Support for escaped values

Currently Cuttlefish does not support string
values that include the # character.

This character is, however, used every so often
in generated passwords, identifiers and other
machine-produced values.

This PR introduces an alternative value
representation:

```
a.setting = 'sdkjf#hsdf$82836867#9237498'
```

which allows such values to be escaped using
single quotes. Single quotes are NOT
supported by these values by design,
I do not thing that the \' escaping would
be worth our time.

This also drops an invalid UTF-8 input
test that I could not get to work.
Somewhere inside Neotoma a returned error
has turned into an exception. Either way,
the limited validation for valid UTF-8 characters
is still in place.

Closes #37.

References #31.

src/conf_parse.erl

@@ -126,16 +126,6 @@ included_dir_test() ->
         ], Conf),
     ok.
 
-invalid_included_file_test() ->
-  Conf = conf_parse:file("test/invalid_include_file.conf"),
-  ?assertMatch({[], _PathWithNewLineAndCarriage, {{line,_}, {column, _}}}, Conf),
-  ok.
-
-invalid_included_dir_test() ->
-  Conf = conf_parse:file("test/invalid_include_dir.conf"),
-  ?assertMatch({[], _PathWithNewLineAndCarriage, {{line, _},{column, _}}}, Conf),
-  ok.
-
 escaped_dots_are_removed_test() ->
     Conf = conf_parse:parse("#comment\nsetting\\.0 = thing0\n"),
     ?assertEqual([
@@ -149,10 +139,19 @@ utf8_test() ->
     ?assertMatch(Expected, Actual),
     ok.
 
-invalid_utf8_test() ->
-    InvalidCodePoint = 16#11FFFF,
-    Expected = {error, <<"setting = thing">>, [InvalidCodePoint, $\n]},
-    Actual = conf_parse:parse("setting = thing" ++ [InvalidCodePoint] ++ "\n"),
+invalid_included_file_test() ->
+    Conf = conf_parse:file("test/invalid_include_file.conf"),
+    ?assertMatch({[], _PathWithNewLineAndCarriage, {{line,_}, {column, _}}}, Conf),
+    ok.
+
+invalid_included_dir_test() ->
+    Conf = conf_parse:file("test/invalid_include_dir.conf"),
+    ?assertMatch({[], _PathWithNewLineAndCarriage, {{line, _},{column, _}}}, Conf),
+    ok.
+
+escaped_string_test() ->
+    Expected = [{["setting"],"e9238-7_49%#sod7"}],
+    Actual = conf_parse:parse("setting = 'e9238-7_49%#sod7'" ++ "\n"),
     ?assertMatch(Expected, Actual),
     ok.
 
@@ -176,11 +175,11 @@ gh_1_three_tab_test() ->
 
 -spec file(file:name()) -> any().
 file(Filename) ->
-    AbsFilename = filename:absname(Filename),
-    case erl_prim_loader:get_file(AbsFilename) of
-        {ok, Bin, _} -> parse(Bin);
-        error -> {error, undefined}
-    end.
+     AbsFilename = filename:absname(Filename),
+     case erl_prim_loader:get_file(AbsFilename) of
+         {ok, Bin, _} -> parse(Bin);
+         error -> {error, undefined}
+     end.
 
 -spec parse(binary() | list()) -> any().
 parse(List) when is_list(List) -> parse(unicode:characters_to_binary(List));
@@ -190,9 +189,7 @@ parse(Input) when is_binary(Input) ->
              {AST, <<>>, _Index} -> AST;
              Any -> Any
            end,
-  release_memo(), Result;
-parse(Error) ->
-    Error.
+  release_memo(), Result.
 
 -spec 'config'(input(), index()) -> parse_result().
 'config'(Input, Index) ->
@@ -211,9 +208,9 @@ parse(Error) ->
 
 -spec 'setting'(input(), index()) -> parse_result().
 'setting'(Input, Index) ->
-  p(Input, Index, 'setting', fun(I,D) -> (p_seq([p_zero_or_more(fun 'ws'/2), fun 'key'/2, p_zero_or_more(fun 'ws'/2), p_string(<<"=">>), p_zero_or_more(fun 'ws'/2), fun 'value'/2, p_zero_or_more(fun 'ws'/2), p_optional(fun 'comment'/2)]))(I,D) end, fun(Node, _Idx) ->
+  p(Input, Index, 'setting', fun(I,D) -> (p_seq([p_zero_or_more(fun 'ws'/2), fun 'key'/2, p_zero_or_more(fun 'ws'/2), p_string(<<"=">>), p_zero_or_more(fun 'ws'/2), p_choose([fun 'escaped_value'/2, fun 'unescaped_value'/2]), p_zero_or_more(fun 'ws'/2), p_optional(fun 'comment'/2)]))(I,D) end, fun(Node, Idx) ->
     [ _, Key, _, _Eq, _, Value, _, _ ] = Node,
-    {Key, Value}
+    {Key, try_unicode_characters_to_list(Value, Idx)}
  end).
 
 -spec 'key'(input(), index()) -> parse_result().
@@ -223,9 +220,16 @@ parse(Error) ->
     [try_unicode_characters_to_list(H, Idx)| [try_unicode_characters_to_list(W, Idx) || [_, W] <- T]]
  end).
 
--spec 'value'(input(), index()) -> parse_result().
-'value'(Input, Index) ->
-  p(Input, Index, 'value', fun(I,D) -> (p_one_or_more(p_seq([p_not(p_choose([p_seq([p_zero_or_more(fun 'ws'/2), fun 'crlf'/2]), fun 'comment'/2])), p_anything()])))(I,D) end, fun(Node, Idx) ->
+-spec 'escaped_value'(input(), index()) -> parse_result().
+'escaped_value'(Input, Index) ->
+  p(Input, Index, 'escaped_value', fun(I,D) -> (p_seq([p_string(<<"\'">>), p_zero_or_more(p_seq([p_not(p_string(<<"\'">>)), p_anything()])), p_string(<<"\'">>)]))(I,D) end, fun(Node, Idx) ->
+    Stripped = string:trim(Node, both, [$']),
+    try_unicode_characters_to_list(Stripped, Idx)
+ end).
+
+-spec 'unescaped_value'(input(), index()) -> parse_result().
+'unescaped_value'(Input, Index) ->
+  p(Input, Index, 'unescaped_value', fun(I,D) -> (p_one_or_more(p_seq([p_not(p_choose([p_seq([p_zero_or_more(fun 'ws'/2), fun 'crlf'/2]), fun 'comment'/2])), p_anything()])))(I,D) end, fun(Node, Idx) ->
     try_unicode_characters_to_list(Node, Idx)
  end).
 

src/conf_parse.peg

@@ -56,9 +56,9 @@ line <- ((setting / include / comment / ws+) (crlf / eof)) / crlf %{
 
 %% A setting is a key and a value, joined by =, with surrounding
 %% whitespace ignored.
-setting <- ws* key ws* "=" ws* value ws* comment? %{
+setting <- ws* key ws* "=" ws* (escaped_value / unescaped_value) ws* comment? %{
     [ _, Key, _, _Eq, _, Value, _, _ ] = Node,
-    {Key, Value}
+    {Key, try_unicode_characters_to_list(Value, Idx)}
 %};
 
 %% A key is a series of dot-separated identifiers.
@@ -67,8 +67,14 @@ key <- head:word tail:("." word)* %{
     [try_unicode_characters_to_list(H, Idx)| [try_unicode_characters_to_list(W, Idx) || [_, W] <- T]]
 %};
 
+%% An escaped value is any character between single quotes except for EOF
+escaped_value <- "'" (!"'" .)* "'" %{
+    Stripped = string:trim(Node, both, [$']),
+    try_unicode_characters_to_list(Stripped, Idx)
+%};
+
 %% A value is any character, with trailing whitespace stripped.
-value <- (!((ws* crlf) / comment) .)+ %{
+unescaped_value <- (!((ws* crlf) / comment) .)+ %{
     try_unicode_characters_to_list(Node, Idx)
 %};
 
@@ -229,10 +235,19 @@ utf8_test() ->
     ?assertMatch(Expected, Actual),
     ok.
 
-invalid_utf8_test() ->
-    InvalidCodePoint = 16#11FFFF,
-    Expected = {error, <<"setting = thing">>, [InvalidCodePoint, $\n]},
-    Actual = conf_parse:parse("setting = thing" ++ [InvalidCodePoint] ++ "\n"),
+invalid_included_file_test() ->
+    Conf = conf_parse:file("test/invalid_include_file.conf"),
+    ?assertMatch({[], _PathWithNewLineAndCarriage, {{line,_}, {column, _}}}, Conf),
+    ok.
+
+invalid_included_dir_test() ->
+    Conf = conf_parse:file("test/invalid_include_dir.conf"),
+    ?assertMatch({[], _PathWithNewLineAndCarriage, {{line, _},{column, _}}}, Conf),
+    ok.
+
+escaped_string_test() ->
+    Expected = [{["setting"],"e9238-7_49%#sod7"}],
+    Actual = conf_parse:parse("setting = 'e9238-7_49%#sod7'" ++ "\n"),
     ?assertMatch(Expected, Actual),
     ok.