Stack-Based Language Interpreter

This C++ program implements a simple stack-based interpreter that reads and executes a custom language. The interpreter supports basic stack operations, arithmetic calculations, I/O operations, and conditional jumps.

Features

• Stack Operations: push, pop, dup, swap, over, rot, top (outputs the top value), abs
• Arithmetic Operations: add, sub, mul, div, mod
• I/O Commands: write (output strings/values), read (input numbers)
• Control Flow: Conditional jumps (goto) and labels
• Program Structure: Support for labels, vars, comments and line-based execution

Supported Instructions

Command	Description
push N	Push integer N onto the stack
pop	Remove top element from stack
dup	Duplicate top stack element
swap	Swap top two stack elements
over	Copy second stack element to top
rot	Rotate top three elements (c, b, a → b, a, c)
abs	Replace top element with its absolute value
add / sub / mul / div / mod	Arithmetic operations (uses top two elements)
write STR	Output string STR (supports multi-word strings)
read	Read integer from stdin and push to stack
top	Print top element without popping
goto sign value L	Jump to label L if top element is <, >, <=, >=, = or != to `value'
return	Terminate program execution
L:	Define jump target (must end with colon)
get _L	Getting the value of the variable _L
chvar _L	Changing the value of the variable _L to the stack.top()
// comment	Comments

Usage

1. Compile the program
2. Create a program file (e.g., program.ssb):

read
get _EVEN
mod
goto = 0 Gt
write "odd"
return

// runs only when top is equal to 0
Gt:
write "even"
return

_EVEN= 2

3. Run the interpreter passing program.ssb as an argument

Requirements

• C++17 compatible compiler
• Standard Library headers: <iostream>, <fstream>, <sstream>, <string>, <vector>, <map>