Add a new LexicalBlock for entering a new block scope

Prepare some data when enter each lexical block

Enter a new function AST, and add a new LexicalFunction data structure

Prepare function data when enter each lexical function

Prepare data for loop AST

Generate one register id from current function

Get current function data

Get current loop AST

Get next register id, do not change register generator

Get upvalue info by index

Current function has a vararg or not

Insert a name into current block, replace its info when existed

Insert name into current local scope, replace its info when existed

Is register count overflow

Delete current LexicalBlock when leaving a block scope

Clean up when leave lexical block

Leave a function AST, and delete current LexicalFunction data structure

Clean up when leave lexical function

Complete loop AST in current block