Understanding context-free grammars
In this section, we will define the notation used by programming language inventors to describe the syntax of their language. You will be able to use what you learn in this section to supply syntax rules as input to the parser generators used in the next section. Let's begin by understanding what context-free grammars are.
Context-free grammars are the most widely used notation for describing the syntax allowed in a programming language in terms of patterns of lexemes. They are formulated from very simple rules that are easy to understand. Context-free grammars are built from the following components:
- Terminal symbols: A set of input symbols are called terminal symbols. Terminal symbols in a grammar are read in from a scanner such as the one we produced in the last chapter. Although they are referred to as symbols, terminal symbols correspond to an entire word, operator, or punctuation mark; a terminal symbol identifies the category...
