Merged in feature/from-pantheon (pull request #16)

code from pantheon

* code from pantheon

wp/wp-content/plugins/contact-form-7/includes/swv/rules/dayofweek.php

@@ -0,0 +1,48 @@
+<?php
+
+class WPCF7_SWV_DayofweekRule extends WPCF7_SWV_Rule {
+
+	const rule_name = 'dayofweek';
+
+	public function matches( $context ) {
+		if ( false === parent::matches( $context ) ) {
+			return false;
+		}
+
+		if ( empty( $context['text'] ) ) {
+			return false;
+		}
+
+		return true;
+	}
+
+	public function validate( $context ) {
+		$field = $this->get_property( 'field' );
+
+		$input = isset( $_POST[$field] ) ? $_POST[$field] : '';
+
+		$input = wpcf7_array_flatten( $input );
+		$input = wpcf7_exclude_blank( $input );
+
+		$acceptable_values = (array) $this->get_property( 'accept' );
+		$acceptable_values = array_map( 'intval', $acceptable_values );
+		$acceptable_values = array_filter( $acceptable_values );
+		$acceptable_values = array_unique( $acceptable_values );
+
+		foreach ( $input as $i ) {
+			if ( wpcf7_is_date( $i ) ) {
+				$datetime = date_create_immutable( $i, wp_timezone() );
+				$dow = (int) $datetime->format( 'N' );
+
+				if ( ! in_array( $dow, $acceptable_values, true ) ) {
+					return new WP_Error( 'wpcf7_invalid_dayofweek',
+						$this->get_property( 'error' )
+					);
+				}
+			}
+		}
+
+		return true;
+	}
+
+}