Lint: extract the arithmetic for cleaner code

lib/archethic/contracts/interpreter/ast_helper.ex

@@ -182,4 +182,27 @@ defmodule Archethic.Contracts.Interpreter.ASTHelper do
   """
   def wrap_in_block(ast = {:__block__, _, _}), do: ast
   def wrap_in_block(ast), do: {:__block__, [], [ast]}
+
+  @doc """
+  Delegate the arithmetic to the Decimal library
+  """
+  @spec decimal_arithmetic(Macro.t(), number(), number()) :: float()
+  def decimal_arithmetic(ast, lhs, rhs) do
+    operation =
+      case ast do
+        :* -> &Decimal.mult/2
+        :/ -> &Decimal.div/2
+        :+ -> &Decimal.add/2
+        :- -> &Decimal.sub/2
+      end
+
+    # the `0.0 + x` is used to cast integers to floats
+    Decimal.to_float(
+      Decimal.round(
+        operation.(Decimal.from_float(0.0 + lhs), Decimal.from_float(0.0 + rhs)),
+        8,
+        :floor
+      )
+    )
+  end
 end

lib/archethic/contracts/interpreter/common_interpreter.ex

@@ -361,74 +361,10 @@ defmodule Archethic.Contracts.Interpreter.CommonInterpreter do
   end
 
   # BigInt mathematics to avoid floating point issues
-  # the `0.0 + x` is used to cast integers to floats
-  def postwalk(_node = {:*, meta, [lhs, rhs]}, acc) do
+  def postwalk(_node = {ast, meta, [lhs, rhs]}, acc) when ast in [:*, :/, :+, :-] do
     new_node =
       quote line: Keyword.fetch!(meta, :line) do
-        Decimal.to_float(
-          Decimal.round(
-            Decimal.mult(
-              Decimal.from_float(0.0 + unquote(lhs)),
-              Decimal.from_float(0.0 + unquote(rhs))
-            ),
-            8,
-            :floor
-          )
-        )
-      end
-
-    {new_node, acc}
-  end
-
-  def postwalk(_node = {:/, meta, [lhs, rhs]}, acc) do
-    new_node =
-      quote line: Keyword.fetch!(meta, :line) do
-        Decimal.to_float(
-          Decimal.round(
-            Decimal.div(
-              Decimal.from_float(0.0 + unquote(lhs)),
-              Decimal.from_float(0.0 + unquote(rhs))
-            ),
-            8,
-            :floor
-          )
-        )
-      end
-
-    {new_node, acc}
-  end
-
-  def postwalk(_node = {:+, meta, [lhs, rhs]}, acc) do
-    new_node =
-      quote line: Keyword.fetch!(meta, :line) do
-        Decimal.to_float(
-          Decimal.round(
-            Decimal.add(
-              Decimal.from_float(0.0 + unquote(lhs)),
-              Decimal.from_float(0.0 + unquote(rhs))
-            ),
-            8,
-            :floor
-          )
-        )
-      end
-
-    {new_node, acc}
-  end
-
-  def postwalk(_node = {:-, meta, [lhs, rhs]}, acc) do
-    new_node =
-      quote line: Keyword.fetch!(meta, :line) do
-        Decimal.to_float(
-          Decimal.round(
-            Decimal.sub(
-              Decimal.from_float(0.0 + unquote(lhs)),
-              Decimal.from_float(0.0 + unquote(rhs))
-            ),
-            8,
-            :floor
-          )
-        )
+        AST.decimal_arithmetic(unquote(ast), unquote(lhs), unquote(rhs))
       end
 
     {new_node, acc}