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<!doctype html public "-//w3c//dtd html 4.0 transitional//en">
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<meta name="robots" content="noindex">
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<title>Legend Context Free Grammar</title>
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<H1>Legend Context Free Grammar</H1></center>
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<font color="#000000">The syntax rules are described in
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<b><i>EBNF</i></b> ( Extended Backus-Naur-Form ).
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A startsymbol must exist for each source file type. That means the syntax
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of each file must match the corresponding start rule.
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The other are internal helper rules. </font><font color="#000000"></font>
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<p><font color="#000000">Each <b><i><font size="+1">rule</font></i></b>
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is structured as follows: <Rule Type: <b><i>start</i></b> or <b><i>let</i></b>> </font>
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<<font color="#B22222">Rule Identifier</font>> :: <EBNF-konform Expression>
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<br>An <b><i><font size="+1">EBNF-konform expression</font></i></b> defines a part
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of the language syntax. It consists of a set of alternative productions i.e.
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partial expressions, separated by the character '|'.
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<p>A production is specified with the help of the following elements and operators:
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<b><i><font size="+1">Expression1 Expression2 ... ExpressionN</font></i></b></li>
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<br>Concatenation of partial expressions
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<b><i><font size="+1">Expression1 | Expression2 | ... | ExpressionN</font></i></b></li>
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<br>Union of partial expressions ( alternatives )
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<b><i><font size="+1">[ Expression ]</font></i></b></li>
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<br>Optional partial expression
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<b><i><font size="+1">{ Expression }</font></i></b></li>
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<br>Iteration of a partial expression ( 0 .. )
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<b><i><font size="+1">Expression +</font></i></b></li>
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<br>Iteration of a partial expression ( 1 .. )
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<b><i><font size="+1">( Expression )</font></i></b></li>
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<br>Combination of a partial expression ( subexpression )
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<b><i><font color="#3366FF"><font size="+1">Token Identifier</font></font></i></b></li>
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<br><font color="#000000">... from the regular grammar</font>
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<b><i><font color="#3366FF"><font size="+1">Rule Identifier<br>
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</font></font></i></b><font color="#000000">... from the context-free grammar</font></li>
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<b><i><font color="#009900"><font size="+1">Keyword<br>
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</font></font></i></b><font color="#000000">Constant string / character sequence</font><br>
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<b><i><font color="#000000"><font size="+1">[other]<br>
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</font></font></i></b><font color="#000000">Special keyword denoting the
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character sequences from the set 'Sigma* \ Tokenset'</font><br>
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<br><font color="#000000"></font> </ul>
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doc/legend_cfg_cfg.html
