为什么 switch（true） 的 NPath 复杂度比 if（） elseif（） 要小？
2022-08-31 01:18:14
我有这个函数，负责将文件名和哑剧类型转换为更“人性化”的东西（例如file.png，image/ png到[Image，PNG]）。我发现有趣的是，语句组的 NPath 复杂性高于语句。if() elseif()switch(true)
使用以下代码，PHP Mess Detector 输出 NPath 4410：
public function humanKind()
{
$typeRA = explode("/", strtolower($this->type));
$fileRA = explode(".", $this->name);
$fileType = strtoupper($fileRA[count($fileRA) - 1]);
switch($typeRA[0]) {
case "image":
$humanType = "Image";
break;
case "video":
$humanType = "Video";
break;
case "audio":
$humanType = "Sound";
break;
case "font":
$humanType = "Font";
break;
default:
$humanType = "File";
}
switch ($this->type) {
case "application/msword":
case "application/pdf":
case "applicaiton/wordperfect":
case "text/plain":
case "text/rtf":
case "image/vnd.photoshop":
case "image/psd":
case "image/vnd.adobe.photoshop":
case "image/x-photoshop":
case "application/xml":
case "application/x-mspublisher":
case "text/html":
case "application/xhtml+xml":
case "text/richtext":
case "application/rtf":
case "application/x-iwork-pages-sffpages":
case "application/vnd.apple.pages":
$humanType = "Document";
break;
case "application/vnd.ms-excel":
case "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet":
case "application/x-iwork-numbers-sffnumbers":
case "application/vnd.apple.numbers":
$humanType = "Spreadsheet";
break;
case "application/vnd.ms-powerpoint":
case "application/vnd.openxmlformats-officedocument.presentationml.presentation":
case "application/vnd.openxmlformats-officedocument.presentationml.slideshow":
case "application/x-iwork-keynote-sffkey":
case "application/vnd.apple.keynote":
$humanType = "Slideshow";
break;
case "application/zip":
case "application/x-zip-compressed":
case "application/x-compressed":
case "application/x-compress":
case "application/x-rar-compressed":
case "applicaiton/x-7z-compressed":
case "application/x-ace-compressed":
$humanType = "Archive";
break;
case "text/x-vcard":
case "text/x-ms-contact":
$humanType = "Contact";
break;
case "text/x-php":
case "application/x-dosexec":
case "application/x-xpinstall":
case "application/x-opera-extension":
case "application/x-chrome-extension":
case "application/x-perl":
case "application/x-shockwave-flash":
case "application/java-archive":
$humanType = "Program";
break;
case "application/vnd.ms-fontobject":
case "application/font-woff":
case "application/x-font-truetype":
case "application/x-font-opentype":
case "application/x-font-ttf":
case "application/font-sfnt":
$humanType = "Font";
break;
}
// Special Cases
if ($humanType == "Archive" && $fileType == "APK") { // Android App
$humanType = "App";
} elseif ($humanType == "Archive" && $fileType == "XPS") {
$humanType = "Document";
} elseif ($this->type == "application/xml" && $fileType == "CONTACT") {
$humanType = "Contact";
} elseif ($this->type == "application/octet-stream" && $fileType == "JNT") {
$humanType = "Document";
}
if (strlen($fileType) > 4) {
$fileType = "";
}
return array($humanType, $fileType);
如果我们用以下方式替换特殊情况：if elseif
// Special Cases
switch(true) {
case ($humanType == "Archive" && $fileType == "APK"): // Android App
$humanType = "App";
break;
case ($humanType == "Archive" && $fileType == "XPS"):
$humanType = "Document";
break;
case ($this->type == "application/xml" && $fileType == "CONTACT"):
$humanType = "Contact";
break;
case ($this->type == "application/octet-stream" && $fileType == "JNT"):
$humanType = "Document";
break;
}
PHP Mess Detector 报告了 1960 年的 NPath 复杂性。
这是为什么呢？是什么让 switch（true） 比在我看来几乎相同的控制结构更不复杂？
