Function newMetadataPruner

compiler/optimizer/pruner.go:162–184

(pred dag.Expr)

}

func newMetadataPruner(pred dag.Expr) dag.Expr {
	switch e := pred.(type) {
	case *dag.BinaryExpr:
		return metaPrunerBinaryExpr(e)
	case *dag.RegexpSearchExpr:
		this, ok := e.Expr.(*dag.ThisExpr)
		if !ok {
			return nil
		}
		prefix := regexpPrefix(e.Pattern)
		maxPrefix := regexpMaxPrefix(prefix)
		if prefix == "" || maxPrefix == "" {
			return nil
		}
		min := &dag.PrimitiveExpr{Kind: "PrimitiveExpr", Value: sup.QuotedString(prefix)}
		max := &dag.PrimitiveExpr{Kind: "PrimitiveExpr", Value: sup.QuotedString(maxPrefix)}
		return dag.NewBinaryExpr("and",
			compare("<=", min, dag.NewThis(append(slices.Clone(this.Path), "max"))),
			compare(">", max, dag.NewThis(append(slices.Clone(this.Path), "min"))))
	default:
		return nil
	}
}

// regexpPrefix returns the prefix of the provided regular expression (if one
// exists) only if the regular expression matches the beginning of a string.