From dcba8efc837f42a6cb6e8c40f9abab741f6f8bf4 Mon Sep 17 00:00:00 2001
From: Adrian Conlon <adrian.conlon@gmail.com>
Date: Tue, 12 Oct 2021 10:10:45 +0100
Subject: [PATCH] All experimentation on the effect of JSON parser reuser.

Signed-off-by: Adrian Conlon <adrian.conlon@gmail.com>
---
 M6502/HarteTest_6502/opcode_test_suite_t.cpp | 15 +++++++++++----
 M6502/HarteTest_6502/opcode_test_suite_t.h   | 11 ++++++++++-
 M6502/HarteTest_6502/stdafx.h                |  2 ++
 M6502/HarteTest_6502/tests.cpp               |  2 +-
 4 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/M6502/HarteTest_6502/opcode_test_suite_t.cpp b/M6502/HarteTest_6502/opcode_test_suite_t.cpp
index a109a38..8e9ed14 100644
--- a/M6502/HarteTest_6502/opcode_test_suite_t.cpp
+++ b/M6502/HarteTest_6502/opcode_test_suite_t.cpp
@@ -6,11 +6,13 @@
 #include <fstream>
 #include <filesystem>
 
+#ifdef JSON_PREFER_REUSE_OF_PARSER
 #ifdef USE_JSONCPP_JSON
 std::unique_ptr<Json::CharReader> opcode_test_suite_t::m_parser;
 #endif
 #ifdef USE_SIMDJSON_JSON
-std::unique_ptr<simdjson::dom::parser> opcode_test_suite_t::m_parser;
+simdjson::dom::parser opcode_test_suite_t::m_parser;
+#endif
 #endif
 
 std::string opcode_test_suite_t::read(std::string path) {
@@ -50,11 +52,18 @@ void opcode_test_suite_t::load() {
 #ifdef USE_JSONCPP_JSON
 
 void opcode_test_suite_t::load() {
+#ifdef JSON_PREFER_REUSE_OF_PARSER
     if (m_parser == nullptr)
         m_parser.reset(Json::CharReaderBuilder().newCharReader());
     const auto contents = read(path());
     if (!m_parser->parse(contents.data(), contents.data() + contents.size(), &m_raw, nullptr))
         throw std::runtime_error("Unable to parse tests");
+#else
+    const auto contents = read(path());
+    std::unique_ptr<Json::CharReader> parser(Json::CharReaderBuilder().newCharReader());
+    if (!parser->parse(contents.data(), contents.data() + contents.size(), &m_raw, nullptr))
+        throw std::runtime_error("Unable to parse tests");
+#endif
 }
 
 #endif
@@ -62,10 +71,8 @@ void opcode_test_suite_t::load() {
 #ifdef USE_SIMDJSON_JSON
 
 void opcode_test_suite_t::load() {
-    if (m_parser == nullptr)
-        m_parser = std::make_unique<simdjson::dom::parser>();
     const auto contents = read(path());
-    m_raw = m_parser->parse(contents);
+    m_raw = m_parser.parse(contents);
 }
 
 #endif
diff --git a/M6502/HarteTest_6502/opcode_test_suite_t.h b/M6502/HarteTest_6502/opcode_test_suite_t.h
index 0e2ba26..5413867 100644
--- a/M6502/HarteTest_6502/opcode_test_suite_t.h
+++ b/M6502/HarteTest_6502/opcode_test_suite_t.h
@@ -21,11 +21,16 @@
 
 class opcode_test_suite_t final {
 private:
+#ifdef JSON_PREFER_REUSE_OF_PARSER
 #ifdef USE_JSONCPP_JSON
     static std::unique_ptr<Json::CharReader> m_parser;
 #endif
 #ifdef USE_SIMDJSON_JSON
-    static std::unique_ptr<simdjson::dom::parser> m_parser;
+    // N.B.
+    // The parser must be kept for the lifetime of any parsed data.
+    // Therefore, it can only be used for one document at a time.
+    static simdjson::dom::parser m_parser;
+#endif
 #endif
 
     [[nodiscard]] static std::string read(std::string path);
@@ -42,6 +47,10 @@ private:
 #endif
 #ifdef USE_SIMDJSON_JSON
     simdjson::dom::element m_raw;
+#ifndef JSON_PREFER_REUSE_OF_PARSER
+    // N.B. The parser must be kept for the lifetime of any parsed data.
+    simdjson::dom::parser m_parser;
+#endif
 #endif
 
 public:
diff --git a/M6502/HarteTest_6502/stdafx.h b/M6502/HarteTest_6502/stdafx.h
index 2233df9..8415d3b 100644
--- a/M6502/HarteTest_6502/stdafx.h
+++ b/M6502/HarteTest_6502/stdafx.h
@@ -27,10 +27,12 @@
 #endif
 
 #ifdef USE_JSONCPP_JSON
+#	define JSON_PREFER_REUSE_OF_PARSER
 #	include <json/json.h>
 #endif
 
 #ifdef USE_SIMDJSON_JSON
 #	define JSON_PREFER_PASS_BY_VALUE
+#	define JSON_PREFER_REUSE_OF_PARSER
 #	include "simdjson/simdjson.h"
 #endif
diff --git a/M6502/HarteTest_6502/tests.cpp b/M6502/HarteTest_6502/tests.cpp
index 2745f11..b6bfa7c 100644
--- a/M6502/HarteTest_6502/tests.cpp
+++ b/M6502/HarteTest_6502/tests.cpp
@@ -35,7 +35,7 @@ int main() {
 #endif
 #ifdef USE_SIMDJSON_JSON
         assert(opcode.raw().is_array());
-        const auto& opcode_test_array = opcode.raw().get_array();
+        const auto opcode_test_array = opcode.raw().get_array();
 #endif
 
         bool opcode_bad = false;