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<h2 id="sec4" class="section">2 IDL syntax</h2>
<p>This section describes the syntax of IDL files. IDL syntax is very
close to that of C declarations, with extra attributes between
brackets adding information to the C types. The following example
should give the flavor of the syntax:
</p><pre> int f([in,string] char * msg);
</pre><p>This reads: “<span class=machine><span class=font-tt>f</span></span> is a function taking a character string as input and
returning an <span class=machine><span class=font-tt>int</span></span>”.</p>
<h3 id="sec5" class="subsection">2.1 Lexical conventions</h3>
<h4 id="sec6" class="paragraph">Blanks.</h4>
<p> Space, newline, horizontal tabulation, carriage
return, line feed and form feed are considered as blanks. Blanks are
ignored, but they separate adjacent tokens.</p>
<h4 id="sec7" class="paragraph">Comments.</h4>
<p> Both C-style comments <span class=machine><span class=font-tt>/* ... */</span></span> and
Java-style comments <span class=machine><span class=font-tt>// ...</span></span> are supported. C-style comments are
introduced by <span class=machine><span class=font-tt>/*</span></span> and terminated by <span class=machine><span class=font-tt>*/</span></span>. Java-style comments are
introduced by <span class=machine><span class=font-tt>//</span></span> and extend to the end of the line. Comments are
treated as blank characters. Comments do not occur inside string or
character literals. Nested C-style comments are not supported.</p>
<h4 id="sec8" class="paragraph">Identifiers.</h4>
<p> Identifiers have the same syntax as in C.
</p><div class="syntax"><table class="display dcenter"><tr style="vertical-align:middle"><td class="dcell"><table style="border-spacing:6px;border-collapse:separate;" class="cellpading0"><tr><td style="text-align:right;white-space:nowrap" ><a id="ident" class="syntax"><span class=nonterminal>ident</span></a></td><td style="text-align:center;white-space:nowrap" >::=</td><td style="text-align:left;white-space:nowrap" > (<span class=syntax-token>A</span> … <span class=syntax-token>Z</span> ∣ <span class=syntax-token>a</span> … <span class=syntax-token>z</span> ∣ <span class=syntax-token>_</span>)
{<span class=syntax-token>A</span> … <span class=syntax-token>Z</span> ∣ <span class=syntax-token>a</span> … <span class=syntax-token>z</span> ∣ <span class=syntax-token>0</span> … <span class=syntax-token>9</span> ∣ <span class=syntax-token>_</span>}</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td></tr>
</table></td></tr>
</table></div>
<h4 id="sec9" class="paragraph">Literals.</h4>
<p> Integer literals, character literals and string
literals have the same syntax as in C.
</p><div class="syntax"><table class="display dcenter"><tr style="vertical-align:middle"><td class="dcell"><table style="border-spacing:6px;border-collapse:separate;" class="cellpading0"><tr><td style="text-align:right;white-space:nowrap" ><a id="integer" class="syntax"><span class=nonterminal>integer</span></a></td><td style="text-align:center;white-space:nowrap" >::=</td><td style="text-align:left;white-space:nowrap" > [<span class=syntax-token>-</span>] {<span class=syntax-token>0</span> … <span class=syntax-token>9</span>}
[<span class=syntax-token>-</span>] <span class=syntax-token>0x</span> {<span class=syntax-token>0</span> … <span class=syntax-token>9</span> ∣ <span class=syntax-token>a</span> … <span class=syntax-token>f</span> ∣ <span class=syntax-token>A</span> … <span class=syntax-token>F</span>}
[<span class=syntax-token>-</span>] <span class=syntax-token>0</span> {<span class=syntax-token>0</span> … <span class=syntax-token>7</span>}</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td></tr>
<tr><td style="text-align:right;white-space:nowrap" >
<a id="character" class="syntax"><span class=nonterminal>character</span></a></td><td style="text-align:center;white-space:nowrap" >::=</td><td style="text-align:left;white-space:nowrap" > (<span class=nonterminal>regular-char</span> ∣ <a href="#escape-char" class="syntax"><span class=nonterminal>escape-char</span></a>) </td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td></tr>
<tr><td style="text-align:right;white-space:nowrap" >
<a id="string" class="syntax"><span class=nonterminal>string</span></a></td><td style="text-align:center;white-space:nowrap" >::=</td><td style="text-align:left;white-space:nowrap" > <span class=syntax-token>"</span> {<span class=nonterminal>regular-char</span> ∣ <a href="#escape-char" class="syntax"><span class=nonterminal>escape-char</span></a>} <span class=syntax-token>"</span></td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td></tr>
<tr><td style="text-align:right;white-space:nowrap" >
<a id="escape-char" class="syntax"><span class=nonterminal>escape-char</span></a></td><td style="text-align:center;white-space:nowrap" >::=</td><td style="text-align:left;white-space:nowrap" > <span class=syntax-token>\</span> (<span class=syntax-token>b</span>∣<span class=syntax-token>n</span>∣<span class=syntax-token>r</span>∣<span class=syntax-token>t</span>)
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <span class=syntax-token>\</span> (<span class=syntax-token>0</span>…<span class=syntax-token>7</span>) [<span class=syntax-token>0</span>…<span class=syntax-token>7</span>] [<span class=syntax-token>0</span>…<span class=syntax-token>7</span>]</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td></tr>
</table></td></tr>
</table></div>
<h4 id="sec10" class="paragraph">UUID.</h4>
<p> Unique identifiers are composed of 16 hexadecimal
digits, in groups of 8, 4, 4, 4 and 12, separated by dashes.
</p><div class="syntax"><table class="display dcenter"><tr style="vertical-align:middle"><td class="dcell"><table style="border-spacing:6px;border-collapse:separate;" class="cellpading0"><tr><td style="text-align:right;white-space:nowrap" ><a id="uuid" class="syntax"><span class=nonterminal>uuid</span></a></td><td style="text-align:center;white-space:nowrap" >::=</td><td style="text-align:left;white-space:nowrap" > <a href="#hex" class="syntax"><span class=nonterminal>hex</span></a><sup>8</sup> <span class=syntax-token>-</span> <a href="#hex" class="syntax"><span class=nonterminal>hex</span></a><sup>4</sup> <span class=syntax-token>-</span> <a href="#hex" class="syntax"><span class=nonterminal>hex</span></a><sup>4</sup> <span class=syntax-token>-</span> <a href="#hex" class="syntax"><span class=nonterminal>hex</span></a><sup>4</sup> <span class=syntax-token>-</span> <a href="#hex" class="syntax"><span class=nonterminal>hex</span></a><sup>4</sup> <a href="#hex" class="syntax"><span class=nonterminal>hex</span></a><sup>4</sup> <a href="#hex" class="syntax"><span class=nonterminal>hex</span></a><sup>4</sup></td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td></tr>
<tr><td style="text-align:right;white-space:nowrap" >
<a id="hex" class="syntax"><span class=nonterminal>hex</span></a></td><td style="text-align:center;white-space:nowrap" >::=</td><td style="text-align:left;white-space:nowrap" > <span class=syntax-token>0</span> … <span class=syntax-token>9</span> ∣ <span class=syntax-token>a</span> … <span class=syntax-token>f</span> ∣ <span class=syntax-token>A</span> … <span class=syntax-token>F</span></td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td></tr>
</table></td></tr>
</table></div>
<h3 id="sec11" class="subsection">2.2 Limited expressions</h3>
<p>Limited expressions are similar to C expressions, with the omission of
assignment operators (<span class=machine><span class=font-tt>=</span></span>, <span class=machine><span class=font-tt>+=</span></span>, etc), and the addition of the
unsigned (logical) right shift operator <span class=machine><span class=font-tt>>>></span></span>. Operators have the same
precedences and associativities as in C. They are listed below in
decreasing priority order.
</p><div class="syntax"><table class="display dcenter"><tr style="vertical-align:middle"><td class="dcell"><table style="border-spacing:6px;border-collapse:separate;" class="cellpading0"><tr><td style="text-align:right;white-space:nowrap" ><a id="lexpr" class="syntax"><span class=nonterminal>lexpr</span></a></td><td style="text-align:center;white-space:nowrap" >::=</td><td style="text-align:left;white-space:nowrap" >
<a href="#ident" class="syntax"><span class=nonterminal>ident</span></a>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <a href="#integer" class="syntax"><span class=nonterminal>integer</span></a>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <a href="#character" class="syntax"><span class=nonterminal>character</span></a>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <span class=syntax-token>true</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <span class=syntax-token>false</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <a href="#string" class="syntax"><span class=nonterminal>string</span></a>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <span class=nonterminal>sizeof</span> <span class=syntax-token>(</span> <span class=nonterminal>type-expr</span> <span class=syntax-token>)</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <span class=syntax-token>(</span> <a href="#lexpr" class="syntax"><span class=nonterminal>lexpr</span></a> <span class=syntax-token>)</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <a href="#lexpr" class="syntax"><span class=nonterminal>lexpr</span></a> (<span class=syntax-token>.</span> ∣ <span class=syntax-token>-></span>) <a href="#ident" class="syntax"><span class=nonterminal>ident</span></a>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <span class=syntax-token>(</span> <span class=nonterminal>type-expr</span> <span class=syntax-token>)</span> <a href="#lexpr" class="syntax"><span class=nonterminal>lexpr</span></a>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > (<span class=syntax-token>&</span>∣<span class=syntax-token>*</span>∣<span class=syntax-token>!</span>∣<span class=syntax-token>~</span>∣<span class=syntax-token>-</span>∣<span class=syntax-token>+</span>) <a href="#lexpr" class="syntax"><span class=nonterminal>lexpr</span></a>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <a href="#lexpr" class="syntax"><span class=nonterminal>lexpr</span></a> (<span class=syntax-token>*</span>∣<span class=syntax-token>/</span>∣<span class=syntax-token>%</span>) <a href="#lexpr" class="syntax"><span class=nonterminal>lexpr</span></a>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <a href="#lexpr" class="syntax"><span class=nonterminal>lexpr</span></a> (<span class=syntax-token>+</span>∣<span class=syntax-token>-</span>) <a href="#lexpr" class="syntax"><span class=nonterminal>lexpr</span></a>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <a href="#lexpr" class="syntax"><span class=nonterminal>lexpr</span></a> (<span class=syntax-token><<</span>∣<span class=syntax-token>>></span></td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" ><span class=syntax-token>>>></span>) <a href="#lexpr" class="syntax"><span class=nonterminal>lexpr</span></a>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <a href="#lexpr" class="syntax"><span class=nonterminal>lexpr</span></a> (<span class=syntax-token>==</span>∣<span class=syntax-token>!=</span>∣<span class=syntax-token>>=</span>∣<span class=syntax-token><=</span>∣<span class=syntax-token>></span>∣<span class=syntax-token><</span>)
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <a href="#lexpr" class="syntax"><span class=nonterminal>lexpr</span></a> (<span class=syntax-token>&</span>∣<span class=syntax-token>^</span>∣<span class=syntax-token>|</span>) <a href="#lexpr" class="syntax"><span class=nonterminal>lexpr</span></a>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <a href="#lexpr" class="syntax"><span class=nonterminal>lexpr</span></a> (<span class=syntax-token>&&</span>∣<span class=syntax-token>||</span>) <a href="#lexpr" class="syntax"><span class=nonterminal>lexpr</span></a>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <a href="#lexpr" class="syntax"><span class=nonterminal>lexpr</span></a> <span class=syntax-token>?</span> <a href="#lexpr" class="syntax"><span class=nonterminal>lexpr</span></a> <span class=syntax-token>:</span> <a href="#lexpr" class="syntax"><span class=nonterminal>lexpr</span></a>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td></tr>
</table></td></tr>
</table></div><p>
Constant limited expressions, written <span class=nonterminal>const-lexpr</span> below, can only
reference identifiers that are bound by the IDL <span class=machine><span class=font-tt>const</span></span> declaration.</p>
<h3 id="sec12" class="subsection">2.3 Attributes</h3>
<div class="syntax"><table class="display dcenter"><tr style="vertical-align:middle"><td class="dcell"><table style="border-spacing:6px;border-collapse:separate;" class="cellpading0"><tr><td style="text-align:right;white-space:nowrap" ><a id="attributes" class="syntax"><span class=nonterminal>attributes</span></a></td><td style="text-align:center;white-space:nowrap" >::=</td><td style="text-align:left;white-space:nowrap" >
<span class=syntax-token>[</span> <a href="#attribute" class="syntax"><span class=nonterminal>attribute</span></a> { <span class=syntax-token>,</span> <a href="#attribute" class="syntax"><span class=nonterminal>attribute</span></a> } <span class=syntax-token>]</span> </td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td></tr>
<tr><td style="text-align:right;white-space:nowrap" >
<a id="attribute" class="syntax"><span class=nonterminal>attribute</span></a></td><td style="text-align:center;white-space:nowrap" >::=</td><td style="text-align:left;white-space:nowrap" >
<a href="#ident" class="syntax"><span class=nonterminal>ident</span></a>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <a href="#ident" class="syntax"><span class=nonterminal>ident</span></a> <span class=syntax-token>(</span> [<a href="#lexpr" class="syntax"><span class=nonterminal>lexpr</span></a>] { <span class=syntax-token>,</span> [<a href="#lexpr" class="syntax"><span class=nonterminal>lexpr</span></a>] } <span class=syntax-token>)</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <a href="#ident" class="syntax"><span class=nonterminal>ident</span></a> <span class=syntax-token>(</span> <a href="#uuid" class="syntax"><span class=nonterminal>uuid</span></a> <span class=syntax-token>)</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <a href="#attribute" class="syntax"><span class=nonterminal>attribute</span></a> <span class=syntax-token>*</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <span class=syntax-token>*</span> <a href="#attribute" class="syntax"><span class=nonterminal>attribute</span></a>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td></tr>
</table></td></tr>
</table></div><p>
Attribute lists are written in brackets <span class=machine><span class=font-tt>[...]</span></span>, and are always
optional. Each attribute is identified by a name, and may carry
optional arguments. Starred attributes apply to the element type of a
pointer or array type, rather than to the pointer or array type itself.
The following table summarizes the recognized attributes and their
arguments.</p><div class="tableau">
<div class="center"><table border=1 style="border-spacing:0;width:80%" class="cellpadding1"><tr><td style="text-align:center;border:solid 1px;white-space:nowrap" ><span class=font-bold>Attribute</span></td><td style="text-align:center;border:solid 1px;white-space:nowrap" ><span class=font-bold>Context where it can appear</span> </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" >
<span class=syntax-token>abstract</span> </td><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=machine><span class=font-tt>typedef</span></span> </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>bigarray</span> </td><td style="text-align:left;border:solid 1px;white-space:nowrap" >array type </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>blocking</span> </td><td style="text-align:left;border:solid 1px;white-space:nowrap" >function declaration </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>camlint</span> </td><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=machine><span class=font-tt>int</span></span> or <span class=machine><span class=font-tt>long</span></span> integer type </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>compare</span><span class=syntax-token>(</span><span class=nonterminal>fun-name</span><span class=syntax-token>)</span> </td><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=machine><span class=font-tt>typedef</span></span> </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>c2ml</span><span class=syntax-token>(</span><span class=nonterminal>fun-name</span><span class=syntax-token>)</span> </td><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=machine><span class=font-tt>typedef</span></span> </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>errorcheck</span><span class=syntax-token>(</span><span class=nonterminal>fun-name</span><span class=syntax-token>)</span> </td><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=machine><span class=font-tt>typedef</span></span> </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>errorcode</span> </td><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=machine><span class=font-tt>typedef</span></span> </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>finalize</span><span class=syntax-token>(</span><span class=nonterminal>fun-name</span><span class=syntax-token>)</span> </td><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=machine><span class=font-tt>typedef</span></span> </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>fortran</span> </td><td style="text-align:left;border:solid 1px;white-space:nowrap" >array type with <span class=machine><span class=font-tt>bigarray</span></span> attribute </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>hash</span><span class=syntax-token>(</span><span class=nonterminal>fun-name</span><span class=syntax-token>)</span> </td><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=machine><span class=font-tt>typedef</span></span> </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>ignore</span> </td><td style="text-align:left;border:solid 1px;white-space:nowrap" >any pointer type </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>in</span> </td><td style="text-align:left;border:solid 1px;white-space:nowrap" >function parameter </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>int_default</span><span class=syntax-token>(</span> <span class=syntax-token>camlint</span>∣<span class=syntax-token>nativeint</span>∣<span class=syntax-token>int32</span>∣<span class=syntax-token>int64</span><span class=syntax-token>)</span> </td><td style="text-align:left;border:solid 1px;white-space:nowrap" >interface </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>int32</span> </td><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=machine><span class=font-tt>int</span></span> or <span class=machine><span class=font-tt>long</span></span> integer type </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>int64</span> </td><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=machine><span class=font-tt>int</span></span> or <span class=machine><span class=font-tt>long</span></span> integer type </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>length_is</span><span class=syntax-token>(</span><span class=nonterminal>le</span><sub>1</sub><span class=syntax-token>,</span><span class=nonterminal>le</span><sub>2</sub><span class=syntax-token>,</span>…<span class=syntax-token>)</span> </td><td style="text-align:left;border:solid 1px;white-space:nowrap" >array type </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>long_default</span><span class=syntax-token>(</span> <span class=syntax-token>camlint</span>∣<span class=syntax-token>nativeint</span>∣<span class=syntax-token>int32</span>∣<span class=syntax-token>int64</span><span class=syntax-token>)</span> </td><td style="text-align:left;border:solid 1px;white-space:nowrap" >interface </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>managed</span> </td><td style="text-align:left;border:solid 1px;white-space:nowrap" >array type with <span class=machine><span class=font-tt>bigarray</span></span> attribute </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>ml2c</span><span class=syntax-token>(</span><span class=nonterminal>fun-name</span><span class=syntax-token>)</span> </td><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=machine><span class=font-tt>typedef</span></span> </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>mlname(</span> <span class=nonterminal>fun-or-field-name</span> <span class=syntax-token>)</span> </td><td style="text-align:left;border:solid 1px;white-space:nowrap" >function declaration, <span class=machine><span class=font-tt>struct</span></span> field </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>mltype("</span> <span class=nonterminal>caml-type-expr</span> <span class=syntax-token>")</span> </td><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=machine><span class=font-tt>typedef</span></span> </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>nativeint</span> </td><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=machine><span class=font-tt>int</span></span> or <span class=machine><span class=font-tt>long</span></span> integer type </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>null_terminated</span> </td><td style="text-align:left;border:solid 1px;white-space:nowrap" >array of pointers </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>object</span></td><td style="text-align:left;border:solid 1px;white-space:nowrap" >interface </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>out</span> </td><td style="text-align:left;border:solid 1px;white-space:nowrap" >function parameter </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>pointer_default</span><span class=syntax-token>(</span> <span class=syntax-token>ref</span>∣<span class=syntax-token>unique</span>∣<span class=syntax-token>ptr</span><span class=syntax-token>)</span> </td><td style="text-align:left;border:solid 1px;white-space:nowrap" >interface </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>propget</span></td><td style="text-align:left;border:solid 1px;white-space:nowrap" >function declaration </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>propput</span></td><td style="text-align:left;border:solid 1px;white-space:nowrap" >function declaration </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>propputref</span></td><td style="text-align:left;border:solid 1px;white-space:nowrap" >function declaration </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>ptr</span> </td><td style="text-align:left;border:solid 1px;white-space:nowrap" >any pointer type </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>ref</span> </td><td style="text-align:left;border:solid 1px;white-space:nowrap" >any pointer type </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>set</span> </td><td style="text-align:left;border:solid 1px;white-space:nowrap" >enum type </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>size_is</span><span class=syntax-token>(</span><span class=nonterminal>le</span><sub>1</sub><span class=syntax-token>,</span><span class=nonterminal>le</span><sub>2</sub><span class=syntax-token>,</span>…<span class=syntax-token>)</span> </td><td style="text-align:left;border:solid 1px;white-space:nowrap" >array type </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>string</span> </td><td style="text-align:left;border:solid 1px;white-space:nowrap" >character array or pointer </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>switch_is</span><span class=syntax-token>(</span><span class=nonterminal>le</span><span class=syntax-token>)</span> </td><td style="text-align:left;border:solid 1px;white-space:nowrap" >union type or pointer to union </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>switch_type</span><span class=syntax-token>(</span><span class=nonterminal>ty</span><span class=syntax-token>)</span> </td><td style="text-align:left;border:solid 1px;white-space:nowrap" >union or pointer to union </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>unique</span> </td><td style="text-align:left;border:solid 1px;white-space:nowrap" >any pointer, array, or bigarray type </td></tr>
<tr><td style="text-align:left;border:solid 1px;white-space:nowrap" ><span class=syntax-token>uuid</span><span class=syntax-token>(</span> <a href="#uuid" class="syntax"><span class=nonterminal>uuid</span></a> <span class=syntax-token>)</span> </td><td style="text-align:left;border:solid 1px;white-space:nowrap" >interface </td></tr>
</table></div></div>
<h3 id="sec13" class="subsection">2.4 Types and declarators</h3>
<p>The declaration of an identifier along with its type is as in C:
a type specification comes first, followed by the identifier possibly
decorated with <span class=machine><span class=font-tt>*</span></span> and <span class=machine><span class=font-tt>[...]</span></span> to denote pointers and array types.
For instance, <span class=machine><span class=font-tt>int x</span></span> declares an identifier <span class=machine><span class=font-tt>x</span></span> of type <span class=machine><span class=font-tt>int</span></span>,
while <span class=machine><span class=font-tt>int (*x)[]</span></span> declares an identifier <span class=machine><span class=font-tt>x</span></span> that is a pointer to an
array of integers.
</p><div class="syntax"><table class="display dcenter"><tr style="vertical-align:middle"><td class="dcell"><table style="border-spacing:6px;border-collapse:separate;" class="cellpading0"><tr><td style="text-align:right;white-space:nowrap" ><a id="type-spec" class="syntax"><span class=nonterminal>type-spec</span></a></td><td style="text-align:center;white-space:nowrap" >::=</td><td style="text-align:left;white-space:nowrap" >
[<span class=syntax-token>unsigned</span>∣<span class=syntax-token>signed</span>]
(<span class=syntax-token>int</span>∣<span class=syntax-token>short</span>∣<span class=syntax-token>long</span>∣<span class=syntax-token>char</span>∣<span class=syntax-token>hyper</span>∣<span class=syntax-token>long</span> <span class=syntax-token>long</span>∣<span class=syntax-token>__int64</span>)
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <span class=syntax-token>byte</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <span class=syntax-token>float</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <span class=syntax-token>double</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <span class=syntax-token>boolean</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <span class=syntax-token>void</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <a href="#ident" class="syntax"><span class=nonterminal>ident</span></a>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <span class=syntax-token>wchar_t</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <span class=syntax-token>handle_t</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <span class=syntax-token>struct</span> <a href="#ident" class="syntax"><span class=nonterminal>ident</span></a>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <span class=syntax-token>union</span> <a href="#ident" class="syntax"><span class=nonterminal>ident</span></a>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <span class=syntax-token>enum</span> <a href="#ident" class="syntax"><span class=nonterminal>ident</span></a>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <a href="#struct-decl" class="syntax"><span class=nonterminal>struct-decl</span></a>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <a href="#union-decl" class="syntax"><span class=nonterminal>union-decl</span></a>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <a href="#enum-decl" class="syntax"><span class=nonterminal>enum-decl</span></a>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td></tr>
<tr><td style="text-align:right;white-space:nowrap" >
<a id="declarator" class="syntax"><span class=nonterminal>declarator</span></a></td><td style="text-align:center;white-space:nowrap" >::=</td><td style="text-align:left;white-space:nowrap" >
{<span class=syntax-token>*</span>} <a href="#direct-declarator" class="syntax"><span class=nonterminal>direct-declarator</span></a>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td></tr>
<tr><td style="text-align:right;white-space:nowrap" >
<a id="direct-declarator" class="syntax"><span class=nonterminal>direct-declarator</span></a></td><td style="text-align:center;white-space:nowrap" >::=</td><td style="text-align:left;white-space:nowrap" >
<a href="#ident" class="syntax"><span class=nonterminal>ident</span></a>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <span class=syntax-token>(</span> <a href="#declarator" class="syntax"><span class=nonterminal>declarator</span></a> <span class=syntax-token>)</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <a href="#direct-declarator" class="syntax"><span class=nonterminal>direct-declarator</span></a> <span class=syntax-token>[</span> [<span class=nonterminal>const-lexpr</span>] <span class=syntax-token>]</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td></tr>
</table></td></tr>
</table></div>
<h3 id="sec14" class="subsection">2.5 Structures, unions and enumerations</h3>
<div class="syntax"><table class="display dcenter"><tr style="vertical-align:middle"><td class="dcell"><table style="border-spacing:6px;border-collapse:separate;" class="cellpading0"><tr><td style="text-align:right;white-space:nowrap" ><a id="struct-decl" class="syntax"><span class=nonterminal>struct-decl</span></a></td><td style="text-align:center;white-space:nowrap" >::=</td><td style="text-align:left;white-space:nowrap" >
<span class=syntax-token>struct</span> [<a href="#ident" class="syntax"><span class=nonterminal>ident</span></a>] <span class=syntax-token>{</span> {<a href="#field-decl" class="syntax"><span class=nonterminal>field-decl</span></a>} <span class=syntax-token>}</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td></tr>
<tr><td style="text-align:right;white-space:nowrap" >
<a id="field-decl" class="syntax"><span class=nonterminal>field-decl</span></a></td><td style="text-align:center;white-space:nowrap" >::=</td><td style="text-align:left;white-space:nowrap" >
<a href="#attributes" class="syntax"><span class=nonterminal>attributes</span></a> <a href="#type-spec" class="syntax"><span class=nonterminal>type-spec</span></a> <a href="#declarator" class="syntax"><span class=nonterminal>declarator</span></a> { <span class=syntax-token>,</span> <a href="#declarator" class="syntax"><span class=nonterminal>declarator</span></a> } <span class=syntax-token>;</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td></tr>
<tr><td style="text-align:right;white-space:nowrap" >
<a id="union-decl" class="syntax"><span class=nonterminal>union-decl</span></a></td><td style="text-align:center;white-space:nowrap" >::=</td><td style="text-align:left;white-space:nowrap" >
<span class=syntax-token>union</span> [<a href="#ident" class="syntax"><span class=nonterminal>ident</span></a>] <span class=syntax-token>{</span> {<a href="#union-case" class="syntax"><span class=nonterminal>union-case</span></a>} <span class=syntax-token>}</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <span class=syntax-token>union</span> [<a href="#ident" class="syntax"><span class=nonterminal>ident</span></a>] <span class=syntax-token>switch</span> <span class=syntax-token>(</span> <a href="#type-spec" class="syntax"><span class=nonterminal>type-spec</span></a> <a href="#ident" class="syntax"><span class=nonterminal>ident</span></a> <span class=syntax-token>)</span> <span class=syntax-token>{</span> {<a href="#union-case" class="syntax"><span class=nonterminal>union-case</span></a>} <span class=syntax-token>}</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td></tr>
<tr><td style="text-align:right;white-space:nowrap" >
<a id="union-case" class="syntax"><span class=nonterminal>union-case</span></a></td><td style="text-align:center;white-space:nowrap" >::=</td><td style="text-align:left;white-space:nowrap" >
{<span class=syntax-token>case</span> <a href="#ident" class="syntax"><span class=nonterminal>ident</span></a> <span class=syntax-token>:</span>}<sup>+</sup> [<a href="#field-decl" class="syntax"><span class=nonterminal>field-decl</span></a>] <span class=syntax-token>;</span>
<span class=syntax-token>default</span> <span class=syntax-token>:</span> [<a href="#field-decl" class="syntax"><span class=nonterminal>field-decl</span></a>] <span class=syntax-token>;</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td></tr>
<tr><td style="text-align:right;white-space:nowrap" >
<a id="enum-decl" class="syntax"><span class=nonterminal>enum-decl</span></a></td><td style="text-align:center;white-space:nowrap" >::=</td><td style="text-align:left;white-space:nowrap" >
<span class=syntax-token>enum</span> [<a href="#ident" class="syntax"><span class=nonterminal>ident</span></a>] <span class=syntax-token>{</span> <a href="#enum-case" class="syntax"><span class=nonterminal>enum-case</span></a> {<span class=syntax-token>,</span> <a href="#enum-case" class="syntax"><span class=nonterminal>enum-case</span></a>} [<span class=syntax-token>,</span>] <span class=syntax-token>}</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td></tr>
<tr><td style="text-align:right;white-space:nowrap" >
<a id="enum-case" class="syntax"><span class=nonterminal>enum-case</span></a></td><td style="text-align:center;white-space:nowrap" >::=</td><td style="text-align:left;white-space:nowrap" >
<a href="#ident" class="syntax"><span class=nonterminal>ident</span></a> [<span class=syntax-token>=</span> <span class=nonterminal>const-lexpr</span>]
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td></tr>
</table></td></tr>
</table></div><p>IDL <span class=machine><span class=font-tt>struct</span></span> declarations are like those of C, with the addition of
optional attributes on each field. <span class=machine><span class=font-tt>union</span></span> declarations are also as
in C, except that each case of an union must be labeled by one or
several <span class=syntax-token>case</span> <a href="#ident" class="syntax"><span class=nonterminal>ident</span></a> <span class=syntax-token>:</span>. The first form of union declaration
assumes that the discriminant of the union is provided separately
via a <span class=machine><span class=font-tt>switch</span></span><span class=machine><span class=font-tt>_</span></span><span class=machine><span class=font-tt>is</span></span> annotation on the union type, while the second form
encapsulates the discriminant along with the union itself
(like in Pascal’s <span class=machine><span class=font-tt>record case of</span></span> construct).</p>
<h3 id="sec15" class="subsection">2.6 Function declarations</h3>
<div class="syntax"><table class="display dcenter"><tr style="vertical-align:middle"><td class="dcell"><table style="border-spacing:6px;border-collapse:separate;" class="cellpading0"><tr><td style="text-align:right;white-space:nowrap" ><a id="function-decl" class="syntax"><span class=nonterminal>function-decl</span></a></td><td style="text-align:center;white-space:nowrap" >::=</td><td style="text-align:left;white-space:nowrap" >
<a href="#attributes" class="syntax"><span class=nonterminal>attributes</span></a> <a href="#type-spec" class="syntax"><span class=nonterminal>type-spec</span></a> {<span class=syntax-token>*</span>} <a href="#ident" class="syntax"><span class=nonterminal>ident</span></a> <span class=syntax-token>(</span> <a href="#params" class="syntax"><span class=nonterminal>params</span></a> <span class=syntax-token>)</span> {<span class=syntax-token>quote</span><span class=syntax-token>(</span><a href="#ident" class="syntax"><span class=nonterminal>ident</span></a><span class=syntax-token>,</span><a href="#string" class="syntax"><span class=nonterminal>string</span></a><span class=syntax-token>)</span>}
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td></tr>
<tr><td style="text-align:right;white-space:nowrap" >
<a id="params" class="syntax"><span class=nonterminal>params</span></a></td><td style="text-align:center;white-space:nowrap" >::=</td><td style="text-align:left;white-space:nowrap" >
є
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <span class=syntax-token>void</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <a href="#param" class="syntax"><span class=nonterminal>param</span></a> { <span class=syntax-token>,</span> <a href="#param" class="syntax"><span class=nonterminal>param</span></a> }
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td></tr>
<tr><td style="text-align:right;white-space:nowrap" >
<a id="param" class="syntax"><span class=nonterminal>param</span></a></td><td style="text-align:center;white-space:nowrap" >::=</td><td style="text-align:left;white-space:nowrap" >
<a href="#attributes" class="syntax"><span class=nonterminal>attributes</span></a> <a href="#type-spec" class="syntax"><span class=nonterminal>type-spec</span></a> <a href="#declarator" class="syntax"><span class=nonterminal>declarator</span></a>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td></tr>
</table></td></tr>
</table></div><p>
Function declarations are like in ANSI C, with the addition of
attributes on each parameter and on the function itself.
Parameters must be named. The optional <span class=nonterminal>quote</span> statements following the
declaration are user-provided calling sequences and deallocation
sequences that replaces the default sequences in the
<span class=machine><span class=font-tt>camlidl</span></span>-generated stub code for the function.</p>
<h3 id="sec16" class="subsection">2.7 Constant definitions</h3>
<div class="syntax"><table class="display dcenter"><tr style="vertical-align:middle"><td class="dcell"><table style="border-spacing:6px;border-collapse:separate;" class="cellpading0"><tr><td style="text-align:right;white-space:nowrap" ><a id="constant-decl" class="syntax"><span class=nonterminal>constant-decl</span></a></td><td style="text-align:center;white-space:nowrap" >::=</td><td style="text-align:left;white-space:nowrap" > <span class=syntax-token>const</span> <a href="#attributes" class="syntax"><span class=nonterminal>attributes</span></a> <a href="#type-spec" class="syntax"><span class=nonterminal>type-spec</span></a> {<span class=syntax-token>*</span>} <a href="#ident" class="syntax"><span class=nonterminal>ident</span></a> <span class=syntax-token>=</span> <span class=nonterminal>const-lexpr</span> <span class=syntax-token>;</span>
</td></tr>
</table></td></tr>
</table></div><p>
A constant declaration associates a name to a limited expression.
The limited expression can refer to constant names declared earlier,
but cannot refer to other kinds of identifiers. The optional
attributes influence the interpretation of the type specification,
e.g. <span class=machine><span class=font-tt>const int x = 3</span></span> defines <span class=machine><span class=font-tt>x</span></span> with Caml type <span class=machine><span class=font-tt>int</span></span>, but
<span class=machine><span class=font-tt>const [int64] long x = 5</span></span> defines <span class=machine><span class=font-tt>x</span></span> with Caml type <span class=machine><span class=font-tt>int64</span></span>.</p>
<h3 id="sec17" class="subsection">2.8 IDL files</h3>
<div class="syntax"><table class="display dcenter"><tr style="vertical-align:middle"><td class="dcell"><table style="border-spacing:6px;border-collapse:separate;" class="cellpading0"><tr><td style="text-align:right;white-space:nowrap" ><a id="file" class="syntax"><span class=nonterminal>file</span></a></td><td style="text-align:center;white-space:nowrap" >::=</td><td style="text-align:left;white-space:nowrap" > {<a href="#decl" class="syntax"><span class=nonterminal>decl</span></a>} </td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td></tr>
<tr><td style="text-align:right;white-space:nowrap" >
<a id="decl" class="syntax"><span class=nonterminal>decl</span></a></td><td style="text-align:center;white-space:nowrap" >::=</td><td style="text-align:left;white-space:nowrap" >
<a href="#function-decl" class="syntax"><span class=nonterminal>function-decl</span></a> <span class=syntax-token>;</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <a href="#constant-decl" class="syntax"><span class=nonterminal>constant-decl</span></a> <span class=syntax-token>;</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <a href="#struct-decl" class="syntax"><span class=nonterminal>struct-decl</span></a> <span class=syntax-token>;</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <a href="#union-decl" class="syntax"><span class=nonterminal>union-decl</span></a> <span class=syntax-token>;</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <a href="#enum-decl" class="syntax"><span class=nonterminal>enum-decl</span></a> <span class=syntax-token>;</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <span class=syntax-token>typedef</span> <a href="#attributes" class="syntax"><span class=nonterminal>attributes</span></a> <a href="#type-spec" class="syntax"><span class=nonterminal>type-spec</span></a> <a href="#declarator" class="syntax"><span class=nonterminal>declarator</span></a> { <span class=syntax-token>,</span> <a href="#declarator" class="syntax"><span class=nonterminal>declarator</span></a> } <span class=syntax-token>;</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <a href="#attributes" class="syntax"><span class=nonterminal>attributes</span></a> <span class=syntax-token>interface</span> <a href="#ident" class="syntax"><span class=nonterminal>ident</span></a> [ <span class=syntax-token>:</span> <a href="#ident" class="syntax"><span class=nonterminal>ident</span></a> ] <span class=syntax-token>{</span> {<a href="#decl" class="syntax"><span class=nonterminal>decl</span></a>} <span class=syntax-token>}</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <span class=syntax-token>struct</span> <a href="#ident" class="syntax"><span class=nonterminal>ident</span></a> <span class=syntax-token>;</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <span class=syntax-token>union</span> <a href="#ident" class="syntax"><span class=nonterminal>ident</span></a> <span class=syntax-token>;</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <span class=syntax-token>union</span> <span class=syntax-token>switch</span> <span class=syntax-token>(</span> <a href="#type-spec" class="syntax"><span class=nonterminal>type-spec</span></a> <a href="#ident" class="syntax"><span class=nonterminal>ident</span></a> <span class=syntax-token>)</span> <span class=syntax-token>;</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <a href="#attributes" class="syntax"><span class=nonterminal>attributes</span></a> <span class=syntax-token>interface</span> <a href="#ident" class="syntax"><span class=nonterminal>ident</span></a> <span class=syntax-token>;</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <span class=syntax-token>import</span> <a href="#string" class="syntax"><span class=nonterminal>string</span></a> <span class=syntax-token>;</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <span class=syntax-token>quote</span> <span class=syntax-token>(</span> [<a href="#ident" class="syntax"><span class=nonterminal>ident</span></a> <span class=syntax-token>,</span>] <a href="#string" class="syntax"><span class=nonterminal>string</span></a> <span class=syntax-token>)</span>
</td></tr>
<tr><td style="text-align:right;white-space:nowrap" > </td><td style="text-align:center;white-space:nowrap" >∣</td><td style="text-align:left;white-space:nowrap" > <span class=syntax-token>cpp_quote</span> <span class=syntax-token>(</span> <a href="#string" class="syntax"><span class=nonterminal>string</span></a> <span class=syntax-token>)</span>
</td></tr>
</table></td></tr>
</table></div><p>
An IDL file is a sequence of IDL declarations. Declarations include
function declarations, constant declarations, type declarations
(structs, unions, enums, as well as a C-style <span class=machine><span class=font-tt>typedef</span></span> declaration to
name a type expression), and interfaces.</p><p>An interface declaration gives a name and attributes to a collection
of declarations. For interfaces with the <span class=machine><span class=font-tt>object</span></span> attribute,
an optional super-interface can be provided, as in
<span class=syntax-token>interface</span> <span class=nonterminal>intf</span> <span class=syntax-token>:</span> <span class=nonterminal>super-intf</span>. The name of the interface can be
used as a type name in the remainder of the file.</p><p>Forward declarations of structs, unions and interfaces are supported
in the usual C manner, by just giving the name of the struct, union or
interface, but not its actual contents.</p><p>The <span class=machine><span class=font-tt>import</span></span> statement reads another IDL file and makes available its
type and constant declarations in the remainder of the file.
No code is generated for the functions and interfaces declared in the
imported file. The same file can be imported several times, but is
read in only the first time.</p><p>The <span class=syntax-token>quote</span> <span class=syntax-token>(</span> <a href="#ident" class="syntax"><span class=nonterminal>ident</span></a> <span class=syntax-token>,</span> <span class=nonterminal>str</span> <span class=syntax-token>)</span> diversion copies the string <span class=nonterminal>str</span>
verbatim to one of the files generated by the <span class=machine><span class=font-tt>camlidl</span></span> compiler.
The <a href="#ident" class="syntax"><span class=nonterminal>ident</span></a> determines the file where <span class=nonterminal>str</span> is copied:
it can be <span class=machine><span class=font-tt>ml</span></span> for the Caml implementation file (<span class=machine><span class=font-tt>.ml</span></span>),
<span class=machine><span class=font-tt>mli</span></span> for the Caml interface file (<span class=machine><span class=font-tt>.mli</span></span>),
<span class=machine><span class=font-tt>mlmli</span></span> for both Caml files,
<span class=machine><span class=font-tt>h</span></span> for the C header file (<span class=machine><span class=font-tt>.h</span></span>),
and <span class=machine><span class=font-tt>c</span></span> for the C source file containing the generated stub code (<span class=machine><span class=font-tt>.c</span></span>
file). For backward compatibility, <span class=syntax-token>cpp_quote</span> <span class=syntax-token>(</span> <span class=nonterminal>str</span> <span class=syntax-token>)</span> is
recognized as synonymous for <span class=syntax-token>quote</span> <span class=syntax-token>(</span> <span class=syntax-token>h</span> <span class=syntax-token>,</span> <span class=nonterminal>str</span> <span class=syntax-token>)</span>.</p>
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