v1.0.0

core/context.go

@@ -0,0 +1,29 @@
+// +build !confonly
+
+package core
+
+import (
+	"context"
+)
+
+// XrayKey is the key type of Instance in Context, exported for test.
+type XrayKey int
+
+const xrayKey XrayKey = 1
+
+// FromContext returns an Instance from the given context, or nil if the context doesn't contain one.
+func FromContext(ctx context.Context) *Instance {
+	if s, ok := ctx.Value(xrayKey).(*Instance); ok {
+		return s
+	}
+	return nil
+}
+
+// MustFromContext returns an Instance from the given context, or panics if not present.
+func MustFromContext(ctx context.Context) *Instance {
+	x := FromContext(ctx)
+	if x == nil {
+		panic("X is not in context.")
+	}
+	return x
+}