initial commit

.formatter.exs

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+# Used by "mix format"
+[
+  inputs: ["{mix,.formatter}.exs", "{config,lib,test}/**/*.{ex,exs}"]
+]

.gitignore

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+# The directory Mix will write compiled artifacts to.
+/_build/
+
+# If you run "mix test --cover", coverage assets end up here.
+/cover/
+
+# The directory Mix downloads your dependencies sources to.
+/deps/
+
+# Where third-party dependencies like ExDoc output generated docs.
+/doc/
+
+# Ignore .fetch files in case you like to edit your project deps locally.
+/.fetch
+
+# If the VM crashes, it generates a dump, let's ignore it too.
+erl_crash.dump
+
+# Also ignore archive artifacts (built via "mix archive.build").
+*.ez
+
+# Ignore package tarball (built via "mix hex.build").
+elixir_rpg-*.tar
+
+
+# Temporary files for e.g. tests
+/tmp

README.md

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+# ElixirRpg
+
+**TODO: Add description**
+
+## Installation
+
+If [available in Hex](https://hex.pm/docs/publish), the package can be installed
+by adding `elixir_rpg` to your list of dependencies in `mix.exs`:
+
+```elixir
+def deps do
+  [
+    {:elixir_rpg, "~> 0.1.0"}
+  ]
+end
+```
+
+Documentation can be generated with [ExDoc](https://github.com/elixir-lang/ex_doc)
+and published on [HexDocs](https://hexdocs.pm). Once published, the docs can
+be found at [https://hexdocs.pm/elixir_rpg](https://hexdocs.pm/elixir_rpg).
+

lib/DSL/entity.ex

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+defmodule ElixirRPG.DSL.Entity do
+
+end

lib/DSL/system.ex

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+defmodule ElixirRPG.DSL.System do
+  defmacro __using__(_options) do
+    quote do
+      import ElixirRPG.DSL.System
+    end
+  end
+
+  defmacro defsystem(name, do: block) do
+    quote do
+      defmodule ElixirRPG.RuntimeSystems.unquote(name) do
+        Module.register_attribute(__MODULE__, :wants, accumulate: true, persist: true)
+        Module.register_attribute(__MODULE__, :system_name, persist: true)
+
+        unquote(block)
+
+        def wants do
+          @wants
+        end
+
+        def name do
+          @system_name
+        end
+      end
+    end
+  end
+
+  defmacro name(name) do
+    quote do
+      @system_name unquote(name)
+    end
+  end
+
+  defmacro wants(component_name) do
+    quote do
+      @wants unquote(component_name)
+    end
+  end
+
+  defmacro on_tick(do: block) do
+    quote do
+      def __tick() do
+        unquote(block)
+        :tock
+      end
+    end
+  end
+end

lib/elixir_rpg.ex

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+defmodule ElixirRPG do
+  alias ElixirRPG.World
+
+  require Logger
+
+  def test_harness do
+    {:ok, world_pid} = World.start_link("test_world", :the_world)
+    Logger.info("Started World at PID: #{inspect(world_pid)}")
+  end
+end

lib/system/system.ex

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+defmodule ElixirRPG.System do
+  @callback wants() :: list(atom())
+end

lib/system/test_system.ex

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+use ElixirRPG.DSL.System
+
+defsystem TestSystem do
+
+  name "A Simple Testing System"
+
+  wants :player_stats
+  wants :input
+
+  on_tick do
+    IO.inspect("tick")
+  end
+end

lib/world/data.ex

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+defmodule ElixirRPG.World.Data do
+  use TypedStruct
+
+  typedstruct do
+    field(:name, String.t(), default: "world")
+    field(:clock, pid(), default: nil)
+    field(:target_tick_rate, integer(), default: 0)
+
+    field(:systems, list(), default: [])
+    field(:entities, list(), default: [])
+  end
+end

lib/world/world.ex

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+defmodule ElixirRPG.World do
+  use GenServer
+
+  alias ElixirRPG.World
+
+  @initial_state %World.Data{target_tick_rate: 60}
+
+  def start_link(name, proc_name) when is_binary(name) and is_atom(proc_name) do
+    GenServer.start_link(__MODULE__, [name: name], name: proc_name)
+  end
+
+  @impl GenServer
+  def init(name: world_name) do
+    state = @initial_state
+
+    clock_ref = World.Clock.start_tick(state.target_tick_rate, self())
+    {:ok, %World.Data{state | name: world_name, clock: clock_ref}}
+  end
+
+  @impl GenServer
+  def handle_cast(:pause, current_state) do
+    :timer.cancel(current_state.clock)
+    {:noreply, %{current_state | clock: nil}}
+  end
+
+  def handle_cast(:resume, current_state) do
+    :timer.cancel(current_state.clock)
+    clock_ref = World.Clock.start_tick(current_state.target_tick_rate, self())
+    {:ok, %{@initial_state | clock: clock_ref}}
+  end
+
+  def handle_cast({:broadcast, msg}, current_state) do
+    Enum.each(current_state.children, fn pid -> GenServer.cast(pid, msg) end)
+    {:noreply, current_state}
+  end
+
+  @impl GenServer
+  def handle_info(:tick, current_state) do
+    # Enum.each(current_state.children, fn pid -> GenServer.cast(pid, :tick) end)
+    {:noreply, current_state}
+  end
+
+  @impl GenServer
+  def handle_call({:add_child, child, args}, _from, current_state) do
+    {:ok, new_child_pid} = GenServer.start_link(child, args)
+    new_state = %{current_state | children: [new_child_pid | current_state.children]}
+    {:reply, new_child_pid, new_state}
+  end
+end

lib/world/world_clock.ex

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+defmodule ElixirRPG.World.Clock do
+  def start_tick(target_ticks_per_sec, target_pid)
+      when is_pid(target_pid) and is_integer(target_ticks_per_sec) do
+    ms = trunc(1000 / target_ticks_per_sec)
+    {:ok, timer_ref} = :timer.send_interval(ms, target_pid, :tick)
+    timer_ref
+  end
+end

mix.exs

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+defmodule ElixirRpg.MixProject do
+  use Mix.Project
+
+  def project do
+    [
+      app: :elixir_rpg,
+      version: "0.1.0",
+      elixir: "~> 1.11",
+      start_permanent: Mix.env() == :prod,
+      deps: deps()
+    ]
+  end
+
+  # Run "mix help compile.app" to learn about applications.
+  def application do
+    [
+      extra_applications: [:logger]
+    ]
+  end
+
+  # Run "mix help deps" to learn about dependencies.
+  defp deps do
+    [
+      {:typed_struct, "~> 0.2.1"}
+    ]
+  end
+end

mix.lock

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+%{
+  "typed_struct": {:hex, :typed_struct, "0.2.1", "e1993414c371f09ff25231393b6430bd89d780e2a499ae3b2d2b00852f593d97", [:mix], [], "hexpm", "8f5218c35ec38262f627b2c522542f1eae41f625f92649c0af701a6fab2e11b3"},
+}

test/test_helper.exs

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+ExUnit.start()