Add helpers to easily read and write a serializable type to JSON

modules/standard/JSON.chpl

@@ -1171,4 +1171,21 @@ module JSON {
       }
     }
   }
+
+  @unstable
+  proc fromJson(jsonString: string, type loadAs): loadAs throws {
+    var fileReader = openStringReader(jsonString,
+                                      deserializer=new jsonDeserializer());
+    return fileReader.read(loadAs);
+  }
+
+  @unstable
+  proc toJson(arg): string throws {
+    var memWriter = openMemFile();
+    var writer = memWriter.writer(locking=false).withSerializer(jsonSerializer);
+    writer.write(arg);
+    writer.close();
+
+    return memWriter.reader(locking=false).readAll(string);
+  }
 }

test/io/serializers/jsonHelpers/basicread.chpl

@@ -0,0 +1,11 @@
+use IO, JSON;
+
+record myPair : serializable {
+  var x: int;
+  var y: string;
+}
+
+var myValue = new myPair(1, "hello");
+var myValueJson = toJson(myValue);
+
+writeln(fromJson("{\"x\": 1, \"y\": \"hello\"}", myPair));

test/io/serializers/jsonHelpers/basicread.good

@@ -0,0 +1 @@
+(x = 1, y = hello)

test/io/serializers/jsonHelpers/basicwrite.chpl

@@ -0,0 +1,9 @@
+use IO, JSON;
+
+record myPair : serializable {
+  var x: int;
+  var y: string;
+}
+
+var myValue = new myPair(1, "hello");
+writeln(toJson(myValue));

test/io/serializers/jsonHelpers/basicwrite.good

@@ -0,0 +1 @@
+{"x":1, "y":"hello"}

test/io/serializers/jsonHelpers/issue-8278.chpl

@@ -0,0 +1,10 @@
+use JSON;
+
+class Fighter {
+  var subclass:string;
+  var level:int;
+}
+
+var s = "{\"subclass\":\"Ninja\", \"level\":7}";
+var n = fromJson(s, owned Fighter);
+writeln(n);

test/io/serializers/jsonHelpers/issue-8278.good

@@ -0,0 +1 @@
+{subclass = Ninja, level = 7}

test/io/serializers/jsonHelpers/readarray.chpl

@@ -0,0 +1,8 @@
+use IO, JSON;
+
+record myPair : serializable {
+  var x: int;
+  var y: string;
+}
+
+writeln(fromJson("[{\"x\":1, \"y\":\"hello\"}, {\"x\":1, \"y\":\"hello\"}, {\"x\":1, \"y\":\"hello\"}]", [0..2] myPair));

test/io/serializers/jsonHelpers/readarray.good

@@ -0,0 +1 @@
+(x = 1, y = hello) (x = 1, y = hello) (x = 1, y = hello)

test/io/serializers/jsonHelpers/writearray.chpl

@@ -0,0 +1,9 @@
+use IO, JSON;
+
+record myPair : serializable {
+  var x: int;
+  var y: string;
+}
+
+var myValue = new myPair(1, "hello");
+writeln(toJson([myValue, myValue, myValue]));

test/io/serializers/jsonHelpers/writearray.good

@@ -0,0 +1 @@
+[{"x":1, "y":"hello"}, {"x":1, "y":"hello"}, {"x":1, "y":"hello"}]

test/unstable/jsonhelpers.chpl

@@ -0,0 +1,12 @@
+use IO, JSON;
+
+record myPair : serializable {
+  var x: int;
+  var y: string;
+}
+
+var myValue = new myPair(1, "hello");
+var myValueJson = toJson(myValue);
+
+writeln(myValueJson);
+writeln(fromJson(myValueJson, myPair));

test/unstable/jsonhelpers.good

@@ -0,0 +1,4 @@
+jsonmethods.chpl:9: warning: toJson is unstable
+jsonmethods.chpl:12: warning: fromJson is unstable
+{"x":1, "y":"hello"}
+(x = 1, y = hello)