Add Lua.parse_chunk/1 for runtime parsing of chunks (#44)

guides/working-with-lua.livemd

@@ -4,7 +4,7 @@
 
 ```elixir
 Mix.install([
-  {:lua, "~> 0.0.16"}
+  {:lua, "~> 0.0.17"}
 ])
 ```
 

lib/lua.ex

@@ -240,7 +240,7 @@ defmodule Lua do
 
 
   `eval!/2` can also evaluate chunks by passing instead of a script. As a
-  peformance optimization, it is recommended to call `load_chunk/2` if you
+  performance optimization, it is recommended to call `load_chunk!/2` if you
   will be executing a chunk many times, but it is not necessary.
 
       iex> {[4], _} = Lua.eval!(~LUA[return 2 + 2]c)
@@ -273,7 +273,7 @@ defmodule Lua do
   end
 
   def eval!(%__MODULE__{} = lua, %Lua.Chunk{} = chunk) do
-    {chunk, lua} = load_chunk(lua, chunk)
+    {chunk, lua} = load_chunk!(lua, chunk)
 
     case :luerl_new.call_chunk(chunk.ref, lua.state) do
       {:ok, result, new_state} ->
@@ -299,18 +299,58 @@ defmodule Lua do
   end
 
   @doc """
-  Similar to `:luerl_new.load/3`, it takes a `t:Lua.Chunk.t`, and loads
-  it into state so that it can be evaluated via `eval!/2`
+  Parses a chunk of Lua code into a `t:Lua.Chunk.t/0`, which then can
+  be loaded via `load_chunk!/2` or run via `eval!`.
+
+  This function is particularly useful for checking Lua code for syntax
+  erorrs and warnings at runtime. If you would like to just load a chunk,
+  use `load_chunk!/1` instead.
+
+      iex> {:ok, %Lua.Chunk{}} = Lua.parse_chunk("local foo = 1")
+
+  Errors found during parsing will be returned as a list of formatted strings
+
+      iex> Lua.parse_chunk("local foo =;")
+      {:error, ["Line 1: syntax error before: ';'"]}
 
-      iex> {%Lua.Chunk{}, %Lua{}} = Lua.load_chunk(Lua.new(), ~LUA[return 2 + 2]c)
   """
-  def load_chunk(%__MODULE__{state: state} = lua, %Lua.Chunk{ref: nil} = chunk) do
+  def parse_chunk(code) do
+    case :luerl_comp.string(code, [:return]) do
+      {:ok, chunk} ->
+        {:ok, %Lua.Chunk{instructions: chunk}}
+
+      {:error, errors, _warnings} ->
+        {:error, Enum.map(errors, &Util.format_error/1)}
+    end
+  end
+
+  @doc """
+  Loads string or `t:Lua.Chunk.t/0` into state so that it can be
+  evaluated via `eval!/2`
+
+  Strings can be loaded as chunks, which are parsed and loaded
+
+      iex> {%Lua.Chunk{}, %Lua{}} = Lua.load_chunk!(Lua.new(), "return 2 + 2")
+
+  Or a pre-compiled chunk can be loaded as well. Loaded chunks will be marked as loaded,
+  otherwise they will be re-loaded everytime `eval!/2` is called
+
+      iex> {%Lua.Chunk{}, %Lua{}} = Lua.load_chunk!(Lua.new(), ~LUA[return 2 + 2]c)
+  """
+  def load_chunk!(%__MODULE__{} = lua, code) when is_binary(code) do
+    case parse_chunk(code) do
+      {:ok, chunk} -> load_chunk!(lua, chunk)
+      {:error, errors} -> raise Lua.CompilerException, formatted: errors
+    end
+  end
+
+  def load_chunk!(%__MODULE__{state: state} = lua, %Lua.Chunk{ref: nil} = chunk) do
     {ref, state} = :luerl_emul.load_chunk(chunk.instructions, state)
 
     {%Lua.Chunk{chunk | ref: ref}, %__MODULE__{lua | state: state}}
   end
 
-  def load_chunk(%__MODULE__{} = lua, %Lua.Chunk{} = chunk) do
+  def load_chunk!(%__MODULE__{} = lua, %Lua.Chunk{} = chunk) do
     {chunk, lua}
   end
 

lib/lua/compiler_exception.ex

@@ -1,46 +1,41 @@
 defmodule Lua.CompilerException do
-  defexception [:message]
+  defexception [:errors, :state]
 
   alias Lua.Util
 
-  def exception(errors) when is_list(errors) do
-    for error <- errors do
-      Util.format_error(error)
-    end
+  def exception(formatted: errors) when is_list(errors) do
+    %__MODULE__{errors: errors}
+  end
 
-    errors = Enum.map_join(errors, "\n", &Util.format_error/1)
+  def exception(errors) when is_list(errors) do
+    %__MODULE__{errors: Enum.map(errors, &Util.format_error/1)}
+  end
 
-    message = """
-    Failed to compile Lua!
+  def exception({:lua_error, error, state}) do
+    %__MODULE__{errors: [Util.format_error(error)], state: state}
+  end
 
-    #{errors}
+  def exception({_line, _type, _failure} = error) do
+    %__MODULE__{errors: [Util.format_error(error)]}
+  end
 
+  def message(%__MODULE__{state: nil, errors: errors}) do
     """
+    Failed to compile Lua!
 
-    %__MODULE__{message: message}
+    #{Enum.join(errors, "\n")}
+    """
   end
 
-  def exception({:lua_error, error, state}) do
+  def message(%__MODULE__{errors: errors, state: state}) do
     stacktrace = Luerl.New.get_stacktrace(state)
 
-    message = """
-    Failed to compile Lua script!
-
-    #{Util.format_error(error)}
-
-    #{Util.format_stacktrace(stacktrace, state)}
     """
+    Failed to compile Lua!
 
-    %__MODULE__{message: message}
-  end
-
-  def exception({_line, _type, _failure} = error) do
-    message = """
-    Failed to compile Lua script!
+    #{Enum.join(errors, "\n")}
 
-    #{Util.format_error(error)}
+    #{Util.format_stacktrace(stacktrace, state)}
     """
-
-    %__MODULE__{message: message}
   end
 end

mix.exs

@@ -2,7 +2,7 @@ defmodule Lua.MixProject do
   use Mix.Project
 
   @url "https://github.com/tv-labs/lua"
-  @version "0.0.16"
+  @version "0.0.17"
 
   def project do
     [

test/lua_test.exs

@@ -28,7 +28,6 @@ defmodule LuaTest do
       Failed to compile Lua!
 
       Failed to tokenize: illegal token on line 1: \"hi)
-
       """
 
       assert_raise Lua.CompilerException, message, fn ->
@@ -55,7 +54,6 @@ defmodule LuaTest do
       Failed to compile Lua!
 
       Line 3: syntax error before: '&'
-
       """
 
       assert_raise Lua.CompilerException, message, fn ->
@@ -101,7 +99,7 @@ defmodule LuaTest do
       path = test_file("illegal_token")
 
       error = """
-      Failed to compile Lua script!
+      Failed to compile Lua!
 
       Failed to tokenize: illegal token on line 1: '
 
@@ -127,7 +125,7 @@ defmodule LuaTest do
       path = test_file("syntax_error")
 
       error = """
-      Failed to compile Lua script!
+      Failed to compile Lua!
 
       Line 1: syntax error before: ','
       """
@@ -142,7 +140,7 @@ defmodule LuaTest do
 
       error =
         """
-        Failed to compile Lua script!
+        Failed to compile Lua!
 
         undefined function nil
 
@@ -197,7 +195,7 @@ defmodule LuaTest do
     test "parsing errors raise" do
       lua = Lua.new()
 
-      assert_raise Lua.CompilerException, ~r/Failed to compile Lua script/, fn ->
+      assert_raise Lua.CompilerException, ~r/Failed to compile Lua/, fn ->
         Lua.eval!(lua, """
         local map = {a="1", b="2"}
 
@@ -220,20 +218,37 @@ defmodule LuaTest do
     end
   end
 
-  describe "load_chunk/2" do
+  describe "load_chunk!/2" do
     test "loads a chunk into state" do
       assert %Lua.Chunk{ref: nil} = chunk = ~LUA[print("hello")]c
-      assert {%Lua.Chunk{} = chunk, %Lua{}} = Lua.load_chunk(Lua.new(), chunk)
+      assert {%Lua.Chunk{} = chunk, %Lua{}} = Lua.load_chunk!(Lua.new(), chunk)
       assert chunk.ref
     end
 
+    test "can load strings as well" do
+      assert {%Lua.Chunk{} = chunk, %Lua{}} = Lua.load_chunk!(Lua.new(), ~S[print("hello")])
+      assert chunk.ref
+    end
+
+    test "invalid strings raise Lua.CompilerException" do
+      message = """
+      Failed to compile Lua!
+
+      Line 1: syntax error before: ';'
+      """
+
+      assert_raise Lua.CompilerException, message, fn ->
+        Lua.load_chunk!(Lua.new(), "local foo = ;")
+      end
+    end
+
     test "chunks can be loaded multiple times" do
       lua = Lua.new()
       chunk = ~LUA[print("hello")]c
 
-      assert {chunk, lua} = Lua.load_chunk(lua, chunk)
-      assert {chunk, lua} = Lua.load_chunk(lua, chunk)
-      assert {_chunk, _lua} = Lua.load_chunk(lua, chunk)
+      assert {chunk, lua} = Lua.load_chunk!(lua, chunk)
+      assert {chunk, lua} = Lua.load_chunk!(lua, chunk)
+      assert {_chunk, _lua} = Lua.load_chunk!(lua, chunk)
     end
   end
 
@@ -351,7 +366,7 @@ defmodule LuaTest do
       lua = Lua.new()
 
       error = """
-      Failed to compile Lua script!
+      Failed to compile Lua!
 
       Failed to tokenize: illegal token on line 1: ")
 
@@ -364,7 +379,7 @@ defmodule LuaTest do
       end
 
       error = """
-      Failed to compile Lua script!
+      Failed to compile Lua!
 
       Failed to tokenize: illegal token on line 1: "yuup)