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<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:13.5pt;color:black">From: Michael van Acken <</span><a href="mailto:michael.van.acken@gmail.com" target="_blank" title="mailto:michael.van.acken@gmail.com"><span style="color:#0078D4">michael.van.acken@gmail.com</span></a><span style="font-size:13.5pt;color:black">><o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><o:p> </o:p></p>
<p class="MsoNormal" style="margin-left:36.0pt">I have a single use of CodeBuilder.labelToBci(): decide whether the labels marking</p>
<p class="MsoNormal" style="margin-left:36.0pt">the start and end of a try block refer to the same position, as a proxy for "enclosed<br>
region is empty". If this is the case, then no exceptionCatch can be installed and
<br>
all exception handlers become unreachable.<br>
<br>
How can this scenario still be supported?<br>
<br>
-- mva</p>
<p class="MsoNormal" style="margin-left:36.0pt"><o:p> </o:p></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">It is not guaranteed to get the right bytecode indexes from CodeBuilder::labelToBci, the method is really an exposure of internal implementation.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">Frequent common cases (like for example dropping exception handler when try block is empty) can be solved with CodeBuilder::trying support.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">CodeBuilder::trying uses CodeBuilder::block and before further actions asks CodeBuilder.BlockCodeBuilder::isEmpty.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">Now it throws an exception in case of an empty try block, however I can imagine it might skip all handlers instead:<o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">/**</span><span style="font-size:10.0pt;font-family:"Courier New";color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Courier New";color:#969696"> *
<b>Adds</b></span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><b><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">a "try-catch" block</span></b><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><b><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">comprising</span></b><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><b><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">one</span></b><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><b><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">try</span></b><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><b><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">block</span></b><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><b><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">and</span></b><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><b><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">zero</span></b><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><b><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">or</span></b><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><b><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">more</span></b><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><b><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">catch</span></b><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><b><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">blocks.</span></b><span style="font-size:10.0pt;font-family:"Courier New";color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Courier New";color:#969696"> * Exceptions</span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">thrown</span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">by</span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">instructions</span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">in</span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">the</span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">try</span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">block</span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">may</span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">be</span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">caught</span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">by</span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">catch</span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">blocks.</span><span style="font-size:10.0pt;font-family:"Courier New";color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Courier New";color:#969696"> *</span><span style="font-size:10.0pt;font-family:"Courier New";color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Courier New";color:#969696"> *
<b>@param</b></span><span style="font-size:10.0pt;font-family:"Courier New";color:black"> tryHandler
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">handler</span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">that</span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">receives</span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">a {<b>@linkplain</b></span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">CodeBuilder} to</span><span style="font-size:10.0pt;font-family:"Courier New";color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Courier New";color:#969696"> * generate</span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">the</span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">body</span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">of</span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">the</span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">try</span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">block.</span><span style="font-size:10.0pt;font-family:"Courier New";color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Courier New";color:#969696"> *
<b>@param</b></span><span style="font-size:10.0pt;font-family:"Courier New";color:black"> catchesHandler
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">a</span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">handler</span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">that</span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">receives</span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">a {<b>@linkplain</b></span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">CatchBuilder}</span><span style="font-size:10.0pt;font-family:"Courier New";color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Courier New";color:#969696"> * to</span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">generate</span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">bodies</span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">of</span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">catch</span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">blocks.</span><span style="font-size:10.0pt;font-family:"Courier New";color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Courier New";color:#969696"> *
<b>@return</b></span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">this</span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">builder</span><span style="font-size:10.0pt;font-family:"Courier New";color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Courier New";color:#969696"> *
<b>@see</b></span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">CatchBuilder</span><span style="font-size:10.0pt;font-family:"Courier New";color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">*/</span><span style="font-size:10.0pt;font-family:"Courier New";color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#336BDD">default</span><span style="font-size:10.0pt;font-family:"Courier New";color:black"> CodeBuilder
<b>trying</b>(Consumer<<i>BlockCodeBuilder</i>> tryHandler,<o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Courier New";color:black"> Consumer<<i>CatchBuilder</i>> catchesHandler) {<o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Courier New";color:black"> Label tryCatchEnd = newLabel();<o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Courier New";color:black"><o:p> </o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">// @@@ the tryHandler does not have access to tryCatchEnd</span><span style="font-size:10.0pt;font-family:"Courier New";color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Courier New";color:black"> BlockCodeBuilderImpl tryBlock =
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#336BDD">new</span><span style="font-size:10.0pt;font-family:"Courier New";color:black"> BlockCodeBuilderImpl(</span><span style="font-size:10.0pt;font-family:"Courier New";color:#336BDD">this</span><span style="font-size:10.0pt;font-family:"Courier New";color:black">,
tryCatchEnd);<o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Courier New";color:black"> tryBlock.start();<o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Courier New";color:black"> tryHandler.accept(tryBlock);<o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Courier New";color:black"> tryBlock.end();<o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Courier New";color:black"><o:p> </o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><b><i><span style="font-size:10.0pt;font-family:"Courier New";color:#969696">// Check for empty try block</span></i></b><b><i><span style="font-size:10.0pt;font-family:"Courier New";color:black"><o:p></o:p></span></i></b></p>
<p class="MsoNormal" style="background:white"><b><i><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span></i></b><b><i><span style="font-size:10.0pt;font-family:"Courier New";color:#336BDD">if</span></i></b><b><i><span style="font-size:10.0pt;font-family:"Courier New";color:black"> (</span></i></b><b><i><span lang="EN-US" style="font-size:10.0pt;font-family:"Courier New";color:black">!</span></i></b><b><i><span style="font-size:10.0pt;font-family:"Courier New";color:black">tryBlock.isEmpty())
{<o:p></o:p></span></i></b></p>
<p class="MsoNormal" style="background:white"><b><i><span lang="EN-US" style="font-size:10.0pt;font-family:"Courier New";color:black">
</span></i></b><b><i><span style="font-size:10.0pt;font-family:"Courier New";color:black"> </span></i></b><b><i><span style="font-size:10.0pt;font-family:"Courier New";color:#336BDD">var</span></i></b><b><i><span style="font-size:10.0pt;font-family:"Courier New";color:black">
catchBuilder = </span></i></b><b><i><span style="font-size:10.0pt;font-family:"Courier New";color:#336BDD">new</span></i></b><b><i><span style="font-size:10.0pt;font-family:"Courier New";color:black"> CatchBuilderImpl(</span></i></b><b><i><span style="font-size:10.0pt;font-family:"Courier New";color:#336BDD">this</span></i></b><b><i><span style="font-size:10.0pt;font-family:"Courier New";color:black">,
tryBlock, tryCatchEnd);<o:p></o:p></span></i></b></p>
<p class="MsoNormal" style="background:white"><b><i><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span></i></b><b><i><span lang="EN-US" style="font-size:10.0pt;font-family:"Courier New";color:black"> </span></i></b><b><i><span style="font-size:10.0pt;font-family:"Courier New";color:black"> catchesHandler.accept(catchBuilder);<o:p></o:p></span></i></b></p>
<p class="MsoNormal" style="background:white"><b><i><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span></i></b><b><i><span lang="EN-US" style="font-size:10.0pt;font-family:"Courier New";color:black"> </span></i></b><b><i><span style="font-size:10.0pt;font-family:"Courier New";color:black">catchBuilder.finish();<o:p></o:p></span></i></b></p>
<p class="MsoNormal" style="background:white"><b><i><span style="font-size:10.0pt;font-family:"Courier New";color:black"> }<o:p></o:p></span></i></b></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Courier New";color:black"><o:p> </o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#336BDD">return</span><span style="font-size:10.0pt;font-family:"Courier New";color:black">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#336BDD">this</span><span style="font-size:10.0pt;font-family:"Courier New";color:black">;<o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Courier New";color:black"> }<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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