Elixir 1.1 support

lib/array.ex

@@ -15,7 +15,7 @@ defmodule Array do
   Creates a new, extendible array with initial size zero.
   The default value is the atom nil, not undefined.
   """
-  @spec new() :: t 
+  @spec new() :: t
   def new() do
     %Array{content: :array.new({:default, nil})}
   end
@@ -85,7 +85,7 @@ defmodule Array do
 
   @doc """
   Folds the elements of the array using the given function and initial accumulator value.
-  The elements are visited in order from the lowest index to the highest. 
+  The elements are visited in order from the lowest index to the highest.
 
   If `fun` is not a function, the call raises `ArgumentError`.
   """
@@ -96,7 +96,7 @@ defmodule Array do
   @doc """
   Folds the elements of the array right-to-left using the given function and initial accumulator value.
   The elements are visited in order from the highest index to the lowest.
- 
+
   If `fun` is not a function, the call raises `ArgumentError`.
   """
   @spec foldr(t, acc, (index, element, acc -> acc)) :: acc when acc: var
@@ -155,11 +155,36 @@ defmodule Array do
 
   @doc """
   Gets the value of entry `idx`. If `idx` is not a nonnegative integer, or if the array has
-  fixed size and `idx` is larger than the maximum index, the call raises `ArgumentError`.
+  fixed size and `idx` is larger than the maximum index, the call returns :error
   """
-  @spec get(t, index) :: element
-  def get(%Array{content: c}, idx),
-    do: :array.get(idx, c)
+  @spec fetch(t, index) :: element
+  def fetch(%Array{content: c}, idx) do
+    cond do
+      :array.size(c) == 0 -> :error
+      idx in 0..(:array.size(c) - 1) -> {:ok, :array.get(idx, c)}
+      true -> :error
+    end
+  end
+
+  @doc """
+  Gets the value of entry `idx`. If `idx` is not a nonnegative integer, or if the array has
+  fixed size and `idx` is larger than the maximum index it returns `default` or array's default value.
+  """
+  @spec get(t, index, any) :: element
+  def get(array, idx, default \\ nil) do
+    case Array.fetch(array, idx) do
+      {:ok, value} -> value
+      :error -> default || Array.default(array)
+    end
+  end
+
+  @doc """
+  Gets and updates the container’s value for the given key, in a single pass.
+  """
+  def get_and_update(arr, idx, fun) do
+    {get, update} = fun.(Array.get(arr, idx))
+    {get, Array.set(arr, idx, update)}
+  end
 
   @doc """
   Returns `true` if `arr` appears to be an array, otherwise `false`.
@@ -184,7 +209,7 @@ defmodule Array do
   @doc """
   Maps the given function onto each element of the array.
   The elements are visited in order from the lowest index to the highest.
- 
+
   If `fun` is not a function, the call raises `ArgumentError`.
   """
   @spec map(t, (index, element -> any)) :: t
@@ -260,7 +285,7 @@ defmodule Array do
   Folds the elements of the array right-to-left using the given function and initial accumulator value,
   skipping default-valued entries.
   The elements are visited in order from the highest index to the lowest.
- 
+
   If `fun` is not a function, the call raises `ArgumentError`.
   """
   @spec sparse_foldr(t, acc, (index, element, acc -> acc)) :: acc when acc: var
@@ -270,7 +295,7 @@ defmodule Array do
   @doc """
   Maps the given function onto each element of the array, skipping default-valued entries.
   The elements are visited in order from the lowest index to the highest.
- 
+
   If `fun` is not a function, the call raises `ArgumentError`.
   """
   @spec sparse_map(t, (element -> any)) :: t
@@ -322,17 +347,6 @@ defmodule Array do
     do: :array.to_orddict(c)
 end
 
-defimpl Access, for: Array do
-  def get(arr, idx) do
-    Array.get(arr, idx)
-  end
-
-  def get_and_update(arr, idx, fun) do
-    {get, update} = fun.(Array.get(arr, idx))
-    {get, Array.set(arr, idx, update)}
-  end
-end
-
 defimpl Enumerable, for: Array do
   def count(arr), do: {:ok, Array.size(arr)}
 

test/array_test.exs

@@ -27,9 +27,7 @@ defmodule ArrayTest do
 
     assert nil == Array.get(a, 9)
 
-    assert_raise ArgumentError, fn ->
-      Array.get(a, 10)
-    end
+    assert nil == Array.get(a, 10)
 
     a = Array.set(a, 0, 1)
     assert 1 == Array.get(a, 0)
@@ -87,7 +85,7 @@ defmodule ArrayTest do
   test "fix" do
     a = Array.new()
     a = Array.set(a, 100, 0)
-    
+
     a = Array.fix(a)
     assert_raise ArgumentError, fn ->
       Array.set(a, 101, 0)
@@ -293,22 +291,28 @@ defmodule ArrayTest do
     end
   end
 
-  test "get/set" do
+  test "get/fetch/set" do
     a = Array.new()
 
     a = Array.set(a, 5, 10)
     assert nil == Array.get(a, 4)
+    assert {:ok, nil} == Array.fetch(a, 4)
     assert 10 == Array.get(a, 5)
+    assert {:ok, 10} == Array.fetch(a, 5)
     assert nil == Array.get(a, 6)
+    assert :error == Array.fetch(a, 6)
 
     a = Array.set(a, 0, 100)
     assert 100 == Array.get(a, 0)
     assert_raise ArgumentError, fn ->
       Array.set(a, -1, 1000)
     end
-    assert_raise ArgumentError, fn ->
-      Array.get(a, -1)
-    end
+    assert nil == Array.get(a, -1)
+    assert :error == Array.fetch(a, -1)
+
+    a = Array.from_list([])
+    assert :error == Array.fetch(a, 0)
+    assert 0 == Array.get(a, 0, 0)
   end
 
   test "size" do
@@ -405,7 +409,7 @@ defmodule ArrayTest do
   test "to_erlang_array" do
     a = Array.from_list([1,2,3])
     ea = Array.to_erlang_array(a)
-    
+
     assert :array.is_array(ea)
     assert 3 == :array.size(ea)
     assert 1 == :array.get(0, ea)
@@ -423,7 +427,7 @@ defmodule ArrayTest do
     assert [{0, 1}, {1, 2}, {2, 3}] == Array.to_orddict(a)
   end
 
-  test "Access.get" do
+  test "Access.fetch" do
     a = Array.from_list([1,2,3])
     assert 1 == a[0]
     assert 2 == a[1]