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