From 6cdacec6bcc3822658fbd490936a4a522d071369 Mon Sep 17 00:00:00 2001
From: Peter Solnica <peter@solnica.online>
Date: Fri, 26 Jan 2024 09:47:24 +0100
Subject: [PATCH 1/2] Add built-in Number type

---
 lib/drops/contract.ex                         |  2 +-
 lib/drops/type.ex                             | 10 ++-
 lib/drops/type/compiler.ex                    |  5 ++
 lib/drops/type/dsl.ex                         | 27 +++++++
 lib/drops/types/cast.ex                       |  2 +-
 lib/drops/types/map/key.ex                    |  6 +-
 lib/drops/types/number.ex                     | 12 ++++
 lib/drops/types/union.ex                      | 57 +++++++++++----
 lib/drops/validator/messages/backend.ex       | 26 +++++--
 .../validator/messages/default_backend.ex     | 10 ++-
 test/contract/types/number_test.exs           | 71 +++++++++++++++++++
 11 files changed, 199 insertions(+), 29 deletions(-)
 create mode 100644 lib/drops/types/number.ex
 create mode 100644 test/contract/types/number_test.exs

diff --git a/lib/drops/contract.ex b/lib/drops/contract.ex
index 9ce40d4..0360c81 100644
--- a/lib/drops/contract.ex
+++ b/lib/drops/contract.ex
@@ -90,7 +90,7 @@ defmodule Drops.Contract do
               {:error, right_error} ->
                 {:error,
                  @message_backend.errors(
-                   {:error, {path, {:or, {left_error, right_error}}}}
+                   {:error, {path, {:or, {left_error, right_error, type.opts}}}}
                  )}
             end
         end
diff --git a/lib/drops/type.ex b/lib/drops/type.ex
index 2560b41..8be8275 100644
--- a/lib/drops/type.ex
+++ b/lib/drops/type.ex
@@ -89,14 +89,18 @@ defmodule Drops.Type do
 
       @type t :: %__MODULE__{}
 
-      defstruct(unquote(attributes))
+      Module.register_attribute(__MODULE__, :type_spec, accumulate: false)
+      Module.register_attribute(__MODULE__, :opts, accumulate: false)
+
+      @opts []
+
+      defstruct(unquote(attributes) ++ [opts: @opts])
     end
   end
 
   defmacro deftype(primitive, attributes) when is_atom(primitive) do
     all_attrs =
-      [primitive: primitive, constraints: Type.infer_constraints(primitive)] ++
-        attributes
+      [primitive: primitive, constraints: Type.infer_constraints(primitive)] ++ attributes
 
     quote do
       deftype(unquote(all_attrs))
diff --git a/lib/drops/type/compiler.ex b/lib/drops/type/compiler.ex
index 4661930..979af23 100644
--- a/lib/drops/type/compiler.ex
+++ b/lib/drops/type/compiler.ex
@@ -6,6 +6,7 @@ defmodule Drops.Type.Compiler do
   alias Drops.Types.{
     Primitive,
     Union,
+    Number,
     List,
     Cast,
     Map,
@@ -27,6 +28,10 @@ defmodule Drops.Type.Compiler do
     Union.new(visit(left, opts), visit(right, opts))
   end
 
+  def visit({:type, {:number, predicates}}, opts) do
+    Number.new(predicates, opts)
+  end
+
   def visit({:type, {:list, member_type}}, opts)
       when is_tuple(member_type) or is_map(member_type) do
     List.new(visit(member_type, opts))
diff --git a/lib/drops/type/dsl.ex b/lib/drops/type/dsl.ex
index 99373fc..f84d130 100644
--- a/lib/drops/type/dsl.ex
+++ b/lib/drops/type/dsl.ex
@@ -377,6 +377,33 @@ defmodule Drops.Type.DSL do
     type(cast_spec, float(predicates))
   end
 
+  @doc ~S"""
+  Returns a number type specification.
+
+  ## Examples
+
+      # a number with no constraints
+      number()
+
+      # a number with constraints
+      number(gt?: 1.0)
+
+  """
+
+  @spec number() :: type()
+
+  def number() do
+    type(:number)
+  end
+
+  def number(predicate) when is_atom(predicate) do
+    type(:number, [predicate])
+  end
+
+  def number(predicates) when is_list(predicates) do
+    type(:number, predicates)
+  end
+
   @doc ~S"""
   Returns a boolean type specification.
 
diff --git a/lib/drops/types/cast.ex b/lib/drops/types/cast.ex
index f57c415..8402222 100644
--- a/lib/drops/types/cast.ex
+++ b/lib/drops/types/cast.ex
@@ -26,7 +26,7 @@ defmodule Drops.Types.Cast do
   alias Drops.Casters
 
   use Drops.Type do
-    deftype([:input_type, :output_type, opts: []])
+    deftype([:input_type, :output_type])
 
     def new(input_type, output_type, opts) do
       struct(__MODULE__, input_type: input_type, output_type: output_type, opts: opts)
diff --git a/lib/drops/types/map/key.ex b/lib/drops/types/map/key.ex
index eae317c..0fe81ba 100644
--- a/lib/drops/types/map/key.ex
+++ b/lib/drops/types/map/key.ex
@@ -42,8 +42,10 @@ defmodule Drops.Types.Map.Key do
     Map.has_key?(map, key) and present?(map[key], tail)
   end
 
-  defp nest_result({:error, {:or, {left, right}}}, root) do
-    {:error, {:or, {nest_result(left, root), nest_result(right, root)}}}
+  defp nest_result({:error, {:or, {left, right, opts}}}, root) do
+    {:error,
+     {:or,
+      {nest_result(left, root), nest_result(right, root), Keyword.merge(opts, path: root)}}}
   end
 
   defp nest_result({:error, {:list, results}}, root) when is_list(results) do
diff --git a/lib/drops/types/number.ex b/lib/drops/types/number.ex
new file mode 100644
index 0000000..bfb5eee
--- /dev/null
+++ b/lib/drops/types/number.ex
@@ -0,0 +1,12 @@
+defmodule Drops.Types.Number do
+  @moduledoc ~S"""
+  Drops.Types.Number is a struct that represents a number type
+  that can be either an integer or a float
+
+  ## Examples
+  """
+
+  use(Drops.Type, union([:integer, :float]))
+
+  @opts name: :number
+end
diff --git a/lib/drops/types/union.ex b/lib/drops/types/union.ex
index 8baed90..2c49eaf 100644
--- a/lib/drops/types/union.ex
+++ b/lib/drops/types/union.ex
@@ -20,7 +20,10 @@ defmodule Drops.Types.Union do
   """
 
   defmodule Validator do
-    def validate(%{left: %{primitive: _} = left, right: %{primitive: _} = right}, input) do
+    def validate(
+          %{left: %{primitive: _} = left, right: %{primitive: _} = right} = type,
+          input
+        ) do
       case Drops.Type.Validator.validate(left, input) do
         {:ok, value} ->
           {:ok, value}
@@ -34,13 +37,13 @@ defmodule Drops.Types.Union do
                 {:ok, value}
 
               {:error, _} = right_error ->
-                {:error, {:or, {left_error, right_error}}}
+                {:error, {:or, {left_error, right_error, type.opts}}}
             end
           end
       end
     end
 
-    def validate(%{left: left, right: right}, input) do
+    def validate(%{left: left, right: right} = type, input) do
       case Drops.Type.Validator.validate(left, input) do
         {:ok, value} ->
           {:ok, value}
@@ -51,7 +54,7 @@ defmodule Drops.Types.Union do
               {:ok, value}
 
             {:error, _} = right_error ->
-              {:error, {:or, {left_error, right_error}}}
+              {:error, {:or, {left_error, right_error, type.opts}}}
           end
       end
     end
@@ -60,20 +63,13 @@ defmodule Drops.Types.Union do
   defmacro __using__(spec) do
     quote do
       use Drops.Type do
-        deftype([:left, :right, :opts])
+        deftype([:left, :right])
 
-        alias Drops.Type.Compiler
         import Drops.Types.Union
 
-        def new(opts) do
-          {:union, {left, right}} = unquote(spec)
+        @type_spec unquote(spec)
 
-          struct(__MODULE__, %{
-            left: Compiler.visit(left, opts),
-            right: Compiler.visit(right, opts),
-            opts: opts
-          })
-        end
+        @before_compile Drops.Types.Union
 
         defimpl Drops.Type.Validator, for: __MODULE__ do
           def validate(type, data), do: Validator.validate(type, data)
@@ -82,8 +78,39 @@ defmodule Drops.Types.Union do
     end
   end
 
+  defmacro __before_compile__(_env) do
+    quote do
+      alias Drops.Type.Compiler
+
+      def new(predicates, opts) do
+        type = new(Keyword.merge(@opts, opts))
+
+        Map.merge(type, %{
+          left: constrain(type.left, predicates),
+          right: constrain(type.right, predicates)
+        })
+      end
+
+      def new(opts) do
+        {:union, {left, right}} = @type_spec
+
+        struct(__MODULE__, %{
+          left: Compiler.visit(left, opts),
+          right: Compiler.visit(right, opts),
+          opts: Keyword.merge(@opts, opts)
+        })
+      end
+
+      defp constrain(type, predicates) do
+        Map.merge(type, %{
+          constraints: type.constraints ++ infer_constraints(predicates)
+        })
+      end
+    end
+  end
+
   use Drops.Type do
-    deftype([:left, :right, :opts])
+    deftype([:left, :right])
 
     def new(left, right) when is_struct(left) and is_struct(right) do
       struct(__MODULE__, left: left, right: right)
diff --git a/lib/drops/validator/messages/backend.ex b/lib/drops/validator/messages/backend.ex
index 0119db7..46b83af 100644
--- a/lib/drops/validator/messages/backend.ex
+++ b/lib/drops/validator/messages/backend.ex
@@ -136,12 +136,26 @@ defmodule Drops.Validator.Messages.Backend do
         %Error.Rule{path: path, text: text}
       end
 
-      defp error({:error, {:or, {left, right}}}) do
-        %Error.Union{left: error(left), right: error(right)}
-      end
-
-      defp error({:error, {path, {:or, {left, right}}}}) do
-        nest(error({:error, {:or, {left, right}}}), path)
+      defp error({:error, {:or, {left, right, opts}}}) do
+        if not is_nil(opts[:name]) and not is_nil(opts[:path]) do
+          meta = Keyword.drop(opts, [:name, :path])
+
+          %Error.Type{path: opts[:path], text: text(opts[:name], opts), meta: meta}
+        else
+          %Error.Union{left: error(left), right: error(right)}
+        end
+      end
+
+      defp error({:error, {path, {:or, {left, right, opts}}}}) do
+        nest(
+          error(
+            {:error,
+             {:or,
+              {left, right,
+               Keyword.merge(opts, path: Keyword.get(opts, :path, []) ++ path)}}}
+          ),
+          path
+        )
       end
 
       defp error({:error, {path, {:cast, error}}}) do
diff --git a/lib/drops/validator/messages/default_backend.ex b/lib/drops/validator/messages/default_backend.ex
index 35cb8e6..7c14fe5 100644
--- a/lib/drops/validator/messages/default_backend.ex
+++ b/lib/drops/validator/messages/default_backend.ex
@@ -34,9 +34,17 @@ defmodule Drops.Validator.Messages.DefaultBackend do
     includes?: "must include %input%",
     excludes?: "must exclude %input%",
     in?: "must be one of: %input%",
-    not_in?: "must not be one of: %input%"
+    not_in?: "must not be one of: %input%",
+
+    # built-in types
+    number: "must be a number"
   }
 
+  @impl true
+  def text(:number, _opts) do
+    @text_mapping[:number]
+  end
+
   @impl true
   def text(predicate, _input) do
     @text_mapping[predicate]
diff --git a/test/contract/types/number_test.exs b/test/contract/types/number_test.exs
new file mode 100644
index 0000000..7f1255d
--- /dev/null
+++ b/test/contract/types/number_test.exs
@@ -0,0 +1,71 @@
+defmodule Drops.Contract.Types.NumberTest do
+  use Drops.ContractCase
+
+  describe "number/0" do
+    contract do
+      schema do
+        %{required(:test) => number()}
+      end
+    end
+
+    test "returns success with valid data", %{contract: contract} do
+      assert {:ok, %{test: 312}} = contract.conform(%{test: 312})
+    end
+
+    test "returns error with invalid data", %{contract: contract} do
+      assert_errors(["test must be a number"], contract.conform(%{test: :invalid}))
+    end
+  end
+
+  describe "number/1 with an extra predicate" do
+    contract do
+      schema do
+        %{required(:test) => number(:odd?)}
+      end
+    end
+
+    test "returns success with valid data", %{contract: contract} do
+      assert {:ok, %{test: 311}} = contract.conform(%{test: 311})
+    end
+
+    test "returns error with invalid data", %{contract: contract} do
+      assert_errors(["test must be a number"], contract.conform(%{test: :invalid}))
+      assert_errors(["test must be odd"], contract.conform(%{test: 312}))
+    end
+  end
+
+  describe "number/1 with an extra predicate with args" do
+    contract do
+      schema do
+        %{required(:test) => number(gt?: 2)}
+      end
+    end
+
+    test "returns success with valid data", %{contract: contract} do
+      assert {:ok, %{test: 312}} = contract.conform(%{test: 312})
+    end
+
+    test "returns error with invalid data", %{contract: contract} do
+      assert_errors(["test must be a number"], contract.conform(%{test: :invalid}))
+      assert_errors(["test must be greater than 2"], contract.conform(%{test: 0}))
+    end
+  end
+
+  describe "number/1 with extra predicates" do
+    contract do
+      schema do
+        %{required(:test) => number([:even?, gt?: 2])}
+      end
+    end
+
+    test "returns success with valid data", %{contract: contract} do
+      assert {:ok, %{test: 312}} = contract.conform(%{test: 312})
+    end
+
+    test "returns error with invalid data", %{contract: contract} do
+      assert_errors(["test must be a number"], contract.conform(%{test: :invalid}))
+      assert_errors(["test must be even"], contract.conform(%{test: 311}))
+      assert_errors(["test must be greater than 2"], contract.conform(%{test: 0}))
+    end
+  end
+end

From f8211181fcacfee5281a6b850c38ae66eb352340 Mon Sep 17 00:00:00 2001
From: Peter Solnica <peter@solnica.online>
Date: Tue, 30 Jan 2024 08:26:08 +0100
Subject: [PATCH 2/2] Add basic doctest for Number

---
 examples/types/number-01.ex         | 17 +++++++++++++++++
 lib/drops/types/number.ex           | 27 +++++++++++++++++++++++++++
 test/contract/types/number_test.exs |  2 ++
 3 files changed, 46 insertions(+)
 create mode 100644 examples/types/number-01.ex

diff --git a/examples/types/number-01.ex b/examples/types/number-01.ex
new file mode 100644
index 0000000..ebeb784
--- /dev/null
+++ b/examples/types/number-01.ex
@@ -0,0 +1,17 @@
+defmodule ProductContract do
+  use Drops.Contract
+
+  schema do
+    %{
+      required(:name) => string(:filled?),
+      required(:price) => number()
+    }
+  end
+end
+
+ProductContract.conform(%{name: "Book", price: 31.2})
+
+ProductContract.conform(%{name: "Book", price: 31})
+
+{:error, errors} = ProductContract.conform(%{name: "Book", price: []})
+Enum.map(errors, &to_string/1)
diff --git a/lib/drops/types/number.ex b/lib/drops/types/number.ex
index bfb5eee..5b63142 100644
--- a/lib/drops/types/number.ex
+++ b/lib/drops/types/number.ex
@@ -4,7 +4,34 @@ defmodule Drops.Types.Number do
   that can be either an integer or a float
 
   ## Examples
+
+      iex> defmodule ProductContract do
+      ...>   use Drops.Contract
+      ...>
+      ...>   schema do
+      ...>     %{
+      ...>       required(:name) => string(:filled?),
+      ...>       required(:price) => number()
+      ...>     }
+      ...>   end
+      ...> end
+      iex> ProductContract.conform(%{name: "Book", price: 31.2})
+      {:ok, %{name: "Book", price: 31.2}}
+      iex> ProductContract.conform(%{name: "Book", price: 31})
+      {:ok, %{name: "Book", price: 31}}
+      iex> {:error, errors} = ProductContract.conform(%{name: "Book", price: []})
+      {:error,
+       [
+         %Drops.Validator.Messages.Error.Type{
+           path: [:price],
+           text: "must be a number",
+           meta: []
+         }
+       ]}
+      iex> Enum.map(errors, &to_string/1)
+      ["price must be a number"]
   """
+  @doc since: "0.2.0"
 
   use(Drops.Type, union([:integer, :float]))
 
diff --git a/test/contract/types/number_test.exs b/test/contract/types/number_test.exs
index 7f1255d..b4f8eb7 100644
--- a/test/contract/types/number_test.exs
+++ b/test/contract/types/number_test.exs
@@ -1,6 +1,8 @@
 defmodule Drops.Contract.Types.NumberTest do
   use Drops.ContractCase
 
+  doctest Drops.Types.Number
+
   describe "number/0" do
     contract do
       schema do