escape_implicit_backslashes.rst

Rule escape_implicit_backslashes

Escape implicit backslashes in strings and heredocs to ease the understanding of which are special chars interpreted by PHP and which not.

Description

In PHP double-quoted strings and heredocs some chars like n, $ or u have special meanings if preceded by a backslash (and some are special only if followed by other special chars), while a backslash preceding other chars are interpreted like a plain backslash. The precise list of those special chars is hard to remember and to identify quickly: this fixer escapes backslashes that do not start a special interpretation with the char after them. It is possible to fix also single-quoted strings: in this case there is no special chars apart from single-quote and backslash itself, so the fixer simply ensure that all backslashes are escaped. Both single and double backslashes are allowed in single-quoted strings, so the purpose in this context is mainly to have a uniformed way to have them written all over the codebase.

Warning

This rule is deprecated and will be removed in the next major version

You should use string_implicit_backslashes instead.

Configuration

double_quoted

Whether to fix double-quoted strings.

Allowed types: bool

Default value: true

heredoc_syntax

Whether to fix heredoc syntax.

Allowed types: bool

Default value: true

single_quoted

Whether to fix single-quoted strings.

Allowed types: bool

Default value: false

Examples

Example #1

Default configuration.

--- Original
+++ New
 <?php

 $singleQuoted = 'String with \" and My\Prefix\\';

-$doubleQuoted = "Interpret my \n but not my \a";
+$doubleQuoted = "Interpret my \n but not my \\a";

 $hereDoc = <<<HEREDOC
-Interpret my \100 but not my \999
+Interpret my \100 but not my \\999
 HEREDOC;

Example #2

With configuration: ['single_quoted' => true].

--- Original
+++ New
 <?php

-$singleQuoted = 'String with \" and My\Prefix\\';
+$singleQuoted = 'String with \\" and My\\Prefix\\';

-$doubleQuoted = "Interpret my \n but not my \a";
+$doubleQuoted = "Interpret my \n but not my \\a";

 $hereDoc = <<<HEREDOC
-Interpret my \100 but not my \999
+Interpret my \100 but not my \\999
 HEREDOC;

Example #3

With configuration: ['double_quoted' => false].

--- Original
+++ New
 <?php

 $singleQuoted = 'String with \" and My\Prefix\\';

 $doubleQuoted = "Interpret my \n but not my \a";

 $hereDoc = <<<HEREDOC
-Interpret my \100 but not my \999
+Interpret my \100 but not my \\999
 HEREDOC;

Example #4

With configuration: ['heredoc_syntax' => false].

--- Original
+++ New
 <?php

 $singleQuoted = 'String with \" and My\Prefix\\';

-$doubleQuoted = "Interpret my \n but not my \a";
+$doubleQuoted = "Interpret my \n but not my \\a";

 $hereDoc = <<<HEREDOC
 Interpret my \100 but not my \999
 HEREDOC;

References

• Fixer class: PhpCsFixer\Fixer\StringNotation\EscapeImplicitBackslashesFixer
• Test class: PhpCsFixer\Tests\Fixer\StringNotation\EscapeImplicitBackslashesFixerTest

The test class defines officially supported behaviour. Each test case is a part of our backward compatibility promise.