Support informal delimiter literals

[ammar]

Interprets the {, }, and ] delimiters as literals depending on the context.

Notes

• Reduce ambiguity in the quantifier_interval pattern by replacing the optional matchers with 4 fixed patterns.
• Remove the premature_end_error final state handler from quantifier_interval to permit valid literal sequences.

Closes #63

[jaynetics]

looks great!

i've checked some more edge cases and found no issues. maybe we should add one example to spec/parser/quantifiers_spec.rb to document that leading zeros are correctly ignored as in MRI:

include_examples 'quantifier', /a{004}+b/, '{004}+', :possessive, :interval, 4, 4

[jaynetics]

slightly more concise:

Suggested change

	quantifier_exact = range_open . (digit+) . range_close . quantifier_mode?;
	quantifier_minimum = range_open . (digit+) . ',' . range_close . quantifier_mode?;
	quantifier_maximum = range_open . ',' . (digit+) . range_close . quantifier_mode?;
	quantifier_range = range_open . (digit+) . ',' . (digit+) .
	range_close . quantifier_mode?;
	quantifier_interval = quantifier_exact | quantifier_minimum |
	quantifier_maximum | quantifier_range;
	quantity_exact = (digit+);
	quantity_minimum = (digit+) . ',';
	quantity_maximum = ',' . (digit+);
	quantity_range = (digit+) . ',' . (digit+);
	quantifier_interval = range_open . ( quantity_exact | quantity_minimum |
	quantity_maximum | quantity_range ) . range_close .
	quantitfier_mode?;

but this is more a matter of taste, ragel probably optimises away the redundancy (?)

[ammar]

I like it a lot. The intention is clearer. There's a typo in the name of the mode pattern so I will make the change manually.

[ammar]

Thank you for the review. Very helpful.

i've checked some more edge cases and found no issues. maybe we should add one example to spec/parser/quantifiers_spec.rb to document that leading zeros are correctly ignored as in MRI:

include_examples 'quantifier', /a{004}+b/, '{004}+', :possessive, :interval, 4, 4

Good call. I will add it.

I will wrap this up and push out a new release (1.8) this afternoon.

[ammar]

On second thought, I'll consider this a bug fix, and release as 1.7.1.