Add version validation rule.

src/Validation/Rules/Date_Validation_Rule.php

@@ -61,6 +61,10 @@ public function sanitize( $value ) {
 		try {
 			$this->validate( $value );
 		} catch ( Validation_Exception $e ) {
+			// If a valid string is contained within the overall string, extract it.
+			if ( is_string( $value ) && preg_match( '/\d{4}-\d{2}-\d{2}/', $value, $matches ) ) {
+				return $matches[0];
+			}
 			return '';
 		}
 

src/Validation/Rules/Datetime_Validation_Rule.php

@@ -62,6 +62,17 @@ public function sanitize( $value ) {
 		try {
 			$this->validate( $value );
 		} catch ( Validation_Exception $e ) {
+			// If a valid string is contained within the overall string, extract it.
+			if (
+				is_string( $value )
+				&& preg_match(
+					'/\d{4}-\d{2}-\d{2}[Tt ]\d{2}:\d{2}:\d{2}(?:\.\d+)?(?:Z|[+-]\d{2}(?::\d{2})?)?/',
+					$value,
+					$matches
+				)
+			) {
+				return $matches[0];
+			}
 			return '';
 		}
 

src/Validation/Rules/Version_Validation_Rule.php

@@ -0,0 +1,84 @@
+<?php
+/**
+ * Class Felix_Arntz\WP_OOP_Plugin_Lib\Validation\Rules\Version_Validation_Rule
+ *
+ * @since n.e.x.t
+ * @package wp-oop-plugin-lib
+ */
+
+namespace Felix_Arntz\WP_OOP_Plugin_Lib\Validation\Rules;
+
+use Felix_Arntz\WP_OOP_Plugin_Lib\Validation\Contracts\Types;
+use Felix_Arntz\WP_OOP_Plugin_Lib\Validation\Contracts\Validation_Rule;
+use Felix_Arntz\WP_OOP_Plugin_Lib\Validation\Contracts\With_Type_Support;
+use Felix_Arntz\WP_OOP_Plugin_Lib\Validation\Exception\Validation_Exception;
+use Felix_Arntz\WP_OOP_Plugin_Lib\Validation\Traits\Type_Support;
+
+/**
+ * Class for a validation rule that ensures values are valid version numbers.
+ *
+ * @since n.e.x.t
+ */
+class Version_Validation_Rule implements Validation_Rule, With_Type_Support {
+	use Type_Support;
+
+	/**
+	 * Validates the given value.
+	 *
+	 * Validation will be strict and throw an exception for any unmet requirements.
+	 *
+	 * @since n.e.x.t
+	 *
+	 * @param mixed $value Value to validate.
+	 *
+	 * @throws Validation_Exception Thrown when validation fails.
+	 */
+	public function validate( $value ): void {
+		if ( ! preg_match( '/^(\d+\.\d+(?:\.\d+)?)(-[A-Za-z0-9.]+)?$/', (string) $value ) ) {
+			throw Validation_Exception::create(
+				'invalid_version',
+				sprintf(
+					/* translators: %s: value */
+					esc_html__( '%s is not a valid version number.', 'wp-oop-plugin-lib' ),
+					esc_html( (string) $value )
+				)
+			);
+		}
+	}
+
+	/**
+	 * Sanitizes the given value.
+	 *
+	 * This should be called before storing the value in the persistency layer (e.g. the database).
+	 * If the value does not satisfy validation requirements, it will be sanitized to a value that does, e.g. a default.
+	 *
+	 * @since n.e.x.t
+	 *
+	 * @param mixed $value Value to sanitize.
+	 * @return mixed Sanitized value.
+	 */
+	public function sanitize( $value ) {
+		try {
+			$this->validate( $value );
+		} catch ( Validation_Exception $e ) {
+			// If a valid string is contained within the overall string, extract it.
+			if ( is_string( $value ) && preg_match( '/^(\d+\.\d+(?:\.\d+)?)(-[A-Za-z0-9.]+)?$/', $value, $matches ) ) {
+				return $matches[0];
+			}
+			return '';
+		}
+
+		return sanitize_url( $value );
+	}
+
+	/**
+	 * Gets the supported types for the validation rule.
+	 *
+	 * @since n.e.x.t
+	 *
+	 * @return int One or more of the type constants from the Types interface, combined with a bitwise OR.
+	 */
+	protected function get_supported_types(): int {
+		return Types::TYPE_STRING;
+	}
+}

src/Validation/String_Validation_Rule_Builder.php

@@ -20,6 +20,7 @@
 use Felix_Arntz\WP_OOP_Plugin_Lib\Validation\Rules\Regexp_Validation_Rule;
 use Felix_Arntz\WP_OOP_Plugin_Lib\Validation\Rules\String_Validation_Rule;
 use Felix_Arntz\WP_OOP_Plugin_Lib\Validation\Rules\URL_Validation_Rule;
+use Felix_Arntz\WP_OOP_Plugin_Lib\Validation\Rules\Version_Validation_Rule;
 
 /**
  * Class for a string validation rule builder.
@@ -77,6 +78,17 @@ public function format_email(): static {
 		return $this->with_rule( new Email_Validation_Rule() );
 	}
 
+	/**
+	 * Adds a version validation rule.
+	 *
+	 * @since n.e.x.t
+	 *
+	 * @return static Builder instance for chaining.
+	 */
+	public function format_version(): static {
+		return $this->with_rule( new Version_Validation_Rule() );
+	}
+
 	/**
 	 * Adds a hex color validation rule.
 	 *