feat(BB): Free Lane (#167)

blockbuster/utils/ante.go

@@ -0,0 +1,43 @@
+package utils
+
+import (
+	sdk "github.com/cosmos/cosmos-sdk/types"
+)
+
+type (
+	// Lane defines the required functionality for a lane. The ignore decorator
+	// will check if a transaction belongs to a lane by calling the Match function.
+	Lane interface {
+		Match(tx sdk.Tx) bool
+	}
+
+	// IgnoreDecorator is an AnteDecorator that wraps an existing AnteDecorator. It allows
+	// for the AnteDecorator to be ignored for specified lanes.
+	IgnoreDecorator struct {
+		decorator sdk.AnteDecorator
+		lanes     []Lane
+	}
+)
+
+// NewIgnoreDecorator returns a new IgnoreDecorator instance.
+func NewIgnoreDecorator(decorator sdk.AnteDecorator, lanes ...Lane) *IgnoreDecorator {
+	return &IgnoreDecorator{
+		decorator: decorator,
+		lanes:     lanes,
+	}
+}
+
+// AnteHandle implements the sdk.AnteDecorator interface. If the transaction belongs to
+// one of the lanes, the next AnteHandler is called. Otherwise, the decorator's AnteHandler
+// is called.
+func (sd IgnoreDecorator) AnteHandle(
+	ctx sdk.Context, tx sdk.Tx, simulate bool, next sdk.AnteHandler,
+) (sdk.Context, error) {
+	for _, lane := range sd.lanes {
+		if lane.Match(tx) {
+			return next(ctx, tx, simulate)
+		}
+	}
+
+	return sd.decorator.AnteHandle(ctx, tx, simulate, next)
+}