cannam@48: // Copyright (c) 2013-2014 Sandstorm Development Group, Inc. and contributors
cannam@48: // Licensed under the MIT License:
cannam@48: //
cannam@48: // Permission is hereby granted, free of charge, to any person obtaining a copy
cannam@48: // of this software and associated documentation files (the "Software"), to deal
cannam@48: // in the Software without restriction, including without limitation the rights
cannam@48: // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
cannam@48: // copies of the Software, and to permit persons to whom the Software is
cannam@48: // furnished to do so, subject to the following conditions:
cannam@48: //
cannam@48: // The above copyright notice and this permission notice shall be included in
cannam@48: // all copies or substantial portions of the Software.
cannam@48: //
cannam@48: // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
cannam@48: // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
cannam@48: // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
cannam@48: // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
cannam@48: // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
cannam@48: // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
cannam@48: // THE SOFTWARE.
cannam@48: 
cannam@48: #include "calculator.capnp.h"
cannam@48: #include <kj/debug.h>
cannam@48: #include <capnp/ez-rpc.h>
cannam@48: #include <capnp/message.h>
cannam@48: #include <iostream>
cannam@48: 
cannam@48: typedef unsigned int uint;
cannam@48: 
cannam@48: kj::Promise<double> readValue(Calculator::Value::Client value) {
cannam@48:   // Helper function to asynchronously call read() on a Calculator::Value and
cannam@48:   // return a promise for the result.  (In the future, the generated code might
cannam@48:   // include something like this automatically.)
cannam@48: 
cannam@48:   return value.readRequest().send()
cannam@48:       .then([](capnp::Response<Calculator::Value::ReadResults> result) {
cannam@48:     return result.getValue();
cannam@48:   });
cannam@48: }
cannam@48: 
cannam@48: kj::Promise<double> evaluateImpl(
cannam@48:     Calculator::Expression::Reader expression,
cannam@48:     capnp::List<double>::Reader params = capnp::List<double>::Reader()) {
cannam@48:   // Implementation of CalculatorImpl::evaluate(), also shared by
cannam@48:   // FunctionImpl::call().  In the latter case, `params` are the parameter
cannam@48:   // values passed to the function; in the former case, `params` is just an
cannam@48:   // empty list.
cannam@48: 
cannam@48:   switch (expression.which()) {
cannam@48:     case Calculator::Expression::LITERAL:
cannam@48:       return expression.getLiteral();
cannam@48: 
cannam@48:     case Calculator::Expression::PREVIOUS_RESULT:
cannam@48:       return readValue(expression.getPreviousResult());
cannam@48: 
cannam@48:     case Calculator::Expression::PARAMETER: {
cannam@48:       KJ_REQUIRE(expression.getParameter() < params.size(),
cannam@48:                  "Parameter index out-of-range.");
cannam@48:       return params[expression.getParameter()];
cannam@48:     }
cannam@48: 
cannam@48:     case Calculator::Expression::CALL: {
cannam@48:       auto call = expression.getCall();
cannam@48:       auto func = call.getFunction();
cannam@48: 
cannam@48:       // Evaluate each parameter.
cannam@48:       kj::Array<kj::Promise<double>> paramPromises =
cannam@48:           KJ_MAP(param, call.getParams()) {
cannam@48:             return evaluateImpl(param, params);
cannam@48:           };
cannam@48: 
cannam@48:       // Join the array of promises into a promise for an array.
cannam@48:       kj::Promise<kj::Array<double>> joinedParams =
cannam@48:           kj::joinPromises(kj::mv(paramPromises));
cannam@48: 
cannam@48:       // When the parameters are complete, call the function.
cannam@48:       return joinedParams.then([func](kj::Array<double>&& paramValues) mutable {
cannam@48:         auto request = func.callRequest();
cannam@48:         request.setParams(paramValues);
cannam@48:         return request.send().then(
cannam@48:             [](capnp::Response<Calculator::Function::CallResults>&& result) {
cannam@48:           return result.getValue();
cannam@48:         });
cannam@48:       });
cannam@48:     }
cannam@48: 
cannam@48:     default:
cannam@48:       // Throw an exception.
cannam@48:       KJ_FAIL_REQUIRE("Unknown expression type.");
cannam@48:   }
cannam@48: }
cannam@48: 
cannam@48: class ValueImpl final: public Calculator::Value::Server {
cannam@48:   // Simple implementation of the Calculator.Value Cap'n Proto interface.
cannam@48: 
cannam@48: public:
cannam@48:   ValueImpl(double value): value(value) {}
cannam@48: 
cannam@48:   kj::Promise<void> read(ReadContext context) {
cannam@48:     context.getResults().setValue(value);
cannam@48:     return kj::READY_NOW;
cannam@48:   }
cannam@48: 
cannam@48: private:
cannam@48:   double value;
cannam@48: };
cannam@48: 
cannam@48: class FunctionImpl final: public Calculator::Function::Server {
cannam@48:   // Implementation of the Calculator.Function Cap'n Proto interface, where the
cannam@48:   // function is defined by a Calculator.Expression.
cannam@48: 
cannam@48: public:
cannam@48:   FunctionImpl(uint paramCount, Calculator::Expression::Reader body)
cannam@48:       : paramCount(paramCount) {
cannam@48:     this->body.setRoot(body);
cannam@48:   }
cannam@48: 
cannam@48:   kj::Promise<void> call(CallContext context) {
cannam@48:     auto params = context.getParams().getParams();
cannam@48:     KJ_REQUIRE(params.size() == paramCount, "Wrong number of parameters.");
cannam@48: 
cannam@48:     return evaluateImpl(body.getRoot<Calculator::Expression>(), params)
cannam@48:         .then([context](double value) mutable {
cannam@48:       context.getResults().setValue(value);
cannam@48:     });
cannam@48:   }
cannam@48: 
cannam@48: private:
cannam@48:   uint paramCount;
cannam@48:   // The function's arity.
cannam@48: 
cannam@48:   capnp::MallocMessageBuilder body;
cannam@48:   // Stores a permanent copy of the function body.
cannam@48: };
cannam@48: 
cannam@48: class OperatorImpl final: public Calculator::Function::Server {
cannam@48:   // Implementation of the Calculator.Function Cap'n Proto interface, wrapping
cannam@48:   // basic binary arithmetic operators.
cannam@48: 
cannam@48: public:
cannam@48:   OperatorImpl(Calculator::Operator op): op(op) {}
cannam@48: 
cannam@48:   kj::Promise<void> call(CallContext context) {
cannam@48:     auto params = context.getParams().getParams();
cannam@48:     KJ_REQUIRE(params.size() == 2, "Wrong number of parameters.");
cannam@48: 
cannam@48:     double result;
cannam@48:     switch (op) {
cannam@48:       case Calculator::Operator::ADD:     result = params[0] + params[1]; break;
cannam@48:       case Calculator::Operator::SUBTRACT:result = params[0] - params[1]; break;
cannam@48:       case Calculator::Operator::MULTIPLY:result = params[0] * params[1]; break;
cannam@48:       case Calculator::Operator::DIVIDE:  result = params[0] / params[1]; break;
cannam@48:       default:
cannam@48:         KJ_FAIL_REQUIRE("Unknown operator.");
cannam@48:     }
cannam@48: 
cannam@48:     context.getResults().setValue(result);
cannam@48:     return kj::READY_NOW;
cannam@48:   }
cannam@48: 
cannam@48: private:
cannam@48:   Calculator::Operator op;
cannam@48: };
cannam@48: 
cannam@48: class CalculatorImpl final: public Calculator::Server {
cannam@48:   // Implementation of the Calculator Cap'n Proto interface.
cannam@48: 
cannam@48: public:
cannam@48:   kj::Promise<void> evaluate(EvaluateContext context) override {
cannam@48:     return evaluateImpl(context.getParams().getExpression())
cannam@48:         .then([context](double value) mutable {
cannam@48:       context.getResults().setValue(kj::heap<ValueImpl>(value));
cannam@48:     });
cannam@48:   }
cannam@48: 
cannam@48:   kj::Promise<void> defFunction(DefFunctionContext context) override {
cannam@48:     auto params = context.getParams();
cannam@48:     context.getResults().setFunc(kj::heap<FunctionImpl>(
cannam@48:         params.getParamCount(), params.getBody()));
cannam@48:     return kj::READY_NOW;
cannam@48:   }
cannam@48: 
cannam@48:   kj::Promise<void> getOperator(GetOperatorContext context) override {
cannam@48:     context.getResults().setFunc(kj::heap<OperatorImpl>(
cannam@48:         context.getParams().getOp()));
cannam@48:     return kj::READY_NOW;
cannam@48:   }
cannam@48: };
cannam@48: 
cannam@48: int main(int argc, const char* argv[]) {
cannam@48:   if (argc != 2) {
cannam@48:     std::cerr << "usage: " << argv[0] << " ADDRESS[:PORT]\n"
cannam@48:         "Runs the server bound to the given address/port.\n"
cannam@48:         "ADDRESS may be '*' to bind to all local addresses.\n"
cannam@48:         ":PORT may be omitted to choose a port automatically." << std::endl;
cannam@48:     return 1;
cannam@48:   }
cannam@48: 
cannam@48:   // Set up a server.
cannam@48:   capnp::EzRpcServer server(kj::heap<CalculatorImpl>(), argv[1]);
cannam@48: 
cannam@48:   // Write the port number to stdout, in case it was chosen automatically.
cannam@48:   auto& waitScope = server.getWaitScope();
cannam@48:   uint port = server.getPort().wait(waitScope);
cannam@48:   if (port == 0) {
cannam@48:     // The address format "unix:/path/to/socket" opens a unix domain socket,
cannam@48:     // in which case the port will be zero.
cannam@48:     std::cout << "Listening on Unix socket..." << std::endl;
cannam@48:   } else {
cannam@48:     std::cout << "Listening on port " << port << "..." << std::endl;
cannam@48:   }
cannam@48: 
cannam@48:   // Run forever, accepting connections and handling requests.
cannam@48:   kj::NEVER_DONE.wait(waitScope);
cannam@48: }