add YED geometry convertation + separate cyb string module

cyb_string.c

@@ -0,0 +1,79 @@
+/* -----------------------------------------------------------------------------
+ * The Cyberiada GraphML library implemention
+ *
+ * The string utilities
+ *
+ * Copyright (C) 2024 Alexey Fedoseev <aleksey@fedoseev.net>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see https://www.gnu.org/licenses/
+ *
+ * ----------------------------------------------------------------------------- */
+
+#include <stdlib.h>
+#include <string.h>
+#include <ctype.h>
+
+#include "cyberiadaml.h"
+#include "cyb_string.h"
+
+int cyberiada_copy_string(char** target, size_t* size, const char* source)
+{
+	char* target_str;
+	size_t strsize;
+	if (!source) {
+		*target = NULL;
+		*size = 0;
+		return CYBERIADA_NO_ERROR;
+	}
+	strsize = strlen(source);  
+	if (strsize > MAX_STR_LEN - 1) {
+		strsize = MAX_STR_LEN - 1;
+	}
+	target_str = (char*)malloc(strsize + 1);
+	strncpy(target_str, source, strsize);
+	target_str[strsize] = 0;
+	*target = target_str;
+	if (size) {
+		*size = strsize;
+	}
+	return CYBERIADA_NO_ERROR;
+}
+
+int cyberiada_string_is_empty(const char* s)
+{
+	while(*s) {
+		if (!isspace(*s)) {
+			return 0;
+		}
+		s++;
+	}
+	return 1;
+}
+
+int cyberiada_string_trim(char* orig)
+{
+	char* s;
+	if (!orig) return 1;
+	if (!*orig) return 0;
+	s = orig + strlen(orig) - 1;
+	while(s > orig) {
+		if (isspace(*s)) {
+			*s = 0;
+			s--;
+		} else {
+			break;
+		}
+	}
+	return 0;
+}