feat(parser): default parser

1 files changed, 39 insertions, 8 deletions

diff --git a/lib/elixir_math_parser.ex b/lib/elixir_math_parser.ex
index cd300e9..1f147aa 100644
--- a/lib/elixir_math_parser.ex
+++ b/lib/elixir_math_parser.ex
@@ -3,16 +3,47 @@ defmodule ElixirMathParser do
   Documentation for `ElixirMathParser`.
   """
 
-  @doc """
-  Hello world.
+  defp reduce_to_value({:int, _line, value}, _state) do
+    value
+  end
+
+  defp reduce_to_value({:add_op, lhs, rhs}, state) do
+    reduce_to_value(lhs, state) + reduce_to_value(rhs, state)
+  end
 
-  ## Examples
+  defp reduce_to_value({:sub_op, lhs, rhs}, state) do
+    reduce_to_value(lhs, state) - reduce_to_value(rhs, state)
+  end
 
-      iex> ElixirMathParser.hello()
-      :world
+  defp reduce_to_value({:mul_op, lhs, rhs}, state) do
+    reduce_to_value(lhs, state) * reduce_to_value(rhs, state)
+  end
 
-  """
-  def hello do
-    :world
+  defp reduce_to_value({:div_op, lhs, rhs}, state) do
+    reduce_to_value(lhs, state) / reduce_to_value(rhs, state)
   end
+
+  defp reduce_to_value({:atom, _line, atom}, state) do
+    state[atom]
+  end
+  
+  defp evaluate_tree([{:assign, {:atom, _line, lhs}, rhs} | tail], state) do
+    rhs_value = reduce_to_value(rhs, state)
+    evaluate_tree(tail, Map.merge(state, %{lhs => rhs_value}))
+  end
+
+   defp evaluate_tree([], state) do
+     state
+   end
+
+   def process_tree(tree) do
+     evaluate_tree(tree, %{})
+   end
+
+   def parse_file(filename) do
+     text = File.read!(filename)
+     {:ok, tokens, _line} = :elixir_math_parser_lexer.string(String.to_charlist(text))
+     {:ok, tree} = :elixir_math_parser.parse(tokens)
+     process_tree(tree)        
+   end
 end