lib/curl/Delegate: helper class for response body parsers

Eliminate duplicate code.

src/input/plugins/TidalErrorParser.cxx

@@ -40,24 +40,18 @@ static constexpr yajl_callbacks tidal_error_parser_callbacks = {
 
 TidalErrorParser::TidalErrorParser(unsigned _status,
 				   const std::multimap<std::string, std::string> &headers)
-	:status(_status),
-	 parser(&tidal_error_parser_callbacks, nullptr, this)
+	:YajlResponseParser(&tidal_error_parser_callbacks, nullptr, this),
+	 status(_status)
 {
 	auto i = headers.find("content-type");
 	if (i == headers.end() || i->second.find("/json") == i->second.npos)
 		throw FormatRuntimeError("Status %u from Tidal", status);
 }
 
-void
-TidalErrorParser::OnData(ConstBuffer<void> data)
-{
-	parser.Parse((const unsigned char *)data.data, data.size);
-}
-
 void
 TidalErrorParser::OnEnd()
 {
-	parser.CompleteParse();
+	YajlResponseParser::OnEnd();
 
 	if (!message.empty())
 		throw FormatRuntimeError("Error from Tidal: %s",

src/input/plugins/TidalErrorParser.hxx

@@ -21,9 +21,8 @@
 #define TIDAL_ERROR_PARSER_HXX
 
 #include "check.h"
-#include "lib/yajl/Handle.hxx"
+#include "lib/yajl/ResponseParser.hxx"
 
-#include <exception>
 #include <string>
 #include <map>
 
@@ -33,11 +32,9 @@ struct StringView;
 /**
  * Parse an error JSON response.
  */
-class TidalErrorParser {
+class TidalErrorParser final : public YajlResponseParser {
 	const unsigned status;
 
-	Yajl::Handle parser;
-
 	enum class State {
 		NONE,
 		USER_MESSAGE,
@@ -53,16 +50,9 @@ public:
 	TidalErrorParser(unsigned status,
 			 const std::multimap<std::string, std::string> &headers);
 
-	/**
-	 * Feed response body data into the JSON parser.
-	 */
-	void OnData(ConstBuffer<void> data);
-
-	/**
-	 * Throw an exception describing the error condition.  Call
-	 * this at the end of the response body.
-	 */
-	void OnEnd();
+protected:
+	/* virtual methods from CurlResponseParser */
+	void OnEnd() override;
 
 public:
 	/* yajl callbacks */

src/input/plugins/TidalLoginRequest.cxx

@@ -21,10 +21,12 @@
 #include "TidalLoginRequest.hxx"
 #include "TidalErrorParser.hxx"
 #include "lib/curl/Form.hxx"
+#include "lib/yajl/Handle.hxx"
 #include "lib/yajl/Callbacks.hxx"
+#include "lib/yajl/ResponseParser.hxx"
 #include "util/RuntimeError.hxx"
 
-using Wrapper = Yajl::CallbacksWrapper<TidalLoginRequest>;
+using Wrapper = Yajl::CallbacksWrapper<TidalLoginRequest::ResponseParser>;
 static constexpr yajl_callbacks parse_callbacks = {
 	nullptr,
 	nullptr,
@@ -39,6 +41,31 @@ static constexpr yajl_callbacks parse_callbacks = {
 	nullptr,
 };
 
+class TidalLoginRequest::ResponseParser final : public YajlResponseParser {
+	enum class State {
+		NONE,
+		SESSION_ID,
+	} state = State::NONE;
+
+	std::string session;
+
+public:
+	explicit ResponseParser() noexcept
+		:YajlResponseParser(&parse_callbacks, nullptr, this) {}
+
+	std::string &&GetSession() {
+		if (session.empty())
+			throw std::runtime_error("No sessionId in login response");
+
+		return std::move(session);
+	}
+
+	/* yajl callbacks */
+	bool String(StringView value) noexcept;
+	bool MapKey(StringView value) noexcept;
+	bool EndMap() noexcept;
+};
+
 static std::string
 MakeLoginUrl(const char *base_url)
 {
@@ -66,47 +93,26 @@ TidalLoginRequest::~TidalLoginRequest() noexcept
 	request.StopIndirect();
 }
 
-void
-TidalLoginRequest::OnHeaders(unsigned status,
-			     std::multimap<std::string, std::string> &&headers)
+std::unique_ptr<CurlResponseParser>
+TidalLoginRequest::MakeParser(unsigned status,
+			      std::multimap<std::string, std::string> &&headers)
 {
-	if (status != 200) {
-		error_parser = std::make_unique<TidalErrorParser>(status, headers);
-		return;
-	}
+	if (status != 200)
+		return std::make_unique<TidalErrorParser>(status, headers);
 
 	auto i = headers.find("content-type");
 	if (i == headers.end() || i->second.find("/json") == i->second.npos)
 		throw std::runtime_error("Not a JSON response from Tidal");
 
-	parser = {&parse_callbacks, nullptr, this};
+	return std::make_unique<ResponseParser>();
 }
 
 void
-TidalLoginRequest::OnData(ConstBuffer<void> data)
+TidalLoginRequest::FinishParser(std::unique_ptr<CurlResponseParser> p)
 {
-	if (error_parser) {
-		error_parser->OnData(data);
-		return;
-	}
-
-	parser.Parse((const unsigned char *)data.data, data.size);
-}
-
-void
-TidalLoginRequest::OnEnd()
-{
-	if (error_parser) {
-		error_parser->OnEnd();
-		return;
-	}
-
-	parser.CompleteParse();
-
-	if (session.empty())
-		throw std::runtime_error("No sessionId in login response");
-
-	handler.OnTidalLoginSuccess(std::move(session));
+	assert(dynamic_cast<ResponseParser *>(p.get()) != nullptr);
+	auto &rp = (ResponseParser &)*p;
+	handler.OnTidalLoginSuccess(rp.GetSession());
 }
 
 void
@@ -116,7 +122,7 @@ TidalLoginRequest::OnError(std::exception_ptr e) noexcept
 }
 
 inline bool
-TidalLoginRequest::String(StringView value) noexcept
+TidalLoginRequest::ResponseParser::String(StringView value) noexcept
 {
 	switch (state) {
 	case State::NONE:
@@ -131,7 +137,7 @@ TidalLoginRequest::String(StringView value) noexcept
 }
 
 inline bool
-TidalLoginRequest::MapKey(StringView value) noexcept
+TidalLoginRequest::ResponseParser::MapKey(StringView value) noexcept
 {
 	if (value.Equals("sessionId"))
 		state = State::SESSION_ID;
@@ -142,7 +148,7 @@ TidalLoginRequest::MapKey(StringView value) noexcept
 }
 
 inline bool
-TidalLoginRequest::EndMap() noexcept
+TidalLoginRequest::ResponseParser::EndMap() noexcept
 {
 	state = State::NONE;
 

src/input/plugins/TidalLoginRequest.hxx

@@ -21,17 +21,9 @@
 #define TIDAL_LOGIN_REQUEST_HXX
 
 #include "check.h"
-#include "lib/curl/Handler.hxx"
+#include "lib/curl/Delegate.hxx"
 #include "lib/curl/Slist.hxx"
 #include "lib/curl/Request.hxx"
-#include "lib/yajl/Handle.hxx"
-
-#include <exception>
-#include <memory>
-#include <string>
-
-class CurlRequest;
-class TidalErrorParser;
 
 /**
  * Callback class for #TidalLoginRequest.
@@ -49,27 +41,16 @@ public:
  *
  * After construction, call Start() to initiate the request.
  */
-class TidalLoginRequest final : CurlResponseHandler {
+class TidalLoginRequest final : DelegateCurlResponseHandler {
 	CurlSlist request_headers;
 
 	CurlRequest request;
 
-	std::unique_ptr<TidalErrorParser> error_parser;
-
-	Yajl::Handle parser;
-
-	enum class State {
-		NONE,
-		SESSION_ID,
-	} state = State::NONE;
-
-	std::string session;
-
-	std::exception_ptr error;
-
 	TidalLoginHandler &handler;
 
 public:
+	class ResponseParser;
+
 	TidalLoginRequest(CurlGlobal &curl,
 			  const char *base_url, const char *token,
 			  const char *username, const char *password,
@@ -82,18 +63,13 @@ public:
 	}
 
 private:
-	/* virtual methods from CurlResponseHandler */
-	void OnHeaders(unsigned status,
-		       std::multimap<std::string, std::string> &&headers) override;
-	void OnData(ConstBuffer<void> data) override;
-	void OnEnd() override;
-	void OnError(std::exception_ptr e) noexcept override;
+	/* virtual methods from DelegateCurlResponseHandler */
+	std::unique_ptr<CurlResponseParser> MakeParser(unsigned status,
+						       std::multimap<std::string, std::string> &&headers) override;
+	void FinishParser(std::unique_ptr<CurlResponseParser> p) override;
 
-public:
-	/* yajl callbacks */
-	bool String(StringView value) noexcept;
-	bool MapKey(StringView value) noexcept;
-	bool EndMap() noexcept;
+	/* virtual methods from CurlResponseHandler */
+	void OnError(std::exception_ptr e) noexcept override;
 };
 
 #endif

src/input/plugins/TidalTrackRequest.cxx

@@ -23,7 +23,7 @@
 #include "lib/yajl/Callbacks.hxx"
 #include "util/RuntimeError.hxx"
 
-using Wrapper = Yajl::CallbacksWrapper<TidalTrackRequest>;
+using Wrapper = Yajl::CallbacksWrapper<TidalTrackRequest::ResponseParser>;
 static constexpr yajl_callbacks parse_callbacks = {
 	nullptr,
 	nullptr,
@@ -38,6 +38,31 @@ static constexpr yajl_callbacks parse_callbacks = {
 	nullptr,
 };
 
+class TidalTrackRequest::ResponseParser final : public YajlResponseParser {
+	enum class State {
+		NONE,
+		URLS,
+	} state = State::NONE;
+
+	std::string url;
+
+public:
+	explicit ResponseParser() noexcept
+		:YajlResponseParser(&parse_callbacks, nullptr, this) {}
+
+	std::string &&GetUrl() {
+		if (url.empty())
+			throw std::runtime_error("No url in track response");
+
+		return std::move(url);
+	}
+
+	/* yajl callbacks */
+	bool String(StringView value) noexcept;
+	bool MapKey(StringView value) noexcept;
+	bool EndMap() noexcept;
+};
+
 static std::string
 MakeTrackUrl(const char *base_url, const char *track_id)
 {
@@ -68,47 +93,26 @@ TidalTrackRequest::~TidalTrackRequest() noexcept
 	request.StopIndirect();
 }
 
-void
-TidalTrackRequest::OnHeaders(unsigned status,
-			     std::multimap<std::string, std::string> &&headers)
+std::unique_ptr<CurlResponseParser>
+TidalTrackRequest::MakeParser(unsigned status,
+			      std::multimap<std::string, std::string> &&headers)
 {
-	if (status != 200) {
-		error_parser = std::make_unique<TidalErrorParser>(status, headers);
-		return;
-	}
+	if (status != 200)
+		return std::make_unique<TidalErrorParser>(status, headers);
 
 	auto i = headers.find("content-type");
 	if (i == headers.end() || i->second.find("/json") == i->second.npos)
 		throw std::runtime_error("Not a JSON response from Tidal");
 
-	parser = {&parse_callbacks, nullptr, this};
+	return std::make_unique<ResponseParser>();
 }
 
 void
-TidalTrackRequest::OnData(ConstBuffer<void> data)
+TidalTrackRequest::FinishParser(std::unique_ptr<CurlResponseParser> p)
 {
-	if (error_parser) {
-		error_parser->OnData(data);
-		return;
-	}
-
-	parser.Parse((const unsigned char *)data.data, data.size);
-}
-
-void
-TidalTrackRequest::OnEnd()
-{
-	if (error_parser) {
-		error_parser->OnEnd();
-		return;
-	}
-
-	parser.CompleteParse();
-
-	if (url.empty())
-		throw std::runtime_error("No url in track response");
-
-	handler.OnTidalTrackSuccess(std::move(url));
+	assert(dynamic_cast<ResponseParser *>(p.get()) != nullptr);
+	auto &rp = (ResponseParser &)*p;
+	handler.OnTidalTrackSuccess(rp.GetUrl());
 }
 
 void
@@ -118,7 +122,7 @@ TidalTrackRequest::OnError(std::exception_ptr e) noexcept
 }
 
 inline bool
-TidalTrackRequest::String(StringView value) noexcept
+TidalTrackRequest::ResponseParser::String(StringView value) noexcept
 {
 	switch (state) {
 	case State::NONE:
@@ -134,7 +138,7 @@ TidalTrackRequest::String(StringView value) noexcept
 }
 
 inline bool
-TidalTrackRequest::MapKey(StringView value) noexcept
+TidalTrackRequest::ResponseParser::MapKey(StringView value) noexcept
 {
 	if (value.Equals("urls"))
 		state = State::URLS;
@@ -145,7 +149,7 @@ TidalTrackRequest::MapKey(StringView value) noexcept
 }
 
 inline bool
-TidalTrackRequest::EndMap() noexcept
+TidalTrackRequest::ResponseParser::EndMap() noexcept
 {
 	state = State::NONE;
 

src/input/plugins/TidalTrackRequest.hxx

@@ -21,17 +21,9 @@
 #define TIDAL_TRACK_REQUEST_HXX
 
 #include "check.h"
-#include "lib/curl/Handler.hxx"
+#include "lib/curl/Delegate.hxx"
 #include "lib/curl/Slist.hxx"
 #include "lib/curl/Request.hxx"
-#include "lib/yajl/Handle.hxx"
-
-#include <exception>
-#include <memory>
-#include <string>
-
-class CurlRequest;
-class TidalErrorParser;
 
 /**
  * Callback class for #TidalTrackRequest.
@@ -51,27 +43,16 @@ public:
  *
  * After construction, call Start() to initiate the request.
  */
-class TidalTrackRequest final : CurlResponseHandler {
+class TidalTrackRequest final : DelegateCurlResponseHandler {
 	CurlSlist request_headers;
 
 	CurlRequest request;
 
-	std::unique_ptr<TidalErrorParser> error_parser;
-
-	Yajl::Handle parser;
-
-	enum class State {
-		NONE,
-		URLS,
-	} state = State::NONE;
-
-	std::string url;
-
-	std::exception_ptr error;
-
 	TidalTrackHandler &handler;
 
 public:
+	class ResponseParser;
+
 	TidalTrackRequest(CurlGlobal &curl,
 			  const char *base_url, const char *token,
 			  const char *session,
@@ -85,18 +66,13 @@ public:
 	}
 
 private:
-	/* virtual methods from CurlResponseHandler */
-	void OnHeaders(unsigned status,
-		       std::multimap<std::string, std::string> &&headers) override;
-	void OnData(ConstBuffer<void> data) override;
-	void OnEnd() override;
-	void OnError(std::exception_ptr e) noexcept override;
+	/* virtual methods from DelegateCurlResponseHandler */
+	std::unique_ptr<CurlResponseParser> MakeParser(unsigned status,
+						       std::multimap<std::string, std::string> &&headers) override;
+	void FinishParser(std::unique_ptr<CurlResponseParser> p) override;
 
-public:
-	/* yajl callbacks */
-	bool String(StringView value) noexcept;
-	bool MapKey(StringView value) noexcept;
-	bool EndMap() noexcept;
+	/* virtual methods from CurlResponseHandler */
+	void OnError(std::exception_ptr e) noexcept override;
 };
 
 #endif