Fix incorrect backslash escaping of `\\`

The regular expression part `\\` must be written as `\\\\`, not `\\\` in
a PHP string variable. Although both variants (`\\\\` and `\\\`) will be
passed as `\` to the regex engine in this specific case, it's correct to
use 4 backslashes, as the PHP manual tells you:

https://www.php.net/manual/en/regexp.reference.escape.php

1 files changed, 2 insertions, 2 deletions

diff --git a/core/namespace/Parsers/FunctionParser.php b/core/namespace/Parsers/FunctionParser.php
index 5b2656e..02570a0 100644
--- a/core/namespace/Parsers/FunctionParser.php
+++ b/core/namespace/Parsers/FunctionParser.php
@@ -26,8 +26,8 @@ class FunctionParser implements ParserInterface {
 	private const ARGUMENT_PATTERN_PARTIAL =
 	'(?<arg>                      # Either a quoted string or a plain number
 		(?<qmark>["\'])           # Either a single or double quote
-		(?>[^"\'\\\]++            # String between the quotes
-		|    [\\\].               # A `\` followed by anything but literal newline
+		(?>[^"\'\\\\]++           # String between the quotes
+		|    [\\\\].              # A `\` followed by anything but literal newline
 		|    (?!\k<qmark>)["\']   # A quote, but not our opening quote
 		)*+
 		\k<qmark>                 # Closing quote (same as opening quote)