<HTML><BODY style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; "><BR><DIV><DIV>On Aug 17, 2007, at 9:58 AM, Ted Kremenek wrote:</DIV><BR class="Apple-interchange-newline"><BLOCKQUOTE type="cite"><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Recently I added a comment to the class definition for <SPAN class="Apple-converted-space"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">ArraySubscriptExpr (in Sema/Expr.h) noting that the true "base" of the <SPAN class="Apple-converted-space"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">array may actually be returned by "getIdx()" if the array happened to <SPAN class="Apple-converted-space"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">be written in the source (for example) as "4[A]" instead of "A[4]."<SPAN class="Apple-converted-space"> </SPAN>I <SPAN class="Apple-converted-space"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">think this is confusing, and may cause glitches down the line for <SPAN class="Apple-converted-space"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">semantic analysis tools built on the frontend.</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><BR></DIV></BLOCKQUOTE><DIV><BR class="khtml-block-placeholder"></DIV>I agree. I had similar thoughts, and was going to discuss this with you.</DIV><DIV><BR><BLOCKQUOTE type="cite"><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">I propose renaming the current getBase and getIdx methods to "getLHS" <SPAN class="Apple-converted-space"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">and "getRHS" respectively, as the current interpretation of these <SPAN class="Apple-converted-space"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">functions has more do with source code syntax (their position in the <SPAN class="Apple-converted-space"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">source code) rather than semantics.<SPAN class="Apple-converted-space"> </SPAN>I then propose adding new getBase <SPAN class="Apple-converted-space"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">and getIdx functions that look something like this:</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><BR></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Expr *getBase() { return (Base->getType()->isPointerType()) ? Base : <SPAN class="Apple-converted-space"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Idx; }</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Expr *getIdx() { return (!Idx->getType()->IsPointerType()) ? Idx : <SPAN class="Apple-converted-space"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Base; }</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><BR></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Naturally, along with these changes I suggest changing the member <SPAN class="Apple-converted-space"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">variables "Base" and "Idx" to "LHS" and "RHS" respectively.</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><BR></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Comments?<SPAN class="Apple-converted-space"> </SPAN>One disadvantage that I see of this change is that using <SPAN class="Apple-converted-space"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">getBase() and getIdx() in tandem may require some extra unnecessary <SPAN class="Apple-converted-space"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">checking (as the same check is performed in both functions).<SPAN class="Apple-converted-space"> </SPAN>For such <SPAN class="Apple-converted-space"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">cases, we could consider adding an extra method that returns both the <SPAN class="Apple-converted-space"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Base and the Idx expressions in a std::pair (would there be an <SPAN class="Apple-converted-space"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">efficiency issue here?).</DIV></BLOCKQUOTE><DIV><BR class="khtml-block-placeholder"></DIV>I have no problem with the extra checking. I do have another suggestion:</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>Why not simply change the following...</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;"> </SPAN></FONT><FONT class="Apple-style-span" color="#760F50" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">return</SPAN></FONT><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;"> </SPAN></FONT><FONT class="Apple-style-span" color="#760F50" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">new</SPAN></FONT><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;"> ArraySubscriptExpr(LHSExp, RHSExp, ResultType, RLoc);</SPAN></FONT></DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>to...</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;"> </SPAN></FONT><FONT class="Apple-style-span" color="#760F50" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">return</SPAN></FONT><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;"> </SPAN></FONT><FONT class="Apple-style-span" color="#760F50" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">new</SPAN></FONT><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;"> ArraySubscriptExpr(BaseExpr, IndexExpr, ResultType, RLoc);</SPAN></FONT></DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>? And keep everything else the same...</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>The only disadvantage with this is the crazy case of idx[base] will always be output as base[idx] (if we are doing a pretty printer or source analysis tool). From my perspective, this loss is extremely minor (and can be fixed one day if necessary). In other words, I think it makes sense for the AST to normalize this case.</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>Let me know what you think,</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>snaroff</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV><BR><BLOCKQUOTE type="cite"><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">_______________________________________________</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">cfe-dev mailing list</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><A href="mailto:cfe-dev@cs.uiuc.edu">cfe-dev@cs.uiuc.edu</A></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><A href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev">http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev</A></DIV> </BLOCKQUOTE></DIV><BR></BODY></HTML>