simplify parser

[boostorg]

simplify parser

[viccpp]

Don't think it is a simplification. User will need to keep an addition state - the last write result.

[viccpp]

Off topic:
Why write()? parse() would be more logical for me. Parser is for reading. write() is appropriate for serializer (output)

[vinniefalco]

User will need to keep an addition state - the last write result

Users have to observe that anyway, since they need to check the error code. 99% of users don't care about processing additional data which lies past the JSON, so this is certainly a simplification. We still get the same features but with fewer functions. Having the proliferation of functions was confusing.

To be clear consider this input string: "[ 1, 2, 3 ] #abc"

There is a JSON followed by something that isn't a JSON. The parser can handle this, it will simply return 12 indicating that 12 characters were consumed, and the error will be set to error::extra_data. Almost all users will want to consider this an error, since the input string is not valid JSON. The users which want to process the remaining string (the "#abc") as something other than JSON, can easily do so by checking for the error and then handling the remaining part of the buffer themselves.

[viccpp]

What about truncated input? Like:

"{ a: ...." // ok
" ... [ 1, 2" // ok
---EOF--- // ??? what we supposed to do here?

[vinniefalco]

I don't understand the question here.

"{ a: ..." is not valid JSON, the key needs to be a string (i.e. in double quotes).

If you can write out exactly what is in each buffer, that would be helpful. For example consider this json:

json::value jv = { 1, 2, 3 };

This produces an array which serializes to the string "[1,2,3]".

We can parse this in two buffers thusly:

json::parser p;
p.write( "[1," );
assert( ! p.is_complete() );
p.write( "2,3]" );
assert( p.is_complete() );

A number however, needs a call to finish:

json::parser p;
p.write( "1" );
assert( ! p.is_complete) );
p.write( "0" );
assert( ! p.is_complete) );
p.finish();
assert( p.is_complete() );
assert( number_cast<int>(p.release()) == 10 );

If the end of the buffer is indicated (from a call to finish) and the resulting JSON is incomplete, then an error is returned:

error_code ec;
json::parser p;
p.write( "[" );
p.finish( ec );
assert( ec ); // incomplete JSON

[viccpp]

... means some omitted part of valid JSON. OK, full example:

{ "a" : 1,

"b" : "abc"

--EOF--

How to correctly process this without finish() that you want to kill?

[vinniefalco]

How to correctly process this without finish() that you want to kill?

I only removed one overload of finish, the one which takes the buffer as a parameter. We still have finish with no parameters, which is necessary in your example above.

[viccpp]

Ah... Ok, undestand now.

we dont need finish()

sounded too radical for me :-)

[vinniefalco]

sounded too radical for me :-)

Heh, I should have been more clear. Note, that there were previously eight member functions (2 each of write_some, write, finish, and finish, one for errors and one for exceptions).

[vinniefalco]

This is done