将ANTLR 3语法转换为ANTLR 4时如何删除“ k”选项

Question

The token lookahead option is gone in ANTLR 4, so ... This is the ANTLR 3 code:

declarations: // Order is important here.
    ( options { k = 3; }: DECLARE_SYMBOL identifier (variable_declaration | condition_declaration))*
        cursor_declaration* handler_declaration*
;

Answer 1

Remove the k option. It was used to tell the parser generator the necessary lookahead. The new ALL(*) algorithm in ANTLR4 doesn't require this setting anymore as it can dynamically use any required lookahead (in theory even unlimited).