ruleset.xml

<?xml version="1.0"?>
<ruleset xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" name="WordPress Core" xsi:noNamespaceSchemaLocation="https://raw.githubusercontent.com/PHPCSStandards/PHP_CodeSniffer/master/phpcs.xsd">

	<description>Non-controversial generally-agreed upon WordPress Coding Standards</description>

	<!-- Default tab width for indentation fixes and such. -->
	<arg name="tab-width" value="4"/>

	<!--
		 Trigger error if PHPCSUtils cannot be found.
		 PHPCSUtils does not contain any sniffs, so this rule isn't strictly necessary, but
		 by having this here anyway, if PHPCSUtils is missing, the user will get a
		 descriptive error message during the loading of the ruleset instead of
		 a fatal "class not found" error once the sniffs start running.
	-->
	<rule ref="PHPCSUtils"/>

	<!--
	#############################################################################
	Handbook: General - Opening and Closing PHP Tags.
	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#opening-and-closing-php-tags
	#############################################################################
	-->
	<!-- Covers rule: When embedding multi-line PHP snippets within a HTML block, the
		 PHP open and close tags must be on a line by themselves. -->
	<rule ref="Squiz.PHP.EmbeddedPhp"/>
	<rule ref="Squiz.PHP.EmbeddedPhp.SpacingBefore">
		<severity>0</severity>
	</rule>
	<rule ref="Squiz.PHP.EmbeddedPhp.Indent">
		<severity>0</severity>
	</rule>
	<rule ref="Squiz.PHP.EmbeddedPhp.OpenTagIndent">
		<severity>0</severity>
	</rule>
	<rule ref="Squiz.PHP.EmbeddedPhp.SpacingAfter">
		<severity>0</severity>
	</rule>


	<!--
	#############################################################################
	Handbook: General - No Shorthand PHP Tags.
	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#no-shorthand-php-tags
	#############################################################################
	-->
	<!-- Covers rule: Never use shorthand PHP start tags. Always use full PHP tags. -->
	<rule ref="Generic.PHP.DisallowShortOpenTag"/>
	<rule ref="Generic.PHP.DisallowAlternativePHPTags"/>


	<!--
	#############################################################################
	Handbook: General - Single and Double Quotes.
	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#single-and-double-quotes
	#############################################################################
	-->
	<!-- Covers rule: Use single and double quotes when appropriate.
		 If you're not evaluating anything in the string, use single quotes. -->
	<rule ref="Squiz.Strings.DoubleQuoteUsage.NotRequired"/>

	<!-- Rule: Text that goes into HTML or XML attributes should be escaped so that
		 single or double quotes do not end the attribute value.
		 https://github.com/WordPress/WordPress-Coding-Standards/issues/527 -->


	<!--
	#############################################################################
	Handbook: General - Writing include/require statements.
	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#writing-include-require-statements
	#############################################################################
	-->

	<!-- Covers rule: include[_once] and require[_once] are language constructs, they do
		 not need parentheses around the path, so those shouldn't be used. -->
	<rule ref="PEAR.Files.IncludingFile.BracketsNotRequired"/>

	<!-- Covers rule: There should only be one space between the path and the include/require keywords.
		 Note: the sniff covers more language constructs than just include/require. While not in the handbook,
		 WP Core already complies with this, so we may as well enforce it.  -->
	<rule ref="Generic.WhiteSpace.LanguageConstructSpacing"/>

	<!-- Covers rule: It is strongly recommended to use require[_once] for unconditional includes. -->
	<rule ref="PEAR.Files.IncludingFile.UseRequire">
		<type>warning</type>
	</rule>
	<rule ref="PEAR.Files.IncludingFile.UseRequireOnce">
		<type>warning</type>
	</rule>


	<!--
	#############################################################################
	Handbook: Naming - Naming Conventions.
	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#naming-conventions
	#############################################################################
	-->
	<!-- Covers rule: Use lowercase letters in variable, action/filter, and function names.
		 Separate words via underscores. -->
	<rule ref="WordPress.NamingConventions.ValidFunctionName"/>
	<rule ref="WordPress.NamingConventions.ValidHookName"/>
	<rule ref="WordPress.NamingConventions.ValidVariableName"/>

	<!-- Covers rule: It is _strongly recommended_ to avoid reserved keywords as function parameter names. -->
	<rule ref="Universal.NamingConventions.NoReservedKeywordParameterNames"/>

	<!-- Covers rule: Class, trait, interface, enum names should use capitalized words separated by underscores. -->
	<rule ref="PEAR.NamingConventions.ValidClassName"/>

	<!-- Covers rule: Constants should be in all upper-case with underscores separating words. -->
	<rule ref="Generic.NamingConventions.UpperCaseConstantName"/>

	<!-- Covers rule: Files should be named descriptively using lowercase letters.
		 Hyphens should separate words. -->
	<!-- Covers rule: Class file names should be based on the class name with "class-"
		 prepended and the underscores in the class name replaced with hyphens. -->
	<!-- Covers rule: Files containing template tags in wp-includes should have "-template"
		 appended to the end of the name. -->
	<rule ref="WordPress.Files.FileName"/>

	<!-- Rule: For files containing test classes, the file name should reflect the class name exactly, as per PSR4.
		 https://github.com/WordPress/WordPress-Coding-Standards/issues/1995 -->


	<!--
	#############################################################################
	Handbook: Naming - Interpolation for Naming Dynamic Hooks.
	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#interpolation-for-naming-dynamic-hooks

	https://github.com/WordPress/WordPress-Coding-Standards/issues/751
	#############################################################################
	-->
	<!-- Rule: Dynamic hooks should be named using interpolation rather than concatenation. -->

	<!-- Rule: Variables used in hook tags should be wrapped in curly braces { and },
		 with the complete outer tag name wrapped in double quotes. -->

	<!-- Rule: Where possible, dynamic values in tag names should also be as succinct
		 and to the point as possible. -->


	<!--
	#############################################################################
	Handbook: Whitespace - Space Usage.
	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#space-usage
	#############################################################################
	-->
	<!-- Covers rule: Always put spaces after commas... -->
	<!-- No space before a comma and one space or a new line after. -->
	<rule ref="Universal.WhiteSpace.CommaSpacing"/>
	<rule ref="Universal.WhiteSpace.CommaSpacing.TooMuchSpaceAfterCommaBeforeTrailingComment">
		<!-- Alignment of trailing comments is allowed. -->
		<severity>0</severity>
	</rule>
	<!-- Comma spacing in function declarations, including closure use statements, is handled by the
		 Squiz.Functions.FunctionDeclarationArgumentSpacing sniff. -->
	<rule ref="Universal.WhiteSpace.CommaSpacing.SpaceBeforeInFunctionDeclaration">
		<severity>0</severity>
	</rule>
	<rule ref="Universal.WhiteSpace.CommaSpacing.TooMuchSpaceAfterInFunctionDeclaration">
		<severity>0</severity>
	</rule>
	<rule ref="Universal.WhiteSpace.CommaSpacing.NoSpaceAfterInFunctionDeclaration">
		<severity>0</severity>
	</rule>
	<rule ref="Universal.WhiteSpace.CommaSpacing.SpaceBeforeInClosureUse">
		<severity>0</severity>
	</rule>
	<rule ref="Universal.WhiteSpace.CommaSpacing.TooMuchSpaceAfterInClosureUse">
		<severity>0</severity>
	</rule>
	<rule ref="Universal.WhiteSpace.CommaSpacing.NoSpaceAfterInClosureUse">
		<severity>0</severity>
	</rule>
	<!-- Comma spacing in function calls is handled by the Generic.Functions.FunctionCallArgumentSpacing sniff. -->
	<rule ref="Universal.WhiteSpace.CommaSpacing.SpaceBeforeInFunctionCall">
		<severity>0</severity>
	</rule>
	<rule ref="Universal.WhiteSpace.CommaSpacing.TooMuchSpaceAfterInFunctionCall">
		<severity>0</severity>
	</rule>
	<rule ref="Universal.WhiteSpace.CommaSpacing.NoSpaceAfterInFunctionCall">
		<severity>0</severity>
	</rule>

	<!-- Covers rule: Always put spaces ... on both sides of logical,
		 arithmetic, comparison, string and assignment operators. -->
	<rule ref="WordPress.WhiteSpace.OperatorSpacing"/>
	<rule ref="Squiz.Strings.ConcatenationSpacing">
		<properties>
			<property name="spacing" value="1"/>
			<property name="ignoreNewlines" value="true"/>
		</properties>
	</rule>

	<!-- Covers rule: Put spaces on both sides of the opening and closing parentheses of control structure blocks. -->
	<rule ref="WordPress.WhiteSpace.ControlStructureSpacing"/>

	<!-- Covers rule: Define a function like so: function my_function( $param1 = 'foo', $param2 = 'bar' ) { -->
	<rule ref="Generic.Functions.OpeningFunctionBraceKernighanRitchie">
		<properties>
			<property name="checkClosures" value="false"/>
		</properties>
	</rule>
	<!-- Prevent duplicate message. This is now checked by the Squiz.Functions.MultiLineFunctionDeclaration sniff. -->
	<rule ref="Generic.Functions.OpeningFunctionBraceKernighanRitchie.ContentAfterBrace">
		<severity>0</severity>
	</rule>

	<rule ref="Squiz.Functions.MultiLineFunctionDeclaration"/>
	<!-- WP demands brace on same line, not on the next line. Silence errors related to "brace on same line". -->
	<rule ref="Squiz.Functions.MultiLineFunctionDeclaration.BraceOnSameLine">
		<severity>0</severity>
	</rule>
	<rule ref="Squiz.Functions.MultiLineFunctionDeclaration.BraceSpacing">
		<severity>0</severity>
	</rule>
	<rule ref="Squiz.Functions.MultiLineFunctionDeclaration.BraceIndent">
		<severity>0</severity>
	</rule>

	<rule ref="Squiz.Functions.FunctionDeclarationArgumentSpacing">
		<properties>
			<property name="equalsSpacing" value="1"/>
			<property name="requiredSpacesAfterOpen" value="1"/>
			<property name="requiredSpacesBeforeClose" value="1"/>
		</properties>
	</rule>
	<rule ref="Squiz.Functions.FunctionDeclarationArgumentSpacing.SpacingAfterVariadic">
		<severity>0</severity>
	</rule>

	<!-- Covers rule: Call a function, like so: my_function( $param1, func_param( $param2 ) ); -->
	<rule ref="PEAR.Functions.FunctionCallSignature">
		<properties>
			<property name="requiredSpacesAfterOpen" value="1"/>
			<property name="requiredSpacesBeforeClose" value="1"/>

			<!-- ... and for multi-line function calls, there should only be one parameter per line. -->
			<property name="allowMultipleArguments" value="false"/>
		</properties>
	</rule>

	<rule ref="Generic.Functions.FunctionCallArgumentSpacing"/>

	<!-- Rule: Perform logical comparisons, like so: if ( ! $foo ) { -->

	<!-- Covers rule: Type casts must be lowercase. Always prefer the short form
		 of type casts, (int) instead of (integer) and (bool) rather than (boolean).
		 For float casts use (float), not (real) which is deprecated in PHP 7.4, and removed in PHP 8. -->
	<rule ref="Generic.Formatting.SpaceAfterCast"/>
	<rule ref="Squiz.WhiteSpace.CastSpacing"/>
	<rule ref="WordPress.WhiteSpace.CastStructureSpacing"/>
	<rule ref="WordPress.PHP.TypeCasts"/>
	<rule ref="PSR12.Keywords.ShortFormTypeKeywords"/>
	<!-- N.B.: This sniff also checks the case of (parameter/return) type declarations, not just type casts. -->
	<rule ref="Generic.PHP.LowerCaseType"/>

	<!-- Covers rule: ... array items, only include a space around the index if it is a variable. -->
	<rule ref="WordPress.Arrays.ArrayKeySpacingRestrictions"/>

	<!-- Covers rule: In a switch block, there must be no space between the case condition and the colon. -->
	<!-- Covered by the PSR2.ControlStructures.SwitchDeclaration sniff. -->

	<!-- Covers rule: Unless otherwise specified, parentheses should have spaces inside them. -->
	<rule ref="Generic.WhiteSpace.ArbitraryParenthesesSpacing">
		<properties>
			<property name="spacing" value="1"/>
			<property name="ignoreNewlines" value="true"/>
		</properties>
	</rule>

	<!-- Covers rule: When using increment or decrement operators, there should be
		 no spaces between the operator and the variable it applies to. -->
	<rule ref="Generic.WhiteSpace.IncrementDecrementSpacing"/>

	<!-- Implied through the examples: Object operators should not have whitespace around them unless they are multi-line. -->
	<rule ref="WordPress.WhiteSpace.ObjectOperatorSpacing">
		<properties>
			<property name="ignoreNewlines" value="true"/>
		</properties>
	</rule>


	<!--
	#############################################################################
	Handbook: Whitespace - Indentation.
	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#indentation
	#############################################################################
	-->
	<!-- Covers rule: Your indentation should always reflect logical structure. -->
	<rule ref="Generic.WhiteSpace.ScopeIndent">
		<properties>
			<property name="exact" value="false"/>
			<property name="indent" value="4"/>
			<property name="tabIndent" value="true"/>
			<property name="ignoreIndentationTokens" type="array">
				<element value="T_HEREDOC"/>
				<element value="T_NOWDOC"/>
				<element value="T_INLINE_HTML"/>
			</property>
		</properties>
	</rule>
	<rule ref="WordPress.Arrays.ArrayIndentation"/>

	<!-- Covers rule: Use real tabs and not spaces. -->
	<rule ref="Generic.WhiteSpace.DisallowSpaceIndent"/>
	<rule ref="Universal.WhiteSpace.PrecisionAlignment"/>

	<!-- Generic array layout check. -->
	<!-- Covers rule: For associative arrays, each item should start on a new line
		 when the array contains more than one item. -->
	<rule ref="WordPress.Arrays.ArrayDeclarationSpacing"/>

	<!-- Covers various array whitespace issues. -->
	<rule ref="NormalizedArrays.Arrays.ArrayBraceSpacing">
		<properties>
			<property name="spacesWhenEmpty" value="0"/>
			<property name="spacesSingleLine" value="1"/>
			<property name="spacesMultiLine" value="newline"/>
		</properties>
	</rule>

	<!-- Covers rule: Note the comma after the last array item: this is recommended. -->
	<rule ref="NormalizedArrays.Arrays.CommaAfterLast"/>

	<!-- Covers rule: For switch control structures, case statements should be indented one tab
		 from the switch statement and the contents of the case should be indented one tab
		 from the case condition statement. -->
	<rule ref="PSR2.ControlStructures.SwitchDeclaration"/>
	<!-- Prevent duplicate messages for the same issue. Covered by other sniffs. -->
	<rule ref="PSR2.ControlStructures.SwitchDeclaration.NotLower">
		<severity>0</severity>
	</rule>
	<rule ref="PSR2.ControlStructures.SwitchDeclaration.BreakNotNewLine">
		<severity>0</severity>
	</rule>
	<rule ref="PSR2.ControlStructures.SwitchDeclaration.BodyOnNextLine">
		<severity>0</severity>
	</rule>

	<!-- Covers rule: ... while spaces can be used mid-line for alignment. -->
	<rule ref="Universal.WhiteSpace.DisallowInlineTabs"/>

	<!-- Implied through the examples: align the assignment operator in a block of assignments. -->
	<rule ref="Generic.Formatting.MultipleStatementAlignment">
		<properties>
			<property name="maxPadding" value="40"/>
		</properties>
	</rule>

	<!-- Implied through the examples: align the double arrows. -->
	<rule ref="WordPress.Arrays.MultipleStatementAlignment">
		<properties>
			<property name="maxColumn" value="60"/>
		</properties>
	</rule>


	<!--
	#############################################################################
	Handbook: Whitespace - Remove Trailing Spaces.
	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#remove-trailing-spaces
	#############################################################################
	-->
	<!-- Covers rule: Remove trailing whitespace at the end of each line of code. -->
	<rule ref="Squiz.WhiteSpace.SuperfluousWhitespace"/>

	<!-- Covers rule: Omitting the closing PHP tag at the end of a file is preferred. -->
	<rule ref="PSR2.Files.ClosingTag"/>

	<!-- Covers rule: There should be no trailing blank lines at the end of a function body. -->
	<rule ref="PSR2.Methods.FunctionClosingBrace"/>


	<!--
	#############################################################################
	Handbook: Formatting - Brace Style.
	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#brace-style
	#############################################################################
	-->
	<!-- Covers rule: Braces shall be used for all blocks. -->
	<rule ref="Squiz.ControlStructures.ControlSignature"/>

	<!-- Covers rule: Braces should always be used, even when they are not required. -->
	<rule ref="Generic.ControlStructures.InlineControlStructure"/>


	<!--
	#############################################################################
	Handbook: Formatting - Declaring Arrays.
	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#declaring-arrays
	#############################################################################
	-->
	<!-- Covers rule: Arrays must be declared using long array syntax. -->
	<rule ref="Universal.Arrays.DisallowShortArraySyntax"/>


	<!--
	#############################################################################
	Handbook: Formatting - Multiline Function Calls.
	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#multiline-function-calls
	#############################################################################
	-->
	<!-- Covers rule: When splitting a function call over multiple lines, each parameter must be on a separate line. -->
	<!-- Covered via PEAR.Functions.FunctionCallSignature in Space Usage section. -->

	<!-- Rule: Single line inline comments can take up their own line. -->
	<!-- Rule: Each parameter must take up no more than a single line. Multi-line parameter
		 values must be assigned to a variable and then that variable should be passed to the function call.
		 https://github.com/WordPress/WordPress-Coding-Standards/issues/1330 -->


	<!--
	#############################################################################
	Handbook: Formatting - Type declarations.
	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#type-declarations
	#############################################################################
	-->
	<!-- Covers rule: Type declarations must have exactly one space before and after the type. -->
	<!-- Covered by the Squiz.Functions.FunctionDeclarationArgumentSpacing sniff. -->

	<!-- Covers rule: There should be no space between the nullability operator and the actual type. -->
	<rule ref="PSR12.Functions.NullableTypeDeclaration"/>

	<!-- Rule: Class/interface/enum name based type declarations should use the case of the
		 class/interface/enum name as declared... -->
	<!-- Not sniffable except for PHP native names and known WP class names (this last part via
		 the WordPress.WP.ClassNameCase sniff once switched to the (upcoming/future)
		 PHPCSUtils AbstractClassUseSniff. -->

	<!-- Covers rule: ... while the keyword-based type declarations should be lowercased. -->
	<!-- Covered by the Generic.PHP.LowerCaseType sniff. -->

	<!-- Covers rule: Return type declarations should have no space between the closing parenthesis
		 of the function declaration and the colon starting a return type. -->
	<rule ref="PSR12.Functions.ReturnTypeDeclaration"/>

	<!-- Implied through the examples: There should no space around the union or intersection type operators. -->
	<rule ref="Universal.Operators.TypeSeparatorSpacing"/>


	<!--
	#############################################################################
	Handbook: Formatting - Magic constants.
	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#magic-constants
	#############################################################################
	-->
	<!-- Covers rule: The PHP native __*__ magic constants should be written in uppercase. -->
	<rule ref="Universal.Constants.UppercaseMagicConstants"/>

	<!-- Covers rule: When using the ::class constant for class name resolution, the class keyword should be in lowercase... -->
	<rule ref="Universal.Constants.LowercaseClassResolutionKeyword"/>

	<!-- Covers rule: ... and there should be no spaces around the :: operator. -->
	<!-- Covered by the WordPress.WhiteSpace.ObjectOperatorSpacing sniff. -->


	<!--
	#############################################################################
	Handbook: Formatting - Spread operator.
	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#spread-operator
	#############################################################################
	-->
	<!-- Covers rule: When using the spread operator, there should be one space or a new line
		 with the appropriate indentation before the spread operator. -->
	<!-- Covered by a variety of sniffs which deal with function calls, function declarations, array declarations. -->

	<!-- Covers rule: There should be no spaces between the spread operator and the variable/function call it applies to. -->
	<rule ref="Generic.WhiteSpace.SpreadOperatorSpacingAfter"/>

	<!-- Covers rule: When combining the spread operator with the reference operator (&), there should be no spaces between them.. -->
	<!-- Covered by the Squiz.Functions.FunctionDeclarationArgumentSpacing.SpacingAfterReference error code. -->


	<!--
	#############################################################################
	Handbook: Declare Statements, Namespace, and Import Statements - Namespace declarations.
	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#namespace-declarations
	#############################################################################
	-->
	<!-- Rule: Each part of a namespace name should consist of capitalized words separated by underscores.
		 https://github.com/WordPress/WordPress-Coding-Standards/issues/2304 -->

	<!-- Rule: Namespace declarations should have exactly one blank line before the declaration and at least one blank line after.
		 https://github.com/WordPress/WordPress-Coding-Standards/issues/2305 -->

	<!-- Covers rule: There should be only one namespace declaration per file... -->
	<rule ref="Universal.Namespaces.OneDeclarationPerFile"/>

	<!-- Covers rule: ... and it should be at the top of the file.
		 Note: with only one namespace declaration, it not being at the top of the file would be a parse error. -->
	<!-- When in the file header, covered by PSR12.Files.FileHeader.IncorrectOrder. -->

	<!-- Covers rule: Namespace declarations using curly brace syntax are not allowed. -->
	<rule ref="Universal.Namespaces.DisallowCurlyBraceSyntax"/>

	<!-- Covers rule: Explicit global namespace declaration (namespace declaration without name) are also not allowed. -->
	<rule ref="Universal.Namespaces.DisallowDeclarationWithoutName"/>


	<!--
	#############################################################################
	Handbook: Declare Statements, Namespace, and Import Statements - Using import use statements.
	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#using-import-use-statements
	#############################################################################
	-->
	<!-- Covers rule: Import use statements should be at the top of the file and follow the (optional) namespace declaration. -->
	<rule ref="PSR12.Files.FileHeader.IncorrectOrder"/>

	<!-- Covers rule: Import use statements should follow a specific order based on the type of the import:
		 1. use statements for namespaces, classes, interfaces, traits and enums
		 2. use statements for functions
		 3. use statements for constants -->
	<!-- Not yet covered: use statements which are not part of the file header. -->
	<rule ref="PSR12.Files.FileHeader.IncorrectGrouping"/>

	<!-- Rule: When using aliases, make sure the aliases follow the WordPress naming convention ...
		 https://github.com/WordPress/WordPress-Coding-Standards/issues/2306 -->

	<!-- Covers rule: ... and are unique. -->
	<rule ref="Universal.UseStatements.NoUselessAliases"/>

	<!-- Covers rules: (example based rules, group use formatting, spacing around keywords) -->

	<!-- Implied through the examples: There should be exactly one space before/after keywords. -->
	<!-- Spacing after "use" keyword: covered by the Generic.WhiteSpace.LanguageConstructSpacing sniff. -->
	<rule ref="Universal.UseStatements.KeywordSpacing"/>
	<rule ref="Universal.UseStatements.KeywordSpacing.SpaceAfterUse">
		<severity>0</severity>
	</rule>

	<!-- Implied through the examples: Names in an import use statement should not start with a leading backslash. -->
	<rule ref="Universal.UseStatements.NoLeadingBackslash"/>

	<!-- Implied through the examples: The use, function, const and as keywords should be lowercase.
		 For the "use" and "as" keywords, this is covered via the Generic.PHP.LowerCaseKeyword sniff. -->
	<rule ref="Universal.UseStatements.LowercaseFunctionConst"/>

	<!-- Implied through the examples: When using group use statements, there should be one statement
		 for each type - OO constructs (classes/interfaces/traits), functions, constants.
		 The various types should not be combined in one group use statement. -->
	<rule ref="Universal.UseStatements.DisallowMixedGroupUse"/>


	<!--
	#############################################################################
	Handbook: Object-Oriented Programming - Only One Object Structure (Class/Interface/Trait) per File.
	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#only-one-object-structure-class-interface-trait-per-file
	#############################################################################
	-->
	<!-- Covers rule: Only One Object Structure (Class/Interface/Trait) per file. -->
	<rule ref="Generic.Files.OneObjectStructurePerFile"/>


	<!--
	#############################################################################
	Handbook: Object-Oriented Programming - Trait Use Statements.
	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#trait-use-statements
	#############################################################################
	-->
	<!-- Covers rule: Trait use statements should be at the top of a class ... -->
	<!-- Covered by the PSR12.Traits.UseDeclaration sniff. -->

	<!-- Rule: ... and should have exactly one blank line before the first use statement,
		 and at least one blank line after the last statement.
		 The only exception is when the class only contains trait use statements,
		 in which case the blank line after may be omitted. -->
	<!-- Blank line after covered by the PSR12.Traits.UseDeclaration sniff. -->

	<!-- Covers rule: (example based rules: spacing, grouping and indentation). -->
	<rule ref="PSR12.Traits.UseDeclaration"/>

	<!-- Allow for a blank line between the OO statement and the first trait use statement. -->
	<rule ref="PSR12.Traits.UseDeclaration.UseAfterBrace">
		<severity>0</severity>
	</rule>

	<!-- Prevent duplicate messages - spacing after use is already covered by `Generic.WhiteSpace.LanguageConstructSpacing`. -->
	<rule ref="PSR12.Traits.UseDeclaration.SpaceAfterUse">
		<severity>0</severity>
	</rule>
	<!-- Prevent duplicate messages - spacing around a comma is already covered by `Universal.WhiteSpace.CommaSpacing`. -->
	<rule ref="PSR12.Traits.UseDeclaration.SpaceBeforeComma">
		<severity>0</severity>
	</rule>
	<rule ref="PSR12.Traits.UseDeclaration.SpaceAfterComma">
		<severity>0</severity>
	</rule>


	<!--
	#############################################################################
	Handbook: Object-Oriented Programming - Visibility should always be declared.
	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#visibility-should-always-be-declared
	#############################################################################
	-->
	<!-- Covers rule: For all constructs that allow it (properties, methods, class constants since PHP 7.1),
		 visibility should be explicitly declared.
		 Includes "only one property declaration per statement". -->
	<rule ref="PSR2.Classes.PropertyDeclaration"/>
	<rule ref="PSR2.Classes.PropertyDeclaration.Underscore">
		<severity>0</severity>
	</rule>
	<rule ref="Squiz.Scope.MethodScope"/>

	<!-- Covers rule: Using the var keyword for property declarations is not allowed. -->
	<!-- Covered by the PSR2.Classes.PropertyDeclaration sniff. -->


	<!--
	#############################################################################
	Handbook: Object-Oriented Programming - Visibility and modifier order.
	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#visibility-and-modifier-order
	#############################################################################
	-->
	<!-- Covers rule: When using multiple modifiers for a class declaration, the order should be as follows:
		 - First the optional abstract or final modifier.
		 - Next, the optional readonly modifier. -->
	<rule ref="Universal.Classes.ModifierKeywordOrder"/>

	<!-- Covers rule: When using multiple modifiers for a constant declaration inside object-oriented structures,
		 the order should be as follows:
		 - First the optional final modifier.
		 - Next, the visibility modifier. -->
	<rule ref="Universal.Constants.ModifierKeywordOrder"/>

	<!-- Covers rule: When using multiple modifiers for a property declaration, the order should be as follows:
		 - First a visibility modifier.
		 - Next, the optional static or readonly modifier (these keywords are mutually exclusive).
		 - Finally, the optional type declaration. -->
	<!-- Covered by the PSR2.Classes.PropertyDeclaration sniff. -->

	<!-- Covers rule: When using multiple modifiers for a method declaration, the order should be as follows:
		 - First the optional abstract or final modifier.
		 - Then, a visibility modifier.
		 - Finally, the optional static modifier. -->
	<rule ref="PSR2.Methods.MethodDeclaration"/>
	<rule ref="PSR2.Methods.MethodDeclaration.Underscore">
		<severity>0</severity>
	</rule>

	<!-- Implied through the examples: Single space after each modifier keyword. -->
	<rule ref="Squiz.WhiteSpace.ScopeKeywordSpacing"/>


	<!--
	#############################################################################
	Handbook: Object-Oriented Programming - Object Instantiation.
	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#object-instantiation
	#############################################################################
	-->
	<!-- Covers rule: When instantiating a new object instance, parenthesis must always be used, even when not strictly necessary. -->
	<rule ref="PSR12.Classes.ClassInstantiation"/>
	<rule ref="Universal.Classes.RequireAnonClassParentheses"/>

	<!-- Covers rule: There should be no space between the name of the class being instantiated and the opening parenthesis. -->
	<!-- Covered by the PEAR.Functions.FunctionCallSignature sniff for non-anonymous classes. -->
	<rule ref="Universal.WhiteSpace.AnonClassKeywordSpacing">
		<properties>
			<property name="spacing" value="0"/>
		</properties>
	</rule>


	<!--
	#############################################################################
	Handbook: Control Structures - Use elseif, not else if.
	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#use-elseif-not-else-if
	#############################################################################
	-->
	<!-- Covers rule: ... use elseif for conditionals. -->
	<rule ref="PSR2.ControlStructures.ElseIfDeclaration"/>


	<!--
	#############################################################################
	Handbook: Control Structures - Yoda Conditions.
	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#yoda-conditions
	#############################################################################
	-->
	<!-- Covers rule: When doing logical comparisons involving variables, always put the variable on the right side
		 and put constants, literals, or function calls on the left side. -->
	<rule ref="WordPress.PHP.YodaConditions"/>

	<!-- Rule: Yoda conditions for <, >, <= or >= are significantly more difficult to read
		 and are best avoided. -->


	<!--
	#############################################################################
	Handbook: Operators - Ternary Operator.
	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#ternary-operator
	#############################################################################
	-->
	<!-- Rule: Always have ternaries test if the statement is true, not false.
		 An exception would be using ! empty(), as testing for false here is generally more intuitive.
		 https://github.com/WordPress/WordPress-Coding-Standards/issues/643 -->

	<!-- Covers rule: The short ternary operator must not be used. -->
	<rule ref="Universal.Operators.DisallowShortTernary"/>


	<!--
	#############################################################################
	Handbook: Operators - (No) Error Control Operator @.
	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#error-control-operator
	#############################################################################
	-->
	<!-- Covers rule: This operator is often used lazily instead of doing proper error checking.
		 Its use is highly discouraged. -->
	<rule ref="WordPress.PHP.NoSilencedErrors"/>


	<!--
	#############################################################################
	Handbook: Operators - Increment/decrement operators.
	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#increment-decrement-operators
	#############################################################################
	-->
	<!-- Covers rule: Pre-increment/decrement should be favoured over post-increment/decrement
		 for stand-alone statements. -->
	<rule ref="Universal.Operators.DisallowStandalonePostIncrementDecrement">
		<type>warning</type>
	</rule>


	<!--
	#############################################################################
	Handbook: Database - Database Queries.
	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#database-queries
	#############################################################################
	-->
	<!-- Covers rule: Avoid touching the database directly. -->
	<rule ref="WordPress.DB.RestrictedFunctions"/>
	<rule ref="WordPress.DB.RestrictedClasses"/>


	<!--
	#############################################################################
	Handbook: Database - Formatting SQL statements.
	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#formatting-sql-statements
	#############################################################################
	-->
	<!-- Rule: Always capitalize the SQL parts of the statement like UPDATE or WHERE.
		 https://github.com/WordPress/WordPress-Coding-Standards/issues/639 -->

	<!-- Rule: Functions that update the database should expect their parameters to lack
		 SQL slash escaping when passed.
		 https://github.com/WordPress/WordPress-Coding-Standards/issues/640 -->

	<!-- Covers rule: Escaping should be done as close to the time of the query
		 as possible, preferably by using $wpdb->prepare(). -->
	<rule ref="WordPress.DB.PreparedSQL"/>

	<!-- Covers rule: in $wpdb->prepare - %s is used for string placeholders and %d is used for integer
		 placeholders. Note that they are not 'quoted'! -->
	<rule ref="WordPress.DB.PreparedSQLPlaceholders"/>


	<!--
	#############################################################################
	Handbook: Recommendations - Self-Explanatory Flag Values for Function Arguments.
	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#self-explanatory-flag-values-for-function-arguments
	#############################################################################
	-->


	<!--
	#############################################################################
	Handbook: Recommendations - Clever Code.
	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#clever-code
	#############################################################################
	-->
	<!-- Covers rule: In general, readability is more important than cleverness or brevity.
		 https://github.com/WordPress/WordPress-Coding-Standards/issues/607 -->
	<rule ref="Squiz.PHP.DisallowMultipleAssignments"/>
	<rule ref="Generic.Formatting.DisallowMultipleStatements"/>

	<!-- Covers rule: Unless absolutely necessary, loose comparisons should not be used,
		 as their behaviour can be misleading. -->
	<rule phpcs-only="true" ref="Universal.Operators.StrictComparisons">
		<type>warning</type>
	</rule>
	<rule ref="WordPress.PHP.StrictInArray"/>

	<!-- Covers rule: Assignments must not be placed in conditionals.
		 The "assignment in ternary" part of the sniff is currently not yet covered in
		 the upstream version, which is why there is still a WP native sniff as well. -->
	<rule ref="Generic.CodeAnalysis.AssignmentInCondition"/>
	<rule ref="WordPress.CodeAnalysis.AssignmentInTernaryCondition"/>

	<!-- Covers rule: In a switch statement... If a case contains a block, then falls through
		 to the next block, this must be explicitly commented. -->
	<!-- Covered by the PSR2.ControlStructures.SwitchDeclaration sniff. -->

	<!-- Covers rule: The goto statement must never be used. -->
	<rule ref="Generic.PHP.DiscourageGoto">
		<type>error</type>
		<message>The "goto" language construct should not be used.</message>
	</rule>

	<!-- Covers rule: The eval() construct is very dangerous, and is impossible to secure. ... these must not be used. -->
	<rule ref="Squiz.PHP.Eval.Discouraged">
		<type>error</type>
		<message>eval() is a security risk so not allowed.</message>
	</rule>

	<!-- Covers rule: create_function() function, which internally performs an eval(),
		 is deprecated in PHP 7.2 and has been removed in PHP 8.0. ... these must not be used. -->
	<rule ref="WordPress.PHP.RestrictedPHPFunctions"/>


	<!--
	#############################################################################
	Handbook: Recommendations - Closures.
	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#closures-anonymous-functions
	#############################################################################
	-->
	<!-- Rule: Closures should not be passed as filter or action callbacks.
		 https://github.com/WordPress/WordPress-Coding-Standards/issues/1486 -->


	<!--
	#############################################################################
	Handbook: Recommendations - Regular Expressions.
	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#regular-expressions
	#############################################################################
	-->
	<!-- Covers rule: Perl compatible regular expressions should be used in preference
		 to their POSIX counterparts. -->
	<rule ref="WordPress.PHP.POSIXFunctions"/>

	<!-- Rule: Never use the /e switch, use preg_replace_callback instead.
		 https://github.com/WordPress/WordPress-Coding-Standards/issues/632 -->

	<!-- Covers rule: It's most convenient to use single-quoted strings for regular expressions. -->
	<!-- Covered by the Squiz.Strings.DoubleQuoteUsage sniff. -->


	<!--
	#############################################################################
	Handbook: Recommendations - Don't extract().
	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#dont-extract
	#############################################################################
	-->
	<rule ref="WordPress.PHP.DontExtract"/>


	<!--
	#############################################################################
	Handbook: Recommendations - Shell commands.
	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#shell-commands
	#############################################################################
	-->
	<!-- Covers rule: Use of the backtick operator is not allowed. -->
	<rule ref="Generic.PHP.BacktickOperator"/>


	<!--
	#############################################################################
	Not in the handbook: Generic sniffs.
	#############################################################################
	-->
	<!-- Important to prevent issues with content being sent before headers. -->
	<rule ref="Generic.Files.ByteOrderMark"/>

	<!-- Always have a lowertag PHP open tag. -->
	<rule ref="Universal.PHP.LowercasePHPTag"/>

	<!-- All line endings should be \n. -->
	<rule ref="Generic.Files.LineEndings">
		<properties>
			<property name="eolChar" value="\n"/>
		</properties>
	</rule>

	<!-- All files should end with a new line, but only one. -->
	<rule ref="PSR2.Files.EndFileNewline"/>

	<!-- No whitespace should come before semicolons. -->
	<rule ref="Squiz.WhiteSpace.SemicolonSpacing"/>

	<!-- There should be no empty statements, i.e. lone semi-colons or open/close tags without content. -->
	<rule ref="Generic.CodeAnalysis.EmptyPHPStatement"/>

	<!-- Lowercase PHP constants, like true, false and null. -->
	<!-- https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#naming-conventions -->
	<rule ref="Generic.PHP.LowerCaseConstant"/>

	<!-- Lowercase PHP keywords, like class, function and case. -->
	<rule ref="Generic.PHP.LowerCaseKeyword"/>

	<!-- Class opening braces should be on the same line as the statement. -->
	<rule ref="Generic.Classes.OpeningBraceSameLine"/>

	<!-- Implied via examples: one space after keywords in class declaration, class declaration on one line,
		 close brace on line by itself and no blank lines between OO structure body and close brace. -->
	<rule ref="PSR2.Classes.ClassDeclaration"/>
	<rule ref="PSR2.Classes.ClassDeclaration.OpenBraceNewLine">
		<!-- WP expects open brace on same line as class keyword. -->
		<severity>0</severity>
	</rule>
	<rule ref="PSR2.Classes.ClassDeclaration.OpenBraceWrongLine">
		<!-- WP expects open brace on same line as class keyword. -->
		<severity>0</severity>
	</rule>

	<!-- References to self in a class should be lower-case and not have extraneous spaces,
		 per implicit conventions in the core codebase; the NotUsed code refers to using the
		 fully-qualified class name instead of self, for which there are instances in core. -->
	<rule ref="Squiz.Classes.SelfMemberReference"/>
	<rule ref="Squiz.Classes.SelfMemberReference.NotUsed">
		<severity>0</severity>
	</rule>

	<!-- Error on merge conflict markers. -->
	<rule ref="Generic.VersionControl.GitMergeConflict"/>

	<!--
	#############################################################################
	Not in the coding standard handbook: WP specific sniffs.
	Ref: https://make.wordpress.org/core/handbook/best-practices/internationalization/ (limited info)
	Ref: https://developer.wordpress.org/plugins/internationalization/ (more extensive)
	#############################################################################
	-->
	<!-- Check for correct usage of the WP i18n functions. -->
	<rule ref="WordPress.WP.I18n"/>

	<!-- Check for correct spelling of WordPress. -->
	<rule ref="WordPress.WP.CapitalPDangit"/>

	<!-- Use the appropriate DateTime functions.
		 See: https://github.com/WordPress/WordPress-Coding-Standards/issues/1713 -->
	<rule ref="WordPress.DateTime.RestrictedFunctions"/>

	<!-- Don't use current_time() to retrieve a timestamp. -->
	<rule ref="WordPress.DateTime.CurrentTimeTimestamp"/>

	<!-- Check that class name references use the correct case. -->
	<rule ref="WordPress.WP.ClassNameCase"/>

	<!-- Check that __DIR__ is favoured over dirname(__FILE__)
		 and that dirname( __DIR__, $levels ) is favoured over nested calls to dirname().
		 See: https://core.trac.wordpress.org/ticket/48082 -->
	<rule ref="Modernize.FunctionCalls.Dirname"/>

</ruleset>