Loop Unroller in JavaScript

Loop unrolling is a compiler optimization technique that can sometimes improve performance by reducing loop overhead. This challenge asks you to implement a function that manually "unrolls" a simple for loop into a sequence of equivalent statements. This exercise helps understand loop overhead and the potential benefits of manual optimization, although in modern JavaScript engines, this is less critical.

Problem Description

You are tasked with creating a JavaScript function called unrollLoop that takes a for loop's initialization, condition, increment, and body as strings and returns a string containing the unrolled equivalent of the loop. The unrolling factor will be a fixed value (defined below). The unrolled code should be functionally equivalent to the original loop, executing the same number of iterations.

What needs to be achieved:

The function should parse the provided for loop string and transform it into a series of sequential statements that achieve the same result as the original loop.

Key Requirements:

• The function must accept four string arguments: initialization, condition, increment, and body.
• The function must unroll the loop by a factor of UNROLL_FACTOR (defined below).
• The unrolled code must be a single string containing the unrolled statements separated by semicolons.
• The unrolled code must be functionally equivalent to the original loop.
• The function should handle basic for loop structures. Complex expressions within the loop are not required.

Expected Behavior:

The function should return a string representing the unrolled loop. The unrolled loop should execute the same number of times as the original loop, with the loop body repeated UNROLL_FACTOR times.

Edge Cases to Consider:

• Empty loop body.
• Loop with a condition that immediately evaluates to false (zero iterations).
• Simple increment/decrement operations.
• The loop body contains only a single statement.

Examples

Example 1:

Input: initialization = "let i = 0", condition = "i < 5", increment = "i++", body = "console.log(i)"
Output: "let i = 0; console.log(i); console.log(i); console.log(i); console.log(i); i++; let i = 1; console.log(i); console.log(i); console.log(i); console.log(i); i++; let i = 2; console.log(i); console.log(i); console.log(i); console.log(i); i++; let i = 3; console.log(i); console.log(i); console.log(i); console.log(i); i++; let i = 4; console.log(i); console.log(i); console.log(i); console.log(i); i++;"
Explanation: The loop runs from i = 0 to i = 4 (5 iterations). The body `console.log(i)` is repeated 4 times for each unrolled iteration. The increment `i++` is also repeated.

**Example 2:**

Input: initialization = "let j = 0", condition = "j < 3", increment = "j++", body = "console.log('hello')" Output: "let j = 0; console.log('hello'); console.log('hello'); console.log('hello'); j++; let j = 1; console.log('hello'); console.log('hello'); console.log('hello'); j++; let j = 2; console.log('hello'); console.log('hello'); console.log('hello'); j++;" Explanation: The loop runs from j = 0 to j = 2 (3 iterations). The body console.log('hello') is repeated 2 times for each unrolled iteration.

Example 3: (Edge Case - Empty Body)

Input: initialization = "let k = 0", condition = "k < 2", increment = "k++", body = ""
Output: "let k = 0; k++; let k = 1; k++; let k = 2;"
Explanation: The loop runs from k = 0 to k = 1 (2 iterations). The empty body is simply skipped in each unrolled iteration.

Constraints

• UNROLL_FACTOR = 4 (The loop will be unrolled by a factor of 4).
• The input strings initialization, condition, increment, and body will contain valid JavaScript syntax (though not necessarily well-formed in isolation).
• The loop will always have a finite number of iterations.
• The function should return a string.
• The function should not throw errors.

Notes

• This is a simplified loop unrolling implementation. Real-world loop unrolling is much more complex and involves considerations like register allocation and instruction scheduling.
• Focus on correctly replicating the loop's behavior in the unrolled form.
• Consider how to handle the increment step within the unrolled loop. It needs to be repeated for each unrolled iteration.
• The goal is to produce a string that, when executed, is equivalent to the original loop. You don't need to actually execute the string.
• The provided examples are meant to guide you, but you may need to consider other scenarios to ensure your solution is robust.