0x19. C - Stacks, Queues - LIFO, FIFO

By: Julien Barbier

Project to be done in teams of 2 people (your team: Brian Kinyanjui, Esther Wachuka)

Resources

Read or watch:

Learning Objectives

At the end of this project, you are expected to be able to explain to anyone, without the help of Google:

General

What do LIFO and FIFO mean
What is a stack, and when to use it
What is a queue, and when to use it
What are the common implementations of stacks and queues
What are the most common use cases of stacks and queues
What is the proper way to use global variables

Requirements

General

Allowed editors: vi, vim, emacs
All your files will be compiled on Ubuntu 20.04 LTS using gcc, using the options -Wall -Werror -Wextra -pedantic -std=c89
All your files should end with a new line
A README.md file, at the root of the folder of the project is mandatory
Your code should use the Betty style. It will be checked using betty-style.pl and betty-doc.pl
You allowed to use a maximum of one global variable
No more than 5 functions per file
You are allowed to use the C standard library
The prototypes of all your functions should be included in your header file called monty.h
Don’t forget to push your header file
All your header files should be include guarded
You are expected to do the tasks in the order shown in the project

GitHub

There should be one project repository per group. If you clone/fork/whatever a project repository with the same name before the second deadline, you risk a 0% score.

More Info

Data structures Please use the following data structures for this project. Don’t forget to include them in your header file.

/**

* struct stack_s - doubly linked list representation of a stack (or queue)
* @n: integer
* @prev: points to the previous element of the stack (or queue)
* @next: points to the next element of the stack (or queue)
*
* Description: doubly linked list node structure
* for stack, queues, LIFO, FIFO
 */
typedef struct stack_s
{
        int n;
struct stack_s*prev;
        struct stack_s *next;
} stack_t;

/**
* struct instruction_s - opcode and its function
* @opcode: the opcode
* @f: function to handle the opcode
*
* Description: opcode and its function
* for stack, queues, LIFO, FIFO
 */
typedef struct instruction_s
{
char*opcode;
        void (*f)(stack_t **stack, unsigned int line_number);
} instruction_t;

Compilation & Output

Your code will be compiled this way:

$ gcc -Wall -Werror -Wextra -pedantic -std=c89 *.c -o monty

Any output must be printed on stdout
Any error message must be printed on stderr
- Here is a link to a GitHub repository that could help you making sure your errors are printed on stderr

Tests

We strongly encourage you to work all together on a set of tests

The Monty language

Monty 0.98 is a scripting language that is first compiled into Monty byte codes (Just like Python). It relies on a unique stack, with specific instructions to manipulate it. The goal of this project is to create an interpreter for Monty ByteCodes files.

Monty byte code files

Files containing Monty byte codes usually have the .m extension. Most of the industry uses this standard but it is not required by the specification of the language. There is not more than one instruction per line. There can be any number of spaces before or after the opcode and its argument:

julien@ubuntu:~/monty$ cat -e bytecodes/000.m
push 0$
push 1$
push 2$
  push 3$
                   pall    $
push 4$
    push 5    $
      push    6        $
pall$
julien@ubuntu:~/monty$

Monty byte code files can contain blank lines (empty or made of spaces only, and any additional text after the opcode or its required argument is not taken into account:

julien@ubuntu:~/monty$ cat -e bytecodes/001.m
push 0 Push 0 onto the stack$
push 1 Push 1 onto the stack$
$
push 2$
  push 3$
                   pall    $
$
$
                           $
push 4$
$
    push 5    $
      push    6        $
$
pall This is the end of our program. Monty is awesome!$
julien@ubuntu:~/monty$

The monty program

Usage: monty file
- where file is the path to the file containing Monty byte code
If the user does not give any file or more than one argument to your program, print the error message USAGE: monty file, followed by a new line, and exit with the status EXIT_FAILURE
If, for any reason, it’s not possible to open the file, print the error message Error: Can't open file file, followed by a new line, and exit with the status EXIT_FAILURE
- where file is the name of the file
If the file contains an invalid instruction, print the error message Lline_number: unknown instruction opcode, followed by a new line, and exit with the status EXIT_FAILURE where is the line number where the instruction appears. Line numbers always start at 1
The monty program runs the bytecodes line by line and stop if either:
- it executed properly every line of the file
- it finds an error in the file
- an error occured
If you can’t malloc anymore, print the error message Error: malloc failed, followed by a new line, and exit with status EXIT_FAILURE.
You have to use malloc and freeand are not allowed to use any other function from man malloc (realloc, calloc, …)

Tasks

0. push, pall

mandatory

Implement the push and pall opcodes.

The push opcode

The opcode push pushes an element to the stack.

Usage: push
- where is an integer
if is not an integer or if there is no argument given to push, print the error message L<line_number>: usage: push integer, followed by a new line, and exit with the status EXIT_FAILURE
- where is the line number in the file
You won’t have to deal with overflows. Use the atoi function

The pall opcode

The opcode pall prints all the values on the stack, starting from the top of the stack.

Usage pall
Format: see example
If the stack is empty, don’t print anything

julien@ubuntu:~/monty$ cat -e bytecodes/00.m
push 1$
push 2$
push 3$
pall$
julien@ubuntu:~/monty$ ./monty bytecodes/00.m
3
2
1
julien@ubuntu:~/monty$

Repo:

GitHub repository: monty

1. pint

mandatory

Implement the pint opcode.

The pint opcode

The opcode pint prints the value at the top of the stack, followed by a new line.

Usage: pint
If the stack is empty, print the error message L<line_number>: can't pint, stack empty, followed by a new line, and exit with the status EXIT_FAILURE

julien@ubuntu:~/monty$ cat bytecodes/06.m
push 1
pint
push 2
pint
push 3
pint
julien@ubuntu:~/monty$ ./monty bytecodes/06.m
1
2
3
julien@ubuntu:~/monty$

Repo:

GitHub repository: monty

2. pop

mandatory

Implement the pop opcode.

The pop opcode

The opcode pop removes the top element of the stack.

Usage: pop
If the stack is empty, print the error message L<line_number>: can't pop an empty stack, followed by a new line, and exit with the status EXIT_FAILURE

julien@ubuntu:~/monty$ cat bytecodes/07.m
push 1
push 2
push 3
pall
pop
pall
pop
pall
pop
pall
julien@ubuntu:~/monty$ ./monty bytecodes/07.m
3
2
1
2
1
1
julien@ubuntu:~/monty$

Repo:

GitHub repository: monty

3. swap

mandatory

Implement the swap opcode.

The swap opcode

The opcode swap swaps the top two elements of the stack.

Usage: swap
If the stack contains less than two elements, print the error message L<line_number>: can't swap, stack too short, followed by a new line, and exit with the status EXIT_FAILURE

julien@ubuntu:~/monty$ cat bytecodes/09.m
push 1
push 2
push 3
pall
swap
pall
julien@ubuntu:~/monty$ ./monty bytecodes/09.m
3
2
1
2
3
1
julien@ubuntu:~/monty$

Repo:

GitHub repository: monty

4. add

mandatory

Implement the add opcode.

The add opcode

The opcode add adds the top two elements of the stack.

Usage: add
If the stack contains less than two elements, print the error message L<line_number>: can't add, stack too short, followed by a new line, and exit with the status EXIT_FAILURE
The result is stored in the second top element of the stack, and the top element is removed, so that at the end:
- The top element of the stack contains the result
- The stack is one element shorter

julien@ubuntu:~/monty$ cat bytecodes/12.m
push 1
push 2
push 3
pall
add
pall

julien@ubuntu:~/monty$ ./monty bytecodes/12.m
3
2
1
5
1
julien@ubuntu:~/monty$

Repo:

GitHub repository: monty

5. nop

mandatory

Implement the nop opcode.

The nop opcode

The opcode nop doesn’t do anything.

Usage: nop

Repo:

GitHub repository: monty

brianmaleek / monty

0x19. C - Stacks, Queues - LIFO, FIFO

Resources

Learning Objectives

Requirements

GitHub

More Info

Compilation & Output

Tests

The Monty language

Monty byte code files

The monty program

Tasks

0. push, pall

1. pint

2. pop

3. swap

4. add

5. nop

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