simplify color iovec construct

Author: Coldwings

common/alog.cpp

@@ -14,7 +14,6 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-#include <initializer_list>
 #ifdef _WIN64
 #define _POSIX_C_SOURCE 1
 #endif
@@ -37,41 +36,43 @@ using namespace std;
 
 static struct tm alog_time = {0};
 
-#define ALOG_COLOR_RESET "\033[0m"
+struct iovec_str : iovec {
+    template <size_t N>
+    constexpr iovec_str(const char (&s)[N])
+        : iovec{const_cast<char*>(s), N - 1} {}
+    constexpr iovec_str(const char* s, size_t n)
+        : iovec{const_cast<char*>(s), n} {}
+};
+
+constexpr static iovec_str alog_color_reset("\033[0m");
 
 class BaseLogOutput : public ILogOutput {
 public:
     uint64_t throttle = -1UL;
     uint64_t count = 0;
     time_t ts = 0;
     int log_file_fd;
-    struct iovec level_prefix[ALOG_AUDIT + 1];
+    iovec_str level_prefix[ALOG_AUDIT + 1];
 
     constexpr BaseLogOutput(int fd = 0)
         : log_file_fd(fd),
-          level_prefix{
-              {(void*)ALOG_COLOR_DARKGRAY, sizeof(ALOG_COLOR_DARKGRAY) - 1},
-              {(void*)ALOG_COLOR_LIGHTGRAY, sizeof(ALOG_COLOR_LIGHTGRAY) - 1},
-              {(void*)ALOG_COLOR_YELLOW, sizeof(ALOG_COLOR_YELLOW) - 1},
-              {(void*)ALOG_COLOR_RED, sizeof(ALOG_COLOR_RED) - 1},
-              {(void*)ALOG_COLOR_MAGENTA, sizeof(ALOG_COLOR_MAGENTA) - 1},
-              {(void*)ALOG_COLOR_CYAN, sizeof(ALOG_COLOR_CYAN) - 1},
-              {(void*)ALOG_COLOR_GREEN, sizeof(ALOG_COLOR_GREEN) - 1},
-          } {}
+          level_prefix{ALOG_COLOR_DARKGRAY, ALOG_COLOR_LIGHTGRAY,
+                       ALOG_COLOR_YELLOW,   ALOG_COLOR_RED,
+                       ALOG_COLOR_MAGENTA,  ALOG_COLOR_CYAN,
+                       ALOG_COLOR_GREEN} {}
 
     void set_level_color(int level, const char* color, size_t len) override {
         if (level < 0 || level > ALOG_AUDIT) return;
-        level_prefix[level] = {(void*)color, len};
+        level_prefix[level] = {color, len};
     }
 
     void write(int level, const char* begin, const char* end) override {
-        struct iovec iov[3] = {
-            level_prefix[level],
-            {
-                .iov_base = (void*)begin,
-                .iov_len = (size_t)(end - begin),
-            },
-            {(void*)ALOG_COLOR_RESET, sizeof(ALOG_COLOR_RESET) - 1}};
+        struct iovec iov[3] = {level_prefix[level],
+                               {
+                                   .iov_base = (void*)begin,
+                                   .iov_len = (size_t)(end - begin),
+                               },
+                               alog_color_reset};
         std::ignore = ::writev(log_file_fd, iov, 2 + !!iov[0].iov_len);
         throttle_block();
     }