WP_CLI

Inflector::singularize │ public static │ WP-CLI 1.0

Returns a word in singular form.

Method of the class: Inflector{}

No Hooks.

Returns

String. The word in singular form.

Usage

$result = Inflector::singularize( $word );
$word(string) (required)
The word in plural form.

Inflector::singularize() code WP-CLI 2.13.0-alpha

wp-cli/php/WP_CLI/Inflector.php 
public static function singularize( $word ) {
	if ( isset( self::$cache['singularize'][ $word ] ) ) {
		return self::$cache['singularize'][ $word ];
	}

	if ( ! isset( self::$singular['merged']['uninflected'] ) ) {
		self::$singular['merged']['uninflected'] = array_merge(
			self::$singular['uninflected'],
			self::$uninflected
		);
	}

	if ( ! isset( self::$singular['merged']['irregular'] ) ) {
		self::$singular['merged']['irregular'] = array_merge(
			self::$singular['irregular'],
			array_flip( self::$plural['irregular'] )
		);
	}

	if ( ! isset( self::$singular['cacheUninflected'] ) || ! isset( self::$singular['cacheIrregular'] ) ) {
		self::$singular['cacheUninflected'] = '(?:' . join( '|', self::$singular['merged']['uninflected'] ) . ')';
		self::$singular['cacheIrregular']   = '(?:' . join( '|', array_keys( self::$singular['merged']['irregular'] ) ) . ')';
	}

	if ( preg_match( '/(.*)\\b(' . self::$singular['cacheIrregular'] . ')$/i', $word, $regs ) ) {
		self::$cache['singularize'][ $word ] = $regs[1] . substr( $word, 0, 1 ) . substr( self::$singular['merged']['irregular'][ strtolower( $regs[2] ) ], 1 );

		return self::$cache['singularize'][ $word ];
	}

	if ( preg_match( '/^(' . self::$singular['cacheUninflected'] . ')$/i', $word, $regs ) ) {
		self::$cache['singularize'][ $word ] = $word;

		return $word;
	}

	foreach ( self::$singular['rules'] as $rule => $replacement ) {
		if ( preg_match( $rule, $word ) ) {
			self::$cache['singularize'][ $word ] = preg_replace( $rule, $replacement, $word );

			return self::$cache['singularize'][ $word ];
		}
	}

	self::$cache['singularize'][ $word ] = $word;

	return $word;
}