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

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 Interpreter

Welcome to the Monty Bytecode Interpreter. This interpreter was built in the C language and is compliant with ISO90, ISO99, & ISO11. It reads Monty bytecode files of any extension (preferably .m although it doesn't matter), and interprets the opcodes contained.

Our interpreter can be run as either a stack (LIFO) or queue (FIFO). Mode can be switched mid-script. The interpreter can handle a variety of Monty opcodes, including printing, mathematical operations, and more - all handled opcodes are listed below.

🏃 Getting Started

• Ubuntu 14.04 LTS - Operating system reqd.

• GCC 4.8.4 - Compiler used

⚠️ Prerequisites

• Must have git installed.

• Must have repository cloned.

$ sudo apt-get install git

⬇️ Installing and Using

Clone the repository into a new directory:

$ git clone https://github.com/BennettDixon/monty.git

Compile with the following:

gcc -Wall -Werror -Wextra -pedantic *.c -o monty

Run the interpreter on a file:

./monty file.m

🔧 Monty Opcodes

• push

  • Usage: push <int>
  • Pushes an element to the stack.
  • The parameter <int> must be an integer.

• pall

  • Prints all values in the stack/queue, starting from the top.

• pint

  • Prints the top value of the stack/queue.

• pop

  • Removes the top element of the stack/queue.

• swap

  • Swaps the top two elements of the stack/queue.

• nop

  • Does not do anything.

• add

  • Adds the top two elements of the stack/queue.
  • The result is stored in the second element from the top and the top element is popped.

• sub

  • Subtracts the top element of the stack/queue from the second element from the top.
  • The result is stored in the second element from the top and the top element is removed.

• mul

  • Multiplies the top two elements of the stack/queue.
  • The result is stored in the second element from the top and the top element is removed.

• div

  • Divides the second element from the top of the stack/queue by the top element.
  • The result is stored in the second element from the top and the top element is removed.

• mod

  • Computes the modulus of the second element from the top of the stack/queue divided by the top element.
  • The result is stored in the second element from the top and the top element is removed.

• pchar

  • Prints the character value of the top element of the stack/queue.
  • The integer at the top is treated as an ASCII value.

• pstr

  • Prints the string contained in the stack/queue.
  • Prints characters element by element until the stack/queue is empty, a value is 0, or an error occurs.

• rotl

  • Rotates the top element of the stack/queue to the bottom.

• rotr

  • Rotates the bottom element of the stack/queue to the top.

• stack

  • Switches a queue to stack mode.

• queue

  • Switches a stack to queue mode.

▶️ Opcodes preceeded by a # are treated as comments and the corresponding line is ignored.

▶️ Lines can be empty and can contain any number of spaces before or after an opcode and its argument (only the first opcode and/or argument is taken into account).

📋 Examples

Note, Monty Interpreter runs in the default mode of STACK mode. Meaning it uses a stack. To switch to queue mode, see examples below.

Push values onto the stack and print them all, or the top of the stack/front of queue.

$ cat push_pall_pint.m
push 1
push 2
push 3
pall
pint
$ ./monty push_pall_pint.m
3
2
1
3

Using mathmatical operations to add, multiply, divide, etc. Takes the second from the top and performs the operation on the top: second_from_top / top, second_from_top - top, etc. Then assigns that to the second_from_top and pops the top element off the stack.

$ cat math.m
push 3
push 2
push 1
pall
mul
pall
$ ./monty math.m
1
2
3
1
6

Entering queue mode to perform all operations in FIFO (queue) mode instead of default LIFO (stack) mode. Note: does not change current stack, sets front of queue to top of stack.

$ cat queue.m
queue
push 1
push 2
push 3
pall
stack
push 4
push 5
push 6
pall
$ ./monty queue.m
1
2
3
6
5
4
1
2
3

📚 Coding Style Tests

Strictly followed Betty style guide. To install

$ git clone https://github.com/holbertonschool/Betty.git

$ cd Betty; ./install.sh

📝 Version

• 0.1.0

📘 Authors

• Faith Nyaberi - @Obony

• Peter Ochieng - @virtuoso254

🔍 License

This project is licensed under the MIT License - see the LICENSE.md file for details

📣 Acknowledgments

• Holberton School (providing guidance)
• Stack Overflow (help on various memory errors (not leaks))
• ALX Africa (for the Software Engineering learning opportunity)