framework/i18n/PhpMessageSource.php
protected function getMessageFilePath($category, $language)
    {
        $messageFile = Yii::getAlias($this->basePath) . "/$language/";
        if (isset($this->fileMap[$category])) {
            $messageFile .= $this->fileMap[$category];
        } else {
            $messageFile .= str_replace('\\', '/', $category) . '.php';
        }

        return $messageFile;
    }
protected function getMessageFilePath($category, $language)
    {
        $messageFile = Yii::getAlias($this->basePath) . "/$language/";
        if (isset($this->fileMap[$category])) {
            $messageFile .= $this->fileMap[$category];
        } else {
            $messageFile .= str_replace('\\', '/', $category) . '.php';
        }

        return $messageFile;
    }
Returns message file path for the specified language and category.

@param string $category the message category
@param string $language the target language
@return string path to message file