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| <div class="section"> |
| <div class="titlepage"><div><div><h3 class="title"> |
| <a name="spirit.notes.style_guide"></a><a class="link" href="style_guide.html" title="Style Guide">Style Guide</a> |
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| <p> |
| At some point, especially when there are lots of semantic actions attached |
| to various points, the grammar tends to be quite difficult to follow. In |
| order to keep an easy-to-read, consistent and aesthetically pleasing look |
| to the Spirit code, the following coding style guide is advised. |
| </p> |
| <p> |
| This coding style is adapted and extended from the ANTLR/PCCTS style and |
| <a href="http://www.boost.org/development/requirements.html" target="_top">Boost Library |
| Requirements and Guidelines</a> and is the combined work of Joel de Guzman, |
| Chris Uzdavinis, and Hartmut Kaiser. |
| </p> |
| <div class="itemizedlist"><ul class="itemizedlist" type="disc"> |
| <li class="listitem"> |
| Rule names use std C++ (Boost) convention. The rule name may be very |
| long. |
| </li> |
| <li class="listitem"> |
| The '=' is neatly indented 4 spaces below. Like in Boost, use spaces |
| instead of tabs. |
| </li> |
| <li class="listitem"> |
| Breaking the operands into separate lines puts the semantic actions neatly |
| to the right. |
| </li> |
| <li class="listitem"> |
| Semicolon at the last line terminates the rule. |
| </li> |
| <li class="listitem"> |
| The adjacent parts of a sequence should be indented accordingly to have |
| all, what belongs to one level, at one indentation level. |
| </li> |
| </ul></div> |
| <pre class="programlisting"><span class="identifier">program</span> |
| <span class="special">=</span> <span class="identifier">program_heading</span> <span class="special">[</span><span class="identifier">heading_action</span><span class="special">]</span> |
| <span class="special">>></span> <span class="identifier">block</span> <span class="special">[</span><span class="identifier">block_action</span><span class="special">]</span> |
| <span class="special">>></span> <span class="char">'.'</span> |
| <span class="special">|</span> <span class="identifier">another_sequence</span> |
| <span class="special">>></span> <span class="identifier">etc</span> |
| <span class="special">;</span> |
| </pre> |
| <div class="itemizedlist"><ul class="itemizedlist" type="disc"> |
| <li class="listitem"> |
| Prefer literals in the grammar instead of identifiers. e.g. <code class="computeroutput"><span class="string">"program"</span></code> instead of <code class="computeroutput"><span class="identifier">PROGRAM</span></code>, <code class="computeroutput"><span class="char">'>='</span></code> |
| instead of <code class="computeroutput"><span class="identifier">GTE</span></code> and <code class="computeroutput"><span class="char">'.'</span></code> instead of <code class="computeroutput"><span class="identifier">DOT</span></code>. |
| This makes it much easier to read. If this isn't possible (for instance |
| where the used tokens must be identified through integers) capitalized |
| identifiers should be used instead. |
| </li> |
| <li class="listitem"> |
| Breaking the operands may not be needed for short expressions. e.g. |
| <code class="computeroutput"><span class="special">*(</span><span class="char">','</span> |
| <span class="special">>></span> <span class="identifier">file_identifier</span><span class="special">)</span></code> as long as the line does not exceed |
| 80 characters. |
| </li> |
| <li class="listitem"> |
| If a sequence fits on one line, put spaces inside the parentheses to |
| clearly separate them from the rules. |
| </li> |
| </ul></div> |
| <pre class="programlisting"><span class="identifier">program_heading</span> |
| <span class="special">=</span> <span class="identifier">no_case</span><span class="special">[</span><span class="string">"program"</span><span class="special">]</span> |
| <span class="special">>></span> <span class="identifier">identifier</span> |
| <span class="special">>></span> <span class="char">'('</span> |
| <span class="special">>></span> <span class="identifier">file_identifier</span> |
| <span class="special">>></span> <span class="special">*(</span> <span class="char">','</span> <span class="special">>></span> <span class="identifier">file_identifier</span> <span class="special">)</span> |
| <span class="special">>></span> <span class="char">')'</span> |
| <span class="special">>></span> <span class="char">';'</span> |
| <span class="special">;</span> |
| </pre> |
| <div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"> |
| Nesting directives: If a rule does not fit on one line (80 characters) |
| it should be continued on the next line intended by one level. The brackets |
| of directives, semantic expressions (using Phoenix or LL lambda expressions) |
| or parsers should be placed as follows. |
| </li></ul></div> |
| <pre class="programlisting"><span class="identifier">identifier</span> |
| <span class="special">=</span> <span class="identifier">no_case</span> |
| <span class="special">[</span> |
| <span class="identifier">lexeme</span> |
| <span class="special">[</span> |
| <span class="identifier">alpha</span> <span class="special">>></span> <span class="special">*(</span><span class="identifier">alnum</span> <span class="special">|</span> <span class="char">'_'</span><span class="special">)</span> <span class="special">[</span><span class="identifier">id_action</span><span class="special">]</span> |
| <span class="special">]</span> |
| <span class="special">]</span> |
| <span class="special">;</span> |
| </pre> |
| <div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"> |
| Nesting unary operators (e.g.Kleene star): Unary rule operators (Kleene |
| star, <code class="computeroutput"><span class="char">'!'</span></code>, <code class="computeroutput"><span class="char">'+'</span></code> |
| etc.) should be moved out one space before the corresponding indentation |
| level, if this rule has a body or a sequence after it, which does not |
| fit on on line. This makes the formatting more consistent and moves the |
| rule 'body' at the same indentation level as the rule itself, highlighting |
| the unary operator. |
| </li></ul></div> |
| <pre class="programlisting"><span class="identifier">block</span> |
| <span class="special">=</span> <span class="special">*(</span> <span class="identifier">label_declaration_part</span> |
| <span class="special">|</span> <span class="identifier">constant_definition_part</span> |
| <span class="special">|</span> <span class="identifier">type_definition_part</span> |
| <span class="special">|</span> <span class="identifier">variable_declaration_part</span> |
| <span class="special">|</span> <span class="identifier">procedure_and_function_declaration_part</span> |
| <span class="special">)</span> |
| <span class="special">>></span> <span class="identifier">statement_part</span> |
| <span class="special">;</span> |
| </pre> |
| </div> |
| <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> |
| <td align="left"></td> |
| <td align="right"><div class="copyright-footer">Copyright © 2001-2010 Joel de Guzman, Hartmut Kaiser<p> |
| Distributed under the Boost Software License, Version 1.0. (See accompanying |
| file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) |
| </p> |
| </div></td> |
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