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- <a name="spirit_x3.abstracts.nonterminal_attributes"></a><a class="link" href="nonterminal_attributes.html" title="Attributes of Nonterminals">Attributes
- of Nonterminals</a>
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- Nonterminals are the main means of constructing more complex parsers out
- of simpler ones. The nonterminals in the parser world are very similar to
- functions in an imperative programming language. They can be used to encapsulate
- parser expressions for a particular input sequence. After being defined,
- the nonterminals can be used as 'normal' parsers in more complex expressions
- whenever the encapsulated input needs to be recognized. Parser nonterminals
- in <span class="emphasis"><em>Spirit.X3</em></span> usually return a value (the synthesized
- attribute).
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- The type of the synthesized attribute as to be explicitly specified while
- defining the particular nonterminal. Example (ignore ID for now):
- </p>
- <pre class="programlisting"><span class="identifier">x3</span><span class="special">::</span><span class="identifier">rule</span><span class="special"><</span><span class="identifier">ID</span><span class="special">,</span> <span class="keyword">int</span><span class="special">></span> <span class="identifier">r</span><span class="special">;</span>
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