1 files changed, 60 insertions, 0 deletions
diff --git a/data_struct.h b/data_struct.h
new file mode 100644
index 0000000..694150a
--- /dev/null
+++ b/data_struct.h
@@ -0,0 +1,60 @@
+#ifndef DATA_STRUCT_H_SENTRY
+#define DATA_STRUCT_H_SENTRY
+
+#include <stddef.h>
+
+/*
+ * data_struct.h
+ *
+ * This module provides basic data structures and helper functions
+ * for handling file information, directory/file arguments, and
+ * transforming them between linked lists and arrays.
+ *
+ */
+
+enum {
+    buffer_size = 512
+};
+
+/*
+ * Stores separated command-line arguments:
+ * dirs is array of directory paths
+ * files is array of file paths
+ */
+struct arg_arrays {
+    const char **dirs;
+    const char **files;
+};
+
+/*
+ * Single-linked list node containing file entry:
+ * info_line -- formatted string with file information
+ * filename used for sorting
+ */
+struct file_item {
+    char *info_line;
+    char *filename;
+    struct file_item *next;
+};
+
+/*
+ * array-based representation of file_item list:
+ * array -- dynamic array of pointers to file_item
+ */
+struct file_item_array {
+    struct file_item **array;
+    size_t length;
+};
+
+void init_arg_arrays(struct arg_arrays *split, int argc);
+void init_item_array(struct file_item_array *arr);
+void add_new_item(struct file_item **list, struct file_item **entry,
+                  const char *file_name);
+void copy_list_to_array(struct file_item *list, struct file_item_array *arr);
+void free_file_item_array(struct file_item_array *arr, struct file_item **list);
+void free_arg_arrays(struct arg_arrays *split);
+int is_empty_array(const char **paths_array, int argc);
+int is_last_arr_element(const char **paths_array, int argc, size_t pos);
+void sort_array_by_names(struct file_item_array *arr);
+
+#endif