Add existing examples (#1)

* Added cpp, go, python examples

* Updated Go steps in README

README.md

@@ -1 +1,48 @@
-# deephaven-client-examples
+# Deephaven Client Examples
+
+This collection of client examples performs (roughly) the same operations
+in several different client languages to compare their interfaces.
+
+The examples do not currently run, because some irrelevant code is omitted.
+However, they do compile.
+
+## Python
+
+Ensure a recent version of the pydeephaven package is installed.
+
+```sh
+$ cd ./python
+$ python3 main.py
+```
+
+## C++
+
+First, build and install the C++ client packages according to `deephaven-core/cpp-client/README.md`.
+Most of the build steps only need to be done once.
+However, `CMAKE_PREFIX_PATH` must always be set appropriately when building the example.
+
+Then, edit `./cpp/CMakeLists.txt` where indicated to set the correct path for the client library.
+
+```sh
+$ cd ./cpp
+$ mkdir build && cd build
+$ cmake ..
+$ make
+$ ./example
+```
+
+## Go
+
+First, ensure you have the Go client present somewhere.
+Since the Go client has not yet been officially released,
+this requires checking out the `go-client-api` branch of
+[this fork](https://github.com/SuperTails/deephaven-core).
+
+Then, edit `./go/go.mod` where indicated to set the correct path for the client library.
+
+```sh
+$ cd ./go
+$ go mod tidy
+$ go build
+$ ./go_client_example
+```

cpp/CMakeLists.txt

@@ -0,0 +1,19 @@
+cmake_minimum_required(VERSION 3.16)
+project(example)
+
+set(CMAKE_CXX_STANDARD 17)
+
+set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
+
+# CHANGE THIS TO THE APPROPRIATE DIRECTORY 
+add_subdirectory(/deephaven/deephaven-core/cpp-client/deephaven deephaven_dir)
+
+find_package(Arrow REQUIRED)
+find_package(ArrowFlight REQUIRED HINTS ${Arrow_DIR})
+find_package(Protobuf REQUIRED)
+find_package(gRPC REQUIRED)
+find_package(Threads REQUIRED)
+
+add_executable(example main.cpp)
+
+target_link_libraries(example deephaven::client)

cpp/main.cpp

@@ -0,0 +1,48 @@
+#include <exception>
+#include <iostream>
+#include "deephaven/client/highlevel/client.h"
+
+using namespace deephaven::client::highlevel;
+
+int main() {
+  try {
+	const char *server = "localhost:10000";
+
+    auto client = Client::connect(server);
+
+	// TODO: Check about information related to field syncing or ListFields.
+
+    auto manager = client.getManager();
+
+	/*
+		Creation of handle1 omitted.
+		The C++ client does not have a direct equivalent of importTable,
+		and uses TableMaker or Arrow Flight instead.
+	*/
+	auto handle1 = TableHandle(/* omitted */);
+
+    auto handle2 = manager.emptyTable(10);
+
+	auto handle3 = handle2.where("a > 10 && b % 2 == 0");
+
+	auto handle4 = handle1.merge("a", { handle3 }); // Note that merge is a method on the table handle here.
+
+	auto combo_agg = aggCombo({
+		aggSum("foo = a", "bar = c"),
+		aggAvg("avgA = a", "avgB = b")
+	});
+	auto handle5 = handle4.by(combo_agg, { "g" });
+
+	/*
+		There is no equivalent of the snapshot method in the C++ client.
+		The C++ client only supports reading table data through Arrow Flight.
+		There is a convenience method to print the table data, though.
+	*/
+	std::cout << handle5.stream(true) << '\n';
+  } catch (const std::exception &e) {
+    std::cerr << "Caught exception: " << e.what() << '\n';
+  }
+
+  return 0;
+}
+

go/go.mod

@@ -0,0 +1,36 @@
+module example.com/go_client_example
+
+go 1.18
+
+require (
+	github.com/apache/arrow/go/v8 v8.0.0
+	github.com/deephaven/deephaven-core/go-client v0.1.0-alpha.0
+)
+
+require (
+	github.com/andybalholm/brotli v1.0.4 // indirect
+	github.com/apache/thrift v0.15.0 // indirect
+	github.com/goccy/go-json v0.9.6 // indirect
+	github.com/golang/protobuf v1.5.2 // indirect
+	github.com/golang/snappy v0.0.4 // indirect
+	github.com/google/flatbuffers v2.0.5+incompatible // indirect
+	github.com/klauspost/asmfmt v1.3.1 // indirect
+	github.com/klauspost/compress v1.14.2 // indirect
+	github.com/klauspost/cpuid/v2 v2.0.9 // indirect
+	github.com/minio/asm2plan9s v0.0.0-20200509001527-cdd76441f9d8 // indirect
+	github.com/minio/c2goasm v0.0.0-20190812172519-36a3d3bbc4f3 // indirect
+	github.com/pierrec/lz4/v4 v4.1.12 // indirect
+	github.com/zeebo/xxh3 v1.0.1 // indirect
+	golang.org/x/mod v0.6.0-dev.0.20220106191415-9b9b3d81d5e3 // indirect
+	golang.org/x/net v0.0.0-20220607020251-c690dde0001d // indirect
+	golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a // indirect
+	golang.org/x/text v0.3.7 // indirect
+	golang.org/x/tools v0.1.10 // indirect
+	golang.org/x/xerrors v0.0.0-20220411194840-2f41105eb62f // indirect
+	google.golang.org/genproto v0.0.0-20220126215142-9970aeb2e350 // indirect
+	google.golang.org/grpc v1.47.0 // indirect
+	google.golang.org/protobuf v1.27.1 // indirect
+)
+
+// CHANGE /deephaven/deephaven-core/go-client TO THE APPROPRIATE DIRECTORY
+replace github.com/deephaven/deephaven-core/go-client => /deephaven/deephaven-core/go-client