Merge pull request #1 from bachittle/attr_format

attribute formatting

example/example.cpp

@@ -390,7 +390,7 @@ void attribute_example() {
     // auto logfmt_logger = spdlog::basic_logger_mt("logfmt_logger", "logs/mylog.txt");
     auto logfmt_logger = spdlog::stdout_color_mt("logfmt_logger");
 
-    std::string logfmt_pattern = "time=%Y-%m-%dT%H:%M:%S.%f%z name=%n level=%^%l%$ process=%P thread=%t message=\"%v\" ";
+    std::string logfmt_pattern = "time=%Y-%m-%dT%H:%M:%S.%f%z name=%n level=%^%l%$ process=%P thread=%t message=\"%v\"%( %K=\"%V\"%)";
     logfmt_logger->set_pattern(logfmt_pattern);
 
     logfmt_logger->info("logfmt structured logging", spdlog::attribute_list{{"key\n1", "value\n1"}, {"key\r\n2", "value\r\n2"}});

include/spdlog/pattern_formatter-inl.h

@@ -929,6 +929,54 @@ private:
     log_clock::time_point last_message_time_;
 };
 
+// attribute formatting: stub
+class attr_formatter_start final : public flag_formatter
+{
+public:
+    explicit attr_formatter_start(padding_info padinfo)
+        : flag_formatter(padinfo, details::attr_flags::start)
+    {}
+    void format(const details::log_msg &, const std::tm &, memory_buf_t &dest) override
+    {
+        fmt_helper::append_string_view("", dest);
+    }
+};
+class attr_formatter_stop final : public flag_formatter
+{
+public:
+    explicit attr_formatter_stop(padding_info padinfo)
+        : flag_formatter(padinfo, details::attr_flags::stop)
+    {}
+    void format(const details::log_msg &, const std::tm &, memory_buf_t &dest) override
+    {
+        fmt_helper::append_string_view("", dest);
+    }
+};
+
+class attr_formatter_key final : public flag_formatter
+{
+public:
+    explicit attr_formatter_key(padding_info padinfo)
+        : flag_formatter(padinfo, details::attr_flags::key)
+    {}
+    void format(const details::log_msg &, const std::tm &, memory_buf_t &dest) override
+    {
+        fmt_helper::append_string_view("", dest);
+    }
+};
+
+class attr_formatter_value final : public flag_formatter
+{
+public:
+    explicit attr_formatter_value(padding_info padinfo)
+        : flag_formatter(padinfo, details::attr_flags::value)
+    {}
+    void format(const details::log_msg &, const std::tm &, memory_buf_t &dest) override
+    {
+        fmt_helper::append_string_view("", dest);
+    }
+};
+
 // Full info formatter
 // pattern: [%Y-%m-%d %H:%M:%S.%e] [%n] [%l] [%s:%#] %v
 class full_formatter final : public flag_formatter
@@ -1012,7 +1060,14 @@ public:
         fmt_helper::append_string_view(msg.payload, dest);
 
         if (msg.attributes.size() > 0) {
+            // by default uses logfmt-esque kv pairs
             fmt_helper::append_string_view(" | ", dest); // separate message from attributes
+            for (const details::attr& a : msg.attributes) {
+                details::fmt_helper::append_string_view(a.key, dest);
+                details::fmt_helper::append_string_view("=\"", dest);
+                details::fmt_helper::append_string_view(a.value, dest);
+                details::fmt_helper::append_string_view("\" ", dest);
+            }
         }
     }
 
@@ -1076,16 +1131,33 @@ SPDLOG_INLINE void pattern_formatter::format(const details::log_msg &msg, memory
         }
     }
 
-    for (auto &f : formatters_)
+    auto it_end = formatters_.begin();
+    for (auto it = formatters_.begin(); it != formatters_.end(); ++it)
     {
-        f->format(msg, cached_tm_, dest);
+        if ((*it)->flag_ == details::attr_flags::start) {
-    }
+            if (msg.attributes.size() == 0) {
-    // TODO: make separate function, and add a custom format to attributes (for now just using logfmt)
+                while((*it)->flag_ != details::attr_flags::stop && it != formatters_.end()) ++it;
-    for (const details::attr& a : msg.attributes) {
+                it_end = it;
-        details::fmt_helper::append_string_view(a.key, dest);
+            }
-        details::fmt_helper::append_string_view("=\"", dest);
+            for (const details::attr& a : msg.attributes) {
-        details::fmt_helper::append_string_view(a.value, dest);
+                for (auto it2 = it; it2 != formatters_.end(); ++it2) {
-        details::fmt_helper::append_string_view("\" ", dest);
+                    if ((*it2)->flag_ == details::attr_flags::stop) {
+                        it_end = it2;
+                        break;
+                    } else if ((*it2)->flag_ == details::attr_flags::key) {
+                        // custom formatting function overload makes this even more messy with reinterpret casts, 
+                        // will just do manual key addition
+                        details::fmt_helper::append_string_view(a.key, dest);
+                    } else if ((*it2)->flag_ == details::attr_flags::value) {
+                        details::fmt_helper::append_string_view(a.value, dest);
+                    } else {
+                        (*it2)->format(msg, cached_tm_, dest);
+                    }
+                }
+            }
+            it = it_end;
+        }
+        (*it)->format(msg, cached_tm_, dest);
     }
 
     // write eol
@@ -1320,6 +1392,22 @@ SPDLOG_INLINE void pattern_formatter::handle_flag_(char flag, details::padding_i
         formatters_.push_back(details::make_unique<details::elapsed_formatter<Padder, std::chrono::seconds>>(padding));
         break;
 
+    case ('('): // start attribute formatting
+        formatters_.push_back(details::make_unique<details::attr_formatter_start>(padding));
+        break;
+
+    case ('K'): // attribute key
+        formatters_.push_back(details::make_unique<details::attr_formatter_key>(padding));
+        break;
+
+    case ('V'): // attribute value 
+        formatters_.push_back(details::make_unique<details::attr_formatter_value>(padding));
+        break;
+
+    case (')'): // stop attribute formatting
+        formatters_.push_back(details::make_unique<details::attr_formatter_stop>(padding));
+        break;
+
     default: // Unknown flag appears as is
         auto unknown_flag = details::make_unique<details::aggregate_formatter>();
 

include/spdlog/pattern_formatter.h

@@ -47,16 +47,30 @@ struct padding_info
     bool enabled_ = false;
 };
 
+enum class attr_flags {
+    none,
+    start,
+    stop,
+    key,
+    value
+};
+
 class SPDLOG_API flag_formatter
 {
 public:
     explicit flag_formatter(padding_info padinfo)
         : padinfo_(padinfo)
     {}
+    explicit flag_formatter(padding_info padinfo, attr_flags flag)
+        : flag_(flag)
+        , padinfo_(padinfo)
+    {}
     flag_formatter() = default;
     virtual ~flag_formatter() = default;
     virtual void format(const details::log_msg &msg, const std::tm &tm_time, memory_buf_t &dest) = 0;
 
+    attr_flags flag_ = attr_flags::none;
+
 protected:
     padding_info padinfo_;
 };