| Pattern 1 | Mapping Grammars to Recursive-Descent Recognizers |
Purpose
This translates a grammar to a recursive-descent recognizer that matches phrases and sentences in the language specified by the grammar.
This pattern identifies the core control-flow framework for any recursive-descent lexer, parser, or tree parser.
Discussion
Even when building lexers and parsers by hand, the best starting point is a grammar. Grammars are a very concise way to express the languages you intend to recognize. Not only that, but grammars are excellent documentation that can go into a reference manual and into parsing code as comments. This pattern gives us a way to build recognizers directly from grammars.
A word of caution: this pattern works for many but not all ...
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