Add: [Script] Native priority queue; useful e.g. for pathfinders.

src/script/api/script_priorityqueue.cpp

@@ -0,0 +1,107 @@
+/*
+ * This file is part of OpenTTD.
+ * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
+ * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/** @file script_priorityqueue.cpp Implementation of ScriptPriorityQueue. */
+
+#include "../../stdafx.h"
+#include "script_priorityqueue.hpp"
+#include "script_error.hpp"
+#include "../squirrel_helper.hpp"
+#include "../script_instance.hpp"
+#include "../../debug.h"
+#include <algorithm>
+
+#include "../../safeguards.h"
+
+
+static bool operator==(const ScriptPriorityQueue::PriorityItem &lhs, const HSQOBJECT &rhs)
+{
+	return lhs.second._type == rhs._type && lhs.second._unVal.raw == rhs._unVal.raw;
+}
+
+
+ScriptPriorityQueue::~ScriptPriorityQueue()
+{
+	/* Release reference to stored objects. */
+	auto inst = ScriptObject::GetActiveInstance();
+	if (!inst->InShutdown()) {
+		for (auto &i : this->queue) inst->ReleaseSQObject(const_cast<HSQOBJECT *>(&i.second));
+	}
+}
+
+SQInteger ScriptPriorityQueue::Insert(HSQUIRRELVM vm)
+{
+	HSQOBJECT item;
+	int64 priority;
+	sq_resetobject(&item);
+	sq_getstackobj(vm, 2, &item);
+	sq_getinteger(vm, 3, &priority);
+
+	sq_addref(vm, &item); // Keep object alive.
+
+	this->queue.emplace_back(priority, item);
+	std::push_heap(this->queue.begin(), this->queue.end(), this->comp);
+
+	return SQConvert::Return(vm, true);
+}
+
+SQInteger ScriptPriorityQueue::Pop(HSQUIRRELVM vm)
+{
+	if (this->IsEmpty()) {
+		ScriptObject::SetLastError(ScriptError::ERR_PRECONDITION_FAILED);
+		sq_pushnull(vm);
+		return 1;
+	}
+
+	HSQOBJECT item = this->queue.front().second;
+	std::pop_heap(this->queue.begin(), this->queue.end(), this->comp);
+	this->queue.pop_back();
+
+	/* Store the object on the Squirrel stack before releasing it to make sure the ref count can't drop to zero. */
+	auto ret = SQConvert::Return(vm, item);
+	sq_release(vm, &item);
+	return ret;
+}
+
+SQInteger ScriptPriorityQueue::Peek(HSQUIRRELVM vm)
+{
+	if (this->IsEmpty()) {
+		ScriptObject::SetLastError(ScriptError::ERR_PRECONDITION_FAILED);
+		sq_pushnull(vm);
+		return 1;
+	}
+
+	return SQConvert::Return(vm, this->queue.front().second);
+}
+
+SQInteger ScriptPriorityQueue::Exists(HSQUIRRELVM vm)
+{
+	HSQOBJECT item;
+	sq_resetobject(&item);
+	sq_getstackobj(vm, 2, &item);
+
+	return SQConvert::Return(vm, std::find(this->queue.cbegin(), this->queue.cend(), item) != this->queue.cend());
+}
+
+SQInteger ScriptPriorityQueue::Clear(HSQUIRRELVM vm)
+{
+	/* Release reference to stored objects. */
+	for (auto &i : this->queue) sq_release(vm, const_cast<HSQOBJECT *>(&i.second));
+	this->queue.clear();
+
+	return 0;
+}
+
+bool ScriptPriorityQueue::IsEmpty()
+{
+	return this->queue.empty();
+}
+
+SQInteger ScriptPriorityQueue::Count()
+{
+	return (SQInteger)this->queue.size();
+}