Merge pull request #47 from moul/dev/moul/check-level

README.md

@@ -70,6 +70,9 @@ func CheckAnyLevel(logger *zap.Logger) bool
     CheckAnyLevel determines whether at least one log level isn't filtered-out
     by the logger.
 
+func CheckLevel(logger *zap.Logger, level zapcore.Level) bool
+    CheckLevel determines whether a specific log level would produce log or not.
+
 func NewFilteringCore(next zapcore.Core, filter FilterFunc) zapcore.Core
     NewFilteringCore returns a core middleware that uses the given filter
     function to determine whether to actually call Write on the next core in the

zapfilter.go

@@ -35,6 +35,11 @@ func CheckAnyLevel(logger *zap.Logger) bool {
 	return false
 }
 
+// CheckLevel determines whether a specific log level would produce log or not.
+func CheckLevel(logger *zap.Logger, level zapcore.Level) bool {
+	return logger.Check(level, "") != nil
+}
+
 type filteringCore struct {
 	next   zapcore.Core
 	filter FilterFunc

zapfilter_test.go

@@ -436,6 +436,37 @@ func ExampleCheckAnyLevel() {
 	// true
 }
 
+func ExampleCheckLevel() {
+	c := zap.NewExample().Core()
+	logger := zap.New(zapfilter.NewFilteringCore(c, zapfilter.MustParseRules("debug:*.* info:demo*")))
+
+	fmt.Println(zapfilter.CheckLevel(logger, zap.DebugLevel))
+	fmt.Println(zapfilter.CheckLevel(logger.Named("demo"), zap.DebugLevel))
+	fmt.Println(zapfilter.CheckLevel(logger.Named("blahdemo"), zap.DebugLevel))
+	fmt.Println(zapfilter.CheckLevel(logger.Named("demoblah"), zap.DebugLevel))
+	fmt.Println(zapfilter.CheckLevel(logger.Named("blah"), zap.DebugLevel))
+	fmt.Println(zapfilter.CheckLevel(logger.Named("blah.blah"), zap.DebugLevel))
+	fmt.Println(zapfilter.CheckLevel(logger, zap.InfoLevel))
+	fmt.Println(zapfilter.CheckLevel(logger.Named("demo"), zap.InfoLevel))
+	fmt.Println(zapfilter.CheckLevel(logger.Named("blahdemo"), zap.InfoLevel))
+	fmt.Println(zapfilter.CheckLevel(logger.Named("demoblah"), zap.InfoLevel))
+	fmt.Println(zapfilter.CheckLevel(logger.Named("blah"), zap.InfoLevel))
+	fmt.Println(zapfilter.CheckLevel(logger.Named("blah.blah"), zap.InfoLevel))
+	// Output:
+	// false
+	// false
+	// false
+	// false
+	// false
+	// true
+	// false
+	// true
+	// false
+	// true
+	// false
+	// false
+}
+
 func Example_with() {
 	core := zap.NewExample().Core()
 	logger := zap.New(zapfilter.NewFilteringCore(core, zapfilter.ByNamespaces("demo1.*,demo3.*")))