git_stack.c

diff --git a/stack.c b/stack.c
index b77fda0..ec5d1d0 100644
--- a/stack.c
+++ b/stack.c
@@ -1,13 +1,35 @@
+/*
+ *    "Stack" is very simple implementation of stack data structure
+ *    Copyright (C) 2015  Robin Obůrka
+ *
+ *    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 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, see <http://www.gnu.org/licenses/>.
+ */
+
 #include "stack.h"
 #include <stdlib.h>
 #include <stdbool.h>

+// This is helper function.
+// It is eventually used by stack_push() for resize inner data structures.
 static void stack_realloc(struct stack_ctx *ctx)
 {
 	ctx->stack_size = 2 * ctx->stack_size;
 	ctx->data = (int *) realloc(ctx->data, ctx->stack_size * sizeof(int));
 }

+// Initialize empty stack of size initial_stack_size.
+// Returns: complete stack's context.
 struct stack_ctx *stack_init(int initial_stack_size)
 {
 	struct stack_ctx *ctx = (struct stack_ctx *) malloc(sizeof(struct stack_ctx));
@@ -19,12 +41,14 @@ struct stack_ctx *stack_init(int initial_stack_size)
 	return ctx;
 }

+// Free inner data structures and stack's context.
 void stack_destroy(struct stack_ctx *ctx)
 {
 	free(ctx->data);
 	free(ctx);
 }

+// Push one number to stack
 void stack_push(struct stack_ctx *ctx, int num)
 {
 	if (ctx->pointer == ctx->stack_size) {
@@ -34,16 +58,23 @@ void stack_push(struct stack_ctx *ctx, int num)
 	ctx->data[ctx->pointer++] = num;
 }

+// Pop top-most number from stack
+// Returns: stored number
 int stack_pop(struct stack_ctx *ctx)
 {
 	return ctx->data[--ctx->pointer];
 }

+// Check stack status
+// Returns: true if stack is empty; false otherwise
 bool stack_is_empty(struct stack_ctx *ctx)
 {
-	if (ctx->pointer == 0) {
-		return true;
-	}
+	return (ctx->pointer == 0);
+}

-	return false;
+// Check how much items are stored
+// Returns: Count of stored numbers
+bool stack_has_items(struct stack_ctx *ctx)
+{
+	return (ctx->pointer != 0);
 }