Add some comments

lib/inc/drogon/Cookie.h

@@ -45,6 +45,7 @@ class Cookie
     const std::string &path() const { return _path; }
     const std::string &key() const { return _key; }
     const std::string &value() const { return _value; }
+    operator bool() const { return (!_key.empty()) && (!_value.empty()); }
 
   private:
     trantor::Date _expiresDate;

lib/inc/drogon/HttpResponse.h

@@ -28,70 +28,105 @@ typedef std::shared_ptr<HttpResponse> HttpResponsePtr;
 class HttpResponse
 {
   public:
-    explicit HttpResponse()
+    HttpResponse()
     {
     }
-
+    /// Get the status code such as 200, 404
     virtual HttpStatusCode statusCode() = 0;
 
-    virtual const trantor::Date &creationDate() const = 0;
-
+    /// Set the status code of the response.
     virtual void setStatusCode(HttpStatusCode code) = 0;
 
+    /// Set the status code and the status message of the response. Usually not used.
     virtual void setStatusCode(HttpStatusCode code, const std::string &status_message) = 0;
 
+    /// Get the creation timestamp of the response.
+    virtual const trantor::Date &creationDate() const = 0;
+
+    /// Set the http version, http1.0 or http1.1
     virtual void setVersion(const Version v) = 0;
 
+    /// If @param on is false, the connection will keep alive on the condition that the client request has a
+    //  'keep-alive' head, otherwise it will be closed. It's false by default when the reponse is created.
     virtual void setCloseConnection(bool on) = 0;
 
+    /// Get the status set by the setCloseConnetion() method.
     virtual bool closeConnection() const = 0;
 
+    /// Set the reponse content type, such as text/html, text/plaint, image/png and so on. If the content type
+    /// is a text type, the character set is utf8.
     virtual void setContentTypeCode(ContentType type) = 0;
 
+    /// Set the reponse content type and the character set.
     virtual void setContentTypeCodeAndCharacterSet(ContentType type, const std::string &charSet = "utf-8") = 0;
 
+    /// Get the response content type.
     virtual ContentType getContentTypeCode() = 0;
 
+    /// Get the header string identified by the @param key. If there is no the header, the @param defaultVal will be retured.
+    /// The @param key is case insensitive
     virtual const std::string &getHeader(const std::string &key, const std::string &defaultVal = std::string()) const = 0;
-
     virtual const std::string &getHeader(std::string &&key, const std::string &defaultVal = std::string()) const = 0;
 
+    /// Add a header.
     virtual void addHeader(const std::string &key, const std::string &value) = 0;
-
     virtual void addHeader(const std::string &key, std::string &&value) = 0;
 
-    virtual void addHeader(const char *start, const char *colon, const char *end) = 0;
-
+    /// Add a cookie
     virtual void addCookie(const std::string &key, const std::string &value) = 0;
-
     virtual void addCookie(const Cookie &cookie) = 0;
 
+    /// Get the cookie identified by the @param key. If there is no the cookie, the @param defaultCookie will be retured.
     virtual const Cookie &getCookie(const std::string &key, const Cookie &defaultCookie = Cookie()) const = 0;
 
+    /// Get all cookies.
     virtual const std::unordered_map<std::string, Cookie> &cookies() const = 0;
 
+    /// Remove the cookie identified by the @param key.
     virtual void removeCookie(const std::string &key) = 0;
 
+    /// Set the response body(content). The @param body must match the content type
     virtual void setBody(const std::string &body) = 0;
-
     virtual void setBody(std::string &&body) = 0;
 
-    virtual void redirect(const std::string &url) = 0;
-
-    virtual void clear() = 0;
-
-    virtual void setExpiredTime(ssize_t expiredTime) = 0;
-    virtual ssize_t expiredTime() const = 0;
-
+    /// Get the response body.
     virtual const std::string &getBody() const = 0;
     virtual std::string &getBody() = 0;
 
+    /// Reset the reponse object to its initial state
+    virtual void clear() = 0;
+
+    /// Set the expiration time of the response cache in memory.
+    /// in seconds, 0 means always cache, negative means not cache, default is -1.
+    virtual void setExpiredTime(ssize_t expiredTime) = 0;
+
+    /// Get the expiration time of the response.
+    virtual ssize_t expiredTime() const = 0;
+
+    /// Get the json object from the server response. If the response is not in json format, 
+    /// then a empty shared_ptr will be retured.
     virtual const std::shared_ptr<Json::Value> getJsonObject() const = 0;
+
+    /// The following methods are a series of factory methods that help users create response objects.
+
+    /// Create a normal response with a status code of 200ok and a content type of text/html.
     static HttpResponsePtr newHttpResponse();
+    /// Create a response which returns a 404 page.
     static HttpResponsePtr newNotFoundResponse();
+    /// Create a response which returns a json object. Its content type is set to set/json.
     static HttpResponsePtr newHttpJsonResponse(const Json::Value &data);
+    /// Create a response that returns a page rendered by a view named @param viewName.
+    /// @param data is the data displayed on the page.
+    /// For more details, see the wiki pages, the "View" section.
     static HttpResponsePtr newHttpViewResponse(const std::string &viewName, const HttpViewData &data = HttpViewData());
+    /// Create a response that returns a 302 Found page, redirecting to another page located in the @param path.
     static HttpResponsePtr newLocationRedirectResponse(const std::string &path);
+    /// Create a response that returns a file to the client.
+    /**
+     * @param fullPath is the full path to the file.
+     * If @param attachmentFileName is not empty, the browser does not open the file, but saves it as an attachment.
+     * If the @param type is CT_NONE, the content type will be set by drogon based on the file extension.
+     */
     static HttpResponsePtr newFileResponse(const std::string &fullPath, const std::string &attachmentFileName = "", ContentType type = CT_NONE);
 
     virtual ~HttpResponse() {}

lib/inc/drogon/MultiPart.h

@@ -71,6 +71,7 @@ class HttpFile
     std::string _fileContent;
 };
 
+/// A parser class which help the user to get the files and the parameters in the multipart format request.
 class MultiPartParser
 {
   public:
@@ -85,8 +86,8 @@ class MultiPartParser
     /// Parse the http request stream to get files and parameters.
     int parse(const HttpRequestPtr &req);
 
-    /// Parse the http response stream to get files and parameters.
-    int parse(const HttpResponsePtr &req);
+    /// Parse the http response stream to get files and parameters. 
+    /// int parse(const HttpResponsePtr &req);
 
   protected:
     std::vector<HttpFile> _files;

lib/src/HttpFileUploadRequest.h

@@ -25,7 +25,7 @@ class HttpFileUploadRequest : public HttpRequestImpl
   public:
     const std::string &boundary() const { return _boundary; }
     const std::vector<UploadFile> &files() const { return _files; }
-    HttpFileUploadRequest(const std::vector<UploadFile> &files);
+    explicit HttpFileUploadRequest(const std::vector<UploadFile> &files);
 
   private:
     std::string _boundary;

lib/src/HttpRequestImpl.h

@@ -42,7 +42,7 @@ class HttpRequestImpl : public HttpRequest
   public:
     friend class HttpRequestParser;
 
-    HttpRequestImpl(trantor::EventLoop *loop)
+    explicit HttpRequestImpl(trantor::EventLoop *loop)
         : _method(Invalid),
           _version(kUnknown),
           _date(trantor::Date::now()),

lib/src/HttpRequestParser.h

@@ -36,7 +36,7 @@ class HttpRequestParser
         kGotAll,
     };
 
-    HttpRequestParser(const trantor::TcpConnectionPtr &connPtr);
+    explicit HttpRequestParser(const trantor::TcpConnectionPtr &connPtr);
 
     // return false if any error
     bool parseRequest(MsgBuffer *buf);

lib/src/HttpResponseImpl.h

@@ -136,7 +136,7 @@ class HttpResponseImpl : public HttpResponse
         _headers[std::move(field)] = std::move(value);
     }
 
-    virtual void addHeader(const char *start, const char *colon, const char *end) override
+    void addHeader(const char *start, const char *colon, const char *end)
     {
         _fullHeaderString.reset();
         std::string field(start, colon);
@@ -260,9 +260,9 @@ class HttpResponseImpl : public HttpResponse
         _bodyPtr = std::make_shared<std::string>(std::move(body));
     }
 
-    virtual void redirect(const std::string &url) override
+    void redirect(const std::string &url)
     {
-        _headers["Location"] = url;
+        _headers["location"] = url;
     }
     std::shared_ptr<std::string> renderToString() const;
 

lib/src/HttpSimpleControllersRouter.h

@@ -35,7 +35,7 @@ class HttpControllersRouter;
 class HttpSimpleControllersRouter : public trantor::NonCopyable
 {
   public:
-    HttpSimpleControllersRouter(HttpControllersRouter &httpCtrlRouter)
+    explicit HttpSimpleControllersRouter(HttpControllersRouter &httpCtrlRouter)
         : _httpCtrlsRouter(httpCtrlRouter) {}
     void registerHttpSimpleController(const std::string &pathName,
                                       const std::string &ctrlName,

lib/src/MultiPart.cc

@@ -67,11 +67,11 @@ int MultiPartParser::parse(const HttpRequestPtr &req)
     return parse(content, boundary);
 }
 
-int MultiPartParser::parse(const HttpResponsePtr &resp)
-{
-    /// TODO:
-    return 0;
-}
+// int MultiPartParser::parse(const HttpResponsePtr &resp)
+// {
+//     /// TODO:
+//     return 0;
+// }
 
 int MultiPartParser::parseEntity(const char *begin, const char *end)
 {