diff options
Diffstat (limited to 'doc/lemon.html')
| -rw-r--r-- | doc/lemon.html | 39 |
1 files changed, 28 insertions, 11 deletions
diff --git a/doc/lemon.html b/doc/lemon.html index 17988deef..714cbfa5b 100644 --- a/doc/lemon.html +++ b/doc/lemon.html @@ -104,9 +104,13 @@ Write all output files into <i>directory</i>. Normally, output files are written into the directory that contains the input grammar file. <li><b>-D<i>name</i></b> Define C preprocessor macro <i>name</i>. This macro is usable by -"<tt><a href='#pifdef'>%ifdef</a></tt>" and -"<tt><a href='#pifdef'>%ifndef</a></tt>" lines +"<tt><a href='#pifdef'>%ifdef</a></tt>", +"<tt><a href='#pifdef'>%ifndef</a></tt>", and +"<tt><a href="#pifdef">%if</a></tt> lines in the grammar file. +<li><b>-E</b> +Run the "%if" preprocessor step only and print the revised grammar +file. <li><b>-g</b> Do not generate a parser. Instead write the input grammar to standard output with all comments, actions, and other extraneous text removed. @@ -555,9 +559,11 @@ other than that, the order of directives in Lemon is arbitrary.</p> <li><tt><a href='#default_destructor'>%default_destructor</a></tt> <li><tt><a href='#default_type'>%default_type</a></tt> <li><tt><a href='#destructor'>%destructor</a></tt> +<li><tt><a href='#pifdef'>%else</a></tt> <li><tt><a href='#pifdef'>%endif</a></tt> <li><tt><a href='#extraarg'>%extra_argument</a></tt> <li><tt><a href='#pfallback'>%fallback</a></tt> +<li><tt><a href='#pifdef'>%if</a></tt> <li><tt><a href='#pifdef'>%ifdef</a></tt> <li><tt><a href='#pifdef'>%ifndef</a></tt> <li><tt><a href='#pinclude'>%include</a></tt> @@ -737,10 +743,11 @@ arguments are tokens which fall back to the token identified by the first argument.</p> <a name='pifdef'></a> -<h4>The <tt>%ifdef</tt>, <tt>%ifndef</tt>, and <tt>%endif</tt> directives</h4> +<h4>The <tt>%if</tt> directive and its friends</h4> -<p>The <tt>%ifdef</tt>, <tt>%ifndef</tt>, and <tt>%endif</tt> directives -are similar to #ifdef, #ifndef, and #endif in the C-preprocessor, +<p>The <tt>%if</tt>, <tt>%ifdef</tt>, <tt>%ifndef</tt>, <tt>%else</tt>, +and <tt>%endif</tt> directives +are similar to #if, #ifdef, #ifndef, #else, and #endif in the C-preprocessor, just not as general. Each of these directives must begin at the left margin. No whitespace is allowed between the "%" and the directive name.</p> @@ -749,12 +756,22 @@ is allowed between the "%" and the directive name.</p> "<tt>%endif</tt>" is ignored unless the "-DMACRO" command-line option is used. Grammar text betwen "<tt>%ifndef MACRO</tt>" and the next nested "<tt>%endif</tt>" is -included except when the "-DMACRO" command-line option is used.</p> - -<p>Note that the argument to <tt>%ifdef</tt> and <tt>%ifndef</tt> must -be a single preprocessor symbol name, not a general expression. -There is no "<tt>%else</tt>" directive.</p> - +included except when the "-DMACRO" command-line option is used.<p> + +<p>The text in between "<tt>%if</tt> <i>CONDITIONAL</i>" and its +corresponding <tt>%endif</tt> is included only if <i>CONDITIONAL</i> +is true. The CONDITION is one or more macro names, optionally connected +using the "||" and "&&" binary operators, the "!" unary operator, +and grouped using balanced parentheses. Each term is true if the +corresponding macro exists, and false if it does not exist.</p> + +<p>An optional "<tt>%else</tt>" directive can occur anywhere in between a +<tt>%ifdef</tt>, <tt>%ifndef</tt>, or <tt>%if</tt> directive and +its corresponding <tt>%endif</tt>.</p> + +<p>Note that the argument to <tt>%ifdef</tt> and <tt>%ifndef</tt> is +intended to be a single preprocessor symbol name, not a general expression. +Use the "<tt>%if</tt>" directive for general expressions.</p> <a name='pinclude'></a> <h4>The <tt>%include</tt> directive</h4> |