Merge pull request #1837 from zambal/decompose_call

Add Macro.decompose_call/1

Author: José Valim

lib/elixir/lib/macro.ex

@@ -103,6 +103,31 @@ defmodule Macro do
     :elixir_clauses.extract_args(expr)
   end
 
+  @doc """
+  Decomposes a local or remote call into its module alias (when a remote
+  call is provided), function name and argument list. 
+  Returns :error when an invalid call syntax is provied.
+
+  ## Examples
+
+      decompose_call(quote do: foo) == { :foo, [] }
+      decompose_call(quote do: foo()) == { :foo, [] }
+      decompose_call(quote do: foo(1, 2, 3)) == { :foo, [1, 2, 3] }
+      decompose_call(quote do: M.N.foo(1, 2, 3)) ==
+        { { :__aliases__, [alias: false], [:M, :N] }, :foo, [1, 2, 3] }
+      decompose_call(quote do: 42) == :error
+
+  """
+  @spec decompose_call(Macro.t) :: { atom, [Macro.t] } | { Macro.t, atom, [Macro.t] } | :error
+  def decompose_call(expr) do
+    case expr do
+      { { :., _, [{ :__aliases__, meta, atoms }, f] }, _, args } ->
+        { { :__aliases__, meta, atoms }, f, args }
+      _local ->
+        :elixir_clauses.extract_args(expr)
+    end
+  end
+
   @doc """
   Recursively escapes a value so it can be inserted
   into a syntax tree.

lib/elixir/test/elixir/macro_test.exs

@@ -406,6 +406,19 @@ defmodule MacroTest do
     assert Macro.extract_args(quote do: 1.(1, 2, 3))  == :error
   end
 
+  ## decompose_call
+
+  test :decompose_call do
+    assert Macro.decompose_call(quote do: foo)        == { :foo, [] }
+    assert Macro.decompose_call(quote do: foo())      == { :foo, [] }
+    assert Macro.decompose_call(quote do: :foo.())    == { :foo, [] }
+    assert Macro.decompose_call(quote do: foo(1, 2, 3)) == { :foo, [1, 2, 3] }
+    assert Macro.decompose_call(quote do: M.N.foo(1, 2, 3)) ==
+           { { :__aliases__, [alias: false], [:M, :N] }, :foo, [1, 2, 3] }
+    assert Macro.decompose_call(quote do: 1.(1, 2, 3))  == :error
+    assert Macro.decompose_call(quote do: "some string")  == :error
+  end
+
   ## env
 
   test :env_stacktrace do