added data model for nodes

.gitignore

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+/_build
+/cover
+/deps
+erl_crash.dump
+*.ez
+*.beam

README.md

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+# Exstreme
+
+**TODO: Add description**
+
+## Installation
+
+If [available in Hex](https://hex.pm/docs/publish), the package can be installed as:
+
+  1. Add exstreme to your list of dependencies in `mix.exs`:
+
+        def deps do
+          [{:exstreme, "~> 0.0.1"}]
+        end
+
+  2. Ensure exstreme is started before your application:
+
+        def application do
+          [applications: [:exstreme]]
+        end
+

config/config.exs

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+# This file is responsible for configuring your application
+# and its dependencies with the aid of the Mix.Config module.
+use Mix.Config
+
+# This configuration is loaded before any dependency and is restricted
+# to this project. If another project depends on this project, this
+# file won't be loaded nor affect the parent project. For this reason,
+# if you want to provide default values for your application for
+# 3rd-party users, it should be done in your "mix.exs" file.
+
+# You can configure for your application as:
+#
+#     config :exstreme, key: :value
+#
+# And access this configuration in your application as:
+#
+#     Application.get_env(:exstreme, :key)
+#
+# Or configure a 3rd-party app:
+#
+#     config :logger, level: :info
+#
+
+# It is also possible to import configuration files, relative to this
+# directory. For example, you can emulate configuration per environment
+# by uncommenting the line below and defining dev.exs, test.exs and such.
+# Configuration from the imported file will override the ones defined
+# here (which is why it is important to import them last).
+#
+#     import_config "#{Mix.env}.exs"

lib/exstreme.ex

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+defmodule Exstreme do
+end

lib/exstreme/stream_graph.ex

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+defmodule Exstreme.StreamGraph do
+  @moduledoc """
+  """
+  defmodule Graph do
+    defstruct params: [], nodes: %{}, connections: []
+  end
+
+  @doc """
+  """
+  def create_graph(params \\ []), do: %Graph{params: params}
+
+  @doc """
+  """
+  def create_node(graph = %Graph{nodes: nodes}, params \\ []) do
+    key = next_node_key(nodes)
+    new_graph = update_in(graph.nodes, &(Map.put(&1, key, params)))
+    {new_graph, key}
+  end
+
+  @doc """
+  """
+  def add_connection(graph = %Graph{nodes: nodes}, start, finish) when start != finish do
+    if Map.has_key?(nodes, start) and Map.has_key?(nodes, finish) do
+      update_in(graph.connections, store_connection_fn(start, finish))
+    else
+      raise ArgumentError, message: "nodes not found"
+    end
+  end
+
+  #private
+
+  defp store_connection_fn(start, finish) do
+    fn(connections) ->
+      connections
+      |> validate_repeated(start, finish)
+      |> validate_repeated(finish, start)
+      |> validate_position(start, :start)
+      |> validate_position(finish, :end)
+      |> Keyword.put(start, finish)
+    end
+  end
+
+  def validate_repeated(connections, start, finish) do
+    if connections |> Enum.any?(&(&1 == {start, finish})) do
+      raise ArgumentError, message: "there is already a connection like that"
+    else
+      connections
+    end
+  end
+
+  defp validate_position(connections, node, position) do
+    case node|> Atom.to_string |> String.first do
+      "n" -> validate_position_node(connections, node, position)
+      # "b" ->
+      # "f" ->
+       _  -> raise ArgumentError, message: "invalid node"
+    end
+  end
+
+  defp validate_position_node(connections, node, :start) do
+    exist =
+      connections
+      |> Keyword.has_key?(node)
+    if exist do
+      raise ArgumentError, message: "the node can't be twice at start position"
+    else
+      connections
+    end
+  end
+
+  defp validate_position_node(connections, node, :end) do
+    exist =
+      connections
+      |> Keyword.values
+      |> Enum.member?(node)
+    if exist do
+      raise ArgumentError, message: "the node can't be twice at end position"
+    else
+      connections
+    end
+  end
+
+  defp next_node_key(nodes) do
+    next_key(nodes, "n")
+  end
+
+  defp next_key(map, letter) do
+    count =
+      map
+      |> Map.keys
+      |> Enum.map(&Atom.to_string/1)
+      |> Enum.filter(fn(str) -> String.starts_with?(str, letter) end)
+      |> Enum.count
+    String.to_atom("#{letter}#{count + 1}")
+  end
+end

mix.exs

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+defmodule Exstreme.Mixfile do
+  use Mix.Project
+
+  def project do
+    [app: :exstreme,
+     version: "0.0.1",
+     elixir: "~> 1.2",
+     build_embedded: Mix.env == :prod,
+     start_permanent: Mix.env == :prod,
+     deps: deps]
+  end
+
+  # Configuration for the OTP application
+  #
+  # Type "mix help compile.app" for more information
+  def application do
+    [applications: [:logger]]
+  end
+
+  # Dependencies can be Hex packages:
+  #
+  #   {:mydep, "~> 0.3.0"}
+  #
+  # Or git/path repositories:
+  #
+  #   {:mydep, git: "https://github.com/elixir-lang/mydep.git", tag: "0.1.0"}
+  #
+  # Type "mix help deps" for more examples and options
+  defp deps do
+    []
+  end
+end

test/exstreme/stream_graph_test.exs

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+defmodule Exstreme.StreamGraphTest do
+  use ExUnit.Case
+  alias Exstreme.StreamGraph
+  alias Exstreme.StreamGraph.Graph
+  doctest Exstreme.StreamGraph
+
+  def params, do: []
+
+  def create_graph do
+    graph = StreamGraph.create_graph(params)
+
+    {graph, n1} = graph |> StreamGraph.create_node(params)
+    {graph, n2} = graph |> StreamGraph.create_node(params)
+
+    graph
+    |> StreamGraph.add_connection(n1, n2)
+  end
+
+  test "creates a valid graph struct" do
+    graph = %Graph{
+      nodes: %{n1: [], n2: []},
+      connections: [{:n1, :n2}]
+    }
+    assert create_graph == graph
+  end
+
+  test "throws an error when adding again the relation" do
+    assert_raise ArgumentError, fn ->
+      create_graph
+      |> StreamGraph.add_connection(:n1, :n2)
+    end
+  end
+
+  test "throws an error when adding again a self relation" do
+    assert_raise FunctionClauseError, fn ->
+      create_graph
+      |> StreamGraph.add_connection(:n1, :n1)
+    end
+  end
+
+  test "throws an error when adding a cicle relation" do
+    assert_raise ArgumentError, "there is already a connection like that", fn ->
+      create_graph
+      |> StreamGraph.add_connection(:n2, :n1)
+    end
+  end
+
+    test "can create n3 and add a relatio between n2 and n3" do
+      graph = %Graph{
+        nodes: %{n1: [], n2: []},
+        connections: [{:n1, :n2}]
+      }
+
+      {new_graph, _} = create_graph |> StreamGraph.create_node(params)
+      new_graph =
+        new_graph
+        |> StreamGraph.add_connection(:n2, :n3)
+    end
+end

test/exstreme_test.exs

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+defmodule ExstremeTest do
+  use ExUnit.Case
+  doctest Exstreme
+
+  test "the truth" do
+    assert 1 + 1 == 2
+  end
+end

test/test_helper.exs

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+ExUnit.start()