cleanups and more test cases

src/lib/utils/stack.c

@@ -0,0 +1,182 @@
+
+/* +--------------------------------------------------------------------------+
+** |                          _   _       _                                   |
+** |                         | \ | |     (_)                                  |
+** |                         |  \| | ___  _  __ _                             |
+** |                         | . ` |/ _ \| |/ _` |                            |
+** |                         | |\  | (_) | | (_| |                            |
+** |                         |_| \_|\___/| |\__,_|                            |
+** |                                    _/ |                                  |
+** |                                   |__/                                   |
+** +--------------------------------------------------------------------------+
+** | Copyright (c) 2022 Francesco Cozzuto <francesco.cozzuto@gmail.com>       |
+** +--------------------------------------------------------------------------+
+** | This file is part of The Noja Interpreter.                               |
+** |                                                                          |
+** | The Noja Interpreter 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 3 of the License, or (at |
+** | your option) any later version.                                          |
+** |                                                                          |
+** | The Noja Interpreter 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 The Noja Interpreter. If not, see <http://www.gnu.org/licenses/>.   |
+** +--------------------------------------------------------------------------+ 
+*/
+
+#include <stdint.h>
+#include <stdlib.h>
+#include "stack.h"
+#include "defs.h"
+
+struct xStack {
+	unsigned int size, 
+				 used;
+	int 		 refs;
+	void 		*body[];
+};
+
+_Bool Stack_IsReadOnlyCopy(Stack *s)
+{
+	return (uintptr_t) s & (uintptr_t) 1;
+}
+
+void *Stack_New(int size)
+{
+	if(size < 0)
+		size = 1024;
+
+	Stack *s = malloc(sizeof(Stack) + sizeof(void*) * size);
+
+	if(s == NULL)
+		return NULL;
+
+	assert((intptr_t) s % 8 == 0);
+
+	s->size = size;
+	s->used = 0;
+	s->refs = 1;
+	return s;
+}
+
+static Stack *unmark(Stack *s)
+{
+	return (Stack*) ((intptr_t) s & ~ (intptr_t) 1);
+}
+
+void *Stack_Top(Stack *s, int n)
+{
+	assert(n <= 0);
+
+	// Remove readonly bit.
+	s = unmark(s);
+
+	if(s->used == 0)
+		return NULL;
+
+	if((int) s->used + n - 1 < 0)
+		return NULL;
+
+	return s->body[s->used + n - 1];
+}
+
+void **Stack_TopRef(Stack *s, int n)
+{
+	assert(n <= 0);
+
+	if(Stack_IsReadOnlyCopy(s))
+		return NULL;
+
+	// Remove readonly bit.
+	s = unmark(s);
+
+	if(s->used == 0)
+		return NULL;
+
+	if((int) s->used + n - 1 < 0)
+		return NULL;
+
+	return &s->body[s->used + n - 1];
+}
+
+
+_Bool Stack_Pop(Stack *s, unsigned int n)
+{
+	if(Stack_IsReadOnlyCopy(s))
+		return 0;
+
+	if(s->used < n)
+		return 0;
+
+	s->used -= n;
+	return 1;
+}
+
+_Bool Stack_Push(Stack *s, void *item)
+{
+	assert(s != NULL);
+	assert(item != NULL);
+
+	if(Stack_IsReadOnlyCopy(s))
+		return 0;
+
+	if(s->used == s->size)
+		return 0;
+
+	s->body[s->used] = item;
+	s->used += 1;
+	return 1;
+}
+
+Stack *Stack_Copy(Stack *s, _Bool readonly)
+{
+	if(Stack_IsReadOnlyCopy(s))
+	{
+		// Reference is readonly,
+		// so the copy must be
+		// readonly.
+		readonly = 1;
+
+		// Remove readonly bit.
+		s = unmark(s);
+	}
+
+	s->refs += 1;
+	
+	if(readonly)
+		return (Stack*) ((uintptr_t) s | (intptr_t) 1);
+	else
+		return s;
+}
+
+void Stack_Free(Stack *s)
+{
+	// Remove readonly bit.
+	s = unmark(s);
+
+	s->refs -= 1;
+	assert(s->refs >= 0);
+
+	if(s->refs == 0)
+		free(s);
+}
+
+unsigned int Stack_Size(Stack *s)
+{
+	// Remove readonly bit.
+	s = unmark(s);
+
+	return s->used;
+}
+
+unsigned int Stack_Capacity(Stack *s)
+{
+	// Remove readonly bit.
+	s = unmark(s);
+
+	return s->size;
+}