Terminal

Solution Overview

In my solution, I implement a terminal that can take either:

• hex streams (0x01 0x03 0x50 0x18 0x01 0x03 0x06 0x3C 0x02 0x03 0x0A 0x07 0x2A 0xFF)
• string inputs (screen_setup 80 24 16colors - translated internally to hex: 0x01 0x03 0x50 0x18 0x01 0xFF )

The challenge was to ensure that the two pipelines (hex and string) remained consistent, robust, and easy to extend. Sufficiently respecting the SOLID principles

Hex Execution Pipeline

graph TD;
    Terminal --> run_hex
    run_hex --> HexCommandValidator
    HexCommandValidator-->validate_hex_input;
    HexCommandValidator-->validate_length_bytes;
    HexCommandValidator-->validate_hex_commands;
    run_hex-->HexParser;
    HexParser-->parse_hex;
    run_hex-->HexCommandHandler;
    HexCommandHandler --> to_executor
    

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Architecture

1. Hex Input Validation - Ensure the incoming hex stream is convertable to hex commands without breaking.
2. Command Parsing - Convert the hex stream into a series of executable commands
3. Command Validation - Ensure all executable commands are accurate and executable
4. Command Execution - Iteratively pass all validated commands for execution

The goal behind this architecture in the pipeline is to ensure easy to follow and debug steps that each validate or transform the data up to the point of execution

Solid principles implemented to achieve this are:

• Single Responsibility Principle (SRP) - Each class and method handles a single aspect of the pipeline. For example, validation, parsing, and execution are separated into distinct methods
• Open/Closed Principle (OCP) - The COMMANDS dictionary allows for easy extension with new commands without modifying existing code.

Example flow

Consider this input hex stream:

0x01 0x03 0x50 0x18 0x01 0x03 0x06 0x3C 0x02 0x03 0x0A 0x07 0x2A 0xFF

The terminal uses " " and "," as delimeters to get a raw string stream

Hex Command Pipeline
Hex Input Validation - runs methods to ensure all the strings in the raw string stream are convertable to hex and parsable
Output: True
Command Parsing Converts the raw string stream to a hex command stream
Output: [0x01 0x03 0x50 0x18 0x01 0xFF], [0x03 0x06 0x3C 0x02 0x03 0x0A 0x07 0x2A 0xFF]
Command Validation Runs checks on all command streams in the hex command stream to ensure all of the are executable
Output: True
Command Execution Validated commands are iteratively ran through the executor for execution
Output: True

Running Hex Commands

To setup your environment and clone this project, please follow instructions here: Instructions

Run the program:

python terminal.py

String Execution Pipeline

graph TD;
    A[Terminal] --> B[run_string]
    B --> C{StringCommandController}
    C-- Switcher -->D[Super PipeLine -> SpecificPipeLine];
    D-->validate_command_structure;
    D-->validate_input;
    D-->parse_input;
    D-->command_handler;

    

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Architecture:

The architecture follows this flow. Should you enter the command:

screen_setup 80 24 16colors

String Command Pipeline
1. CommandPipeline Intiation - A correspoding execution pipeline class is instantiated by StringCommandController
Output: ScreenSetupPipeLine(CommandPipeline)
2. Command Structure Validation Pipeline ensures the command has the right number of arguments
Output: True
3. Command Argument Validation PipeLine ensures that all commands are recognized and are convertable to hex
Output: True
4. Command Parsed PipeLine converts all commands to the expected Hex value according to the command
Output: 0x01 0x03 0x50 0x18 0x01 0xFF
5. Command Execution PipeLine passes command to the executor to be ran
Output: True

The goal of this Architecture is to embrace the Open/Closed Principle to ensure adding new commands does not affect the interparation of other commands.

Running String Commands

To setup your environment and clone this project, please follow instructions here: Instructions

Run the program:

python terminal.py --readable

Running the solution

Preriquisites

1. Python 3.8 or higher
   Download Python from python.org.

2. Dependencies
   Ensure the following standard Python libraries are available:

   • argparse (for parsing command-line arguments)
   • sys (for system-level operations)

3. Terminal Emulator
   A terminal or command prompt (e.g., bash, zsh, cmd, or PowerShell).

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Step-by-Step Setup

1. Clone the Repository

Open your terminal or command prompt and run:

git clone <repository-url>
cd <repository-folder>