rspec/rules/S6535/dart/rule.adoc

== Why is this an issue?

The ``++\++`` (backslash) character indicates that the next character should be treated as a literal character rather than as a special character or string delimiter.
For instance, it is common to escape single quotes inside a string literal using the single quote delimiter like ``++'It\'s a beautiful day'++``. Escaping is only meaningful for special characters.
Escaping non-special characters in strings, template literals, and regular expressions doesn't affect their value.


Therefore, useless escapes impact code readability and could even denote a bug in the code if the developer left it by mistake or intended to escape another special character instead.

You should check if the escape character was not misplaced. Useless character escapes can safely be removed without changing the original value.

Valid escape sequences are those escaping:

* control characters like ``++\n++`` (newline), ``++\t++`` (tab), ``++\r++`` (carriage return), etc.
* the backslash character itself: ``++\\++``
* the single and double quote characters: ``++\'++`` and ``++\"++``
* the dollar sign ``++\$++`` character, used in a string interpolation
* unicode escape sequences like ``++\u{1F600}++`` or ``++\u1F600++``
* hexadecimal escape sequences like ``++\x41++``


=== Noncompliant code example

[source,dart]
----
const number = '\8';
const hello = 'Hello, world\!'; // Noncompliant: '!' is not a special character
const string1  = 'this string contains 2 \"double quotes\"'; // Noncompliant: you can use double quotes here
const string2  = "this string contains 2 \'single quotes\'"; // Noncompliant: you can use single quotes here
----


=== Compliant solution

[source,dart]
----
const number = '8';
const hello = 'Hello, world!';
const string1  = 'this string contains 2 "double quotes"';
const string2  = "this string contains 2 'single quotes'";
----

== Resources

* Dart Docs - https://dart.dev/tools/linter-rules/unnecessary_string_escapes[Dart Linter rule - unnecessary_string_escapes]
* Dart Docs - https://dart.dev/language/built-in-types#strings[Dart Language - Strings]
* Wikipedia - https://en.wikipedia.org/wiki/Escape_character[Escape character]

ifdef::env-github,rspecator-view[]

'''
== Implementation Specification
(visible only on this page)

=== Message

Unnecessary escape in string literal.

=== Highlighting

The escaping backslash character only. The next character is not highlighted. 

'''
== Comments And Links
(visible only on this page)

endif::env-github,rspecator-view[]