From 76775ddf26451b729a0039e791b08e1faf7256d3 Mon Sep 17 00:00:00 2001
From: Vladimir Krivopalov <vladimir@scylladb.com>
Date: Mon, 4 Dec 2017 21:03:05 -0800
Subject: [PATCH] Use CharReaderBuilder/CharReader and StreamWriterBuilder from
 JsonCpp.

In version 1.8.3 of JsonCpp shipped with Fedora 27, old FastWriter and
Reader classes from JsonCpp have been deprecated in favour of
newer/better ones: CharReaderBuilder/CharReader and
StreamWriterBuilder/StreamWriter.
This fix uses the new classes where available or resorts to old ones for
older versions of the library.

Fixes #2989

Signed-off-by: Vladimir Krivopalov <vladimir@scylladb.com>
---
 json.hh | 47 ++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 36 insertions(+), 11 deletions(-)

diff --git a/json.hh b/json.hh
index 92d2a2028d..0a903ec7c2 100644
--- a/json.hh
+++ b/json.hh
@@ -22,34 +22,59 @@
 #pragma once
 
 #include "core/sstring.hh"
+#include "core/print.hh"
 
 #include <json/json.h>
 
 namespace seastar { // FIXME: not ours
 namespace json {
 
+inline sstring to_sstring(const Json::Value& value) {
+#if defined(JSONCPP_VERSION_HEXA) && (JSONCPP_VERSION_HEXA >= 0x010400) // >= 1.4.0
+    Json::StreamWriterBuilder wbuilder;
+    wbuilder.settings_["indentation"] = "";
+    auto str = Json::writeString(wbuilder, value);
+#else
+    Json::FastWriter writer;
+    // Json::FastWriter unnecessarily adds a newline at the end of string.
+    // There is a method omitEndingLineFeed() which prevents that, but it seems
+    // to be too recent addition, so, at least for now, a workaround is needed.
+    auto str = writer.write(value);
+    if (str.length() && str.back() == '\n') {
+        str.pop_back();
+    }
+#endif
+    return str;
+}
+
 template<typename Map>
 inline sstring to_json(const Map& map) {
     Json::Value root(Json::objectValue);
     for (auto&& kv : map) {
         root[kv.first] = Json::Value(kv.second);
     }
-    Json::FastWriter writer;
-    // Json::FastWriter unnecessarily adds a newline at the end of string.
-    // There is a method omitEndingLineFeed() which prevents that, but it seems
-    // to be too recent addition, so, at least for now, a workaround is needed.
-    auto str = writer.write(root);
-    if (str.length() && str.back() == '\n') {
-        str.pop_back();
+    return to_sstring(root);
+}
+
+inline Json::Value to_json_value(const sstring& raw) {
+    Json::Value root;
+#if defined(JSONCPP_VERSION_HEXA) && (JSONCPP_VERSION_HEXA >= 0x010400) // >= 1.4.0
+    Json::CharReaderBuilder rbuilder;
+    std::unique_ptr<Json::CharReader> reader(rbuilder.newCharReader());
+    bool result = reader->parse(raw.begin(), raw.end(), &root, NULL);
+    if (!result) {
+        throw std::runtime_error(sprint("Failed to parse JSON: %s", raw));
     }
-    return str;
+#else
+    Json::Reader reader;
+    reader.parse(std::string{raw}, root);
+#endif
+    return root;
 }
 
 template<typename Map>
 inline Map to_map(const sstring& raw, Map&& map) {
-    Json::Value root;
-    Json::Reader reader;
-    reader.parse(std::string{raw}, root);
+    Json::Value root = to_json_value(raw);
     for (auto&& member : root.getMemberNames()) {
         map.emplace(member, root[member].asString());
     }