LSP for solcjs

libsolc/CMakeLists.txt

@@ -7,6 +7,9 @@ if (EMSCRIPTEN)
 		solidity_alloc
 		solidity_free
 		solidity_reset
+		solidity_lsp_start
+		solidity_lsp_send
+		solidity_lsp_send_receive
 	)
 	# Specify which functions to export in soljson.js.
 	# Note that additional Emscripten-generated methods needed by solc-js are

libsolc/libsolc.cpp

@@ -24,6 +24,8 @@
 #include <libsolc/libsolc.h>
 #include <libsolidity/interface/StandardCompiler.h>
 #include <libsolidity/interface/Version.h>
+#include <libsolidity/lsp/LanguageServer.h>
+#include <libsolidity/lsp/Transport.h>
 #include <libyul/YulString.h>
 
 #include <cstdlib>
@@ -112,6 +114,9 @@ string compile(string _input, CStyleReadFileCallback _readCallback, void* _readC
 	return compiler.compile(move(_input));
 }
 
+unique_ptr<lsp::MockTransport> languageServerTransport;
+unique_ptr<lsp::LanguageServer> languageServer;
+
 }
 
 extern "C"
@@ -132,6 +137,56 @@ extern char* solidity_compile(char const* _input, CStyleReadFileCallback _readCa
 	return solidityAllocations.emplace_back(compile(_input, _readCallback, _readContext)).data();
 }
 
+extern int solidity_lsp_start(CStyleReadFileCallback /*TODO(pr) _readCallback*/, void* /*_readContext*/) noexcept
+{
+	if (languageServer || languageServerTransport)
+		return -1;
+
+	languageServerTransport = make_unique<lsp::MockTransport>();
+	languageServer = make_unique<lsp::LanguageServer>(*languageServerTransport);
+	return 0;
+}
+
+extern int solidity_lsp_send(char const* _input) noexcept
+{
+	if (!languageServer)
+		return -1;
+
+	if (languageServer->isRunning())
+		return -2;
+
+	solAssert(languageServerTransport, "");
+
+	std::string errors{};
+	Json::Value jsonMessage{};
+	if (!jsonParseStrict(_input, jsonMessage, &errors))
+		return -3;
+
+	languageServerTransport->appendInput(jsonMessage);
+	languageServer->runIteration();
+	return 0;
+}
+
+extern char const* solidity_try_receive() noexcept
+{
+	if (!languageServerTransport)
+		return "";
+
+	optional<Json::Value> messageJson = languageServerTransport->popOutput();
+	if (!messageJson)
+		return "";
+
+	return solidityAllocations.emplace_back(jsonPrettyPrint(messageJson.value())).data();
+}
+
+extern char const* solidity_lsp_send_receive(char const* _input) noexcept
+{
+	if (solidity_lsp_send(_input) < 0)
+		return "";
+
+	return solidity_try_receive();
+}
+
 extern char* solidity_alloc(size_t _size) noexcept
 {
 	try
@@ -156,5 +211,7 @@ extern void solidity_reset() noexcept
 	// can be freed here.
 	yul::YulStringRepository::reset();
 	solidityAllocations.clear();
+	languageServer.reset();
+	languageServerTransport.reset();
 }
 }

libsolc/libsolc.h

@@ -90,6 +90,40 @@ void solidity_free(char* _data) SOLC_NOEXCEPT;
 /// @returns A pointer to the result. The pointer returned must be freed by the caller using solidity_free() or solidity_reset().
 char* solidity_compile(char const* _input, CStyleReadFileCallback _readCallback, void* _readContext) SOLC_NOEXCEPT;
 
+/// @TODO the biggest problem here is that the callback has to be synchronous.
+/// With "compile" we would just record requested files and trigger a recompile later,
+/// so we might need a way to trigger a recompile.
+
+/// Switch into LSP mode. Can be undone using solidity_reset().
+///
+/// @returns 0 on success and -1 on failure. A failure can only happen due to mis-use of the API,
+/// such as, the LSP mode has been already initiated.
+int solidity_lsp_start(CStyleReadFileCallback _readCallback, void* _readContext) SOLC_NOEXCEPT;
+
+/// Sends a single JSON-RPC message to the LSP server.
+/// This message must not include any HTTP headers but only hold the payload.
+///
+/// @retval 0 Success.
+/// @retval -1 Server not initialized.
+/// @retval -2 Server not running (e.g. termination initiated).
+/// @retval -3 Could not parse JSON RPC message.
+int solidity_lsp_send(char const* _input) SOLC_NOEXCEPT;
+
+/// Tries to pop a pending message from the LSP server.
+/// @returns either an empty string if not possible
+/// (e.g. no message available or server shut down) or a stringified JSON response message.
+char const* solidity_try_receive() SOLC_NOEXCEPT;
+
+/// Send one or more JSON-RPC messages to the LSP (including the HTTP headers),
+/// expecting a response.
+/// If the input is empty, just checks for a pending response.
+/// @returns JSON-RPC message (inculding HTTP headers), can be empty (or nullptr).
+/// If the result is not null, it has to be freed by the caller using solidity_free.
+///
+/// This can cause the callback provided in solidity_lsp to be invoked.
+/// Should only be called after having called solidity_lsp.
+char const *solidity_lsp_send_receive(char const* _input) SOLC_NOEXCEPT;
+
 /// Frees up any allocated memory.
 ///
 /// NOTE: the pointer returned by solidity_compile as well as any other pointer retrieved via solidity_alloc()

libsolidity/lsp/LanguageServer.cpp

@@ -68,6 +68,7 @@ int toDiagnosticSeverity(Error::Type _errorType)
 
 }
 
+// TODO provide constructor with custom read callback
 LanguageServer::LanguageServer(Transport& _transport):
 	m_client{_transport},
 	m_handlers{
@@ -180,37 +181,9 @@ void LanguageServer::compileAndUpdateDiagnostics()
 
 bool LanguageServer::run()
 {
-	while (m_state != State::ExitRequested && m_state != State::ExitWithoutShutdown && !m_client.closed())
+	while (isRunning())
-	{
+		runIteration();
-		MessageID id;
-		try
-		{
-			optional<Json::Value> const jsonMessage = m_client.receive();
-			if (!jsonMessage)
-				continue;
 
-			if ((*jsonMessage)["method"].isString())
-			{
-				string const methodName = (*jsonMessage)["method"].asString();
-				id = (*jsonMessage)["id"];
-
-				if (auto handler = util::valueOrDefault(m_handlers, methodName))
-					handler(id, (*jsonMessage)["params"]);
-				else
-					m_client.error(id, ErrorCode::MethodNotFound, "Unknown method " + methodName);
-			}
-			else
-				m_client.error({}, ErrorCode::ParseError, "\"method\" has to be a string.");
-		}
-		catch (RequestError const& error)
-		{
-			m_client.error(id, error.code(), error.comment() ? *error.comment() : ""s);
-		}
-		catch (...)
-		{
-			m_client.error(id, ErrorCode::InternalError, "Unhandled exception: "s + boost::current_exception_diagnostic_information());
-		}
-	}
 	return m_state == State::ExitRequested;
 }
 
@@ -223,6 +196,38 @@ void LanguageServer::requireServerInitialized()
 	);
 }
 
+bool LanguageServer::runIteration()
+{
+	MessageID id;
+	try
+	{
+		optional<Json::Value> const jsonMessage = m_client.receive();
+		if (!jsonMessage)
+			return true;
+
+		if ((*jsonMessage)["method"].isString())
+		{
+			string const methodName = (*jsonMessage)["method"].asString();
+			id = (*jsonMessage)["id"];
+
+			if (auto handler = util::valueOrDefault(m_handlers, methodName))
+				handler(id, (*jsonMessage)["params"]);
+			else
+				m_client.error(id, ErrorCode::MethodNotFound, "Unknown method " + methodName);
+		}
+	}
+	catch (RequestError const& error)
+	{
+		m_client.error(id, error.code(), error.comment() ? *error.comment() : ""s);
+	}
+	catch (...)
+	{
+		m_client.error(id, ErrorCode::InternalError, "Unhandled exception: "s + boost::current_exception_diagnostic_information());
+	}
+
+	return isRunning();
+}
+
 void LanguageServer::handleInitialize(MessageID _id, Json::Value const& _args)
 {
 	lspAssert(

libsolidity/lsp/LanguageServer.h

@@ -62,6 +62,17 @@ public:
 	frontend::ASTNode const* astNodeAtSourceLocation(std::string const& _sourceUnitName, langutil::LineColumn const& _filePos);
 	langutil::CharStreamProvider const& charStreamProvider() const noexcept { return m_compilerStack; }
 
+	/// Run a single iteration of processing inputs and generating outputs.
+	/// To be used when we are not in control of the event loop.
+	/// @returns false if the process is supposed to terminate.
+	bool runIteration();
+
+	/// @returns true if the server has not terminated yet, false otherwise.
+	bool isRunning() const noexcept
+	{
+		return m_state != State::ExitRequested && m_state != State::ExitWithoutShutdown && !m_client.closed();
+	}
+
 private:
 	/// Checks if the server is initialized (to be used by messages that need it to be initialized).
 	/// Reports an error and returns false if not.

libsolidity/lsp/Transport.cpp

@@ -30,6 +30,72 @@
 using namespace std;
 using namespace solidity::lsp;
 
+namespace
+{
+template <typename T>
+optional<T> popFromFront(std::list<T>& _queue)
+{
+	if (_queue.empty())
+		return nullopt;
+	Json::Value message = _queue.front();
+	_queue.pop_front();
+	return message;
+}
+}
+
+bool MockTransport::closed() const noexcept
+{
+	return m_closed;
+}
+
+void MockTransport::appendInput(Json::Value _message)
+{
+	solAssert(!m_closed, "");
+	m_input.emplace_back(move(_message));
+}
+
+optional<Json::Value> MockTransport::receive()
+{
+	return popFromFront(m_input);
+}
+
+optional<Json::Value> MockTransport::popOutput()
+{
+	return popFromFront(m_output);
+}
+
+void MockTransport::notify(string _method, Json::Value _message)
+{
+	Json::Value json;
+	json["method"] = move(_method);
+	json["params"] = move(_message);
+	send(move(json));
+}
+
+void MockTransport::reply(MessageID _id, Json::Value _message)
+{
+	Json::Value json;
+	json["result"] = move(_message);
+	send(move(json), _id);
+}
+
+void MockTransport::error(MessageID _id, ErrorCode _code, string _message)
+{
+	Json::Value json;
+	json["error"]["code"] = static_cast<int>(_code);
+	json["error"]["message"] = move(_message);
+	send(move(json), _id);
+}
+
+void MockTransport::send(Json::Value _json, MessageID _id)
+{
+	_json["jsonrpc"] = "2.0";
+	if (_id != Json::nullValue)
+		_json["id"] = _id;
+
+	m_output.push_back(_json);
+}
+
 IOStreamTransport::IOStreamTransport(istream& _in, ostream& _out):
 	m_input{_in},
 	m_output{_out}

libsolidity/lsp/Transport.h

@@ -17,12 +17,14 @@
 // SPDX-License-Identifier: GPL-3.0
 #pragma once
 
+#include <libsolutil/CommonIO.h>
 #include <libsolutil/Exceptions.h>
 
 #include <json/value.h>
 
 #include <functional>
 #include <iosfwd>
+#include <list>
 #include <map>
 #include <optional>
 #include <string>
@@ -91,6 +93,26 @@ public:
 	virtual void error(MessageID _id, ErrorCode _code, std::string _message) = 0;
 };
 
+class MockTransport: public Transport
+{
+public:
+	void close() { m_closed = true; }
+	bool closed() const noexcept override;
+	std::optional<Json::Value> receive() override;
+	void notify(std::string _method, Json::Value _params) override;
+	void reply(MessageID _id, Json::Value _result) override;
+	void error(MessageID _id, ErrorCode _code, std::string _message) override;
+
+	void send(Json::Value _message, MessageID _id = Json::nullValue);
+	std::optional<Json::Value> popOutput();
+	void appendInput(Json::Value _message);
+
+private:
+	bool m_closed = false;
+	std::list<Json::Value> m_input {};
+	std::list<Json::Value> m_output {};
+};
+
 /**
  * LSP Transport using JSON-RPC over iostreams.
  */
@@ -126,4 +148,21 @@ private:
 	std::ostream& m_output;
 };
 
+/**
+ * LSP Transport using pure string buffers.
+ * Used by solcjs.
+ */
+class BufferedTransport: public IOStreamTransport
+{
+public:
+	BufferedTransport(): IOStreamTransport(m_input, m_output) {}
+
+	void appendInput(char const* _input) { m_input.write(_input, static_cast<std::streamsize>(strlen(_input))); }
+	std::string popOutput() { return util::readUntilEnd(m_output); }
+
+private:
+	std::stringstream m_input;
+	std::stringstream m_output;
+};
+
 }