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<div class="moz-cite-prefix">Dear Richard<br>
<br>
On 23/06/2015 21:55, Richard Smith wrote:<br>
</div>
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cite="mid:CAOfiQq=CgqVWRCpE-C2_p5cac9MMFNUgGy--0OQ5BazCHYKaOg@mail.gmail.com"
type="cite">
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<div class="gmail_extra">
<div class="gmail_quote">On Tue, Jun 23, 2015 at 1:05 PM,
Alastair Donaldson <span dir="ltr"><<a moz-do-not-send="true" href="mailto:alastair.donaldson@imperial.ac.uk" target="_blank">alastair.donaldson@imperial.ac.uk</a>></span>
wrote:<br>
<blockquote class="gmail_quote">Dear all<br>
<br>
I am trying to use the Rewriter class to do something
conceptually pretty straightforward to a source file.
What I actually want to do is pretty specific, but if I
could work out how to do the following it would be obvious
how to solve my problem:<br>
<br>
- for every Stmt node in the AST, replace the source code
associated with the Stmt with:<br>
<br>
open(x) original_source_code_for_Stmt close(x)<br>
<br>
where x is a number chosen uniquely for the Stmt node.<br>
<br>
For instance, if the Stmt is the expression:<br>
<br>
x + y<br>
<br>
then I would like to end up with something like:<br>
<br>
open(2) open(0) x close(0) + open(1) y close(1) close(2)<br>
<br>
I hope my objective makes sense.<br>
<br>
What I've tried to do is write a class that extends
RecursiveASTVisitor, equipped with a Rewriter field,
"TheRewriter", and an int field, "counter". The Rewriter
should allow me to rewrite the source code. The counter
is used to give each open and close a unique x. I'm
assuming for now that all my code is in one source file.<br>
<br>
I've tried two things:<br>
<br>
bool TraverseStmt(Stmt *s) {<br>
bool result = RecursiveASTVisitor::TraverseStmt(s);<br>
std::stringstream ss_start;<br>
ss_start << "open(" << counter <<
")";<br>
TheRewriter.InsertTextAfter(s->getLocStart(),
ss_start.str());<br>
std::stringstream ss_end;<br>
ss_end << "close(" << counter <<
")";<br>
TheRewriter.InsertTextAfterToken(s->getLocEnd(),
ss_end.str());<br>
</blockquote>
<div><br>
</div>
<div>InsertTextAfter and InsertTextAfterToken return a bool
indicating whether the insertion was possible (false on
success, true on failure). You could use that to isolate
which particular call is failing.</div>
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</blockquote>
<br>
Thanks for this suggestion. However, the calls do not fail: all the
"open" and "close" strings are emitted. They are just not
balanced. For example, I see this:<br>
<br>
open(8)(open(0)open(1)open(7)d close(1)close(0)+
open(6)(open(2)open(3)open(5)d close(3)close(2)/
open(4)2)close(5)close(4))close(7)close(6);close(8)<br>
<br>
for the expression:<br>
<br>
(d + (d / 2))<br>
<br>
So you can see that all the opens have matching closes. It's just
that they are not balanced.<br>
<br>
Does this bring anything else to mind?<br>
<br>
Many thanks<br>
<br>
Ally<br>
<br>
<br>
<blockquote
cite="mid:CAOfiQq=CgqVWRCpE-C2_p5cac9MMFNUgGy--0OQ5BazCHYKaOg@mail.gmail.com"
type="cite">
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<div class="gmail_extra">
<div class="gmail_quote">
<div><br>
</div>
<div>That said, the only cases where the above calls would
currently fail are if they're given a location for which
TheRewriter.isRewritable returns false. That only happens
if the location provided is within a macro expansion.
Could that be the case in your failing examples?</div>
<div> </div>
<blockquote class="gmail_quote">
counter++;<br>
return result;<br>
}<br>
<br>
(This is what seemed natural to me from the clang APIs)<br>
<br>
and also:<br>
<br>
bool TraverseStmt(Stmt *s) {<br>
bool result = RecursiveASTVisitor::TraverseStmt(s);<br>
std::stringstream ss_start;<br>
ss_start << "open(" << counter <<
")";<br>
TheRewriter.InsertTextAfter(s->getLocStart(),
ss_start.str());<br>
int offset =
Lexer::MeasureTokenLength(s->getLocEnd(),
TheRewriter.getSourceMgr(), TheRewriter.getLangOpts()) +
1;<br>
auto END1 =
s->getLocEnd().getLocWithOffset(offset);<br>
std::stringstream ss_end;<br>
ss_end << "close(" << counter <<
")";<br>
TheRewriter.InsertTextBefore(END1, ss_end.str());<br>
counter++;<br>
return result;<br>
}<br>
<br>
(I came up with this after reading this source code from
Robert Ankeney: <a moz-do-not-send="true" href="https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_loarabia_Clang-2Dtutorial_blob_master_CIrewriter.cpp&d=AwMDaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=CnzuN65ENJ1H9py9XLiRvC_UQz6u3oG6GUNn7_wosSM&m=MYwOQLoKTizpMPyLJ4hErPoyYmkMC1mhX3h1YkER7Ys&s=ifEMtwOU1rxr90UnI0tWWtqHLQB6_eQ7rQrlhvsscyc&e=" rel="noreferrer" target="_blank">https://github.com/loarabia/Clang-tutorial/blob/master/CIrewriter.cpp</a>)<br>
<br>
However, neither work - my parentheses end up being
unbalanced.<br>
<br>
I think the problem may be that in an expression such as:<br>
<br>
x + y<br>
<br>
the sub-expressions "y" and "x + y" have the same end
source location. But I cannot figure out how to get
around this.<br>
<br>
I'd be really grateful if anyone can give me a pointer
here.<br>
<br>
Best wishes<br>
<br>
Ally Donaldson<br>
<br>
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</blockquote>
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<br>
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</blockquote>
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