
+   tcase_add_test(tc, strbuf_strftime_test);
 }