[#120] protogen: Unmarshal stringified integers from JSON

Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>

util/protogen/internalgengo/json.go

@@ -59,6 +59,17 @@ func emitJSONUnmarshal(g *protogen.GeneratedFile, msg *protogen.Message) {
 	g.P("}")
 }
 
+func emitJSONParseInteger(g *protogen.GeneratedFile, ident string, method string, bitSize int, typ string) {
+	g.P("r := in.JsonNumber()")
+	g.P("n := r.String()")
+	g.P("v, err := ", strconvPackage.Ident(method), "(n, 10, ", bitSize, ")")
+	g.P("if err != nil {")
+	g.P("	in.AddError(err)")
+	g.P("	return")
+	g.P("}")
+	g.P(ident, " := ", typ, "(v)")
+}
+
 func emitJSONFieldRead(g *protogen.GeneratedFile, f *protogen.Field, name string) {
 	g.P("{")
 	defer g.P("}")
@@ -100,13 +111,17 @@ func emitJSONFieldRead(g *protogen.GeneratedFile, f *protogen.Field, name string
 		}`)
 		template = "%s = parsedValue"
 	case protoreflect.Int32Kind, protoreflect.Sint32Kind, protoreflect.Sfixed32Kind:
-		template = "%s = in.Int32()"
+		emitJSONParseInteger(g, "pv", "ParseInt", 32, "int32")
+		template = "%s = pv"
 	case protoreflect.Uint32Kind, protoreflect.Fixed32Kind:
-		template = "%s = in.Uint32()"
+		emitJSONParseInteger(g, "pv", "ParseUint", 32, "uint32")
+		template = "%s = pv"
 	case protoreflect.Int64Kind, protoreflect.Sint64Kind, protoreflect.Sfixed64Kind:
-		template = "%s = in.Int64()"
+		emitJSONParseInteger(g, "pv", "ParseInt", 64, "int64")
+		template = "%s = pv"
 	case protoreflect.Uint64Kind, protoreflect.Fixed64Kind:
-		template = "%s = in.Uint64()"
+		emitJSONParseInteger(g, "pv", "ParseUint", 64, "uint64")
+		template = "%s = pv"
 	case protoreflect.FloatKind:
 		template = "%s = in.Float32()"
 	case protoreflect.DoubleKind: