Add script engine and connect to std console

src/openrct2/scripting/ScriptEngine.cpp

@@ -0,0 +1,79 @@
+/*****************************************************************************
+ * Copyright (c) 2014-2018 OpenRCT2 developers
+ *
+ * For a complete list of all authors, please refer to contributors.md
+ * Interested in contributing? Visit https://github.com/OpenRCT2/OpenRCT2
+ *
+ * OpenRCT2 is licensed under the GNU General Public License version 3.
+ *****************************************************************************/
+
+#include "ScriptEngine.h"
+#include "../interface/InteractiveConsole.h"
+#include <duktape.h>
+#include <stdexcept>
+
+using namespace OpenRCT2;
+using namespace OpenRCT2::Scripting;
+
+static std::string Stringify(duk_context * ctx, duk_idx_t idx);
+
+ScriptEngine::ScriptEngine(InteractiveConsole& console, IPlatformEnvironment& env) :
+    _console(console),
+    _env(env)
+{
+    _context = duk_create_heap_default();
+    if (_context == nullptr)
+    {
+        throw std::runtime_error("Unable to initialise duktape context.");
+    }
+}
+
+ScriptEngine::~ScriptEngine()
+{
+    duk_destroy_heap(_context);
+}
+
+void ScriptEngine::Update()
+{
+    while (_evalQueue.size() > 0)
+    {
+        auto item = std::move(_evalQueue.front());
+        _evalQueue.pop();
+        auto promise = std::move(std::get<0>(item));
+        auto command = std::move(std::get<1>(item));
+        if (duk_peval_string(_context, command.c_str()) != 0)
+        {
+            std::string result = std::string(duk_safe_to_string(_context, -1));
+            _console.WriteLineError(result);
+        }
+        else
+        {
+            std::string result = Stringify(_context, -1);
+            _console.WriteLine(result);
+        }
+        duk_pop(_context);
+        // Signal the promise so caller can continue
+        promise.set_value();
+    }
+}
+
+std::future<void> ScriptEngine::Eval(const std::string &s)
+{
+    std::promise<void> barrier;
+    auto future = barrier.get_future();
+    _evalQueue.emplace(std::move(barrier), s);
+    return future;
+}
+
+static std::string Stringify(duk_context * ctx, duk_idx_t idx)
+{
+    auto type = duk_get_type(ctx, idx);
+    if (type == DUK_TYPE_OBJECT && !duk_is_function(ctx, idx))
+    {
+        return duk_json_encode(ctx, idx);
+    }
+    else
+    {
+        return duk_safe_to_string(ctx, idx);
+    }
+}