Fabric: New nice way to deal with DebugStringConvertible items

Summary:
No macros in product code.
(Not all callsites are converted yet.)

Reviewed By: mdvacca

Differential Revision: D7797561

fbshipit-source-id: da899421bf99669a0e0a2b83df6004daf14355c2

ReactCommon/fabric/debug/debugStringConvertibleUtils.h

@@ -0,0 +1,53 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#pragma once
+
+#include <string>
+#include <limits>
+#include <memory>
+#include <vector>
+
+#include <fabric/debug/DebugStringConvertible.h>
+#include <fabric/debug/DebugStringConvertibleItem.h>
+#include <folly/Conv.h>
+
+namespace facebook {
+namespace react {
+
+SharedDebugStringConvertibleList operator+(const SharedDebugStringConvertibleList &lhs, const SharedDebugStringConvertibleList &rhs);
+SharedDebugStringConvertible debugStringConvertibleItem(std::string name, DebugStringConvertible value, std::string defaultValue = "");
+
+#define IS_EQUAL(a, b) ((a) == (b))
+#define IS_EQUAL_FLOAT(a, b) ((isnan(a) == isnan(b)) || ((a) == (b)))
+
+#define DEBUG_STRING_CONVERTIBLE_TEMPLATE(type, converter) \
+DEBUG_STRING_CONVERTIBLE_TEMPLATE_EX(type, converter, {}, IS_EQUAL)
+
+#define DEBUG_STRING_CONVERTIBLE_TEMPLATE_EX(type, converter, defaults, comparator) \
+inline SharedDebugStringConvertible debugStringConvertibleItem(std::string name, type value, type defaultValue = defaults) { \
+  if (comparator(value, defaultValue)) { \
+    return nullptr; \
+  } \
+  return std::make_shared<DebugStringConvertibleItem>(name, converter(value)); \
+} \
+\
+inline SharedDebugStringConvertible debugStringConvertibleItem(std::string name, folly::Optional<type> value, type defaultValue = defaults) { \
+  if (value.has_value()) { \
+    return nullptr; \
+  } \
+  return debugStringConvertibleItem(name, value.value_or(defaultValue), defaultValue); \
+}
+
+DEBUG_STRING_CONVERTIBLE_TEMPLATE(std::string, )
+DEBUG_STRING_CONVERTIBLE_TEMPLATE(int, folly::to<std::string>)
+DEBUG_STRING_CONVERTIBLE_TEMPLATE(bool, folly::to<std::string>)
+DEBUG_STRING_CONVERTIBLE_TEMPLATE_EX(float, folly::to<std::string>, std::numeric_limits<float>::quiet_NaN(), IS_EQUAL_FLOAT)
+DEBUG_STRING_CONVERTIBLE_TEMPLATE_EX(double, folly::to<std::string>, std::numeric_limits<float>::quiet_NaN(), IS_EQUAL_FLOAT)
+
+} // namespace react
+} // namespace facebook