From d4b15cb7ee03429067820ccf1e15c5cb56dd9243 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mat=C4=9Bj=20Such=C3=A1nek?= <matejsuchanek97@gmail.com>
Date: Tue, 3 May 2022 10:59:09 +0200
Subject: [PATCH] Optimize loop in 'diff-split' case

The "substr( $line, 0, 1 )" expression has already assumed
the prefix has length 1. Therefore, it's pointless
to compute its length later. The assumption does hold,
the only two prefixes the code works with are '+' and '-'.

Not changing the check to use str_starts_with now, because
it was suggested in I113a8d052b6845852c15969a2f0e6fbbe3e9f8d9
that this shouldn't be done for performance-sensitive code
at least until we are on PHP 8.

Change-Id: I00cb2fc50ed534bb2bbef3ee1e5f6f466afeeb27
---
 includes/Variables/LazyVariableComputer.php | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/includes/Variables/LazyVariableComputer.php b/includes/Variables/LazyVariableComputer.php
index 94751601f..05475a111 100644
--- a/includes/Variables/LazyVariableComputer.php
+++ b/includes/Variables/LazyVariableComputer.php
@@ -179,8 +179,8 @@ class LazyVariableComputer {
 				$diff_lines = explode( "\n", $diff );
 				$result = [];
 				foreach ( $diff_lines as $line ) {
-					if ( substr( $line, 0, 1 ) === $line_prefix ) {
-						$result[] = substr( $line, strlen( $line_prefix ) );
+					if ( ( $line[0] ?? '' ) === $line_prefix ) {
+						$result[] = substr( $line, 1 );
 					}
 				}
 				break;