feat: add C bindings for getting log levels (#334)

This adds bindings for retrieving the log level name or enum value from
a string. It was already present in C++ but missing in C.

libs/common/include/launchdarkly/bindings/c/config/logging_builder.h

@@ -3,6 +3,8 @@
 
 #pragma once
 
+#include <launchdarkly/bindings/c/logging/log_level.h>
+
 #include <launchdarkly/bindings/c/export.h>
 #include <launchdarkly/bindings/c/status.h>
 
@@ -17,17 +19,6 @@ extern "C" {  // only need to export C interface if
 typedef struct _LDLoggingBasicBuilder* LDLoggingBasicBuilder;
 typedef struct _LDLoggingCustomBuilder* LDLoggingCustomBuilder;
 
-/**
- * Defines the log levels used with the SDK's default logger, or a user-provided
- * custom logger.
- */
-enum LDLogLevel {
-    LD_LOG_DEBUG = 0,
-    LD_LOG_INFO = 1,
-    LD_LOG_WARN = 2,
-    LD_LOG_ERROR = 3,
-};
-
 typedef bool (*EnabledFn)(enum LDLogLevel level, void* user_data);
 typedef void (*WriteFn)(enum LDLogLevel level,
                         char const* msg,

libs/common/include/launchdarkly/bindings/c/logging/log_level.h

@@ -0,0 +1,52 @@
+/** @file */
+// NOLINTBEGIN modernize-use-using
+
+#pragma once
+
+#include <launchdarkly/bindings/c/export.h>
+#include <launchdarkly/bindings/c/status.h>
+
+#include <stdbool.h>
+#include <stddef.h>
+
+#ifdef __cplusplus
+extern "C" {  // only need to export C interface if
+// used by C++ source code
+#endif
+
+/**
+ * Defines the log levels used with the SDK's default logger, or a user-provided
+ * custom logger.
+ */
+enum LDLogLevel {
+    LD_LOG_DEBUG = 0,
+    LD_LOG_INFO = 1,
+    LD_LOG_WARN = 2,
+    LD_LOG_ERROR = 3,
+};
+
+/**
+ * Lookup the name of a LDLogLevel.
+ * @param level Target level.
+ * @param level_if_unknown Default name to return if the level wasn't
+ * recognized.
+ * @return Name of the level as a string, or level_if_unknown if not recognized.
+ */
+LD_EXPORT(char const*)
+LDLogLevel_Name(enum LDLogLevel level, char const* level_if_unknown);
+
+/**
+ * Lookup a LDLogLevel by name.
+ * @param level Name of level.
+ * @param level_if_unknown Default level to return if the level wasn't
+ * recognized.
+ * @return LDLogLevel matching the name, or level_if_unknown if not recognized.
+ */
+LD_EXPORT(enum LDLogLevel)
+LDLogLevel_Enum(char const* level, enum LDLogLevel level_if_unknown);
+
+#ifdef __cplusplus
+}
+#endif
+
+// NOLINTEND modernize-use-using

libs/common/src/CMakeLists.txt

@@ -52,6 +52,7 @@ add_library(${LIBNAME} OBJECT
         bindings/c/flag_listener.cpp
         bindings/c/memory_routines.cpp
         bindings/c/data_source/error_info.cpp
+        bindings/c/logging/log_level.cpp
         log_level.cpp
         config/persistence_builder.cpp
         config/logging_builder.cpp

libs/common/src/bindings/c/logging/log_level.cpp

@@ -0,0 +1,15 @@
+#include <launchdarkly/bindings/c/logging/log_level.h>
+
+#include <launchdarkly/logging/log_level.hpp>
+
+LD_EXPORT(char const*)
+LDLogLevel_Name(LDLogLevel level, char const* name_if_unknown) {
+    return GetLogLevelName(static_cast<launchdarkly::LogLevel>(level),
+                           name_if_unknown);
+}
+
+LD_EXPORT(LDLogLevel)
+LDLogLevel_Enum(char const* level, LDLogLevel level_if_unknown) {
+    return static_cast<LDLogLevel>(GetLogLevelEnum(
+        level, static_cast<launchdarkly::LogLevel>(level_if_unknown)));
+}

libs/common/tests/logging_c_binding_test.cpp

@@ -0,0 +1,21 @@
+#include <launchdarkly/bindings/c/logging/log_level.h>
+
+#include <gtest/gtest.h>
+
+TEST(LogLevelTests, LogLevelToString) {
+    ASSERT_STREQ("debug", LDLogLevel_Name(LD_LOG_DEBUG, "unknown"));
+    ASSERT_STREQ("info", LDLogLevel_Name(LD_LOG_INFO, "unknown"));
+    ASSERT_STREQ("warn", LDLogLevel_Name(LD_LOG_WARN, "unknown"));
+    ASSERT_STREQ("error", LDLogLevel_Name(LD_LOG_ERROR, "unknown"));
+    ASSERT_STREQ("unknown",
+                 LDLogLevel_Name(static_cast<LDLogLevel>(4141), "unknown"));
+}
+
+TEST(LogLevelTests, LogLevelToEnum) {
+    constexpr auto unknown = static_cast<LDLogLevel>(4141);
+    ASSERT_EQ(LD_LOG_DEBUG, LDLogLevel_Enum("debug", unknown));
+    ASSERT_EQ(LD_LOG_INFO, LDLogLevel_Enum("info", unknown));
+    ASSERT_EQ(LD_LOG_WARN, LDLogLevel_Enum("warn", unknown));
+    ASSERT_EQ(LD_LOG_ERROR, LDLogLevel_Enum("error", unknown));
+    ASSERT_EQ(unknown, LDLogLevel_Enum("potato", unknown));
+}