From 9b80ee0046591416366a1d0144ada70033396040 Mon Sep 17 00:00:00 2001
From: Nikolay Osintsev <niosintsev@miem.hse.ru>
Date: Fri, 3 May 2024 03:18:24 +0300
Subject: [PATCH] json: implement JOSN_PRESERVE_ZERO_FRACTION in json_encode()

---
 runtime/json-functions.cpp | 17 +++++++++++++++--
 runtime/json-functions.h   |  6 +++---
 runtime/json-writer.h      |  2 +-
 3 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/runtime/json-functions.cpp b/runtime/json-functions.cpp
index 79c958ca04..ec3446a360 100644
--- a/runtime/json-functions.cpp
+++ b/runtime/json-functions.cpp
@@ -275,12 +275,25 @@ bool JsonEncoder::encode(double d) noexcept {
   if (vk::any_of_equal(std::fpclassify(d), FP_INFINITE, FP_NAN)) {
     php_warning("%s: strange double %lf in function json_encode", json_path_.to_string().c_str(), d);
     if (options_ & JSON_PARTIAL_OUTPUT_ON_ERROR) {
-      static_SB.append("0", 1);
+      if (options_ & JSON_PRESERVE_ZERO_FRACTION) {
+        static_SB.append("0.0", 3);
+      } else {
+        static_SB.append("0", 1);
+      }
     } else {
       return false;
     }
   } else {
-    static_SB << (simple_encode_ ? f$number_format(d, 6, string{"."}, string{}) : string{d});
+    if (simple_encode_) {
+      static_SB << f$number_format(d, 6, string{"."}, string{});
+    } else {
+      static_SB << string{d};
+      if (options_ & JSON_PRESERVE_ZERO_FRACTION) {
+        if (double dummy = 0.0; std::modf(d, &dummy) == 0.0) {
+          static_SB.append(".0", 2);
+        }
+      }
+    }
   }
   return true;
 }
diff --git a/runtime/json-functions.h b/runtime/json-functions.h
index 8754d73dd5..4a6c7eb77d 100644
--- a/runtime/json-functions.h
+++ b/runtime/json-functions.h
@@ -11,12 +11,12 @@
 
 constexpr int64_t JSON_UNESCAPED_UNICODE = 1;
 constexpr int64_t JSON_FORCE_OBJECT = 16;
-constexpr int64_t JSON_PRETTY_PRINT = 128; // TODO: add actual support to untyped
+constexpr int64_t JSON_PRETTY_PRINT = 128;
 constexpr int64_t JSON_PARTIAL_OUTPUT_ON_ERROR = 512;
 constexpr int64_t JSON_PRESERVE_ZERO_FRACTION = 1024;
 
-constexpr int64_t JSON_AVAILABLE_OPTIONS = JSON_UNESCAPED_UNICODE | JSON_FORCE_OBJECT | JSON_PARTIAL_OUTPUT_ON_ERROR;
-constexpr int64_t JSON_AVAILABLE_FLAGS_TYPED = JSON_PRETTY_PRINT | JSON_PRESERVE_ZERO_FRACTION;
+constexpr int64_t JSON_AVAILABLE_OPTIONS = JSON_UNESCAPED_UNICODE | JSON_FORCE_OBJECT | JSON_PARTIAL_OUTPUT_ON_ERROR | JSON_PRESERVE_ZERO_FRACTION;
+constexpr int64_t JSON_AVAILABLE_FLAGS_TYPED = JSON_PRETTY_PRINT;
 
 struct JsonPath {
   constexpr static int MAX_DEPTH = 8;
diff --git a/runtime/json-writer.h b/runtime/json-writer.h
index 76bfd8601b..a22eb99d60 100644
--- a/runtime/json-writer.h
+++ b/runtime/json-writer.h
@@ -52,7 +52,7 @@ class JsonWriter : vk::not_copyable {
 
   array<NestedLevel> stack_;
   string error_;
-  std::size_t double_precision_{0};
+  std::size_t double_precision_{0}; // unused
   const bool pretty_print_{false};
   const bool preserve_zero_fraction_{false};
   bool has_root_{false};