Re: [cdt-dev] Need help scratching an itch (Bug #379684)

[Richard <naddiseo+cdt-dev@xxxxxxxxx>]

Hi Thomas,

Although I'm a little disappointed that wont be able to see this through myself, I'm glad it's actively being worked on. Thanks. 

The solution I managed to come up with looked at the column offsets between the quotes and the identifier, making sure there is at least 1 space. Looking at N2765 (http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2765.pdf) right at the end there is an example of operator definitions which states that there must be a space, otherwise an error because, as you said, it would be seed as one token instead of two.

Looking through you patch at where the operator is defined (GNUCPPSourceParser.java line 717), correct me if I'm wrong, but does consume check the length of tString, or is that done elsewhere?

One other thing, I believe UDLs that do not start with an underscore should be allowed, but issue a warning. My understanding of the CDT lexer makes this difficult to find the suffix for integers and floats, my approach was to parse these two in CPPASTLiteralExpression.java, then knowing where the valid int/float were, anything remaining would be a suffix.

In case you're interested, my partial solution is https://github.com/Naddiseo/cdt/compare/2c63700887ee5...9e6ed0c22a

Thanks again, Richard.

On 4 June 2012 01:59, Corbat Thomas (tcorbat@xxxxxx) <tcorbat@xxxxxx> wrote:

Hi Richard

 

I've already started implementing user defined literals syntactically. Code is in gerrit (https://git.eclipse.org/r/6000).

Regarding your question. As far as I know the standard does not explicitly require a space between "" and the following identifier. But it is not possible according to the lexical conventions to have a matching token sequence for a literal operator. If we consider an example:

                float operator ""E(const char*);

This is invalid as ""E would yield only one token, a user defined string literal, instead of "" and E as separate tokens. As you run into this problem, you might not yet have the corresponding adaption in the lexer.

 

Regards

Thomas

 

 

From: cdt-dev-bounces@xxxxxxxxxxx [mailto:cdt-dev-bounces@xxxxxxxxxxx] On Behalf Of Richard
Sent: Sonntag, 3. Juni 2012 08:04
To: cdt-dev@xxxxxxxxxxx
Subject: [cdt-dev] Need help scratching an itch (Bug #379684)

 

Hello CDT mailing list, 

I'm taking a stab at fixing bug #379684 User-defined literals, mostly just for the fun of it, but I'm probably going to need a lot of help as this is my first time in the eclipse/cdt internals.

Anyway, I have managed to get the parser to recognise the T operator "" L() syntax, with one caveat: I can't figure out how to require the whitespace between the "" and the literal name.

 

Thanks, Richard.

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