kv macro support

Cargo.toml

@@ -22,6 +22,10 @@ features = ["std", "serde", "kv_unstable_sval"]
 name = "filters"
 harness = false
 
+[[test]]
+name = "macros"
+harness = true
+
 [features]
 max_level_off   = []
 max_level_error = []

src/lib.rs

@@ -1384,10 +1384,39 @@ pub fn logger() -> &'static Log {
 
 // WARNING: this is not part of the crate's public API and is subject to change at any time
 #[doc(hidden)]
+#[cfg(not(feature = "kv_unstable"))]
 pub fn __private_api_log(
     args: fmt::Arguments,
     level: Level,
     &(target, module_path, file, line): &(&str, &'static str, &'static str, u32),
+    kvs: Option<&[(&str, &str)]>,
+) {
+    if kvs.is_some() {
+        panic!(
+            "key-value support is experimental and must be enabled using the `kv_unstable` feature"
+        )
+    }
+
+    logger().log(
+        &Record::builder()
+            .args(args)
+            .level(level)
+            .target(target)
+            .module_path_static(Some(module_path))
+            .file_static(Some(file))
+            .line(Some(line))
+            .build(),
+    );
+}
+
+// WARNING: this is not part of the crate's public API and is subject to change at any time
+#[cfg(feature = "kv_unstable")]
+#[doc(hidden)]
+pub fn __private_api_log(
+    args: fmt::Arguments<'_>,
+    level: Level,
+    &(target, module_path, file, line): &(&str, &'static str, &'static str, u32),
+    kvs: Option<&[(&str, &kv::ToValue)]>,
 ) {
     logger().log(
         &Record::builder()
@@ -1397,6 +1426,7 @@ pub fn __private_api_log(
             .module_path_static(Some(module_path))
             .file_static(Some(file))
             .line(Some(line))
+            .key_values(&kvs)
             .build(),
     );
 }

src/macros.rs

@@ -29,17 +29,63 @@
 /// ```
 #[macro_export(local_inner_macros)]
 macro_rules! log {
-    (target: $target:expr, $lvl:expr, $($arg:tt)+) => ({
+    // log!(target: "...", "...")
+    (target: $target:expr, $lvl:expr, $e:expr) => {
+        $crate::log_impl!(target: $target, $lvl, ($e));
+    };
+
+    // log!(target: "...", "...", args...)
+    (target: $target:expr, $lvl:expr, $e:expr, $($rest:tt)*) => {
+        $crate::log_impl!(target: $target, $lvl, ($e) $($rest)*);
+    };
+
+    // log!("...", args...)
+    ($lvl:expr, $($arg:tt)+) => ($crate::log!(target: __log_module_path!(), $lvl, $($arg)+))
+}
+
+#[macro_export(local_inner_macros)]
+#[doc(hidden)]
+macro_rules! log_impl {
+    // End of macro input
+    (target: $target:expr, $lvl:expr, ($($arg:expr),*)) => {
         let lvl = $lvl;
         if lvl <= $crate::STATIC_MAX_LEVEL && lvl <= $crate::max_level() {
             $crate::__private_api_log(
-                __log_format_args!($($arg)+),
+                __log_format_args!($($arg),*),
                 lvl,
                 &($target, __log_module_path!(), __log_file!(), __log_line!()),
+                None,
+            );
+        }
+    };
+
+    // // Trailing k-v pairs containing no trailing comma
+    (target: $target:expr, $lvl:expr, ($($arg:expr),*) { $($key:ident : $value:expr),* }) => {
+        let lvl = log::Level::Info;
+        if lvl <= $crate::STATIC_MAX_LEVEL && lvl <= $crate::max_level() {
+            $crate::__private_api_log(
+                __log_format_args!($($arg),*),
+                lvl,
+                &(__log_module_path!(), __log_module_path!(), __log_file!(), __log_line!()),
+                Some(&[$((__log_stringify!($key), &$value)),*])
             );
         }
-    });
-    ($lvl:expr, $($arg:tt)+) => (log!(target: __log_module_path!(), $lvl, $($arg)+))
+    };
+
+    // Trailing k-v pairs with trailing comma
+    (target: $target:expr, $lvl:expr, ($($e:expr),*) { $($key:ident : $value:expr,)* }) => {
+        $crate::log_impl!(target: $target, $lvl, ($($e),*) { $($key : $value),* });
+    };
+
+    // Last expression arg with no trailing comma
+    (target: $target:expr, $lvl:expr, ($($e:expr),*) $arg:expr) => {
+        $crate::log_impl!(target: $target, $lvl, ($($e,)* $arg));
+    };
+
+    // Expression arg
+    (target: $target:expr, $lvl:expr, ($($e:expr),*) $arg:expr, $($rest:tt)*) => {
+        $crate::log_impl!(target: $target, $lvl, ($($e,)* $arg) $($rest)*);
+    };
 }
 
 /// Logs a message at the error level.
@@ -248,3 +294,11 @@ macro_rules! __log_line {
         line!()
     };
 }
+
+#[doc(hidden)]
+#[macro_export]
+macro_rules! __log_stringify {
+    ($($args:tt)*) => {
+        stringify!($($args)*)
+    };
+}

tests/macros.rs

@@ -0,0 +1,23 @@
+#[macro_use]
+extern crate log;
+
+#[test]
+fn base() {
+    info!("hello");
+    info!("hello",);
+}
+
+#[test]
+fn with_args() {
+    info!("hello {}", "cats");
+    info!("hello {}", "cats",);
+    info!("hello {}", "cats",);
+}
+
+#[test]
+fn kv() {
+    info!("hello {}", "cats", {
+        cat_1: "chashu",
+        cat_2: "nori",
+    });
+}