kata-hand-programming-language

Objective

The goal of this kata is to apply and refine TDD (Test-Driven Development) and Extreme Programming techniques by developing an interpreter for a language based on emojis.

Link to the original description.

Functioning

This language modifies an indefinite-sized memory, composed of cells initialized to 0.

• 👉 moves the memory pointer to the next cell.
• 👈 moves the memory pointer to the previous cell.
• 👆 increases the value of the current memory cell.
• 👇 decreases the value of the current memory cell.
• 👊 displays the value of the current cell according to its ASCII equivalence.
• 🤜 if the memory cell at the current position has a value of 0, jump right after the corresponding 🤛.
• 🤛 if the memory cell at the current position has a non-zero value, jump right after the corresponding 🤜.

⚠️ Clarifications ⚠️

• Memory cells are bytes, with a value from 0 to 255.
  • Decreasing 0 will result in 255.
  • Increasing 255 will result in 0.
• Memory starts at position 0.
• Memory can be increased “infinitely”, but if you decrease the memory address 0, you must return the highest known memory address.

Challenges

1. Increase the memory pointer 👉

• Move from memory position 0 to 1.
• Move from memory position 1 to 2.
• Move from memory position 255 to 256.
• Move from memory position 256 to 257.

2. Decrease the memory pointer 👈

• Move from memory position 3 to 2.
• Move from memory position 2 to 1.
• Move from memory position 1 to 0.

From here, you should consider implementing the data structure that will act as memory.

• Move from memory position 0 to the highest known position.

3. Read memory positions

• Set the following memory addresses to these values:
  • 0 = 1
  • 1 = 2
  • 2 = 3
• Read the memory value at position 0 and get 1.
• Read the memory value at position 1 and get 2.
• Read the memory value at position 2 and get 3.
• Read the value of the highest known memory position and get 3.
• Read the memory value at position 3 and get 0.

4. Increase the value of memory positions 👆

• Increase a cell with value 0 to 1.
• Increase a cell with value 1 to 2.
• Increase a cell with value 2 to 3.
• Increase a cell with value 255 to 0.

5. Decrease the value of a memory position 👇

• Decrease a cell with value 3 to 2.
• Decrease a cell with value 2 to 1.
• Decrease a cell with value 1 to 0.
• Decrease a cell with value 0 to 255.

6. Write to memory positions

• Write 1 in position 0.
• Write 2 in position 1.
• Write 3 in position 2.
• Write 4 in position 3.

7. Get the ASCII character 👊

• From a cell with value 65, get its ASCII value, "A".
• From a cell with value 66, get its ASCII value, "B".
• From a cell with value 67, get its ASCII value, "C".
• From a cell with value 68, get its ASCII value, "D".

8. Execute the following emojis to get their respective messages

• A
  • [Long sequence of 👆 followed by 👊]
• B
  • [Long sequence of 👇 followed by 👊]
• C
  • [Long sequence of 👆 followed by 👊]
• Hello
  • [Long sequence of 👇 followed by 👊, then a series of 👉, 👆, and 👊]

9. Conditionals (🤜 and 🤛)

• When encountering a 🤜, make the program's execution pointer jump to the corresponding 🤛 if the current memory cell value is 0.
  • Test cases
    • 🤜👆🤛
    • 👆🤜👆🤛
• A
  • 👆🤛👆🤜👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👆👊
• B
  • 🤛👆🤜👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👇👊
• When encountering a 🤛, make the program's execution pointer jump to the corresponding 🤜 if the current memory cell value is not 0.
  • Test cases
    • 👆🤛👆🤜
    • 🤛👆🤜
  • A
    • [Sequence involving 👆, 🤛, 👆, 🤜, and 👊]
  • B
    • [Sequence involving 🤛, 👆, 🤜, 👇, and 👊]