From c795f09f550364986be2f15948deb2393f4d1421 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rafael=20Mendon=C3=A7a=20Fran=C3=A7a?=
 <rafaelmfranca@gmail.com>
Date: Tue, 28 Feb 2012 11:29:59 -0300
Subject: [PATCH] Error handler

---
 lib/eex.ex                         | 12 +++++++++++-
 lib/eex/tokenizer.ex               |  6 ++++++
 test/elixir/eex/tokenizer_test.exs |  6 ++++++
 test/elixir/eex_test.exs           | 28 ++++++++++++++++++++++++++++
 4 files changed, 51 insertions(+), 1 deletion(-)

diff --git a/lib/eex.ex b/lib/eex.ex
index 49a63cd88a..5d50be7378 100644
--- a/lib/eex.ex
+++ b/lib/eex.ex
@@ -4,6 +4,8 @@ defmodule EEx do
   end
 end
 
+defexception EEx::SyntaxError, message: nil
+
 defmodule EEx::Compiler do
   def compile(source, engine) do
     tokens = EEx::Tokenizer.tokenize(source)
@@ -40,10 +42,18 @@ defmodule EEx::Compiler do
     { buffer, t }
   end
 
-  defp generate_buffer([], _engine, buffer, _scope, _dict) do
+  defp generate_buffer([{ :end_expr, _, chars }|_], _engine, _buffer, [], _dict) do
+    raise SyntaxError, message: "unexpected token: #{inspect chars}"
+  end
+
+  defp generate_buffer([], _engine, buffer, [], _dict) do
     buffer
   end
 
+  defp generate_buffer([], _engine, _buffer, _scope, _dict) do
+    raise SyntaxError, message: "undetermined end of string"
+  end
+
   ####
 
   def wrap_expr(current, buffer, chars, dict) do
diff --git a/lib/eex/tokenizer.ex b/lib/eex/tokenizer.ex
index 08960a9e28..c0ea175694 100644
--- a/lib/eex/tokenizer.ex
+++ b/lib/eex/tokenizer.ex
@@ -61,6 +61,12 @@ defmodule EEx::Tokenizer do
     tokenize_expr t, [h|buffer]
   end
 
+  # Raise an error if the %> is not found
+
+  defp tokenize_expr([], buffer) do
+    raise EEx::SyntaxError, message: "invalid token: #{inspect List.reverse(buffer)}"
+  end
+
   # Receive an expression content and check
   # if it is a start or an end token.
   # Start tokens finish with `do` or `->`
diff --git a/test/elixir/eex/tokenizer_test.exs b/test/elixir/eex/tokenizer_test.exs
index ae1467b215..85a7a81724 100644
--- a/test/elixir/eex/tokenizer_test.exs
+++ b/test/elixir/eex/tokenizer_test.exs
@@ -48,4 +48,10 @@ defmodule EEx::TokenizerTest do
       { :end_expr, '', ' end ' }
     ], T.tokenize('foo <% if true do %>bar<% elsif: false %>baz<% end %>')
   end
+
+  test "raise syntax error when there is start mark and no end mark" do
+    T.tokenize('foo <% :bar', 1)
+  rescue: error in [EEx::SyntaxError]
+    assert_equal "invalid token: ' :bar'", error.message
+  end
 end
diff --git a/test/elixir/eex_test.exs b/test/elixir/eex_test.exs
index 49d8000e7c..3d215329cb 100644
--- a/test/elixir/eex_test.exs
+++ b/test/elixir/eex_test.exs
@@ -52,6 +52,34 @@ defmodule EExTest do
     assert_eval "foo 1,2,3", "foo <% require Enum, as: E %><%= E.join [1,2,3], \",\" %>"
   end
 
+  test "compile with end of token" do
+    assert_eval "foo bar %>", "foo bar %>"
+  end
+
+  test "raises a syntax error when the token is invalid" do
+    EEx.compile "foo <%= bar"
+  rescue: error in [EEx::SyntaxError]
+    assert_equal "invalid token: ' bar'", error.message
+  end
+
+  test "raises a syntax error when end expression is found without a start expression" do
+    EEx.compile "foo <% end %>"
+  rescue: error in [EEx::SyntaxError]
+    assert_equal "unexpected token: ' end '", error.message
+  end
+
+  test "raises a syntax error when start expression is found without an end expression" do
+    EEx.compile "foo <% if true do %>"
+  rescue: error in [EEx::SyntaxError]
+    assert_equal "undetermined end of string", error.message
+  end
+
+  test "raises a syntax error when nested end expression is found without an start expression" do
+    EEx.compile "foo <%if true do %><% end %><% end %>"
+  rescue: error in [EEx::SyntaxError]
+    assert_equal "unexpected token: ' end '", error.message
+  end
+
   defp assert_eval(expected, atual) do
     compiled = EEx.compile(atual)
     { result, _ } = Code.eval_quoted(compiled, [], __FILE__, __LINE__)