We present a structured reformulation of the seminal algorithm for automatic generation of test cases for a context-free grammar. Our reformulation simplifies the algorithm in several ways. First, we provide a structured reformulation so that it is obvious where to proceed at each step. Second, we partition the intricate third phase into five functions, so that the discussion and comprehension of this phase can be modularized. Our implementation of the algorithm provides information about the grammatic, syntactic and semantic correctness of the generated test cases for two important languages in use today: C and C++. The results of our study of C and C++ highlight a lacuna latent in the research to date. In particular, if one or more of the automatically generated test cases is syntactically or semantically incorrect, then the confidence of structural \coverage" may be compromised for the particular grammar-based tool under test. Our ongoing work focuses on a solution to this problem.