Merge pull request #1 from pylon/section-interpolation

Support normal and inverse section interpolation

lib/mustache.ex

@@ -34,6 +34,41 @@ defmodule Mustache do
     end
   end
 
+  defp process_section(template, data) do
+    matches = Regex.run(section_regex(), template)
+    case matches do
+      nil -> template
+      [full, predicate, var, body] ->
+        val = indifferent_access(data, var)
+        section_val = case predicate do
+          "#" -> process_if(body, val)
+          "^" -> process_unless(body, val)
+        end
+        process_section(String.replace(template, full, section_val), data)
+    end
+  end
+
+  defp process_if(template, val) do
+    case val do
+      nil -> ""
+      false -> ""
+      [] -> ""
+      [_ | _] -> val
+                 |> Stream.map(&(render(template, &1)))
+                 |> Enum.join()
+      val -> render(template, val)
+    end
+  end
+
+  defp process_unless(template, val) do
+    case val do
+      nil -> render(template, val)
+      false -> render(template, val)
+      [] -> render(template, val)
+      _val -> ""
+    end
+  end
+
   defp indifferent_access(map, string_key) do
     map[string_key] || map[string_key |> String.to_atom]
   end
@@ -86,6 +121,10 @@ defmodule Mustache do
     regex("{{{\\s*", "\\s*}}}")
   end
 
+  defp section_regex do
+    ~r<{{\s*(#|\^)\s*([\w.]+)\s*}}(.*?){{\s*/\s*\2\s*}}>
+  end
+
   defp regex(otag, ctag, body \\ "\\w+") do
     Regex.compile!("#{otag}#{body}#{ctag}")
   end
@@ -108,7 +147,9 @@ defmodule Mustache do
   end
 
   defp strategies do
-    [{ fn(template) -> Regex.match?(triple_regex(), template) end,
+    [{ fn(template) -> Regex.match?(section_regex(), template) end,
+        fn(template, data) -> process_section(template, data) end },
+    { fn(template) -> Regex.match?(triple_regex(), template) end,
         fn(template, data) -> triple_mustaches(template, data) end},
     { fn(template) -> Regex.match?(regex("{{", "}}", "\\w+\\.\\w+"), template) end,
         fn(template, data) -> scan_for_dot(template, data) end },

test/mustache_feature_test.exs

@@ -64,12 +64,28 @@ defmodule MustacheFeatureTest do
               %{person: %{name: "Joe"}}) == "\"Joe\" == \"Joe\""
   end
 
-  @tag :pending
-  test "Dotted Names - Basic Interpolation" do
+  #Sections
+
+  test "Section Interpolation" do
     assert Mustache.render("\"{{person.name}}\" == \"{{#person}}{{name}}{{/person}}\"",
               %{person: %{name: "Joe"}}) == "\"Joe\" == \"Joe\""
   end
 
+  test "Section Interpolation - Inverse" do
+    assert Mustache.render("\"{{person.name}}\" == \"{{^person}}{{name}}{{/person}}\"",
+              %{person: %{name: "Joe"}}) == "\"Joe\" == \"\""
+  end
+
+  test "Section Interpolation - Basic and Inverse" do
+    assert Mustache.render("\"{{person.name}}\" == \"{{#person_2}}{{name}}{{/person_2}}{{^person_2}}Joe{{/person_2}}\"",
+              %{person: %{name: "Joe"}}) == "\"Joe\" == \"Joe\""
+  end
+
+  test "Section Interpolation - list values" do
+    assert Mustache.render("\"{{#people}}{{name}} {{/people}}\"",
+              %{people: [%{name: "Joe"}, %{name: "Jill"}]}) == "\"Joe Jill \""
+  end
+
   #Whitespace sensitivity
 
   test "Interpolation - Surrounding Whitespace" do