[cfe-dev] Understanding Clang parsing

[kalyan ponnala]

Hi again,

Could you tell me what's a Qualtype in detail. How does it save space for
representing different types ?

Thanks

On Wed, Mar 3, 2010 at 10:19 PM, Charles Davis <cdavis at mymail.mines.edu>wrote:

> On 3/3/10 7:57 PM, kalyan ponnala wrote:
> > Thanks for the support Charles.
> > Could you tell me a better way to understand how parser works. Or is
> > "steping into" the code is the only solid way to understand it.
> Clang's Parser class works like this:
> 1. Someone calls ParseTopLevelDecl() to parse a top-level declaration
> from the source.
> 2. ParseTopLevelDecl() calls other methods inside the Parser class to
> parse fragments of the source according to the grammar as defined in the
> C and C++ standards. Most functions get called indirectly; for example,
> when the Parser encounters a function declaration, the
> ParseFunctionDeclaration() method gets called.
> 3. These parsing methods notify some object through the "Action"
> interface every time something gets parsed. The default Action object
> does nothing. The Semantic Analyzer (another really important part of
> the compiler), or just "Sema" for short, provides an implementation
> which not only builds the AST but also annotates it with types and
> checks the semantics of the program specified by the source code.
> 4. Steps 1-3 are repeated for every top-level declaration in the
> translation unit (a source file plus all its included headers).
> 5. When it does hit the end of the unit, ParseTopLevelDecl() calls
> Action::ActOnEndOfTranslationUnit(). This lets the object on the other
> side know that the translation unit has ended, and it's time to do
> whatever. The Sema implementation invokes an ASTConsumer object with
> this information.
> > I would like to know some important files inside the solution file which
> > are responsible for building the AST.
> The Sema library is your best bet. Study it; that's where I started with
> Clang. Trust me: it's one of the easiest parts of the compiler to
> understand. Like most of Clang, it was designed to be relatively easy to
> understand, even for someone with little or no prior experience with
> compiler technology. In particular, look at lib/Sema/SemaDecl.cpp and
> lib/Sema/SemaExpr.cpp .
>
> Also, take a look at include/clang/Parse/Action.h . This is the file
> that defines the Action interface.
> > Thanks.
> No problem.
>
> Chip
>
>


-- 
Kalyan Ponnala
phone: 8163772059
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