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 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.

Data structures

/**
 * 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 Holberton project
 */
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 Holberton project
 */
typedef struct instruction_s
{
        char *opcode;
        void (*f)(stack_t **stack, unsigned int line_number);
} instruction_t;

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, its 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 L<line_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 cant 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 free and are not allowed to use any other function from man malloc (realloc, calloc, )

Compilation & Output

• Your code will be compiled this way:

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

The opcode

• pop removes the top element of the stack.
• pint prints the value at the top of the stack, followed by a new line.
• swap swaps the top two elements of the stack.
• add adds the top two elements of the stack.
• nop doesnt do anything.
• sub subtracts the top element of the stack from the second top element of the stack.
• div divides the second top element of the stack by the top element of the stack.
• mul multiplies the second top element of the stack with the top element of the stack.
• mod computes the rest of the division of the second top element of the stack by the top element of the stack.
• pchar prints the char at the top of the stack, followed by a new line.
• pstr prints the string starting at the top of the stack, followed by a new line.
• rotl rotates the stack to the top.
• rotr rotates the stack to the bottom.
• stack sets the format of the data to a stack (LIFO). This is the default behavior of the program.
• queue sets the format of the data to a queue (FIFO).

Example

Output

Author

• Daniel Chinome - Github / Twitter
• Oscar Riaño - Github / Twitter