cmake: Add debugger

- Depends on cppdap and jsoncpp.
- Add --debugger argument to enable the Debugger.
- Add --debugger-pipe argument for DAP traffics over named pipes.
- Support breakpoints by filenames and line numbers.
- Support exception breakpoints.
- Call stack shows filenames and line numbers.
- Show Cache Variables.
- Show the state of currently defined targets,
  tests and directories with their properties.
- Add cmakeVersion to DAP initialize response.
- Include unit tests.

Co-authored-by: Ben McMorran <bemcmorr@microsoft.com>

Source/cmDebuggerPipeConnection.h

@@ -0,0 +1,139 @@
+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+   file Copyright.txt or https://cmake.org/licensing for details.  */
+#pragma once
+
+#include "cmConfigure.h" // IWYU pragma: keep
+
+#include <condition_variable>
+#include <cstddef>
+#include <future>
+#include <memory>
+#include <mutex>
+#include <string>
+#include <thread>
+
+#include <cm3p/cppdap/io.h>
+#include <cm3p/uv.h>
+
+#include "cmDebuggerAdapter.h"
+#include "cmUVHandlePtr.h"
+
+namespace cmDebugger {
+
+class cmDebuggerPipeBase : public dap::ReaderWriter
+{
+public:
+  cmDebuggerPipeBase(std::string name);
+
+  void WaitForConnection();
+
+  // dap::ReaderWriter implementation
+
+  void close() final;
+  size_t read(void* buffer, size_t n) final;
+  bool write(const void* buffer, size_t n) final;
+
+protected:
+  virtual void CloseConnection(){};
+  template <typename T>
+  void StartReading(uv_stream_t* stream)
+  {
+    uv_read_start(
+      stream,
+      // alloc_cb
+      [](uv_handle_t* handle, size_t suggested_size, uv_buf_t* buf) {
+        (void)handle;
+        char* rawBuffer = new char[suggested_size];
+        *buf =
+          uv_buf_init(rawBuffer, static_cast<unsigned int>(suggested_size));
+      },
+      // read_cb
+      [](uv_stream_t* readStream, ssize_t nread, const uv_buf_t* buf) {
+        auto conn = static_cast<T*>(readStream->data);
+        if (conn) {
+          if (nread >= 0) {
+            conn->BufferData(std::string(buf->base, buf->base + nread));
+          } else {
+            conn->close();
+          }
+        }
+        delete[] (buf->base);
+      });
+  }
+  void StopLoop();
+
+  const std::string PipeName;
+  std::thread LoopThread;
+  cm::uv_loop_ptr Loop;
+  cm::uv_pipe_ptr Pipe;
+  std::mutex Mutex;
+  std::condition_variable Connected;
+  bool FailedToOpen = false;
+
+private:
+  void BufferData(const std::string& data);
+  void WriteInternal();
+
+  cm::uv_async_ptr LoopExit;
+  cm::uv_async_ptr WriteEvent;
+  cm::uv_async_ptr PipeClose;
+  std::string WriteBuffer;
+  std::string ReadBuffer;
+  std::condition_variable ReadReady;
+  std::condition_variable WriteComplete;
+};
+
+class cmDebuggerPipeConnection
+  : public cmDebuggerPipeBase
+  , public cmDebuggerConnection
+  , public std::enable_shared_from_this<cmDebuggerPipeConnection>
+{
+public:
+  cmDebuggerPipeConnection(std::string name);
+  ~cmDebuggerPipeConnection() override;
+
+  void WaitForConnection() override
+  {
+    cmDebuggerPipeBase::WaitForConnection();
+  }
+
+  bool StartListening(std::string& errorMessage) override;
+  std::shared_ptr<dap::Reader> GetReader() override;
+  std::shared_ptr<dap::Writer> GetWriter() override;
+
+  // dap::ReaderWriter implementation
+
+  bool isOpen() override;
+
+  // Used for unit test synchronization
+  std::promise<void> StartedListening;
+
+private:
+  void CloseConnection() override;
+  void Connect(uv_stream_t* server);
+
+  cm::uv_pipe_ptr ServerPipe;
+  cm::uv_async_ptr ServerPipeClose;
+};
+
+class cmDebuggerPipeClient : public cmDebuggerPipeBase
+{
+public:
+  using cmDebuggerPipeBase::cmDebuggerPipeBase;
+  ~cmDebuggerPipeClient() override;
+
+  void Start();
+
+  // dap::ReaderWriter implementation
+
+  bool isOpen() override;
+
+private:
+  void CloseConnection() override;
+  void Connect();
+  void FailConnection();
+
+  bool IsConnected = false;
+};
+
+} // namespace cmDebugger