Merge: lib/json: unify the writing API using serialization only

Some context first, before this PR, there were 2 API to write JSON:
* The module `static` provided `to_json` and `to_pretty_json` which supported writing only basic Nit types associated with JSON types and objects with a manually implemented `to_json`.
* The module `serialization` provides `serialize_to_json` which supports all `Serializable` types, a superset of the JSON types, and where standard Nit objects are serialized to JSON objects by generated code.

The advantages of the `serialization` API are:
* Objects written to JSON with some metadata (mainly the name of the Nit type) can be deserialized back to Nit objects.
* The boilerplate code to write the attributes is generated, usually a single `is serialize` after the module declarations does the trick. (`core_serialize_to`, the equivalent of `to_json`, doesn't have to be implemented in each classes, the generated version is usually enough.)
* Implementing `core_serialize_to` (or leaving it to the generated code) instead of `to_json` makes the object compatible with both the JSON and binary serialization services.
* In general, the `serialization` API allows to easily write Nit objects to JSON and build JSON objects using `Map` instances:
~~~
import json::serialization

class Person
    serialize

    var name: String
    var year_of_birth: Int
end

var bob = new Person("Bob", 1986)
assert bob.serialize_to_json(pretty=true, plain=true) == """
{
    "name": "Bob",
    "year_of_birth": 1986
}"""

var charlie = new Map[String, nullable Serializable]
charlie["name"] = "Charlie"
charlie["year_of_birth"] = 1968
assert charlie.serialize_to_json(pretty=true, plain=true) == """
{
    "name": "Charlie",
    "year_of_birth": 1968
}"""
~~~

So this PR drops the `static` writing API, and replaces its services (`to_json` and `to_pretty_json`) by aliases in `serialization`. Some subclasses have been updated to implement the recursive `serialize_to` instead of the `to_json`, the changes are minimal to avoid breaking any software, but they are not optimal. The result is a single JSON writing API!

The generated JSON should not have changed much (maybe a bit less or more white spaces), except for some error messages which were translated to invalid JSON and are now serialized to a valid JSON object.

I expect some tests to fail as this is a big change, and clients of the `json::static` writing services (@Morriar) should probably double check my changes to their code.

In the future, I'm thinking of dropping the name `serialize_to_json` and `to_pretty_json` and move the optionnal parameters to `to_json`. The JSON module also really needs refactoring at this point.

Pull-Request: #2312
Reviewed-by: Alexandre Terrasa <[email protected]>
Reviewed-by: Romain Chanoir <[email protected]>
Reviewed-by: Jean Privat <[email protected]>
Reviewed-by: Lucas Bajolet <[email protected]>

benchmarks/json/scripts/nitcc_parser.nit

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import json
+import json::static
 
 var text = args.first.to_path.read_all
 var json = text.parse_json

contrib/benitlux/src/client/base.nit

@@ -19,7 +19,7 @@ import app::ui
 import app::data_store
 import app::http_request
 import android::aware
-import json::serialization
+import json
 
 import benitlux_model
 import translations

contrib/benitlux/src/server/benitlux_controller.nit

@@ -19,7 +19,7 @@ module benitlux_controller
 
 import nitcorn
 import nitcorn::restful
-private import json::serialization
+private import json
 
 import benitlux_model
 import benitlux_db

contrib/neo_doxygen/src/model/descriptions.nit

@@ -16,6 +16,7 @@
 module model::descriptions
 
 import json::static
+import json
 
 # Documentation associated to an entity.
 #
@@ -106,8 +107,8 @@ class Documentation
 	# Is the documentation empty?
 	fun is_empty: Bool do return content.is_empty
 
-	redef fun to_json do return content.to_json
-	redef fun append_json(b) do content.append_json(b)
+	redef fun serialize_to(v) do content.serialize_to v
+	redef fun accept_json_serializer(v) do content.serialize_to v
 end
 
 # A `Jsonable` array of strings.

contrib/neo_doxygen/src/model/graph.nit

@@ -221,7 +221,7 @@ end
 abstract class Compound
 	super Entity
 
-	# Set the declared visibility (the proctection) of the compound.
+	# Set the declared visibility (the protection) of the compound.
 	fun visibility=(visibility: String) do
 		self["visibility"] = visibility
 	end
@@ -233,7 +233,7 @@ abstract class Compound
 
 	# Declare an inner namespace.
 	#
-	# Note: Althought Doxygen indicates that the name is optional,
+	# Note: Although Doxygen indicates that the name is optional,
 	# declarations with an empty name are not supported yet, except for the root
 	# namespace. For the root namespace, both arguments are empty.
 	#
@@ -246,7 +246,7 @@ abstract class Compound
 
 	# Declare an inner class.
 	#
-	# Note: Althought Doxygen indicates that both arguments are optional,
+	# Note: Although Doxygen indicates that both arguments are optional,
 	# declarations with an empty ID are not supported yet.
 	#
 	# Parameters:
@@ -292,7 +292,7 @@ class Namespace
 		self.labels.add("MGroup")
 	end
 
-	redef fun declare_namespace(id: String, full_name: String) do
+	redef fun declare_namespace(id, full_name) do
 		inner_namespaces.add new NamespaceRef(id, full_name)
 	end
 

contrib/neo_doxygen/src/model/location.nit

@@ -16,6 +16,7 @@
 module location
 
 import json::static
+import json
 
 # A location inside a source file.
 class Location
@@ -36,11 +37,13 @@ class Location
 	# The one-based column index of the last character.
 	var column_end: Int = 1 is writable
 
-	redef fun to_s: String do
+	redef fun to_s do
+		var path = path
 		var file_part = "/dev/null:"
-		if path != null and path.length > 0 then file_part = "{path.as(not null)}:"
+		if path != null and path.length > 0 then file_part = "{path}:"
 		return "{file_part}{line_start},{column_start}--{line_end},{column_end}"
 	end
 
-	redef fun to_json do return to_s.to_json
+	redef fun serialize_to(v) do to_s.serialize_to v
+	redef fun accept_json_serializer(v) do to_s.serialize_to v
 end

contrib/nitrpg/src/achievements.nit

@@ -120,7 +120,7 @@ class Achievement
 			json["reward"].as(Int))
 	end
 
-	redef fun to_json do
+	redef fun to_json_object do
 		var json = super
 		json["id"] = id
 		json["name"] = name

contrib/nitrpg/src/events.nit

@@ -104,7 +104,7 @@ class GameEvent
 		time = new ISODate.from_string(json["time"].as(String))
 	end
 
-	redef fun to_json do
+	redef fun to_json_object do
 		var json = new JsonObject
 		json["internal_id"] = internal_id.to_s
 		json["kind"] = kind

contrib/nitrpg/src/game.nit

@@ -42,10 +42,10 @@ interface GameEntity
 	fun key: String is abstract
 
 	# Saves `self` in db.
-	fun save do game.db.collection(collection_name).save(to_json)
+	fun save do game.db.collection(collection_name).save(to_json_object)
 
 	# Json representation of `self`.
-	fun to_json: JsonObject do
+	fun to_json_object: JsonObject do
 		var json = new JsonObject
 		json["_id"] = key
 		return json
@@ -102,7 +102,7 @@ class Game
 	# Used to load entities from saved data.
 	fun from_json(json: JsonObject) do end
 
-	redef fun to_json do
+	redef fun to_json_object do
 		var json = super
 		json["name"] = name
 		return json
@@ -166,7 +166,7 @@ class Game
 	end
 
 	# Erase all saved data for this game.
-	fun clear do db.collection(collection_name).remove(to_json)
+	fun clear do db.collection(collection_name).remove(to_json_object)
 
 	# Verbosity level used fo stdout.
 	#
@@ -236,7 +236,7 @@ class Player
 		nitcoins = json["nitcoins"].as(Int)
 	end
 
-	redef fun to_json do
+	redef fun to_json_object do
 		var json = super
 		json["game"] = game.key
 		json["name"] = name

contrib/nitrpg/src/statistics.nit

@@ -172,7 +172,7 @@ class GameStats
 		for k, v in values do self[k] = v.as(Int)
 	end
 
-	redef fun to_json do
+	redef fun to_json_object do
 		var obj = super
 		obj["period"] = period
 		obj["owner"] = owner.key

contrib/nitrpg/src/test_achievements.nit

@@ -51,7 +51,7 @@ class TestGame
 		var a3 = new Achievement(game, "test_id3", "test_name", "test_desc", 15)
 		game.add_achievement(a1)
 		game.add_achievement(a2)
-		game.db.collection("achievements").insert(a3.to_json)
+		game.db.collection("achievements").insert(a3.to_json_object)
 		var ok = [a1.id, a2.id]
 		var res = game.load_achievements
 		assert res.length == 2

contrib/nitrpg/src/test_events.nit

@@ -51,7 +51,7 @@ class TestGame
 		var event3 = new GameEvent(game, "test_kind", new JsonObject)
 		game.add_event(event1)
 		game.add_event(event2)
-		game.db.collection("events").insert(event3.to_json)
+		game.db.collection("events").insert(event3.to_json_object)
 		var ok = [event1.internal_id, event2.internal_id]
 		var res = game.load_events
 		assert res.length == 2
@@ -115,7 +115,7 @@ class TestGameEvent
 		var db = gen_test_db
 		var game = load_game("Morriar/nit", db)
 		var event = new GameEvent(game, "test_kind", new JsonObject)
-		assert event.to_json["kind"] == "test_kind"
+		assert event.to_json_object["kind"] == "test_kind"
 	end
 
 	fun test_init_from_json do

contrib/nitrpg/src/test_game.nit

@@ -43,8 +43,8 @@ class TestGame
 
 		var player1 = new Player(game, "Morriar")
 		var player2 = new Player(ogame, "privat")
-		game.db.collection("players").insert(player1.to_json)
-		ogame.db.collection("players").insert(player2.to_json)
+		game.db.collection("players").insert(player1.to_json_object)
+		ogame.db.collection("players").insert(player2.to_json_object)
 
 		assert game.load_player("privat") == null
 		assert game.load_player("Morriar").name == "Morriar"
@@ -60,9 +60,9 @@ class TestGame
 		var player1 = new Player(game, "Morriar")
 		var player2 = new Player(ogame, "privat")
 		var player3 = new Player(game, "xymus")
-		game.db.collection("players").insert(player1.to_json)
-		ogame.db.collection("players").insert(player2.to_json)
-		game.db.collection("players").insert(player3.to_json)
+		game.db.collection("players").insert(player1.to_json_object)
+		ogame.db.collection("players").insert(player2.to_json_object)
+		game.db.collection("players").insert(player3.to_json_object)
 
 		var players = game.load_players
 		var ok = ["Morriar", "xymus"]

contrib/refund/src/refund_json.nit

@@ -19,6 +19,7 @@ module refund_json
 
 import refund_base
 import json::static
+import json
 
 redef class RefundProcessor
 
@@ -89,6 +90,7 @@ redef class RefundProcessor
 	fun write_output(str: String, file: String) do
 		var ofs = new FileWriter.open(file)
 		ofs.write(str)
+		ofs.write("\n")
 		ofs.close
 	end
 
@@ -118,7 +120,7 @@ redef class RefundProcessor
 		exit 1
 	end
 
-	redef fun show_stats do print load_stats.to_json.to_pretty_json
+	redef fun show_stats do print load_stats.to_json_object.to_pretty_json
 
 	redef fun load_stats do
 		# If no stats found, return a new object
@@ -134,7 +136,7 @@ redef class RefundProcessor
 	end
 
 	redef fun save_stats(stats) do
-		write_output(stats.to_json.to_pretty_json, stats_file)
+		write_output(stats.to_json_object.to_pretty_json, stats_file)
 	end
 end
 
@@ -146,7 +148,7 @@ redef class RefundStats
 	end
 
 	# Outputs `self` as a JSON string.
-	fun to_json: JsonObject do
+	fun to_json_object: JsonObject do
 		var obj = new JsonObject
 		for k, v in self do obj[k] = v
 		return obj

contrib/refund/tests/res/json_error1.res

@@ -1,3 +1,3 @@
 {
-	"message": "Wrong input file (Unexpected Eof; is acceptable instead: value)"
+	"message": "Wrong input file (Empty JSON)"
 }

contrib/refund/tests/res/json_error3.res

@@ -1,3 +1,3 @@
 {
-	"message": "Wrong input file (Unexpected Eof; is acceptable instead: members, pair)"
+	"message": "Wrong input file (Malformed JSON object)"
 }

contrib/shibuqam/examples/shibuqamoauth.nit

@@ -172,7 +172,7 @@ module shibuqamoauth
 
 import popcorn
 import shibuqam
-import json::serialization
+import json
 
 redef class HttpRequest
 	# percent decoded get or post parameter.
@@ -304,7 +304,6 @@ end
 
 redef class User
 	super Jsonable
-	redef fun to_json do return serialize_to_json(plain=true)
 end
 
 # Information about an authenticated used stored on the server to be given to the client.

contrib/tinks/src/client/linux_client.nit

@@ -17,7 +17,7 @@ module linux_client
 
 import mnit::linux
 import linux::audio
-import json::serialization
+import json
 
 import client
 

contrib/tnitter/src/action.nit

@@ -18,7 +18,7 @@
 module action
 
 import nitcorn
-import json::serialization
+import json
 
 import model
 import database