[cfe-dev] LibFormat usage question

[Sean Silva]

On Thu, Oct 31, 2013 at 12:59 PM, David Blaikie <dblaikie at gmail.com> wrote:

>
>
>
> On Thu, Oct 31, 2013 at 6:32 AM, Jesper Eskilson <Jesper.Eskilson at iar.com>wrote:
>
>>
>> Hi,
>>
>> I'm trying to figure out how to programmatically invoke clang-format to
>> format code. I would like to get from a declaration ("Decl *") to a plain
>> string containing the reformatted source code.
>>
>
> It's generally advised that one should not attempt to round trip source
> code through the AST. Use the AST to inform mutations of the original
> source (by using source locations to identify pieces to move, insert, or
> remove), rather than to produce new source from the parsed AST.
>

We really need to put this in an FAQ. It seems like it gets reiterated at
least once a week.

-- Sean Silva


>
>
>>
>> Here's my feeble initial attempt:
>>
>>
>> /*
>>  * Non-functioning attempt att trying to extract the source code of
>>  * 'decl' formatted using LLVM style.
>>  */
>> std::string get_formatted_source(SourceManager &mgr, const Decl *decl)
>> {
>>   StringRef code = get_source(mgr, decl); // implemented elsewhere
>>   std::vector<Range> ranges;
>>   LangOptions lo;
>>   Rewriter rw(mgr, lo);
>>
>>   Range range(0, src.size());
>>   ranges.push_back(range);
>>
>>   // Do the reformat
>>   auto repl = reformat(getLLVMStyle(), code, ranges);
>>
>>   // Apply the replacements
>>   for (auto it = repl.begin(); it != repl.end(); ++it) {
>>     it->apply(rw);
>>   }
>>
>>   // Extract the reformatted source code.
>>   auto formatted_source = rw.getRewrittenText(decl->getSourceRange());
>>
>>   // I would have expected 'formatted_source' to be the formatted source
>>   // here, but it is always the same as the original, as if the
>>   // replacements where never applied.
>> }
>>
>>
>> --
>> *Jesper Eskilson* *Development Engineer*
>> IAR Systems AB
>> Box 23051, Strandbodgatan 1
>> SE-750 23 Uppsala, SWEDEN
>> E-mail: jesper.eskilson at iar.com Website: www.iar.com
>>  Twitter: www.twitter.com/iarsystems
>>
>> _______________________________________________
>> cfe-dev mailing list
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>>
>>
>
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