Complex conflicts handling if we need to peek more than 1 token.

[DiscreteTom]

E.g. when we parsing javascript:

f(({a, b}) => a + b);

with the following grammar rules:

exp := '(' '{' identifier (',' identifier)* '}' ')' '=>' exp
exp := '(' exp ')'
exp := object
object := '{' (object_entry (',' object_entry)*)? '}'
object_entry := identifier (':' exp)?

when we digest f(({ a we don't know whether the a is an object entry or an arrow function param. We have to peek maybe many tokens to judge that.

Solution for this issue:

• Re-parse, see #19 . Not recommended.
• Optimize grammar rules to prevent this to happen. Introducing more intermediate NT. Bad user experience.
• Allow grammar rule to do more than reduce AST nodes. E.g. override parser buffer.

[DiscreteTom]

Maybe we can write an algorithm to check if a conflict can be safely resolved by re-parse.

For the above conflict, it can be safely resolved by re-parse without early accept.

[DiscreteTom]

Another idea: subset construction (子集构造法) to turn the NFA into DFA?