basecode-nested-code

name	basecode:nested-code
description	Apply the BaseCode Nested Code practice — flatten structure using guard clauses, conditional boolean returns, and higher-order functions to bring the primary action to the top level.

BaseCode: Nested Code

Apply the BaseCode Nested Code practice to improve the readability of the code under review. The goal is not shorter code or personal style — it is readability: making the code easier for the next human to read.

Reduce nesting to bring the primary action of a function to the top level. Each nesting level adds mental overhead for the reader.

Empty blocks — remove empty if or else blocks entirely. Invert the condition if needed.

Conditional boolean returns — when an if/else returns true/false directly, replace it with a single return of the condition expression:

// before
if ($x === 0) { return true; } else { return false; }

// after
return $x === 0;

Guard clauses — convert nested if blocks into early returns. Negate the condition and return (or throw) to protect the rest of the function:

// before
if ($item !== null) {
    if (!$this->contains($item)) {
        $this->items[] = $item;
    }
}

// after
if ($item === null || $this->contains($item)) {
    return;
}
$this->items[] = $item;

Switch to if — prefer if chains over switch when: there are only 2–3 cases, case blocks contain nested code, or the switch requires type coercion. Keep switch when a clean 1:1 ratio exists between cases and single-line bodies.

Loops — prefer higher-order functions (filter, map, reduce) over manual loops when the intent is accumulation or transformation.