Computer Science – 16.2 Translation Software | e-Consult

Here's a step-by-step breakdown of how an interpreter would execute the provided Python code:

1. Lexical Analysis: The interpreter reads the code and identifies the tokens: x, =, 5, y, =, x, +, 2, print, (, y, ).
2. Syntax Analysis: The tokens are parsed to create an abstract syntax tree (AST). The AST represents the program's structure, showing the assignments and the print statement. The parser verifies that the syntax is correct (e.g., assignment statements have the correct structure).
3. Semantic Analysis: The interpreter performs semantic checks. It checks that x and y are defined before being used. It also checks that the + operator is used with compatible operands (integers in this case). Type checking ensures that the assignment of 5 to x and the result of x + 2 to y are valid.
4. Execution:

   • The interpreter first executes x = 5. It creates a variable x and assigns the value 5 to it.
   • Next, it executes y = x + 2. It retrieves the value of x (which is 5), adds 2 to it (resulting in 7), and assigns the value 7 to the variable y.
   • Finally, it executes print(y). It retrieves the value of y (which is 7) and instructs the operating system to display the value 7 on the console.