Building Parsers with Java™

10.2. Parser Matching

The main goals of a parser are to match text and to use assemblers to build a result in an assembly. Matching is what differentiates, say, a sequence from an alternation from a repetition. As you'll soon see, a parser that contains alternations or repetitions does not always know which way or how many times to perform a match. The solution used in this book is to add all possible alternatives into an output set. Some alternative algorithms for matching are faster, but they impose constraints on allowable grammars. For a thorough analysis of approaches to matching, see Compilers [Aho et al.].

Each parser in the hierarchy beneath Parser implements matching in a different way. Figure 10.1 shows the aspects of the Parser class ...