Embedding mRuby: retrieving mrb_parser_message after parse error - parsing

Question

I'm trying to embed mRuby in a Max MSP object. One of the first things I want to setup is error logging in the Max IDE console window. To that effect, after I parse the code ( stored in a C string ) with mrb_parse_string, I expect errors to be available in the parser's error_buffer array, but the structures in this array are always empty ( lineno and column set to 0 and message set to NULL ) even when there is an error.
Is there a special way to set up the parser before parsing the code so it fills its error_buffer array properly in case an error occurs ? I've looked into the mirb source, but it doesn't look like it. I'm lost. Here is the code I'm using, taken from a small C program I'm using as test:
mrb_state *mrb;
char *code;
struct mrb_parser_state *parser;
parser = mrb_parse_string(mrb, code, mrbc_context_new(mrb));
if (parser->nerr > 0) {
for(i = 0; i < parser->nerr; i++) {
printf("line %d:%d: %s\n", parser->error_buffer[i].lineno,
parser->error_buffer[i].column,
parser->error_buffer[i].message);
}
return -1;
}
When passed the following faulty ruby code:
[1,1,1]]
the previous code outputs :
line 1:8: syntax error, unexpected ']', expecting $end
line 0:0: (null)
I don't know where the first line comes from, since I compiled mRuby with MRB_DISABLE_STDIO defined and as line 14 and following in mrbconf.md suggests, but it is accurate.
The second line is the actual output from my code and shows that the returned mrb_parser_state structure's error_buffer is empty, which is surprising since the parser did see an error.

Answer 1

Sorry totally misunderstood your question.
So you want to:
capture script's syntax errors instead of printing.
make MRB_DISABLE_STDIO work.
For 1st issue
struct mrb_parser_state *parser;
parser = mrb_parse_string(mrb, code, mrbc_context_new(mrb));
should be replaced with:
struct mrbc_context *cxt;
struct mrb_parser_state *parser;
cxt = mrbc_context_new(mrb);
cxt->capture_errors = TRUE;
parser = mrb_parse_string(mrb, code, cxt);
like what mirb does.
For 2nd issue I don't know your build_config.rb so I can't say much about it.
Some notes to make things accurate:
MRB_DISABLE_STDIO is a compile flag for building mruby so you need to pass it in build_config.rb like:
cc.defines << %w(MRB_DISABLE_STDIO)
(see build_config_ArduinoDue.rb)
line 1:8: syntax error, unexpected ']', expecting $end
is the parsing error of mruby parser([1,1,1]] must be [1,1,1]).
And 1:8 means 8th column of 1st line (which points to unnecessary ]) so it seems like your C code is working correctly to me.
(For a reference your code's compilation error in CRuby:
https://wandbox.org/permlink/KRIlW2956TnS6puD )
prog.rb:1: syntax error, unexpected ']', expecting end-of-input
[1,1,1]]
^