[cfe-dev] Statements that end with ;

[Yang Chen]

On 11/16/2012 6:09 PM, Mohammad Adil wrote:
> Hi,
>     I need to rewrite at the end of line. In order for the edited code
> to compile, I must ensure that I write after a ";" character. I just
> need to find that character. I have a ParentMap that has all the
> statements. How can I figure out which type of statements have a ";" at
> the end and which don't? (I just need to differentiate these two types)

I am not sure your purpose of using ParentMap, but for discriminating 
between two kinds of statements you mentioned, one approach would be to 
write an AST Visitor derived from RecursiveASTVisitor:

http://clang.llvm.org/doxygen/classclang_1_1RecursiveASTVisitor.html

And then you implement a couple of VisitXXXStmt methods -

bool YourVisitor::VisitCompoundStmt(CompoundStmt *CS)
{
   // here you iterate the body of CS;

   // for each semi-colon-ended statement with respect to C's syntax 
rules, you can get the end location of it using getLocEnd method;

   // from the end location, you can find the location of ';' (for the 
debugging purpose, you might also want to dump and check the string 
starting from the end location using 
SourceManager::getCharacterData(Loc) method);

   // Last, get a Rewriter instance and do rewriting
}

bool YourVisitor::VisitIfStmt(IfStmt *IS)
{
   // here you check the "Then" Stmt and "Else" Stmt of IS;

   // you only need to handle the case where ThenStmt and ElseStmt are 
semi-colon-ended statements; (Note that you don't want to iterate these 
two statements if they are CompoundStmt[s], which will be visited from 
VisitCompoundStmt)
}

bool YourVisitor::VisitWhileStmt(WhileStmt *WS)
{
   // similar to VisitIfStmt, but you only need to handle the "body" 
Stmt of WS;
}

...


Note that there could be other ways, e.g., using ASTMatcher, which I 
never tried, but it should be easy to use.

In any case, you will still need to follow C's syntax rules while 
analyzing C code, assuming you are dealing with C programs.

- Yang

>
> Regards,
> Adil
>
>
> On Sat, Nov 17, 2012 at 2:09 AM, Mohammad Adil <madil90 at gmail.com
> <mailto:madil90 at gmail.com>> wrote:
>
>     Hi,
>         I think I didn't state my question correctly. I meant that is
>     there some way to visit statements that end with ";" and are
>     executed in one execution cycle. I just want to identify whether a
>     statement started after a ";" and ended with a ";". e.g.
>
>     int a;
>
>     a = a + 2;
>
>         I only want to visit these two lines. How can I tell these two
>     statements apart from things like DeclRefExpr which need to have a
>     parent statement that includes them (DeclRefExpr is not a statement
>     type that can be executed)
>
>     Regards,
>     Adil
>
>
>     On Sat, Nov 17, 2012 at 1:59 AM, Yang Chen <chenyang at cs.utah.edu
>     <mailto:chenyang at cs.utah.edu>> wrote:
>
>         madil90 wrote:
>
>             Hi,
>                I need to identify statements that end with ";". I mean,
>             how does clang
>             represent a statement that is executed independently e.g.
>
>
>         You can check all statement classes here:
>
>         http://clang.llvm.org/doxygen/__classclang_1_1Stmt.html
>         <http://clang.llvm.org/doxygen/classclang_1_1Stmt.html>
>
>             int a;    // what type of statement is this?
>
>
>         I assume you define ``a'' as a local variable, then ``int a;''
>         is a DeclStmt.
>
>             a = a + 2;   // or this?
>
>
>         It's a BinaryOperator -
>
>         http://clang.llvm.org/doxygen/__classclang_1_1BinaryOperator.__html
>         <http://clang.llvm.org/doxygen/classclang_1_1BinaryOperator.html>
>
>         - Yang
>
>             Regards,
>             Adil
>
>
>
>             --
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>
>
>
>
>     --
>     Mohammad Adil
>     LUMS SSE
>
>
>
>
> --
> Mohammad Adil
> LUMS SSE
>