From 4ac065fbe57ed19760dbb55453e5875b3c0c188d Mon Sep 17 00:00:00 2001
From: Anhgelus Morhtuuzh <william@herges.fr>
Date: Tue, 4 Nov 2025 12:30:35 +0100
Subject: feat(parser): default parser

---
 .gitignore                |  2 ++
 lib/elixir_math_parser.ex | 47 +++++++++++++++++++++++++++++++++++++++--------
 lib/main.ex               | 28 ++++++++++++++++++++++++++++
 mix.exs                   |  3 ++-
 4 files changed, 71 insertions(+), 9 deletions(-)
 create mode 100644 lib/main.ex

diff --git a/.gitignore b/.gitignore
index c556df8..af52a17 100644
--- a/.gitignore
+++ b/.gitignore
@@ -22,3 +22,5 @@ erl_crash.dump
 # Ignore package tarball (built via "mix hex.build").
 elixir_math_parser-*.tar
 
+src/elixir_math_parser*.erl
+
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
diff --git a/lib/main.ex b/lib/main.ex
new file mode 100644
index 0000000..ca73cb5
--- /dev/null
+++ b/lib/main.ex
@@ -0,0 +1,28 @@
+defmodule ElixirMathParser.Main do
+   def process_parse({:error, result}) do
+    IO.puts "\nParse error"
+    IO.inspect result
+  end
+
+  def process_parse({:ok, tree}) do
+    IO.puts "\nParse tree"
+    IO.inspect tree, pretty: true
+    state = ElixirMathParser.process_tree(tree)
+    IO.puts "\nFinal state"
+    IO.inspect state, pretty: true
+  end
+  
+  def main(args) do
+    filename = Enum.fetch!(args, 0)
+
+    IO.puts "Parsing #{filename}"
+    text = File.read!(filename)
+
+    {:ok, tokens, line} = :elixir_math_parser_lexer.string(String.to_charlist(text))
+    IO.puts "Parsed #{filename}, stopped at line #{line}"
+    IO.puts "\nTokens:"
+    IO.inspect tokens, pretty: true
+
+    process_parse(:elixir_math_parser.parse(tokens))
+  end 
+end
diff --git a/mix.exs b/mix.exs
index a138d8b..3b7e2dd 100644
--- a/mix.exs
+++ b/mix.exs
@@ -7,7 +7,8 @@ defmodule ElixirMathParser.MixProject do
       version: "0.1.0",
       elixir: "~> 1.19",
       start_permanent: Mix.env() == :prod,
-      deps: deps()
+      deps: deps(),
+      escript: [main_module: ElixirMathParser.Main],
     ]
   end
 
-- 
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