represent yaml mappings as erlang maps, remove sort_mappings feature as it is no longer needed

Author: goertzenator

README.md

@@ -8,15 +8,16 @@ This application loads [YAML](http://en.wikipedia.org/wiki/Yaml) files into Erla
 * The tag `!atom` for explicitely tagging values as atoms.
 * An `implicit_atoms` mode to interpret values that look atom-ish as atoms.
 * Customizable schemas via callback modules.
+* Mappings returned as native Erlang R17 maps. (passes all unit tests on experimental maps branch, edoc currently broken)
 
 This application embeds the C yaml parser "[libyaml](http://pyyaml.org/wiki/LibYAML)" which is compiled as a NIF.
 
 # Example
 
 ###The yaml file...
 
-	# demo1.yaml
-	---
+    # demo1.yaml
+    ---
 	receipt:     Oz-Ware Purchase Invoice
 	date:        2007-08-06
 	customer:
@@ -57,25 +58,25 @@ This application embeds the C yaml parser "[libyaml](http://pyyaml.org/wiki/LibY
 
 	3> yaml:load_file("test/yaml/demo1.yaml", [implicit_atoms]).
 
-	{ok,[[{customer,[{family,<<"Gale">>},{given,<<"Dorothy">>}]},
-	      {items,[[{descrip,<<"Water Bucket (Filled)">>},
-	               {price,1.47},
-	               {quantity,4},
-	               {part_no,<<"A4786">>}],
-	              [{descrip,<<"High Heeled \"Ruby\" Slippers">>},
-	               {price,100.27},
-	               {size,8},
-	               {quantity,1},
-	               {part_no,<<"E1628">>}]]},
-	      {receipt,<<"Oz-Ware Purchase Invoice">>},
-	      {date,<<"2007-08-06">>},
-	      {specialDelivery,<<"Follow the Yellow Brick Road to the Emerald City. Pay no attention to the ma"...>>},
-	      {ship_to,[{street,<<"123 Tornado Alley\nSuite 16\n">>},
-	                {state,<<"KS">>},
-	                {city,<<"East Centerville">>}]},
-	      {bill_to,[{street,<<"123 Tornado Alley\nSuite 16\n">>},
-	                {state,<<"KS">>},
-	                {city,<<"East Centerville">>}]}]]}
+    {ok,[#{bill_to => #{city => <<"East Centerville">>,
+             state => <<"KS">>,
+             street => <<"123 Tornado Alley\nSuite 16\n">>},
+           customer => #{family => <<"Gale">>,given => <<"Dorothy">>},
+           date => <<"2007-08-06">>,
+           items => [#{descrip => <<"Water Bucket (Filled)">>,
+              part_no => <<"A4786">>,
+              price => 1.47,
+              quantity => 4},
+            #{descrip => <<"High Heeled \"Ruby\" Slippers">>,
+              part_no => <<"E1628">>,
+              price => 100.27,
+              quantity => 1,
+              size => 8}],
+           receipt => <<"Oz-Ware Purchase Invoice">>,
+           ship_to => #{city => <<"East Centerville">>,
+             state => <<"KS">>,
+             street => <<"123 Tornado Alley\nSuite 16\n">>},
+           specialDelivery => <<"Follow the Yellow Brick Road to the Emerald City. Pay no attention to the ma"...>>}]}
 
 
 # Installation
@@ -97,14 +98,12 @@ Play with it..
 
 	$ export ERL_LIBS=$(pwd)
 	$ erl
-	Erlang R15B01 (erts-5.9.1) [source] [64-bit] [smp:3:3] [async-threads:0] [kernel-poll:false]
-	
-	Eshell V5.9.1  (abort with ^G)
-	1> yaml:load_file("test/yaml/demo1.yaml").
-	{ok,[[{<<"specialDelivery">>,
-	       <<"Follow the Yellow Brick Road to the Emerald City. Pay no attention to the man 	behind the cur"...>>},
-	      {<<"items">>, ...
-
+    Erlang R17A (erts-5.11) [source-16b4dc1] [64-bit] [smp:3:3] [async-threads:10] [hipe] [kernel-poll:false]
+    
+    Eshell V5.11  (abort with ^G)
+    1> yaml:load_file("test/yaml/demo1.yaml").
+    {ok,[#{<<"bill_to">> => #{<<"city">> => <<"East Centerville">>,
+             <<"state">> => <<"KS">>, ...
 
 
 # Schemas
@@ -116,7 +115,7 @@ The included schemas are:
 * `yaml_schema_failsafe`
 * `yaml_schema_json`
 * `yaml_schema_core`
-* `yaml_schame_erlang` (default)
+* `yaml_schema_erlang` (default)
 
 The schema is selected with the `schema` option, for example:
 
@@ -159,6 +158,8 @@ See the behavior documenation for yaml_schema and the 4 schemas included in this
 
 If you are using erlide, I recommend the eclipse yaml editor [yedit](http://code.google.com/p/yedit/).
 
+Erlang R17 implements a native map type which is used by yamler to represent yaml mappings.  If you need to use an older Erlang see the git branch `mapping_as_list`.
+
 # Limitations
 
 * This app does not emit yaml.

src/yaml_compose.erl

@@ -33,8 +33,7 @@
 				events :: [yaml_libyaml:event()],
 				anchors :: dict(),
 				schema :: atom(),
-				schema_state :: term(),
-				sort_mappings :: boolean()
+				schema_state :: term()
 			   }).
 % composer state
 
@@ -54,8 +53,7 @@ compose(Events, Opts) ->
 				   events = Events,
 				   anchors = dict:new(),
 				   schema = Schema,
-				   schema_state = Schema:init(Opts),
-				   sort_mappings = proplists:get_bool(sort_mappings, Opts)
+				   schema_state = Schema:init(Opts)
 				  },
 	catch compose_stream(State).
 
@@ -79,15 +77,15 @@ compose_doc(State0 = #state{events=[{document_start, _,_,_}, {document_end, _,_,
 	State1 = State0#state{events=Rest},
 	{ok, null, State1};
 
-% normal document case    
+% normal document case
 compose_doc(State0 = #state{events=[{document_start, _,_,_} | Rest]}) ->
 	State1 = State0#state{events=Rest},
 	{{_ResolvedTag, ConstructedValue}, State2} = compose_node(State1),
-	
+
 	% remove document_end
 	[{document_end, _,_,_} | Rest2] = State2#state.events,
 	State3 = State2#state{events=Rest2},
-	
+
 	{ok, ConstructedValue, State3};
 
 % stream end case
@@ -96,8 +94,8 @@ compose_doc(State0 = #state{events=[{stream_end, _,_,_}]}) ->
 	{stream_end, State1}.
 
 
--spec compose_node(#state{}) -> {ynode(), #state{}}. 
-% handle scalar    
+-spec compose_node(#state{}) -> {ynode(), #state{}}.
+% handle scalar
 compose_node(State0 = #state{
 							 events=[Head={scalar, {Anchor,Tag,Value,Style},_,_} |Rest],
 							 schema = Schema,
@@ -165,7 +163,7 @@ compose_node(State0 = #state{
 
 
 
--spec compose_sequence([ynode()], #state{}) -> {sequence(), #state{}}. 
+-spec compose_sequence([ynode()], #state{}) -> {sequence(), #state{}}.
 compose_sequence(ConstructedValues, State0 = #state{
 													events=[{sequence_end, _,_,_} |Rest]}) ->
 	State1 = State0#state{events=Rest},
@@ -176,74 +174,57 @@ compose_sequence(ConstructedValues, State0) ->
 	compose_sequence([ConstructedValue|ConstructedValues], State1).
 
 
--spec compose_mapping(#state{}) -> {mapping(), #state{}}. 
-compose_mapping(State) -> compose_mapping(dict:new(), dict:new(), State).
-compose_mapping(Map0, Merge, State0 = #state{
-											 events=[{mapping_end, _,_,_} |Rest]}) ->
+-spec compose_mapping(#state{}) -> {mapping(), #state{}}.
+compose_mapping(State) -> compose_mapping(#{}, #{}, State).
+
+%% Accumulate plain old mapping entries in Map, and merge entries in Merge.
+compose_mapping(Map0, Merge, State0 = #state{events=[{mapping_end, _,_,_} |Rest]}) ->
 	State1 = State0#state{events=Rest},
-	
+
 	% notes from http://yaml.org/type/merge.html
 	% - merged keys do not overwrite any other keys
 	% - latter merged keys do not overwrite earlier merged keys
-	Map1 = dict:merge(fun(_K, V1, _V2) -> V1 end, Map0, Merge),
-	List0 = dict:to_list(Map1),
-	List1 = case State0#state.sort_mappings of
-				true -> lists:keysort(1,List0);
-				_ -> List0
-			end,
-	{ List1, State1 };
+	{ maps:merge(Merge, Map0),  % keys in Map take precendence over Merge
+	  State1 };
 
 compose_mapping(Map0, Merge0, State0) ->
 	{{ KTag, Key}, State1} = compose_node(State0),
 	{{ VTag, Value}, State2} = compose_node(State1),
-	
+
 	case {KTag, VTag} of
+		%% add single mapping to merge map
 		{'tag:yaml.org,2002:merge', 'tag:yaml.org,2002:map'} ->
-			Merge1 = case catch merge_list_unique(Value, Merge0) of
-						 badarg -> merge_error(hd(State1#state.events));
-						 Else -> Else
-					 end,
+			Merge1 = maps:merge(Value, Merge0),
 			compose_mapping(Map0, Merge1, State2);
+
+		%% add list of mappings to merge map
 		{'tag:yaml.org,2002:merge', 'tag:yaml.org,2002:seq'} ->
-			Merge1 = case catch lists:foldl(fun merge_list_unique/2, Merge0, Value) of
-						 badarg -> merge_error(hd(State1#state.events));
-						 Else -> Else
+			Merge1 = case catch lists:foldl(fun maps:merge/2, Merge0, Value) of
+						 badmap ->
+							 throw_error("Merge sequence must contain only mappings", hd(State1#state.events));
+						 Else when is_map(Else) ->
+							 Else
 					 end,
 			compose_mapping(Map0, Merge1, State2);
+
 		{'tag:yaml.org,2002:merge', _} ->
-			merge_error(hd(State1#state.events));
+			throw_error("Merge value must be mapping or sequence of mappings", hd(State1#state.events));
+
 		_ ->
-			Map1 = case dict:is_key(Key, Map0) of
-					   false -> dict:store(Key,Value,Map0);
+			Map1 = case maps:is_key(Key, Map0) of
+					   false -> maps:put(Key, Value, Map0);
 					   true  -> throw_error("Duplicate key", hd(State0#state.events))
 				   end,
 			compose_mapping(Map1, Merge0, State2)
 	end.
 
-merge_error(Event) ->
-	throw_error("Merge value must be mapping or sequence of mappings", Event).
-
-% merge list of items into dict only if key is not already present
-merge_list_unique(List, Dict) when is_list(List) ->
-	lists:foldl(
-	  fun({K,V}, D) ->
-			  case dict:is_key(K, D) of
-				  false -> dict:store(K,V,D);
-				  true  -> D
-			  end;
-		 (_,_D) ->
-			  throw(badarg)
-	  end,
-	  Dict, List);
-merge_list_unique(_List, _Dict) -> throw(badarg).
-
 -spec maybe_anchor(Anchor, Value, Event, State) -> #state{}
 when
   Anchor :: null | binary(),
   Value :: term(),
   Event :: yaml_libyaml:event(),
   State :: #state{}.
-														  
+
 maybe_anchor(null, _Value, _Event, State0) -> State0;
 maybe_anchor(Anchor, Value, Event, State0=#state{anchors=Anchors0}) ->
 	case dict:is_key(Anchor, Anchors0) of

test/outputs/test_core.term

@@ -1,10 +1,8 @@
 {ok,[[<<"test file for core schema.">>,<<"a">>,<<"b">>,<<"c">>,
-      [{<<"x">>,1},
-       {<<"y">>,[{123,<<"abc">>},{<<"abc">>,123}]},
-       {<<"z">>,[4,5,<<"pqr">>]}],
+      #{<<"x">> => 1,<<"y">> => #{123 => <<"abc">>,<<"abc">> => 123},<<"z">> => [4,5,<<"pqr">>]},
       <<"dddd">>,<<"q">>,<<"r">>,1,<<"2">>,<<"3">>,<<"1">>,<<"2">>,<<"3">>,
       <<"a">>,<<"b">>,<<"c">>,123,123,123,<<"123">>,<<"123">>,123.4,123.4,
       123.4,<<"123.4">>,<<"123.4">>,true,false,<<"true">>,<<"false">>,
       <<"true">>,<<"false">>,true,false,true,false,null,null,<<"spookyspoo">>,
       <<"spooky spoo">>,null,null,null,<<"nulla">>,
-      [{<<"floats">>,[3.14159,3.4e4]},{<<"ints">>,[123,291,83]}]]]}.
+      #{<<"floats">> => [3.14159,3.4e4],<<"ints">> => [123,291,83]}]]}.

test/outputs/test_erlang1.term

@@ -1,21 +1,19 @@
 {ok,[[<<"test file for erlang schema.">>,<<"a">>,<<"b">>,<<"c">>,
-      [{<<"x">>,1},
-       {<<"y">>,[{123,<<"abc">>},{<<"abc">>,123}]},
-       {<<"z">>,[4,5,<<"pqr">>]}],
+      #{<<"x">> => 1,<<"y">> => #{123 => <<"abc">>,<<"abc">> => 123},<<"z">> => [4,5,<<"pqr">>]},
       <<"dddd">>,<<"q">>,<<"r">>,1,<<"2">>,<<"3">>,<<"1">>,<<"2">>,<<"3">>,
       <<"a">>,<<"b">>,<<"c">>,123,123,123,<<"123">>,<<"123">>,123.4,123.4,
       123.4,<<"123.4">>,<<"123.4">>,true,false,<<"true">>,<<"false">>,
       <<"true">>,<<"false">>,true,false,true,false,null,null,<<"spookyspoo">>,
       <<"spooky spoo">>,null,null,null,<<"nulla">>,
-      [{<<"floats">>,[3.14159,3.4e4]},{<<"ints">>,[123,291,83]}],
-      [{<<"x">>,1},{<<"y">>,2}],
-      [{<<"x">>,0},{<<"y">>,2}],
-      [{<<"r">>,10}],
-      [{<<"r">>,1}],
-      [{<<"label">>,<<"center/big">>},{<<"r">>,10},{<<"x">>,1},{<<"y">>,2}],
-      [{<<"label">>,<<"center/big">>},{<<"r">>,10},{<<"x">>,1},{<<"y">>,2}],
-      [{<<"label">>,<<"center/big">>},{<<"r">>,10},{<<"x">>,1},{<<"y">>,2}],
-      [{<<"label">>,<<"center/big">>},{<<"r">>,10},{<<"x">>,1},{<<"y">>,2}],
+      #{<<"floats">> => [3.14159,3.4e4],<<"ints">> => [123,291,83]},
+      #{<<"x">> => 1,<<"y">> => 2},
+      #{<<"x">> => 0,<<"y">> => 2},
+      #{<<"r">> => 10},
+      #{<<"r">> => 1},
+      #{<<"label">> => <<"center/big">>,<<"r">> => 10,<<"x">> => 1,<<"y">> => 2},
+      #{<<"label">> => <<"center/big">>,<<"r">> => 10,<<"x">> => 1,<<"y">> => 2},
+      #{<<"label">> => <<"center/big">>,<<"r">> => 10,<<"x">> => 1,<<"y">> => 2},
+      #{<<"label">> => <<"center/big">>,<<"r">> => 10,<<"x">> => 1,<<"y">> => 2},
       <<"not an atom">>,<<"not an atom">>,<<"an atom">>,'explicit atom',
       <<"an_atom">>,<<"anatom">>,<<"aNA_t@OM@_">>,<<"Not_an_atom">>,
       <<"Notanatom\"">>,<<"not_an_atom">>,123,14.3]]}.

test/outputs/test_erlang2.term

@@ -1,19 +1,19 @@
 {ok,[[<<"test file for erlang schema.">>,a,b,c,
-      [{x,1},{y,[{123,abc},{abc,123}]},{z,[4,5,pqr]}],
+      #{x => 1,y => #{123 => abc,abc => 123},z => [4,5,pqr]},
       <<"dddd">>,<<"q">>,r,1,<<"2">>,'3',<<"1">>,<<"2">>,<<"3">>,<<"a">>,
       <<"b">>,<<"c">>,123,123,123,<<"123">>,<<"123">>,123.4,123.4,123.4,
       <<"123.4">>,<<"123.4">>,true,false,<<"true">>,<<"false">>,<<"true">>,
       <<"false">>,true,false,true,false,null,null,spookyspoo,
       <<"spooky spoo">>,null,null,null,nulla,
-      [{floats,[3.14159,3.4e4]},{ints,[123,291,83]}],
-      [{x,1},{y,2}],
-      [{x,0},{y,2}],
-      [{r,10}],
-      [{r,1}],
-      [{label,<<"center/big">>},{r,10},{x,1},{y,2}],
-      [{label,<<"center/big">>},{r,10},{x,1},{y,2}],
-      [{label,<<"center/big">>},{r,10},{x,1},{y,2}],
-      [{label,<<"center/big">>},{r,10},{x,1},{y,2}],
+      #{floats => [3.14159,3.4e4],ints => [123,291,83]},
+      #{x => 1,y => 2},
+      #{x => 0,y => 2},
+      #{r => 10},
+      #{r => 1},
+      #{label => <<"center/big">>,r => 10,x => 1,y => 2},
+      #{label => <<"center/big">>,r => 10,x => 1,y => 2},
+      #{label => <<"center/big">>,r => 10,x => 1,y => 2},
+      #{label => <<"center/big">>,r => 10,x => 1,y => 2},
       <<"not an atom">>,<<"not an atom">>,'an atom','explicit atom',an_atom,
       anatom,aNA_t@OM@_,<<"Not_an_atom">>,<<"Notanatom\"">>,<<"not_an_atom">>,
       123,14.3]]}.

test/outputs/test_failsafe.term

@@ -1,7 +1,7 @@
 {ok,[[<<"test file for failsafe schema, only strings are accepted.">>,<<"a">>,
       <<"b">>,<<"c">>,
-      [{<<"x">>,<<"1">>},
-       {<<"y">>,[{<<"123">>,<<"abc">>},{<<"abc">>,<<"123">>}]},
-       {<<"z">>,[<<"4">>,<<"5">>,<<"pqr">>]}],
+      #{<<"x">> => <<"1">>,
+        <<"y">> => #{<<"123">> => <<"abc">>,<<"abc">> => <<"123">>},
+        <<"z">> => [<<"4">>,<<"5">>,<<"pqr">>]},
       <<"dddd">>,<<"q">>,<<"r">>,<<"1">>,<<"2">>,<<"3">>,<<"1">>,<<"2">>,
       <<"3">>,<<"a">>,<<"b">>,<<"c">>]]}.

test/outputs/test_json.term

@@ -1,7 +1,5 @@
 {ok,[[<<"test file for json schema.  Unquoted, untagged strings not permitted">>,
-      [{<<"x">>,1},
-       {<<"y">>,[{123,<<"abc">>},{<<"abc">>,123}]},
-       {<<"z">>,[4,5,<<"pqr">>]}],
+      #{<<"x">> => 1,<<"y">> => #{123 => <<"abc">>,<<"abc">> => 123},<<"z">> => [4,5,<<"pqr">>]},
       <<"dddd">>,<<"q">>,<<"r">>,1,<<"2">>,<<"3">>,<<"1">>,<<"2">>,<<"3">>,
       <<"a">>,<<"b">>,<<"c">>,123,123,123,<<"123">>,<<"123">>,123.4,123.4,
       123.4,<<"123.4">>,<<"123.4">>,true,false,<<"true">>,<<"false">>,