Add an array-based generic stack structure to blenlib

Very simple stack with homogeneous contents. Provides push, pop, and
is-empty operations.

source/blender/blenlib/BLI_stack.h

@@ -0,0 +1,50 @@
+/*
+ * ***** BEGIN GPL LICENSE BLOCK *****
+ *
+ * This program is free 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 2
+ * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * Contributor(s): Nicholas Bishop
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ *
+ */
+
+#ifndef __BLI_STACK_H__
+#define __BLI_STACK_H__
+
+typedef struct BLI_Stack BLI_Stack;
+
+/* Create a new homogeneous stack with elements of 'elem_size' bytes */
+BLI_Stack *BLI_stack_new(int elem_size, const char *description);
+
+/* Free the stack's data and the stack itself */
+void BLI_stack_free(BLI_Stack *stack);
+
+/* Copies the source value onto the stack (note that it copies
+ * elem_size bytes from 'src', the pointer itself is not stored) */
+void BLI_stack_push(BLI_Stack *stack, void *src);
+
+/* Retrieves and removes the top element from the stack. The value is
+ * copies to 'dst', which must be at least elem_size bytes.
+ *
+ * Does not reduce amount of allocated memory.
+ *
+ * If stack is empty, 'dst' will not be modified. */
+void BLI_stack_pop(BLI_Stack *stack, void *dst);
+
+/* Returns TRUE if the stack is empty, FALSE otherwise */
+int BLI_stack_empty(const BLI_Stack *stack);
+
+#endif

source/blender/blenlib/CMakeLists.txt

@@ -81,6 +81,7 @@ set(SRC
 	intern/rct.c
 	intern/scanfill.c
 	intern/smallhash.c
+	intern/stack.c
 	intern/storage.c
 	intern/string.c
 	intern/string_cursor_utf8.c
@@ -135,6 +136,7 @@ set(SRC
 	BLI_rect.h
 	BLI_scanfill.h
 	BLI_smallhash.h
+	BLI_stack.h
 	BLI_string.h
 	BLI_string_cursor_utf8.h
 	BLI_string_utf8.h

source/blender/blenlib/intern/stack.c

@@ -0,0 +1,103 @@
+/*
+ * ***** BEGIN GPL LICENSE BLOCK *****
+ *
+ * This program is free 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 2
+ * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * Contributor(s): Nicholas Bishop
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ *
+ */
+
+#include "BLI_stack.h"
+#include "BLI_utildefines.h"
+#include "MEM_guardedalloc.h"
+#include <string.h>
+
+typedef struct BLI_Stack {
+	void *data;
+
+	int totelem;
+	int maxelem;
+
+	int elem_size;
+} BLI_Stack;
+
+BLI_Stack *BLI_stack_new(int elem_size, const char *description)
+{
+	BLI_Stack *stack = MEM_callocN(sizeof(*stack), description);
+
+	stack->elem_size = elem_size;
+
+	return stack;
+}
+
+void BLI_stack_free(BLI_Stack *stack)
+{
+	if (stack) {
+		if (stack->data)
+			MEM_freeN(stack->data);
+		MEM_freeN(stack);
+	}
+}
+
+/* Gets the last element in the stack */
+#define STACK_LAST_ELEM(stack__) \
+	(((char*)(stack__)->data) + \
+	 ((stack__)->elem_size * ((stack__)->totelem - 1)))
+
+void BLI_stack_push(BLI_Stack *stack, void *src)
+{
+	/* Ensure stack is large enough */
+	if (stack->totelem == stack->maxelem) {
+		if (stack->maxelem == 0) {
+			/* Initialize stack with space for a small hardcoded
+			 * number of elements */
+			stack->maxelem = 32;
+			stack->data = MEM_mallocN((stack->elem_size *
+									   stack->maxelem), AT);
+		}
+		else {
+			/* Double stack size */
+			int maxelem = stack->maxelem + stack->maxelem;
+			/* Check for overflow */
+			BLI_assert(maxelem > stack->maxelem);
+			stack->data = MEM_reallocN(stack->data,
+									   (stack->elem_size *
+										maxelem));
+			stack->maxelem = maxelem;
+		}
+	}
+
+	BLI_assert(stack->totelem < stack->maxelem);
+
+	/* Copy source to end of stack */
+	stack->totelem++;
+	memcpy(STACK_LAST_ELEM(stack), src, stack->elem_size);
+}
+
+void BLI_stack_pop(BLI_Stack *stack, void *dst)
+{
+	BLI_assert(stack->totelem > 0);
+	if (stack->totelem > 0) {
+		memcpy(dst, STACK_LAST_ELEM(stack), stack->elem_size);
+		stack->totelem--;
+	}
+}
+
+int BLI_stack_empty(const BLI_Stack *stack)
+{
+	return stack->totelem == 0;
+}