Added an elastic string buffer class to libcitadel. Why do I have a feeling I'm...

[citadel.git] / libcitadel / lib / array.c

diff --git a/libcitadel/lib/array.c b/libcitadel/lib/array.c
new file mode 100644 (file)
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--- /dev/null
+++ b/libcitadel/lib/array.c
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+/*
+ * This is a quickly-hacked-together implementation of an elastic array class.  It includes constructor and destructor
+ * methods, append and access methods, and that's about it.  The memory allocation is very naive: whenever we are about
+ * to append beyond the size of the buffer, we double its size.
+ *
+ * Copyright (c) 2021 by Art Cancro
+ *
+ * This program is open source software; you can redistribute it and/or modify
+ * it under the terms of the GNU 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include "libcitadel.h"
+
+/*
+ * Constructor for elastic array
+ */
+Array *array_new(size_t element_size) {
+       Array *newarr = malloc(sizeof(Array));
+       if (newarr) {
+               memset(newarr, 0, sizeof(Array));
+       }
+       newarr->element_size = element_size;
+       return newarr;
+}
+
+
+/*
+ * Destructor for elastic array
+ */
+void array_free(Array *arr) {
+       free(arr->the_elements);
+       free(arr);
+}
+
+
+/*
+ * Append an element to an array (we already know the element size because it's in the data type)
+ */
+void array_append(Array *arr, void *new_element) {
+
+       if (!arr) {                                             // silently fail if they gave us a null array
+               return;
+       }
+
+       if ( (arr->the_elements == NULL) || (arr->num_alloc == 0)) {
+               arr->num_alloc = 1;
+               arr->num_elements = 0;
+               arr->the_elements = malloc(arr->element_size * arr->num_alloc);
+       }
+
+       ++arr->num_elements;
+       if (arr->num_elements > arr->num_alloc) {
+               arr->num_alloc = arr->num_alloc * 2;
+               arr->the_elements = realloc(arr->the_elements, (arr->element_size * arr->num_alloc));
+       }
+
+       memcpy((arr->the_elements + ( (arr->num_elements-1) * arr->element_size )), new_element, arr->element_size);
+}
+
+
+/*
+ * Return the element in an array at the specified index
+ */
+void *array_get_element_at(Array *arr, int index) {
+       return (arr->the_elements + ( index * arr->element_size ));
+}
+
+
+/*
+ * Return the number of elements in an array
+ */
+int array_len(Array *arr) {
+       return arr->num_elements;
+}