Re: [Boost-users] [Spirit] Qi lexeme only taking the first word

On Tue, Nov 6, 2018 at 11:46 PM Michael Powell wrote:

On Tue, Nov 6, 2018 at 10:28 PM Gavin Lambert via Boost-users wrote:

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On 7/11/2018 15:08, Michael Powell wrote:

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When it matches

id >> *(char_('.') >> id)

this has an attribute of vector>> or something similar.

Where are you getting that from? It makes no sense whatsoever given the struct full_it_t { std::string val; }, which is similarly mapped, and ruled, etc.

This might be wrong, but it's how I read the docs:

The output of parsing is a Fusion sequence of the attributes that were parsed.

So the output of

id >> *(char_('.') >> id)

is something like (but not exactly)

tuple<string> tuple tuple etc

string because that's the output attribute declared for id. char because you've used char_ instead of using '.' by itself (otherwise it would just disappear). And the latter two can be repeated zero or more times because you've used *.

When you assign this to a rule with %=, it tries to best-fit this against the rule's declared output attribute.

full_id_t contains a single string field, so the Fusion adaptation makes it equivalent to tuple<string>, and apparently this results in any additional values being discarded, not in concatenating as you expect.

You can probably use an explicit semantic action to build a single string instead of using %=.

Or you can make full_id_t contain vector<string> as rmawatson and I previously suggested, which should give you all the values.

Another possibility, which I can't test because coliru appears to be grumpy at present, is to try using:

full_id %= as_string[lexeme[id >> *(char_('.') >> id)]];

This approach works for me. And remains true to the AST. +1 Thanks!

Boy, wow... I'll qualify that with this: in "this" case I was able to persuade Spirit/Fusion to produce what I wanted. In other cases, not so much. It really, I mean **REALLY**, wants to produce that std::vector<...>, doesn't it? It will take a bit of digesting to adjust the AST, etc, to that, but it's good (no, GREAT) to know about.

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