Merge "Vector: Update comments in vector.js"

[mediawiki.git] / includes / htmlform / HTMLFormField.php

<?php

/**
 * The parent class to generate form fields.  Any field type should
 * be a subclass of this.
 */
abstract class HTMLFormField {
        public $mParams;

        protected $mValidationCallback;
        protected $mFilterCallback;
        protected $mName;
        protected $mLabel; # String label.  Set on construction
        protected $mID;
        protected $mClass = '';
        protected $mDefault;
        protected $mOptions = false;
        protected $mOptionsLabelsNotFromMessage = false;
        protected $mHideIf = null;

        /**
         * @var bool If true will generate an empty div element with no label
         * @since 1.22
         */
        protected $mShowEmptyLabels = true;

        /**
         * @var HTMLForm
         */
        public $mParent;

        /**
         * This function must be implemented to return the HTML to generate
         * the input object itself.  It should not implement the surrounding
         * table cells/rows, or labels/help messages.
         *
         * @param string $value the value to set the input to; eg a default
         *     text for a text input.
         *
         * @return string Valid HTML.
         */
        abstract function getInputHTML( $value );

        /**
         * Get a translated interface message
         *
         * This is a wrapper around $this->mParent->msg() if $this->mParent is set
         * and wfMessage() otherwise.
         *
         * Parameters are the same as wfMessage().
         *
         * @return Message
         */
        function msg() {
                $args = func_get_args();

                if ( $this->mParent ) {
                        $callback = array( $this->mParent, 'msg' );
                } else {
                        $callback = 'wfMessage';
                }

                return call_user_func_array( $callback, $args );
        }


        /**
         * Fetch a field value from $alldata for the closest field matching a given
         * name.
         *
         * This is complex because it needs to handle array fields like the user
         * would expect. The general algorithm is to look for $name as a sibling
         * of $this, then a sibling of $this's parent, and so on. Keeping in mind
         * that $name itself might be referencing an array.
         *
         * @param array $alldata
         * @param string $name
         * @return string
         */
        protected function getNearestFieldByName( $alldata, $name ) {
                $tmp = $this->mName;
                $thisKeys = array();
                while ( preg_match( '/^(.+)\[([^\]]+)\]$/', $tmp, $m ) ) {
                        array_unshift( $thisKeys, $m[2] );
                        $tmp = $m[1];
                }
                if ( substr( $tmp, 0, 2 ) == 'wp' &&
                        !isset( $alldata[$tmp] ) &&
                        isset( $alldata[substr( $tmp, 2 )] )
                ) {
                        // Adjust for name mangling.
                        $tmp = substr( $tmp, 2 );
                }
                array_unshift( $thisKeys, $tmp );

                $tmp = $name;
                $nameKeys = array();
                while ( preg_match( '/^(.+)\[([^\]]+)\]$/', $tmp, $m ) ) {
                        array_unshift( $nameKeys, $m[2] );
                        $tmp = $m[1];
                }
                array_unshift( $nameKeys, $tmp );

                $testValue = '';
                for ( $i = count( $thisKeys ) - 1; $i >= 0; $i-- ) {
                        $keys = array_merge( array_slice( $thisKeys, 0, $i ), $nameKeys );
                        $data = $alldata;
                        while ( $keys ) {
                                $key = array_shift( $keys );
                                if ( !is_array( $data ) || !isset( $data[$key] ) ) {
                                        continue 2;
                                }
                                $data = $data[$key];
                        }
                        $testValue = $data;
                        break;
                }

                return $testValue;
        }

        /**
         * Helper function for isHidden to handle recursive data structures.
         *
         * @param array $alldata
         * @param array $params
         * @return boolean
         */
        protected function isHiddenRecurse( array $alldata, array $params ) {
                $origParams = $params;
                $op = array_shift( $params );

                try {
                        switch ( $op ) {
                                case 'AND':
                                        foreach ( $params as $i => $p ) {
                                                if ( !is_array( $p ) ) {
                                                        throw new MWException(
                                                                "Expected array, found " . gettype( $p ) . " at index $i"
                                                        );
                                                }
                                                if ( !$this->isHiddenRecurse( $alldata, $p ) ) {
                                                        return false;
                                                }
                                        }
                                        return true;

                                case 'OR':
                                        foreach ( $params as $p ) {
                                                if ( !is_array( $p ) ) {
                                                        throw new MWException(
                                                                "Expected array, found " . gettype( $p ) . " at index $i"
                                                        );
                                                }
                                                if ( $this->isHiddenRecurse( $alldata, $p ) ) {
                                                        return true;
                                                }
                                        }
                                        return false;

                                case 'NAND':
                                        foreach ( $params as $i => $p ) {
                                                if ( !is_array( $p ) ) {
                                                        throw new MWException(
                                                                "Expected array, found " . gettype( $p ) . " at index $i"
                                                        );
                                                }
                                                if ( !$this->isHiddenRecurse( $alldata, $p ) ) {
                                                        return true;
                                                }
                                        }
                                        return false;

                                case 'NOR':
                                        foreach ( $params as $p ) {
                                                if ( !is_array( $p ) ) {
                                                        throw new MWException(
                                                                "Expected array, found " . gettype( $p ) . " at index $i"
                                                        );
                                                }
                                                if ( $this->isHiddenRecurse( $alldata, $p ) ) {
                                                        return false;
                                                }
                                        }
                                        return true;

                                case 'NOT':
                                        if ( count( $params ) !== 1 ) {
                                                throw new MWException( "NOT takes exactly one parameter" );
                                        }
                                        $p = $params[0];
                                        if ( !is_array( $p ) ) {
                                                throw new MWException(
                                                        "Expected array, found " . gettype( $p ) . " at index 0"
                                                );
                                        }
                                        return !$this->isHiddenRecurse( $alldata, $p );

                                case '===':
                                case '!==':
                                        if ( count( $params ) !== 2 ) {
                                                throw new MWException( "$op takes exactly two parameters" );
                                        }
                                        list( $field, $value ) = $params;
                                        if ( !is_string( $field ) || !is_string( $value ) ) {
                                                throw new MWException( "Parameters for $op must be strings" );
                                        }
                                        $testValue = $this->getNearestFieldByName( $alldata, $field );
                                        switch ( $op ) {
                                                case '===':
                                                        return ( $value === $testValue );
                                                case '!==':
                                                        return ( $value !== $testValue );
                                        }

                                default:
                                        throw new MWException( "Unknown operation" );
                        }
                } catch ( MWException $ex ) {
                        throw new MWException(
                                "Invalid hide-if specification for $this->mName: " .
                                $ex->getMessage() . " in " . var_export( $origParams, true ),
                                0, $ex
                        );
                }
        }

        /**
         * Test whether this field is supposed to be hidden, based on the values of
         * the other form fields.
         *
         * @since 1.23
         * @param array $alldata The data collected from the form
         * @return bool
         */
        function isHidden( $alldata ) {
                if ( !$this->mHideIf ) {
                        return false;
                }

                return $this->isHiddenRecurse( $alldata, $this->mHideIf );
        }

        /**
         * Override this function if the control can somehow trigger a form
         * submission that shouldn't actually submit the HTMLForm.
         *
         * @since 1.23
         * @param string|array $value The value the field was submitted with
         * @param array $alldata The data collected from the form
         *
         * @return bool true to cancel the submission
         */
        function cancelSubmit( $value, $alldata ) {
                return false;
        }

        /**
         * Override this function to add specific validation checks on the
         * field input.  Don't forget to call parent::validate() to ensure
         * that the user-defined callback mValidationCallback is still run
         *
         * @param string|array $value The value the field was submitted with
         * @param array $alldata The data collected from the form
         *
         * @return bool|string true on success, or String error to display, or
         *   false to fail validation without displaying an error.
         */
        function validate( $value, $alldata ) {
                if ( $this->isHidden( $alldata ) ) {
                        return true;
                }

                if ( isset( $this->mParams['required'] )
                        && $this->mParams['required'] !== false
                        && $value === ''
                ) {
                        return $this->msg( 'htmlform-required' )->parse();
                }

                if ( isset( $this->mValidationCallback ) ) {
                        return call_user_func( $this->mValidationCallback, $value, $alldata, $this->mParent );
                }

                return true;
        }

        function filter( $value, $alldata ) {
                if ( isset( $this->mFilterCallback ) ) {
                        $value = call_user_func( $this->mFilterCallback, $value, $alldata, $this->mParent );
                }

                return $value;
        }

        /**
         * Should this field have a label, or is there no input element with the
         * appropriate id for the label to point to?
         *
         * @return bool True to output a label, false to suppress
         */
        protected function needsLabel() {
                return true;
        }

        /**
         * Tell the field whether to generate a separate label element if its label
         * is blank.
         *
         * @since 1.22
         *
         * @param bool $show Set to false to not generate a label.
         * @return void
         */
        public function setShowEmptyLabel( $show ) {
                $this->mShowEmptyLabels = $show;
        }

        /**
         * Get the value that this input has been set to from a posted form,
         * or the input's default value if it has not been set.
         *
         * @param WebRequest $request
         * @return string The value
         */
        function loadDataFromRequest( $request ) {
                if ( $request->getCheck( $this->mName ) ) {
                        return $request->getText( $this->mName );
                } else {
                        return $this->getDefault();
                }
        }

        /**
         * Initialise the object
         *
         * @param array $params Associative Array. See HTMLForm doc for syntax.
         *
         * @since 1.22 The 'label' attribute no longer accepts raw HTML, use 'label-raw' instead
         * @throws MWException
         */
        function __construct( $params ) {
                $this->mParams = $params;

                # Generate the label from a message, if possible
                if ( isset( $params['label-message'] ) ) {
                        $msgInfo = $params['label-message'];

                        if ( is_array( $msgInfo ) ) {
                                $msg = array_shift( $msgInfo );
                        } else {
                                $msg = $msgInfo;
                                $msgInfo = array();
                        }

                        $this->mLabel = wfMessage( $msg, $msgInfo )->parse();
                } elseif ( isset( $params['label'] ) ) {
                        if ( $params['label'] === '&#160;' ) {
                                // Apparently some things set &nbsp directly and in an odd format
                                $this->mLabel = '&#160;';
                        } else {
                                $this->mLabel = htmlspecialchars( $params['label'] );
                        }
                } elseif ( isset( $params['label-raw'] ) ) {
                        $this->mLabel = $params['label-raw'];
                }

                $this->mName = "wp{$params['fieldname']}";
                if ( isset( $params['name'] ) ) {
                        $this->mName = $params['name'];
                }

                $validName = Sanitizer::escapeId( $this->mName );
                $validName = str_replace( array( '.5B', '.5D' ), array( '[', ']' ), $validName );
                if ( $this->mName != $validName && !isset( $params['nodata'] ) ) {
                        throw new MWException( "Invalid name '{$this->mName}' passed to " . __METHOD__ );
                }

                $this->mID = "mw-input-{$this->mName}";

                if ( isset( $params['default'] ) ) {
                        $this->mDefault = $params['default'];
                }

                if ( isset( $params['id'] ) ) {
                        $id = $params['id'];
                        $validId = Sanitizer::escapeId( $id );

                        if ( $id != $validId ) {
                                throw new MWException( "Invalid id '$id' passed to " . __METHOD__ );
                        }

                        $this->mID = $id;
                }

                if ( isset( $params['cssclass'] ) ) {
                        $this->mClass = $params['cssclass'];
                }

                if ( isset( $params['validation-callback'] ) ) {
                        $this->mValidationCallback = $params['validation-callback'];
                }

                if ( isset( $params['filter-callback'] ) ) {
                        $this->mFilterCallback = $params['filter-callback'];
                }

                if ( isset( $params['flatlist'] ) ) {
                        $this->mClass .= ' mw-htmlform-flatlist';
                }

                if ( isset( $params['hidelabel'] ) ) {
                        $this->mShowEmptyLabels = false;
                }

                if ( isset( $params['hide-if'] ) ) {
                        $this->mHideIf = $params['hide-if'];
                }
        }

        /**
         * Get the complete table row for the input, including help text,
         * labels, and whatever.
         *
         * @param string $value The value to set the input to.
         *
         * @return string Complete HTML table row.
         */
        function getTableRow( $value ) {
                list( $errors, $errorClass ) = $this->getErrorsAndErrorClass( $value );
                $inputHtml = $this->getInputHTML( $value );
                $fieldType = get_class( $this );
                $helptext = $this->getHelpTextHtmlTable( $this->getHelpText() );
                $cellAttributes = array();
                $rowAttributes = array();
                $rowClasses = '';

                if ( !empty( $this->mParams['vertical-label'] ) ) {
                        $cellAttributes['colspan'] = 2;
                        $verticalLabel = true;
                } else {
                        $verticalLabel = false;
                }

                $label = $this->getLabelHtml( $cellAttributes );

                $field = Html::rawElement(
                        'td',
                        array( 'class' => 'mw-input' ) + $cellAttributes,
                        $inputHtml . "\n$errors"
                );

                if ( $this->mHideIf ) {
                        $rowAttributes['data-hide-if'] = FormatJson::encode( $this->mHideIf );
                        $rowClasses .= ' mw-htmlform-hide-if';
                }

                if ( $verticalLabel ) {
                        $html = Html::rawElement( 'tr',
                                $rowAttributes + array( 'class' => "mw-htmlform-vertical-label $rowClasses" ), $label );
                        $html .= Html::rawElement( 'tr',
                                $rowAttributes + array(
                                        'class' => "mw-htmlform-field-$fieldType {$this->mClass} $errorClass $rowClasses"
                                ),
                                $field );
                } else {
                        $html =
                                Html::rawElement( 'tr',
                                        $rowAttributes + array(
                                                'class' => "mw-htmlform-field-$fieldType {$this->mClass} $errorClass $rowClasses"
                                        ),
                                        $label . $field );
                }

                return $html . $helptext;
        }

        /**
         * Get the complete div for the input, including help text,
         * labels, and whatever.
         * @since 1.20
         *
         * @param string $value The value to set the input to.
         *
         * @return string Complete HTML table row.
         */
        public function getDiv( $value ) {
                list( $errors, $errorClass ) = $this->getErrorsAndErrorClass( $value );
                $inputHtml = $this->getInputHTML( $value );
                $fieldType = get_class( $this );
                $helptext = $this->getHelpTextHtmlDiv( $this->getHelpText() );
                $cellAttributes = array();
                $label = $this->getLabelHtml( $cellAttributes );

                $outerDivClass = array(
                        'mw-input',
                        'mw-htmlform-nolabel' => ( $label === '' )
                );

                $field = Html::rawElement(
                        'div',
                        array( 'class' => $outerDivClass ) + $cellAttributes,
                        $inputHtml . "\n$errors"
                );
                $divCssClasses = array( "mw-htmlform-field-$fieldType", $this->mClass, $errorClass );
                if ( $this->mParent->isVForm() ) {
                        $divCssClasses[] = 'mw-ui-vform-div';
                }

                $wrapperAttributes = array(
                        'class' => $divCssClasses,
                );
                if ( $this->mHideIf ) {
                        $wrapperAttributes['data-hide-if'] = FormatJson::encode( $this->mHideIf );
                        $wrapperAttributes['class'][] = ' mw-htmlform-hide-if';
                }
                $html = Html::rawElement( 'div', $wrapperAttributes, $label . $field );
                $html .= $helptext;

                return $html;
        }

        /**
         * Get the complete raw fields for the input, including help text,
         * labels, and whatever.
         * @since 1.20
         *
         * @param string $value The value to set the input to.
         *
         * @return string Complete HTML table row.
         */
        public function getRaw( $value ) {
                list( $errors, ) = $this->getErrorsAndErrorClass( $value );
                $inputHtml = $this->getInputHTML( $value );
                $helptext = $this->getHelpTextHtmlRaw( $this->getHelpText() );
                $cellAttributes = array();
                $label = $this->getLabelHtml( $cellAttributes );

                $html = "\n$errors";
                $html .= $label;
                $html .= $inputHtml;
                $html .= $helptext;

                return $html;
        }

        /**
         * Generate help text HTML in table format
         * @since 1.20
         *
         * @param string|null $helptext
         * @return string
         */
        public function getHelpTextHtmlTable( $helptext ) {
                if ( is_null( $helptext ) ) {
                        return '';
                }

                $rowAttributes = array();
                if ( $this->mHideIf ) {
                        $rowAttributes['data-hide-if'] = FormatJson::encode( $this->mHideIf );
                        $rowAttributes['class'] = 'mw-htmlform-hide-if';
                }

                $row = Html::rawElement( 'td', array( 'colspan' => 2, 'class' => 'htmlform-tip' ), $helptext );
                $row = Html::rawElement( 'tr', $rowAttributes, $row );

                return $row;
        }

        /**
         * Generate help text HTML in div format
         * @since 1.20
         *
         * @param string|null $helptext
         *
         * @return string
         */
        public function getHelpTextHtmlDiv( $helptext ) {
                if ( is_null( $helptext ) ) {
                        return '';
                }

                $wrapperAttributes = array(
                        'class' => 'htmlform-tip',
                );
                if ( $this->mHideIf ) {
                        $wrapperAttributes['data-hide-if'] = FormatJson::encode( $this->mHideIf );
                        $wrapperAttributes['class'] .= ' mw-htmlform-hide-if';
                }
                $div = Html::rawElement( 'div', $wrapperAttributes, $helptext );

                return $div;
        }

        /**
         * Generate help text HTML formatted for raw output
         * @since 1.20
         *
         * @param string|null $helptext
         * @return string
         */
        public function getHelpTextHtmlRaw( $helptext ) {
                return $this->getHelpTextHtmlDiv( $helptext );
        }

        /**
         * Determine the help text to display
         * @since 1.20
         * @return string
         */
        public function getHelpText() {
                $helptext = null;

                if ( isset( $this->mParams['help-message'] ) ) {
                        $this->mParams['help-messages'] = array( $this->mParams['help-message'] );
                }

                if ( isset( $this->mParams['help-messages'] ) ) {
                        foreach ( $this->mParams['help-messages'] as $name ) {
                                $helpMessage = (array)$name;
                                $msg = $this->msg( array_shift( $helpMessage ), $helpMessage );

                                if ( $msg->exists() ) {
                                        if ( is_null( $helptext ) ) {
                                                $helptext = '';
                                        } else {
                                                $helptext .= $this->msg( 'word-separator' )->escaped(); // some space
                                        }
                                        $helptext .= $msg->parse(); // Append message
                                }
                        }
                } elseif ( isset( $this->mParams['help'] ) ) {
                        $helptext = $this->mParams['help'];
                }

                return $helptext;
        }

        /**
         * Determine form errors to display and their classes
         * @since 1.20
         *
         * @param string $value The value of the input
         * @return array
         */
        public function getErrorsAndErrorClass( $value ) {
                $errors = $this->validate( $value, $this->mParent->mFieldData );

                if ( is_bool( $errors ) || !$this->mParent->wasSubmitted() ) {
                        $errors = '';
                        $errorClass = '';
                } else {
                        $errors = self::formatErrors( $errors );
                        $errorClass = 'mw-htmlform-invalid-input';
                }

                return array( $errors, $errorClass );
        }

        function getLabel() {
                return is_null( $this->mLabel ) ? '' : $this->mLabel;
        }

        function getLabelHtml( $cellAttributes = array() ) {
                # Don't output a for= attribute for labels with no associated input.
                # Kind of hacky here, possibly we don't want these to be <label>s at all.
                $for = array();

                if ( $this->needsLabel() ) {
                        $for['for'] = $this->mID;
                }

                $labelValue = trim( $this->getLabel() );
                $hasLabel = false;
                if ( $labelValue !== '&#160;' && $labelValue !== '' ) {
                        $hasLabel = true;
                }

                $displayFormat = $this->mParent->getDisplayFormat();
                $html = '';

                if ( $displayFormat === 'table' ) {
                        $html =
                                Html::rawElement( 'td',
                                        array( 'class' => 'mw-label' ) + $cellAttributes,
                                        Html::rawElement( 'label', $for, $labelValue ) );
                } elseif ( $hasLabel || $this->mShowEmptyLabels ) {
                        if ( $displayFormat === 'div' ) {
                                $html =
                                        Html::rawElement( 'div',
                                                array( 'class' => 'mw-label' ) + $cellAttributes,
                                                Html::rawElement( 'label', $for, $labelValue ) );
                        } else {
                                $html = Html::rawElement( 'label', $for, $labelValue );
                        }
                }

                return $html;
        }

        function getDefault() {
                if ( isset( $this->mDefault ) ) {
                        return $this->mDefault;
                } else {
                        return null;
                }
        }

        /**
         * Returns the attributes required for the tooltip and accesskey.
         *
         * @return array Attributes
         */
        public function getTooltipAndAccessKey() {
                if ( empty( $this->mParams['tooltip'] ) ) {
                        return array();
                }

                return Linker::tooltipAndAccesskeyAttribs( $this->mParams['tooltip'] );
        }

        /**
         * Returns the given attributes from the parameters
         *
         * @param array $list List of attributes to get
         * @return array Attributes
         */
        public function getAttributes( array $list ) {
                static $boolAttribs = array( 'disabled', 'required', 'autofocus', 'multiple', 'readonly' );

                $ret = array();

                foreach ( $list as $key ) {
                        if ( in_array( $key, $boolAttribs ) ) {
                                if ( !empty( $this->mParams[$key] ) ) {
                                        $ret[$key] = '';
                                }
                        } elseif ( isset( $this->mParams[$key] ) ) {
                                $ret[$key] = $this->mParams[$key];
                        }
                }

                return $ret;
        }

        /**
         * Given an array of msg-key => value mappings, returns an array with keys
         * being the message texts. It also forces values to strings.
         *
         * @param array $options
         * @return array
         */
        private function lookupOptionsKeys( $options ) {
                $ret = array();
                foreach ( $options as $key => $value ) {
                        $key = $this->msg( $key )->plain();
                        $ret[$key] = is_array( $value )
                                ? $this->lookupOptionsKeys( $value )
                                : strval( $value );
                }
                return $ret;
        }

        /**
         * Recursively forces values in an array to strings, because issues arise
         * with integer 0 as a value.
         *
         * @param array $array
         * @return array
         */
        static function forceToStringRecursive( $array ) {
                if ( is_array( $array ) ) {
                        return array_map( array( __CLASS__, 'forceToStringRecursive' ), $array );
                } else {
                        return strval( $array );
                }
        }

        /**
         * Fetch the array of options from the field's parameters. In order, this
         * checks 'options-messages', 'options', then 'options-message'.
         *
         * @return array|null Options array
         */
        public function getOptions() {
                if ( $this->mOptions === false ) {
                        if ( array_key_exists( 'options-messages', $this->mParams ) ) {
                                $this->mOptions = $this->lookupOptionsKeys( $this->mParams['options-messages'] );
                        } elseif ( array_key_exists( 'options', $this->mParams ) ) {
                                $this->mOptionsLabelsNotFromMessage = true;
                                $this->mOptions = self::forceToStringRecursive( $this->mParams['options'] );
                        } elseif ( array_key_exists( 'options-message', $this->mParams ) ) {
                                /** @todo This is copied from Xml::listDropDown(), deprecate/avoid duplication? */
                                $message = $this->msg( $this->mParams['options-message'] )->inContentLanguage()->plain();

                                $optgroup = false;
                                $this->mOptions = array();
                                foreach ( explode( "\n", $message ) as $option ) {
                                        $value = trim( $option );
                                        if ( $value == '' ) {
                                                continue;
                                        } elseif ( substr( $value, 0, 1 ) == '*' && substr( $value, 1, 1 ) != '*' ) {
                                                # A new group is starting...
                                                $value = trim( substr( $value, 1 ) );
                                                $optgroup = $value;
                                        } elseif ( substr( $value, 0, 2 ) == '**' ) {
                                                # groupmember
                                                $opt = trim( substr( $value, 2 ) );
                                                if ( $optgroup === false ) {
                                                        $this->mOptions[$opt] = $opt;
                                                } else {
                                                        $this->mOptions[$optgroup][$opt] = $opt;
                                                }
                                        } else {
                                                # groupless reason list
                                                $optgroup = false;
                                                $this->mOptions[$option] = $option;
                                        }
                                }
                        } else {
                                $this->mOptions = null;
                        }
                }

                return $this->mOptions;
        }

        /**
         * flatten an array of options to a single array, for instance,
         * a set of "<options>" inside "<optgroups>".
         *
         * @param array $options Associative Array with values either Strings or Arrays
         * @return array Flattened input
         */
        public static function flattenOptions( $options ) {
                $flatOpts = array();

                foreach ( $options as $value ) {
                        if ( is_array( $value ) ) {
                                $flatOpts = array_merge( $flatOpts, self::flattenOptions( $value ) );
                        } else {
                                $flatOpts[] = $value;
                        }
                }

                return $flatOpts;
        }

        /**
         * Formats one or more errors as accepted by field validation-callback.
         *
         * @param string|Message|array $errors Array of strings or Message instances
         * @return string HTML
         * @since 1.18
         */
        protected static function formatErrors( $errors ) {
                if ( is_array( $errors ) && count( $errors ) === 1 ) {
                        $errors = array_shift( $errors );
                }

                if ( is_array( $errors ) ) {
                        $lines = array();
                        foreach ( $errors as $error ) {
                                if ( $error instanceof Message ) {
                                        $lines[] = Html::rawElement( 'li', array(), $error->parse() );
                                } else {
                                        $lines[] = Html::rawElement( 'li', array(), $error );
                                }
                        }

                        return Html::rawElement( 'ul', array( 'class' => 'error' ), implode( "\n", $lines ) );
                } else {
                        if ( $errors instanceof Message ) {
                                $errors = $errors->parse();
                        }

                        return Html::rawElement( 'span', array( 'class' => 'error' ), $errors );
                }
        }
}