Specialize target and level arguments that can be statically determined

src/__private_api.rs

@@ -1,89 +1,170 @@
-//! WARNING: this is not part of the crate's public API and is subject to change at any time
-
-use self::sealed::KVs;
-use crate::{Level, Metadata, Record};
-use std::fmt::Arguments;
-pub use std::{file, format_args, line, module_path, stringify};
-
-#[cfg(feature = "kv_unstable")]
-pub type Value<'a> = dyn crate::kv::value::ToValue + 'a;
-
-#[cfg(not(feature = "kv_unstable"))]
-pub type Value<'a> = str;
-
-mod sealed {
-    /// Types for the `kv` argument.
-    pub trait KVs<'a> {
-        fn into_kvs(self) -> Option<&'a [(&'a str, &'a super::Value<'a>)]>;
-    }
-}
-
-// Types for the `kv` argument.
-
-impl<'a> KVs<'a> for &'a [(&'a str, &'a Value<'a>)] {
-    #[inline]
-    fn into_kvs(self) -> Option<&'a [(&'a str, &'a Value<'a>)]> {
-        Some(self)
-    }
-}
-
-impl<'a> KVs<'a> for () {
-    #[inline]
-    fn into_kvs(self) -> Option<&'a [(&'a str, &'a Value<'a>)]> {
-        None
-    }
-}
-
-// Log implementation.
-
-fn log_impl(
-    args: Arguments,
-    level: Level,
-    &(target, module_path, file): &(&str, &'static str, &'static str),
-    line: u32,
-    kvs: Option<&[(&str, &Value)]>,
-) {
-    #[cfg(not(feature = "kv_unstable"))]
-    if kvs.is_some() {
-        panic!(
-            "key-value support is experimental and must be enabled using the `kv_unstable` feature"
-        )
-    }
-
-    let mut builder = Record::builder();
-
-    builder
-        .args(args)
-        .level(level)
-        .target(target)
-        .module_path_static(Some(module_path))
-        .file_static(Some(file))
-        .line(Some(line));
-
-    #[cfg(feature = "kv_unstable")]
-    builder.key_values(&kvs);
-
-    crate::logger().log(&builder.build());
-}
-
-pub fn log<'a, K>(
-    args: Arguments,
-    level: Level,
-    target_module_path_and_file: &(&str, &'static str, &'static str),
-    line: u32,
-    kvs: K,
-) where
-    K: KVs<'a>,
-{
-    log_impl(
-        args,
-        level,
-        target_module_path_and_file,
-        line,
-        kvs.into_kvs(),
-    )
-}
-
-pub fn enabled(level: Level, target: &str) -> bool {
-    crate::logger().enabled(&Metadata::builder().level(level).target(target).build())
-}
+//! WARNING: this is not part of the crate's public API and is subject to change at any time
+
+use self::sealed::{KVs, Level as LevelTrait, Target};
+use crate::{Level, LevelFilter, Metadata, Record};
+use std::cmp::Ordering;
+use std::fmt::Arguments;
+pub use std::{file, format_args, line, module_path, stringify};
+
+#[cfg(feature = "kv_unstable")]
+pub type Value<'a> = dyn crate::kv::value::ToValue + 'a;
+
+#[cfg(not(feature = "kv_unstable"))]
+pub type Value<'a> = &'a str;
+
+mod sealed {
+    /// Types for the `target` argument.
+    pub trait Target<'a>: Copy {
+        fn target(self, module_path: &'a &'a str) -> &'a &'a str;
+    }
+
+    /// Types for the `level` argument.
+    pub trait Level: Copy {
+        fn level(self) -> crate::Level;
+    }
+
+    /// Types for the `kv` argument.
+    pub trait KVs<'a> {
+        fn kvs(self) -> Option<&'a &'a [(&'a str, &'a super::Value<'a>)]>;
+    }
+}
+
+// Types for the `target` argument.
+
+/// Caller specified target explicitly.
+impl<'a> Target<'a> for &'a &'a str {
+    #[inline]
+    fn target(self, _module_path: &'a &'a str) -> &'a &'a str {
+        self
+    }
+}
+
+/// Caller did not specified target.
+impl<'a> Target<'a> for () {
+    #[inline]
+    fn target(self, module_path: &'a &'a str) -> &'a &'a str {
+        module_path
+    }
+}
+
+// Types for the `kvs` argument.
+
+/// Caller specified key-value data explicitly.
+impl<'a> KVs<'a> for &'a &'a [(&'a str, &'a Value<'a>)] {
+    #[inline]
+    fn kvs(self) -> Option<&'a &'a [(&'a str, &'a Value<'a>)]> {
+        Some(self)
+    }
+}
+
+/// Caller did not specify key-value data.
+impl<'a> KVs<'a> for () {
+    #[inline]
+    fn kvs(self) -> Option<&'a &'a [(&'a str, &'a Value<'a>)]> {
+        None
+    }
+}
+
+// Types for the `level` argument.
+
+/// The log level is dynamically determined.
+impl LevelTrait for Level {
+    #[inline]
+    fn level(self) -> Level {
+        self
+    }
+}
+
+macro_rules! define_static_levels {
+    ($(($name:ident, $level:ident),)*) => {$(
+        #[derive(Clone, Copy, Debug)]
+        pub struct $name;
+
+        /// The log level is statically determined.
+        impl LevelTrait for $name {
+            #[inline]
+            fn level(self) -> Level {
+                Level::$level
+            }
+        }
+
+        impl PartialEq<LevelFilter> for $name {
+            #[inline]
+            fn eq(&self, other: &LevelFilter) -> bool {
+                self.level().eq(other)
+            }
+        }
+
+        impl PartialOrd<LevelFilter> for $name {
+            #[inline]
+            fn partial_cmp(&self, other: &LevelFilter) -> Option<Ordering> {
+                self.level().partial_cmp(other)
+            }
+        }
+    )*};
+}
+
+define_static_levels![
+    (LevelError, Error),
+    (LevelWarn, Warn),
+    (LevelInfo, Info),
+    (LevelDebug, Debug),
+    (LevelTrace, Trace),
+];
+
+// Log implementation.
+
+#[derive(Debug)]
+pub struct RequiredArgs<'a> {
+    pub module_path_and_file: &'static (&'static str, &'static str),
+    pub line: u32,
+    pub args: Arguments<'a>,
+}
+
+fn log_impl(
+    required_args: &RequiredArgs,
+    target: &&str,
+    level: Level,
+    kvs: Option<&&[(&str, &Value)]>,
+) {
+    #[cfg(not(feature = "kv_unstable"))]
+    if kvs.is_some() {
+        panic!(
+            "key-value support is experimental and must be enabled using the `kv_unstable` feature"
+        )
+    }
+
+    let mut builder = Record::builder();
+
+    builder
+        .args(required_args.args)
+        .level(level)
+        .target(target)
+        .module_path_static(Some(required_args.module_path_and_file.0))
+        .file_static(Some(required_args.module_path_and_file.1))
+        .line(Some(required_args.line));
+
+    #[cfg(feature = "kv_unstable")]
+    builder.key_values(&kvs);
+
+    crate::logger().log(&builder.build());
+}
+
+#[inline(never)]
+pub fn log<'a, T, L, K>(required_args: &RequiredArgs, target: T, level: L, kvs: K)
+where
+    T: Target<'a>,
+    L: LevelTrait,
+    K: KVs<'a>,
+{
+    log_impl(
+        required_args,
+        target.target(&required_args.module_path_and_file.0),
+        level.level(),
+        kvs.kvs(),
+    )
+}
+
+pub fn enabled(level: Level, target: &str) -> bool {
+    crate::logger().enabled(&Metadata::builder().level(level).target(target).build())
+}